/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use crate::{
    binding_model::{self, CreateBindGroupError, CreatePipelineLayoutError},
    command, conv,
    device::life::WaitIdleError,
    hub::{
        GfxBackend, Global, GlobalIdentityHandlerFactory, Hub, Input, InvalidId, Storage, Token,
    },
    id, pipeline, resource, span, swap_chain,
    track::{BufferState, TextureSelector, TextureState, TrackerSet},
    validation::{self, check_buffer_usage, check_texture_usage},
    FastHashMap, Label, LifeGuard, MultiRefCount, PrivateFeatures, Stored, SubmissionIndex,
    MAX_BIND_GROUPS,
};

use arrayvec::ArrayVec;
use copyless::VecHelper as _;
use gfx_descriptor::DescriptorAllocator;
use gfx_memory::{Block, Heaps};
use hal::{
    command::CommandBuffer as _,
    device::Device as _,
    window::{PresentationSurface as _, Surface as _},
};
use parking_lot::{Mutex, MutexGuard};
use thiserror::Error;
use wgt::{BufferAddress, BufferSize, InputStepMode, TextureDimension, TextureFormat};

use std::{
    borrow::Cow, collections::hash_map::Entry, iter, marker::PhantomData, mem, ops::Range, ptr,
    sync::atomic::Ordering,
};

mod life;
mod queue;
#[cfg(any(feature = "trace", feature = "replay"))]
pub mod trace;

use smallvec::SmallVec;
#[cfg(feature = "trace")]
use trace::{Action, Trace};

pub const MAX_COLOR_TARGETS: usize = 4;
pub const MAX_MIP_LEVELS: u32 = 16;
pub const MAX_VERTEX_BUFFERS: usize = 16;
pub const MAX_ANISOTROPY: u8 = 16;
pub const SHADER_STAGE_COUNT: usize = 3;

pub fn all_buffer_stages() -> hal::pso::PipelineStage {
    use hal::pso::PipelineStage as Ps;
    Ps::DRAW_INDIRECT
        | Ps::VERTEX_INPUT
        | Ps::VERTEX_SHADER
        | Ps::FRAGMENT_SHADER
        | Ps::COMPUTE_SHADER
        | Ps::TRANSFER
        | Ps::HOST
}
pub fn all_image_stages() -> hal::pso::PipelineStage {
    use hal::pso::PipelineStage as Ps;
    Ps::EARLY_FRAGMENT_TESTS
        | Ps::LATE_FRAGMENT_TESTS
        | Ps::COLOR_ATTACHMENT_OUTPUT
        | Ps::VERTEX_SHADER
        | Ps::FRAGMENT_SHADER
        | Ps::COMPUTE_SHADER
        | Ps::TRANSFER
}

#[derive(Clone, Copy, Debug, PartialEq)]
#[cfg_attr(feature = "trace", derive(serde::Serialize))]
#[cfg_attr(feature = "replay", derive(serde::Deserialize))]
pub enum HostMap {
    Read,
    Write,
}

#[derive(Clone, Debug, Hash, PartialEq)]
#[cfg_attr(feature = "serial-pass", derive(serde::Deserialize, serde::Serialize))]
pub(crate) struct AttachmentData<T> {
    pub colors: ArrayVec<[T; MAX_COLOR_TARGETS]>,
    pub resolves: ArrayVec<[T; MAX_COLOR_TARGETS]>,
    pub depth_stencil: Option<T>,
}
impl<T: PartialEq> Eq for AttachmentData<T> {}
impl<T> AttachmentData<T> {
    pub(crate) fn all(&self) -> impl Iterator<Item = &T> {
        self.colors
            .iter()
            .chain(&self.resolves)
            .chain(&self.depth_stencil)
    }
}

pub(crate) type AttachmentDataVec<T> = ArrayVec<[T; MAX_COLOR_TARGETS + MAX_COLOR_TARGETS + 1]>;

pub(crate) type RenderPassKey = AttachmentData<(hal::pass::Attachment, hal::image::Layout)>;
pub(crate) type FramebufferKey = AttachmentData<id::Valid<id::TextureViewId>>;

#[derive(Clone, Debug, Hash, PartialEq)]
#[cfg_attr(feature = "serial-pass", derive(serde::Deserialize, serde::Serialize))]
pub(crate) struct RenderPassContext {
    pub attachments: AttachmentData<TextureFormat>,
    pub sample_count: u8,
}

impl RenderPassContext {
    // Assumed the renderpass only contains one subpass
    pub(crate) fn compatible(&self, other: &RenderPassContext) -> bool {
        self.attachments.colors == other.attachments.colors
            && self.attachments.depth_stencil == other.attachments.depth_stencil
            && self.sample_count == other.sample_count
    }
}

type BufferMapPendingCallback = (resource::BufferMapOperation, resource::BufferMapAsyncStatus);

fn map_buffer<B: hal::Backend>(
    raw: &B::Device,
    buffer: &mut resource::Buffer<B>,
    sub_range: hal::buffer::SubRange,
    kind: HostMap,
) -> Result<ptr::NonNull<u8>, resource::BufferAccessError> {
    let (ptr, segment, needs_sync) = {
        let segment = hal::memory::Segment {
            offset: sub_range.offset,
            size: sub_range.size,
        };
        let mapped = buffer.memory.map(raw, segment)?;
        let mr = mapped.range();
        let segment = hal::memory::Segment {
            offset: mr.start,
            size: Some(mr.end - mr.start),
        };
        (mapped.ptr(), segment, !mapped.is_coherent())
    };

    buffer.sync_mapped_writes = match kind {
        HostMap::Read if needs_sync => unsafe {
            raw.invalidate_mapped_memory_ranges(iter::once((buffer.memory.memory(), segment)))
                .or(Err(DeviceError::OutOfMemory))?;
            None
        },
        HostMap::Write if needs_sync => Some(segment),
        _ => None,
    };
    Ok(ptr)
}

fn unmap_buffer<B: hal::Backend>(
    raw: &B::Device,
    buffer: &mut resource::Buffer<B>,
) -> Result<(), resource::BufferAccessError> {
    if let Some(segment) = buffer.sync_mapped_writes.take() {
        unsafe {
            raw.flush_mapped_memory_ranges(iter::once((buffer.memory.memory(), segment)))
                .or(Err(DeviceError::OutOfMemory))?;
        }
    }
    Ok(())
}

//Note: this logic is specifically moved out of `handle_mapping()` in order to
// have nothing locked by the time we execute users callback code.
fn fire_map_callbacks<I: IntoIterator<Item = BufferMapPendingCallback>>(callbacks: I) {
    for (operation, status) in callbacks {
        unsafe { (operation.callback)(status, operation.user_data) }
    }
}

#[derive(Debug)]
pub struct Device<B: hal::Backend> {
    pub(crate) raw: B::Device,
    pub(crate) adapter_id: Stored<id::AdapterId>,
    pub(crate) queue_group: hal::queue::QueueGroup<B>,
    pub(crate) cmd_allocator: command::CommandAllocator<B>,
    mem_allocator: Mutex<Heaps<B>>,
    desc_allocator: Mutex<DescriptorAllocator<B>>,
    //Note: The submission index here corresponds to the last submission that is done.
    pub(crate) life_guard: LifeGuard,
    pub(crate) active_submission_index: SubmissionIndex,
    pub(crate) trackers: Mutex<TrackerSet>,
    pub(crate) render_passes: Mutex<FastHashMap<RenderPassKey, B::RenderPass>>,
    pub(crate) framebuffers: Mutex<FastHashMap<FramebufferKey, B::Framebuffer>>,
    // Life tracker should be locked right after the device and before anything else.
    life_tracker: Mutex<life::LifetimeTracker<B>>,
    temp_suspected: life::SuspectedResources,
    pub(crate) hal_limits: hal::Limits,
    pub(crate) private_features: PrivateFeatures,
    pub(crate) limits: wgt::Limits,
    pub(crate) features: wgt::Features,
    //TODO: move this behind another mutex. This would allow several methods to switch
    // to borrow Device immutably, such as `write_buffer`, `write_texture`, and `buffer_unmap`.
    pending_writes: queue::PendingWrites<B>,
    #[cfg(feature = "trace")]
    pub(crate) trace: Option<Mutex<Trace>>,
}

#[derive(Clone, Debug, Error)]
pub enum CreateDeviceError {
    #[error("not enough memory left")]
    OutOfMemory,
}

impl<B: GfxBackend> Device<B> {
    pub(crate) fn new(
        raw: B::Device,
        adapter_id: Stored<id::AdapterId>,
        queue_group: hal::queue::QueueGroup<B>,
        mem_props: hal::adapter::MemoryProperties,
        hal_limits: hal::Limits,
        private_features: PrivateFeatures,
        desc: &wgt::DeviceDescriptor,
        trace_path: Option<&std::path::Path>,
    ) -> Result<Self, CreateDeviceError> {
        let cmd_allocator = command::CommandAllocator::new(queue_group.family, &raw)
            .or(Err(CreateDeviceError::OutOfMemory))?;
        let heaps = unsafe {
            Heaps::new(
                &mem_props,
                gfx_memory::GeneralConfig {
                    block_size_granularity: 0x100,
                    max_chunk_size: 0x100_0000,
                    min_device_allocation: 0x1_0000,
                },
                gfx_memory::LinearConfig {
                    line_size: 0x100_0000,
                },
                hal_limits.non_coherent_atom_size as u64,
            )
        };
        let descriptors = unsafe { DescriptorAllocator::new() };
        #[cfg(not(feature = "trace"))]
        match trace_path {
            Some(_) => tracing::error!("Feature 'trace' is not enabled"),
            None => (),
        }

        Ok(Device {
            raw,
            adapter_id,
            cmd_allocator,
            mem_allocator: Mutex::new(heaps),
            desc_allocator: Mutex::new(descriptors),
            queue_group,
            life_guard: LifeGuard::new(),
            active_submission_index: 0,
            trackers: Mutex::new(TrackerSet::new(B::VARIANT)),
            render_passes: Mutex::new(FastHashMap::default()),
            framebuffers: Mutex::new(FastHashMap::default()),
            life_tracker: Mutex::new(life::LifetimeTracker::new()),
            temp_suspected: life::SuspectedResources::default(),
            #[cfg(feature = "trace")]
            trace: trace_path.and_then(|path| match Trace::new(path) {
                Ok(mut trace) => {
                    trace.add(Action::Init {
                        desc: desc.clone(),
                        backend: B::VARIANT,
                    });
                    Some(Mutex::new(trace))
                }
                Err(e) => {
                    tracing::error!("Unable to start a trace in '{:?}': {:?}", path, e);
                    None
                }
            }),
            hal_limits,
            private_features,
            limits: desc.limits.clone(),
            features: desc.features.clone(),
            pending_writes: queue::PendingWrites::new(),
        })
    }

    pub(crate) fn last_completed_submission_index(&self) -> SubmissionIndex {
        self.life_guard.submission_index.load(Ordering::Acquire)
    }

    fn lock_life_internal<'this, 'token: 'this>(
        tracker: &'this Mutex<life::LifetimeTracker<B>>,
        _token: &mut Token<'token, Self>,
    ) -> MutexGuard<'this, life::LifetimeTracker<B>> {
        tracker.lock()
    }

    pub(crate) fn lock_life<'this, 'token: 'this>(
        &'this self,
        token: &mut Token<'token, Self>,
    ) -> MutexGuard<'this, life::LifetimeTracker<B>> {
        Self::lock_life_internal(&self.life_tracker, token)
    }

    fn maintain<'this, 'token: 'this, G: GlobalIdentityHandlerFactory>(
        &'this self,
        hub: &Hub<B, G>,
        force_wait: bool,
        token: &mut Token<'token, Self>,
    ) -> Result<Vec<BufferMapPendingCallback>, WaitIdleError> {
        let mut life_tracker = self.lock_life(token);

        life_tracker.triage_suspected(
            hub,
            &self.trackers,
            #[cfg(feature = "trace")]
            self.trace.as_ref(),
            token,
        );
        life_tracker.triage_mapped(hub, token);
        life_tracker.triage_framebuffers(hub, &mut *self.framebuffers.lock(), token);
        let last_done = life_tracker.triage_submissions(&self.raw, force_wait)?;
        let callbacks = life_tracker.handle_mapping(hub, &self.raw, &self.trackers, token);
        life_tracker.cleanup(&self.raw, &self.mem_allocator, &self.desc_allocator);

        self.life_guard
            .submission_index
            .store(last_done, Ordering::Release);
        self.cmd_allocator.maintain(&self.raw, last_done);
        Ok(callbacks)
    }

    fn untrack<'this, 'token: 'this, G: GlobalIdentityHandlerFactory>(
        &'this mut self,
        hub: &Hub<B, G>,
        trackers: &TrackerSet,
        mut token: &mut Token<'token, Self>,
    ) {
        self.temp_suspected.clear();
        // As the tracker is cleared/dropped, we need to consider all the resources
        // that it references for destruction in the next GC pass.
        {
            let (bind_group_guard, mut token) = hub.bind_groups.read(&mut token);
            let (compute_pipe_guard, mut token) = hub.compute_pipelines.read(&mut token);
            let (render_pipe_guard, mut token) = hub.render_pipelines.read(&mut token);
            let (buffer_guard, mut token) = hub.buffers.read(&mut token);
            let (texture_guard, mut token) = hub.textures.read(&mut token);
            let (texture_view_guard, mut token) = hub.texture_views.read(&mut token);
            let (sampler_guard, _) = hub.samplers.read(&mut token);

            for id in trackers.buffers.used() {
                if buffer_guard[id].life_guard.ref_count.is_none() {
                    self.temp_suspected.buffers.push(id);
                }
            }
            for id in trackers.textures.used() {
                if texture_guard[id].life_guard.ref_count.is_none() {
                    self.temp_suspected.textures.push(id);
                }
            }
            for id in trackers.views.used() {
                if texture_view_guard[id].life_guard.ref_count.is_none() {
                    self.temp_suspected.texture_views.push(id);
                }
            }
            for id in trackers.bind_groups.used() {
                if bind_group_guard[id].life_guard.ref_count.is_none() {
                    self.temp_suspected.bind_groups.push(id);
                }
            }
            for id in trackers.samplers.used() {
                if sampler_guard[id].life_guard.ref_count.is_none() {
                    self.temp_suspected.samplers.push(id);
                }
            }
            for id in trackers.compute_pipes.used() {
                if compute_pipe_guard[id].life_guard.ref_count.is_none() {
                    self.temp_suspected.compute_pipelines.push(id);
                }
            }
            for id in trackers.render_pipes.used() {
                if render_pipe_guard[id].life_guard.ref_count.is_none() {
                    self.temp_suspected.render_pipelines.push(id);
                }
            }
        }

        self.lock_life(&mut token)
            .suspected_resources
            .extend(&self.temp_suspected);
    }

    fn create_buffer(
        &self,
        self_id: id::DeviceId,
        desc: &resource::BufferDescriptor,
        memory_kind: gfx_memory::Kind,
    ) -> Result<resource::Buffer<B>, resource::CreateBufferError> {
        debug_assert_eq!(self_id.backend(), B::VARIANT);
        let (mut usage, _memory_properties) = conv::map_buffer_usage(desc.usage);
        if desc.mapped_at_creation && !desc.usage.contains(wgt::BufferUsage::MAP_WRITE) {
            // we are going to be copying into it, internally
            usage |= hal::buffer::Usage::TRANSFER_DST;
        }

        let mem_usage = {
            use gfx_memory::MemoryUsage;
            use wgt::BufferUsage as Bu;

            //TODO: use linear allocation when we can ensure the freeing is linear
            if !desc.usage.intersects(Bu::MAP_READ | Bu::MAP_WRITE) {
                MemoryUsage::Private
            } else if (Bu::MAP_WRITE | Bu::COPY_SRC).contains(desc.usage) {
                MemoryUsage::Staging { read_back: false }
            } else if (Bu::MAP_READ | Bu::COPY_DST).contains(desc.usage) {
                MemoryUsage::Staging { read_back: true }
            } else {
                let is_native_only = self
                    .features
                    .contains(wgt::Features::MAPPABLE_PRIMARY_BUFFERS);
                if !is_native_only {
                    return Err(resource::CreateBufferError::UsageMismatch(desc.usage));
                }
                MemoryUsage::Dynamic {
                    sparse_updates: false,
                }
            }
        };

        let mut buffer = unsafe { self.raw.create_buffer(desc.size.max(1), usage) }.map_err(
            |err| match err {
                hal::buffer::CreationError::OutOfMemory(_) => DeviceError::OutOfMemory,
                _ => panic!("failed to create buffer: {}", err),
            },
        )?;
        if let Some(ref label) = desc.label {
            unsafe { self.raw.set_buffer_name(&mut buffer, label) };
        }

        let requirements = unsafe { self.raw.get_buffer_requirements(&buffer) };
        let memory = self
            .mem_allocator
            .lock()
            .allocate(&self.raw, &requirements, mem_usage, memory_kind)
            .map_err(DeviceError::from_heaps)?;
        unsafe {
            self.raw
                .bind_buffer_memory(memory.memory(), memory.segment().offset, &mut buffer)
        }
        .map_err(DeviceError::from_bind)?;

        Ok(resource::Buffer {
            raw: buffer,
            device_id: Stored {
                value: id::Valid(self_id),
                ref_count: self.life_guard.add_ref(),
            },
            usage: desc.usage,
            memory,
            size: desc.size,
            full_range: (),
            sync_mapped_writes: None,
            map_state: resource::BufferMapState::Idle,
            life_guard: LifeGuard::new(),
        })
    }

    fn create_texture(
        &self,
        self_id: id::DeviceId,
        desc: &resource::TextureDescriptor,
    ) -> Result<resource::Texture<B>, resource::CreateTextureError> {
        debug_assert_eq!(self_id.backend(), B::VARIANT);

        // Ensure `D24Plus` textures cannot be copied
        match desc.format {
            TextureFormat::Depth24Plus | TextureFormat::Depth24PlusStencil8 => {
                if desc
                    .usage
                    .intersects(wgt::TextureUsage::COPY_SRC | wgt::TextureUsage::COPY_DST)
                {
                    return Err(resource::CreateTextureError::CannotCopyD24Plus);
                }
            }
            _ => {}
        }

        let kind = conv::map_texture_dimension_size(desc.dimension, desc.size, desc.sample_count)?;
        let format = conv::map_texture_format(desc.format, self.private_features);
        let aspects = format.surface_desc().aspects;
        let usage = conv::map_texture_usage(desc.usage, aspects);

        let mip_level_count = desc.mip_level_count;
        if mip_level_count >= MAX_MIP_LEVELS {
            return Err(resource::CreateTextureError::InvalidMipLevelCount(
                mip_level_count,
            ));
        }
        let mut view_capabilities = hal::image::ViewCapabilities::empty();

        // 2D textures with array layer counts that are multiples of 6 could be cubemaps
        // Following gpuweb/gpuweb#68 always add the hint in that case
        if desc.dimension == TextureDimension::D2 && desc.size.depth % 6 == 0 {
            view_capabilities |= hal::image::ViewCapabilities::KIND_CUBE;
        };

        // TODO: 2D arrays, cubemap arrays

        let mut image = unsafe {
            let mut image = self
                .raw
                .create_image(
                    kind,
                    desc.mip_level_count as hal::image::Level,
                    format,
                    hal::image::Tiling::Optimal,
                    usage,
                    view_capabilities,
                )
                .map_err(|err| match err {
                    hal::image::CreationError::OutOfMemory(_) => DeviceError::OutOfMemory,
                    _ => panic!("failed to create texture: {}", err),
                })?;
            if let Some(ref label) = desc.label {
                self.raw.set_image_name(&mut image, label);
            }
            image
        };

        let requirements = unsafe { self.raw.get_image_requirements(&image) };
        let memory = self
            .mem_allocator
            .lock()
            .allocate(
                &self.raw,
                &requirements,
                gfx_memory::MemoryUsage::Private,
                gfx_memory::Kind::General,
            )
            .map_err(DeviceError::from_heaps)?;
        unsafe {
            self.raw
                .bind_image_memory(memory.memory(), memory.segment().offset, &mut image)
        }
        .map_err(DeviceError::from_bind)?;

        Ok(resource::Texture {
            raw: image,
            device_id: Stored {
                value: id::Valid(self_id),
                ref_count: self.life_guard.add_ref(),
            },
            usage: desc.usage,
            aspects,
            dimension: desc.dimension,
            kind,
            format: desc.format,
            full_range: TextureSelector {
                levels: 0..desc.mip_level_count as hal::image::Level,
                layers: 0..kind.num_layers(),
            },
            memory,
            life_guard: LifeGuard::new(),
        })
    }

    /// Create a compatible render pass with a given key.
    ///
    /// This functions doesn't consider the following aspects for compatibility:
    ///  - image layouts
    ///  - resolve attachments
    fn create_compatible_render_pass(
        &self,
        key: &RenderPassKey,
    ) -> Result<B::RenderPass, hal::device::OutOfMemory> {
        let mut color_ids = [(0, hal::image::Layout::ColorAttachmentOptimal); MAX_COLOR_TARGETS];
        for i in 0..key.colors.len() {
            color_ids[i].0 = i;
        }
        let depth_id = key.depth_stencil.as_ref().map(|_| {
            (
                key.colors.len(),
                hal::image::Layout::DepthStencilAttachmentOptimal,
            )
        });

        let subpass = hal::pass::SubpassDesc {
            colors: &color_ids[..key.colors.len()],
            depth_stencil: depth_id.as_ref(),
            inputs: &[],
            resolves: &[],
            preserves: &[],
        };
        let all = key
            .all()
            .map(|(at, _)| at)
            .collect::<AttachmentDataVec<_>>();

        unsafe { self.raw.create_render_pass(all, iter::once(subpass), &[]) }
    }

    fn deduplicate_bind_group_layout(
        self_id: id::DeviceId,
        entry_map: &binding_model::BindEntryMap,
        guard: &Storage<binding_model::BindGroupLayout<B>, id::BindGroupLayoutId>,
    ) -> Option<id::BindGroupLayoutId> {
        guard
            .iter(self_id.backend())
            .find(|(_, bgl)| bgl.device_id.value.0 == self_id && bgl.entries == *entry_map)
            .map(|(id, value)| {
                value.multi_ref_count.inc();
                id
            })
    }

    fn get_introspection_bind_group_layouts<'a>(
        pipeline_layout: &binding_model::PipelineLayout<B>,
        bgl_guard: &'a Storage<binding_model::BindGroupLayout<B>, id::BindGroupLayoutId>,
    ) -> validation::IntrospectionBindGroupLayouts<'a> {
        validation::IntrospectionBindGroupLayouts::Given(
            pipeline_layout
                .bind_group_layout_ids
                .iter()
                .map(|&id| &bgl_guard[id].entries)
                .collect(),
        )
    }

    fn create_bind_group_layout(
        &self,
        self_id: id::DeviceId,
        label: Option<&str>,
        entry_map: binding_model::BindEntryMap,
    ) -> Result<binding_model::BindGroupLayout<B>, binding_model::CreateBindGroupLayoutError> {
        // Validate the count parameter
        for binding in entry_map.values() {
            if binding.count.is_some() {
                match binding.ty {
                    wgt::BindingType::SampledTexture { .. } => {
                        if !self
                            .features
                            .contains(wgt::Features::SAMPLED_TEXTURE_BINDING_ARRAY)
                        {
                            return Err(binding_model::CreateBindGroupLayoutError::MissingFeature(
                                wgt::Features::SAMPLED_TEXTURE_BINDING_ARRAY,
                            ));
                        }
                    }
                    _ => return Err(binding_model::CreateBindGroupLayoutError::ArrayUnsupported),
                }
            }
        }

        let raw_bindings = entry_map
            .values()
            .map(|entry| hal::pso::DescriptorSetLayoutBinding {
                binding: entry.binding,
                ty: conv::map_binding_type(entry),
                count: entry
                    .count
                    .map_or(1, |v| v.get() as hal::pso::DescriptorArrayIndex), //TODO: consolidate
                stage_flags: conv::map_shader_stage_flags(entry.visibility),
                immutable_samplers: false, // TODO
            })
            .collect::<Vec<_>>(); //TODO: avoid heap allocation

        let raw = unsafe {
            let mut raw_layout = self
                .raw
                .create_descriptor_set_layout(&raw_bindings, &[])
                .or(Err(DeviceError::OutOfMemory))?;
            if let Some(label) = label {
                self.raw
                    .set_descriptor_set_layout_name(&mut raw_layout, label);
            }
            raw_layout
        };

        let mut count_validator = binding_model::BindingTypeMaxCountValidator::default();
        for entry in entry_map.values() {
            count_validator.add_binding(entry);
        }
        // If a single bind group layout violates limits, the pipeline layout is definitely
        // going to violate limits too, lets catch it now.
        count_validator
            .validate(&self.limits)
            .map_err(binding_model::CreateBindGroupLayoutError::TooManyBindings)?;

        Ok(binding_model::BindGroupLayout {
            raw,
            device_id: Stored {
                value: id::Valid(self_id),
                ref_count: self.life_guard.add_ref(),
            },
            multi_ref_count: MultiRefCount::new(),
            desc_counts: raw_bindings.iter().cloned().collect(),
            dynamic_count: entry_map
                .values()
                .filter(|b| b.ty.has_dynamic_offset())
                .count(),
            count_validator,
            entries: entry_map,
        })
    }

    fn create_pipeline_layout(
        &self,
        self_id: id::DeviceId,
        desc: &binding_model::PipelineLayoutDescriptor,
        bgl_guard: &Storage<binding_model::BindGroupLayout<B>, id::BindGroupLayoutId>,
    ) -> Result<binding_model::PipelineLayout<B>, CreatePipelineLayoutError> {
        let bind_group_layouts_count = desc.bind_group_layouts.len();
        let device_max_bind_groups = self.limits.max_bind_groups as usize;
        if bind_group_layouts_count > device_max_bind_groups {
            return Err(CreatePipelineLayoutError::TooManyGroups {
                actual: bind_group_layouts_count,
                max: device_max_bind_groups,
            });
        }

        if !desc.push_constant_ranges.is_empty()
            && !self.features.contains(wgt::Features::PUSH_CONSTANTS)
        {
            return Err(CreatePipelineLayoutError::MissingFeature(
                wgt::Features::PUSH_CONSTANTS,
            ));
        }
        let mut used_stages = wgt::ShaderStage::empty();
        for (index, pc) in desc.push_constant_ranges.iter().enumerate() {
            if pc.stages.intersects(used_stages) {
                return Err(
                    CreatePipelineLayoutError::MoreThanOnePushConstantRangePerStage {
                        index,
                        provided: pc.stages,
                        intersected: pc.stages & used_stages,
                    },
                );
            }
            used_stages |= pc.stages;

            let device_max_pc_size = self.limits.max_push_constant_size;
            if device_max_pc_size < pc.range.end {
                return Err(CreatePipelineLayoutError::PushConstantRangeTooLarge {
                    index,
                    range: pc.range.clone(),
                    max: device_max_pc_size,
                });
            }

            if pc.range.start % wgt::PUSH_CONSTANT_ALIGNMENT != 0 {
                return Err(CreatePipelineLayoutError::MisalignedPushConstantRange {
                    index,
                    bound: pc.range.start,
                });
            }
            if pc.range.end % wgt::PUSH_CONSTANT_ALIGNMENT != 0 {
                return Err(CreatePipelineLayoutError::MisalignedPushConstantRange {
                    index,
                    bound: pc.range.end,
                });
            }
        }

        let mut count_validator = binding_model::BindingTypeMaxCountValidator::default();

        // validate total resource counts
        for &id in desc.bind_group_layouts.iter() {
            let bind_group_layout = bgl_guard
                .get(id)
                .map_err(|_| CreatePipelineLayoutError::InvalidBindGroupLayout(id))?;
            count_validator.merge(&bind_group_layout.count_validator);
        }
        count_validator
            .validate(&self.limits)
            .map_err(CreatePipelineLayoutError::TooManyBindings)?;

        let descriptor_set_layouts = desc
            .bind_group_layouts
            .iter()
            .map(|&id| &bgl_guard.get(id).unwrap().raw);
        let push_constants = desc
            .push_constant_ranges
            .iter()
            .map(|pc| (conv::map_shader_stage_flags(pc.stages), pc.range.clone()));

        let raw = unsafe {
            let raw_layout = self
                .raw
                .create_pipeline_layout(descriptor_set_layouts, push_constants)
                .or(Err(DeviceError::OutOfMemory))?;
            if let Some(_) = desc.label {
                //TODO-0.6: needs gfx changes published
                //self.raw.set_pipeline_layout_name(&mut raw_layout, label);
            }
            raw_layout
        };

        Ok(binding_model::PipelineLayout {
            raw,
            device_id: Stored {
                value: id::Valid(self_id),
                ref_count: self.life_guard.add_ref(),
            },
            life_guard: LifeGuard::new(),
            bind_group_layout_ids: desc
                .bind_group_layouts
                .iter()
                .map(|&id| {
                    bgl_guard.get(id).unwrap().multi_ref_count.inc();
                    id::Valid(id)
                })
                .collect(),
            push_constant_ranges: desc.push_constant_ranges.iter().cloned().collect(),
        })
    }

    fn wait_for_submit(
        &self,
        submission_index: SubmissionIndex,
        token: &mut Token<Self>,
    ) -> Result<(), WaitIdleError> {
        if self.last_completed_submission_index() <= submission_index {
            tracing::info!("Waiting for submission {:?}", submission_index);
            self.lock_life(token)
                .triage_submissions(&self.raw, true)
                .map(|_| ())
        } else {
            Ok(())
        }
    }
}

impl<B: hal::Backend> Device<B> {
    pub(crate) fn destroy_bind_group(&self, bind_group: binding_model::BindGroup<B>) {
        unsafe {
            self.desc_allocator.lock().free(iter::once(bind_group.raw));
        }
    }

    pub(crate) fn destroy_buffer(&self, buffer: resource::Buffer<B>) {
        unsafe {
            self.mem_allocator.lock().free(&self.raw, buffer.memory);
            self.raw.destroy_buffer(buffer.raw);
        }
    }

    pub(crate) fn destroy_texture(&self, texture: resource::Texture<B>) {
        unsafe {
            self.mem_allocator.lock().free(&self.raw, texture.memory);
            self.raw.destroy_image(texture.raw);
        }
    }

    /// Wait for idle and remove resources that we can, before we die.
    pub(crate) fn prepare_to_die(&mut self) {
        let mut life_tracker = self.life_tracker.lock();
        if let Err(error) = life_tracker.triage_submissions(&self.raw, true) {
            tracing::error!("failed to triage submissions: {}", error);
        }
        life_tracker.cleanup(&self.raw, &self.mem_allocator, &self.desc_allocator);
    }

    pub(crate) fn dispose(self) {
        let mut desc_alloc = self.desc_allocator.into_inner();
        let mut mem_alloc = self.mem_allocator.into_inner();
        self.pending_writes
            .dispose(&self.raw, &self.cmd_allocator, &mut mem_alloc);
        self.cmd_allocator.destroy(&self.raw);
        unsafe {
            desc_alloc.clear(&self.raw);
            mem_alloc.clear(&self.raw);
            for (_, rp) in self.render_passes.lock().drain() {
                self.raw.destroy_render_pass(rp);
            }
            for (_, fbo) in self.framebuffers.lock().drain() {
                self.raw.destroy_framebuffer(fbo);
            }
        }
    }
}

#[error("device is invalid")]
#[derive(Clone, Debug, Error)]
pub struct InvalidDevice;

#[derive(Clone, Debug, Error)]
pub enum DeviceError {
    #[error("parent device is invalid")]
    Invalid,
    #[error("parent device is lost")]
    Lost,
    #[error("not enough memory left")]
    OutOfMemory,
}

impl From<hal::device::OomOrDeviceLost> for DeviceError {
    fn from(err: hal::device::OomOrDeviceLost) -> Self {
        match err {
            hal::device::OomOrDeviceLost::OutOfMemory(_) => DeviceError::OutOfMemory,
            hal::device::OomOrDeviceLost::DeviceLost(_) => DeviceError::Lost,
        }
    }
}

impl DeviceError {
    fn from_heaps(err: gfx_memory::HeapsError) -> Self {
        match err {
            gfx_memory::HeapsError::AllocationError(hal::device::AllocationError::OutOfMemory(
                _,
            )) => DeviceError::OutOfMemory,
            _ => panic!("Unable to allocate memory: {:?}", err),
        }
    }

    fn from_bind(err: hal::device::BindError) -> Self {
        match err {
            hal::device::BindError::OutOfMemory(_) => DeviceError::OutOfMemory,
            _ => panic!("failed to bind memory: {}", err),
        }
    }
}

pub struct ImplicitPipelineIds<'a, G: GlobalIdentityHandlerFactory> {
    pub root_id: Input<G, id::PipelineLayoutId>,
    pub group_ids: &'a [Input<G, id::BindGroupLayoutId>],
}

impl<G: GlobalIdentityHandlerFactory> Global<G> {
    pub fn device_features<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
    ) -> Result<wgt::Features, InvalidDevice> {
        span!(_guard, INFO, "Device::features");

        let hub = B::hub(self);
        let mut token = Token::root();
        let (device_guard, _) = hub.devices.read(&mut token);
        let device = device_guard.get(device_id).map_err(|_| InvalidDevice)?;

        Ok(device.features)
    }

    pub fn device_limits<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
    ) -> Result<wgt::Limits, InvalidDevice> {
        span!(_guard, INFO, "Device::limits");

        let hub = B::hub(self);
        let mut token = Token::root();
        let (device_guard, _) = hub.devices.read(&mut token);
        let device = device_guard.get(device_id).map_err(|_| InvalidDevice)?;

        Ok(device.limits.clone())
    }

    pub fn device_create_buffer<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        desc: &resource::BufferDescriptor,
        id_in: Input<G, id::BufferId>,
    ) -> Result<id::BufferId, resource::CreateBufferError> {
        span!(_guard, INFO, "Device::create_buffer");

        let hub = B::hub(self);
        let mut token = Token::root();

        tracing::info!("Create buffer {:?} with ID {:?}", desc, id_in);

        if desc.mapped_at_creation && desc.size % wgt::COPY_BUFFER_ALIGNMENT != 0 {
            return Err(resource::CreateBufferError::UnalignedSize);
        }

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;
        let mut buffer = device.create_buffer(device_id, desc, gfx_memory::Kind::General)?;
        let ref_count = buffer.life_guard.add_ref();

        let buffer_use = if !desc.mapped_at_creation {
            resource::BufferUse::EMPTY
        } else if desc.usage.contains(wgt::BufferUsage::MAP_WRITE) {
            // buffer is mappable, so we are just doing that at start
            let ptr = map_buffer(
                &device.raw,
                &mut buffer,
                hal::buffer::SubRange::WHOLE,
                HostMap::Write,
            )?;

            buffer.map_state = resource::BufferMapState::Active {
                ptr,
                sub_range: hal::buffer::SubRange::WHOLE,
                host: HostMap::Write,
            };

            resource::BufferUse::MAP_WRITE
        } else {
            // buffer needs staging area for initialization only
            let mut stage = device.create_buffer(
                device_id,
                &wgt::BufferDescriptor {
                    label: Some(Cow::Borrowed("<init_buffer>")),
                    size: desc.size,
                    usage: wgt::BufferUsage::MAP_WRITE | wgt::BufferUsage::COPY_SRC,
                    mapped_at_creation: false,
                },
                gfx_memory::Kind::Linear,
            )?;
            let mapped = stage
                .memory
                .map(&device.raw, hal::memory::Segment::ALL)
                .map_err(resource::BufferAccessError::from)?;
            buffer.map_state = resource::BufferMapState::Init {
                ptr: mapped.ptr(),
                needs_flush: !mapped.is_coherent(),
                stage_buffer: stage.raw,
                stage_memory: stage.memory,
            };
            resource::BufferUse::COPY_DST
        };

        let id = hub.buffers.register_identity(id_in, buffer, &mut token);
        tracing::info!("Created buffer {:?} with {:?}", id, desc);
        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => {
                let mut desc = desc.clone();
                let mapped_at_creation = mem::replace(&mut desc.mapped_at_creation, false);
                if mapped_at_creation && !desc.usage.contains(wgt::BufferUsage::MAP_WRITE) {
                    desc.usage |= wgt::BufferUsage::COPY_DST;
                }
                trace.lock().add(trace::Action::CreateBuffer(id.0, desc))
            }
            None => (),
        };

        device
            .trackers
            .lock()
            .buffers
            .init(id, ref_count, BufferState::with_usage(buffer_use))
            .unwrap();
        Ok(id.0)
    }

    #[cfg(feature = "replay")]
    pub fn device_wait_for_buffer<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        buffer_id: id::BufferId,
    ) -> Result<(), WaitIdleError> {
        let hub = B::hub(self);
        let mut token = Token::root();
        let (device_guard, mut token) = hub.devices.read(&mut token);
        let last_submission = {
            let (buffer_guard, _) = hub.buffers.write(&mut token);
            match buffer_guard.get(buffer_id) {
                Ok(buffer) => buffer.life_guard.submission_index.load(Ordering::Acquire),
                Err(_) => return Ok(()),
            }
        };

        device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?
            .wait_for_submit(last_submission, &mut token)
    }

    pub fn device_set_buffer_sub_data<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        buffer_id: id::BufferId,
        offset: BufferAddress,
        data: &[u8],
    ) -> Result<(), resource::BufferAccessError> {
        span!(_guard, INFO, "Device::set_buffer_sub_data");

        let hub = B::hub(self);
        let mut token = Token::root();

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let (mut buffer_guard, _) = hub.buffers.write(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;
        let mut buffer = buffer_guard
            .get_mut(buffer_id)
            .map_err(|_| resource::BufferAccessError::InvalidBuffer)?;
        check_buffer_usage(buffer.usage, wgt::BufferUsage::MAP_WRITE)?;
        //assert!(buffer isn't used by the GPU);

        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => {
                let mut trace = trace.lock();
                let data_path = trace.make_binary("bin", data);
                trace.add(trace::Action::WriteBuffer {
                    id: buffer_id,
                    data: data_path,
                    range: offset..offset + data.len() as BufferAddress,
                    queued: false,
                });
            }
            None => (),
        };

        let ptr = map_buffer(
            &device.raw,
            &mut buffer,
            hal::buffer::SubRange {
                offset,
                size: Some(data.len() as BufferAddress),
            },
            HostMap::Write,
        )?;

        unsafe {
            ptr::copy_nonoverlapping(data.as_ptr(), ptr.as_ptr(), data.len());
        }

        unmap_buffer(&device.raw, buffer)?;

        Ok(())
    }

    pub fn device_get_buffer_sub_data<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        buffer_id: id::BufferId,
        offset: BufferAddress,
        data: &mut [u8],
    ) -> Result<(), resource::BufferAccessError> {
        span!(_guard, INFO, "Device::get_buffer_sub_data");

        let hub = B::hub(self);
        let mut token = Token::root();

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let (mut buffer_guard, _) = hub.buffers.write(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;
        let mut buffer = buffer_guard
            .get_mut(buffer_id)
            .map_err(|_| resource::BufferAccessError::InvalidBuffer)?;
        check_buffer_usage(buffer.usage, wgt::BufferUsage::MAP_READ)?;
        //assert!(buffer isn't used by the GPU);

        let ptr = map_buffer(
            &device.raw,
            &mut buffer,
            hal::buffer::SubRange {
                offset,
                size: Some(data.len() as BufferAddress),
            },
            HostMap::Read,
        )?;

        unsafe {
            ptr::copy_nonoverlapping(ptr.as_ptr(), data.as_mut_ptr(), data.len());
        }

        unmap_buffer(&device.raw, buffer)?;

        Ok(())
    }

    pub fn buffer_error<B: GfxBackend>(&self, id_in: Input<G, id::BufferId>) -> id::BufferId {
        B::hub(self)
            .buffers
            .register_error(id_in, &mut Token::root())
    }

    pub fn buffer_drop<B: GfxBackend>(&self, buffer_id: id::BufferId, now: bool) {
        span!(_guard, INFO, "Buffer::drop");

        let hub = B::hub(self);
        let mut token = Token::root();

        tracing::info!("Buffer {:?} is dropped", buffer_id);
        let (ref_count, last_submit_index, device_id) = {
            let (mut buffer_guard, _) = hub.buffers.write(&mut token);
            match buffer_guard.get_mut(buffer_id) {
                Ok(buffer) => {
                    let ref_count = buffer.life_guard.ref_count.take().unwrap();
                    let last_submit_index =
                        buffer.life_guard.submission_index.load(Ordering::Acquire);
                    (ref_count, last_submit_index, buffer.device_id.value)
                }
                Err(InvalidId) => {
                    hub.buffers.unregister_locked(buffer_id, &mut *buffer_guard);
                    return;
                }
            }
        };

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device = &device_guard[device_id];
        if now {
            drop(ref_count);
            device
                .lock_life(&mut token)
                .suspected_resources
                .buffers
                .push(id::Valid(buffer_id));
            match device.wait_for_submit(last_submit_index, &mut token) {
                Ok(()) => (),
                Err(e) => tracing::error!("Failed to wait for buffer {:?}: {:?}", buffer_id, e),
            }
        } else {
            device
                .lock_life(&mut token)
                .future_suspected_buffers
                .push(Stored {
                    value: id::Valid(buffer_id),
                    ref_count,
                });
        }
    }

    pub fn device_create_texture<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        desc: &resource::TextureDescriptor,
        id_in: Input<G, id::TextureId>,
    ) -> Result<id::TextureId, resource::CreateTextureError> {
        span!(_guard, INFO, "Device::create_texture");

        let hub = B::hub(self);
        let mut token = Token::root();

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;

        let texture_features = conv::texture_features(desc.format);
        if texture_features != wgt::Features::empty() && !device.features.contains(texture_features)
        {
            return Err(resource::CreateTextureError::MissingFeature(
                texture_features,
                desc.format,
            ));
        }

        let texture = device.create_texture(device_id, desc)?;
        let num_levels = texture.full_range.levels.end;
        let num_layers = texture.full_range.layers.end;
        let ref_count = texture.life_guard.add_ref();

        let id = hub.textures.register_identity(id_in, texture, &mut token);
        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => trace
                .lock()
                .add(trace::Action::CreateTexture(id.0, desc.clone())),
            None => (),
        };

        device
            .trackers
            .lock()
            .textures
            .init(id, ref_count, TextureState::new(num_levels, num_layers))
            .unwrap();
        Ok(id.0)
    }

    pub fn texture_error<B: GfxBackend>(&self, id_in: Input<G, id::TextureId>) -> id::TextureId {
        B::hub(self)
            .textures
            .register_error(id_in, &mut Token::root())
    }

    pub fn texture_drop<B: GfxBackend>(&self, texture_id: id::TextureId) {
        span!(_guard, INFO, "Texture::drop");

        let hub = B::hub(self);
        let mut token = Token::root();

        let (ref_count, device_id) = {
            let (mut texture_guard, _) = hub.textures.write(&mut token);
            match texture_guard.get_mut(texture_id) {
                Ok(texture) => (
                    texture.life_guard.ref_count.take().unwrap(),
                    texture.device_id.value,
                ),
                Err(InvalidId) => {
                    hub.textures
                        .unregister_locked(texture_id, &mut *texture_guard);
                    return;
                }
            }
        };

        let (device_guard, mut token) = hub.devices.read(&mut token);
        device_guard[device_id]
            .lock_life(&mut token)
            .future_suspected_textures
            .push(Stored {
                value: id::Valid(texture_id),
                ref_count,
            });
    }

    pub fn texture_create_view<B: GfxBackend>(
        &self,
        texture_id: id::TextureId,
        desc: &resource::TextureViewDescriptor,
        id_in: Input<G, id::TextureViewId>,
    ) -> Result<id::TextureViewId, resource::CreateTextureViewError> {
        span!(_guard, INFO, "Texture::create_view");

        let hub = B::hub(self);
        let mut token = Token::root();

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let (texture_guard, mut token) = hub.textures.read(&mut token);
        let texture = texture_guard
            .get(texture_id)
            .map_err(|_| resource::CreateTextureViewError::InvalidTexture)?;
        let device = &device_guard[texture.device_id.value];

        let view_kind = match desc.dimension {
            Some(dim) => conv::map_texture_view_dimension(dim),
            None => match texture.kind {
                hal::image::Kind::D1(_, 1) => hal::image::ViewKind::D1,
                hal::image::Kind::D1(..) => hal::image::ViewKind::D1Array,
                hal::image::Kind::D2(_, _, 1, _) => hal::image::ViewKind::D2,
                hal::image::Kind::D2(..) => hal::image::ViewKind::D2Array,
                hal::image::Kind::D3(..) => hal::image::ViewKind::D3,
            },
        };
        let required_level_count =
            desc.base_mip_level + desc.level_count.map_or(1, |count| count.get());
        let required_layer_count =
            desc.base_array_layer + desc.array_layer_count.map_or(1, |count| count.get());
        let level_end = texture.full_range.levels.end;
        let layer_end = texture.full_range.layers.end;
        if required_level_count > level_end as u32 {
            return Err(resource::CreateTextureViewError::InvalidMipLevelCount {
                requested: required_level_count,
                total: level_end,
            });
        }
        if required_layer_count > layer_end as u32 {
            return Err(resource::CreateTextureViewError::InvalidArrayLayerCount {
                requested: required_layer_count,
                total: layer_end,
            });
        };

        let aspects = match desc.aspect {
            wgt::TextureAspect::All => texture.aspects,
            wgt::TextureAspect::DepthOnly => hal::format::Aspects::DEPTH,
            wgt::TextureAspect::StencilOnly => hal::format::Aspects::STENCIL,
        };
        if !texture.aspects.contains(aspects) {
            return Err(resource::CreateTextureViewError::InvalidAspect {
                requested: aspects,
                total: texture.aspects,
            });
        }

        let format = desc.format.unwrap_or(texture.format);
        let range = hal::image::SubresourceRange {
            aspects,
            level_start: desc.base_mip_level as _,
            level_count: desc.level_count.map(|v| v.get() as _),
            layer_start: desc.base_array_layer as _,
            layer_count: desc.array_layer_count.map(|v| v.get() as _),
        };

        let raw = unsafe {
            device
                .raw
                .create_image_view(
                    &texture.raw,
                    view_kind,
                    conv::map_texture_format(format, device.private_features),
                    hal::format::Swizzle::NO,
                    range.clone(),
                )
                .or(Err(resource::CreateTextureViewError::OutOfMemory))?
        };

        let end_level = desc
            .level_count
            .map_or(level_end, |_| required_level_count as u8);
        let end_layer = desc
            .array_layer_count
            .map_or(layer_end, |_| required_layer_count as u16);
        let selector = TextureSelector {
            levels: desc.base_mip_level as u8..end_level,
            layers: desc.base_array_layer as u16..end_layer,
        };

        let view = resource::TextureView {
            inner: resource::TextureViewInner::Native {
                raw,
                source_id: Stored {
                    value: id::Valid(texture_id),
                    ref_count: texture.life_guard.add_ref(),
                },
            },
            aspects,
            format: texture.format,
            extent: texture.kind.extent().at_level(desc.base_mip_level as _),
            samples: texture.kind.num_samples(),
            selector,
            life_guard: LifeGuard::new(),
        };
        let ref_count = view.life_guard.add_ref();

        let id = hub.texture_views.register_identity(id_in, view, &mut token);
        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => trace.lock().add(trace::Action::CreateTextureView {
                id: id.0,
                parent_id: texture_id,
                desc: desc.clone(),
            }),
            None => (),
        };

        device
            .trackers
            .lock()
            .views
            .init(id, ref_count, PhantomData)
            .unwrap();
        Ok(id.0)
    }

    pub fn texture_view_error<B: GfxBackend>(
        &self,
        id_in: Input<G, id::TextureViewId>,
    ) -> id::TextureViewId {
        B::hub(self)
            .texture_views
            .register_error(id_in, &mut Token::root())
    }

    pub fn texture_view_drop<B: GfxBackend>(
        &self,
        texture_view_id: id::TextureViewId,
    ) -> Result<(), resource::TextureViewDestroyError> {
        span!(_guard, INFO, "TextureView::drop");

        let hub = B::hub(self);
        let mut token = Token::root();

        let device_id = {
            let (texture_guard, mut token) = hub.textures.read(&mut token);
            let (mut texture_view_guard, _) = hub.texture_views.write(&mut token);

            match texture_view_guard.get_mut(texture_view_id) {
                Ok(view) => {
                    view.life_guard.ref_count.take();
                    match view.inner {
                        resource::TextureViewInner::Native { ref source_id, .. } => {
                            texture_guard[source_id.value].device_id.value
                        }
                        resource::TextureViewInner::SwapChain { .. } => {
                            return Err(resource::TextureViewDestroyError::SwapChainImage)
                        }
                    }
                }
                Err(InvalidId) => {
                    hub.texture_views
                        .unregister_locked(texture_view_id, &mut *texture_view_guard);
                    return Ok(());
                }
            }
        };

        let (device_guard, mut token) = hub.devices.read(&mut token);
        device_guard[device_id]
            .lock_life(&mut token)
            .suspected_resources
            .texture_views
            .push(id::Valid(texture_view_id));
        Ok(())
    }

    pub fn device_create_sampler<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        desc: &resource::SamplerDescriptor,
        id_in: Input<G, id::SamplerId>,
    ) -> Result<id::SamplerId, resource::CreateSamplerError> {
        span!(_guard, INFO, "Device::create_sampler");

        let hub = B::hub(self);
        let mut token = Token::root();
        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;

        let actual_clamp = if let Some(clamp) = desc.anisotropy_clamp {
            let clamp = clamp.get();
            let valid_clamp = clamp <= MAX_ANISOTROPY && conv::is_power_of_two(clamp as u32);
            if !valid_clamp {
                return Err(resource::CreateSamplerError::InvalidClamp(clamp));
            }
            if device.private_features.anisotropic_filtering {
                Some(clamp)
            } else {
                None
            }
        } else {
            None
        };

        let info = hal::image::SamplerDesc {
            min_filter: conv::map_filter(desc.min_filter),
            mag_filter: conv::map_filter(desc.mag_filter),
            mip_filter: conv::map_filter(desc.mipmap_filter),
            wrap_mode: (
                conv::map_wrap(desc.address_modes[0]),
                conv::map_wrap(desc.address_modes[1]),
                conv::map_wrap(desc.address_modes[2]),
            ),
            lod_bias: hal::image::Lod(0.0),
            lod_range: hal::image::Lod(desc.lod_min_clamp)..hal::image::Lod(desc.lod_max_clamp),
            comparison: desc.compare.map(conv::map_compare_function),
            border: hal::image::PackedColor(0),
            normalized: true,
            anisotropy_clamp: actual_clamp,
        };

        let raw = unsafe {
            device.raw.create_sampler(&info).map_err(|err| match err {
                hal::device::AllocationError::OutOfMemory(_) => {
                    resource::CreateSamplerError::Device(DeviceError::OutOfMemory)
                }
                hal::device::AllocationError::TooManyObjects => {
                    resource::CreateSamplerError::TooManyObjects
                }
            })?
        };
        let sampler = resource::Sampler {
            raw,
            device_id: Stored {
                value: id::Valid(device_id),
                ref_count: device.life_guard.add_ref(),
            },
            life_guard: LifeGuard::new(),
            comparison: info.comparison.is_some(),
        };
        let ref_count = sampler.life_guard.add_ref();

        let id = hub.samplers.register_identity(id_in, sampler, &mut token);
        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => trace
                .lock()
                .add(trace::Action::CreateSampler(id.0, desc.clone())),
            None => (),
        };

        device
            .trackers
            .lock()
            .samplers
            .init(id, ref_count, PhantomData)
            .unwrap();
        Ok(id.0)
    }

    pub fn sampler_error<B: GfxBackend>(&self, id_in: Input<G, id::SamplerId>) -> id::SamplerId {
        B::hub(self)
            .samplers
            .register_error(id_in, &mut Token::root())
    }

    pub fn sampler_drop<B: GfxBackend>(&self, sampler_id: id::SamplerId) {
        span!(_guard, INFO, "Sampler::drop");

        let hub = B::hub(self);
        let mut token = Token::root();

        let device_id = {
            let (mut sampler_guard, _) = hub.samplers.write(&mut token);
            match sampler_guard.get_mut(sampler_id) {
                Ok(sampler) => {
                    sampler.life_guard.ref_count.take();
                    sampler.device_id.value
                }
                Err(InvalidId) => {
                    hub.samplers
                        .unregister_locked(sampler_id, &mut *sampler_guard);
                    return;
                }
            }
        };

        let (device_guard, mut token) = hub.devices.read(&mut token);
        device_guard[device_id]
            .lock_life(&mut token)
            .suspected_resources
            .samplers
            .push(id::Valid(sampler_id));
    }

    pub fn device_create_bind_group_layout<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        desc: &binding_model::BindGroupLayoutDescriptor,
        id_in: Input<G, id::BindGroupLayoutId>,
    ) -> Result<id::BindGroupLayoutId, binding_model::CreateBindGroupLayoutError> {
        span!(_guard, INFO, "Device::create_bind_group_layout");

        let mut token = Token::root();
        let hub = B::hub(self);
        let mut entry_map = FastHashMap::default();
        for entry in desc.entries.iter() {
            if entry_map.insert(entry.binding, entry.clone()).is_some() {
                return Err(binding_model::CreateBindGroupLayoutError::ConflictBinding(
                    entry.binding,
                ));
            }
        }

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;

        // If there is an equivalent BGL, just bump the refcount and return it.
        // This is only applicable for identity filters that are generating new IDs,
        // so their inputs are `PhantomData` of size 0.
        if mem::size_of::<Input<G, id::BindGroupLayoutId>>() == 0 {
            let (bgl_guard, _) = hub.bind_group_layouts.read(&mut token);
            if let Some(id) =
                Device::deduplicate_bind_group_layout(device_id, &entry_map, &*bgl_guard)
            {
                return Ok(id);
            }
        }

        let layout = device.create_bind_group_layout(
            device_id,
            desc.label.as_ref().map(|cow| cow.as_ref()),
            entry_map,
        )?;

        let id = hub
            .bind_group_layouts
            .register_identity(id_in, layout, &mut token);
        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => trace
                .lock()
                .add(trace::Action::CreateBindGroupLayout(id.0, desc.clone())),
            None => (),
        };
        Ok(id.0)
    }

    pub fn bind_group_layout_error<B: GfxBackend>(
        &self,
        id_in: Input<G, id::BindGroupLayoutId>,
    ) -> id::BindGroupLayoutId {
        B::hub(self)
            .bind_group_layouts
            .register_error(id_in, &mut Token::root())
    }

    pub fn bind_group_layout_drop<B: GfxBackend>(
        &self,
        bind_group_layout_id: id::BindGroupLayoutId,
    ) {
        span!(_guard, INFO, "BindGroupLayout::drop");

        let hub = B::hub(self);
        let mut token = Token::root();
        let device_id = {
            let (mut bind_group_layout_guard, _) = hub.bind_group_layouts.write(&mut token);
            match bind_group_layout_guard.get_mut(bind_group_layout_id) {
                Ok(layout) => layout.device_id.value,
                Err(InvalidId) => {
                    hub.bind_group_layouts
                        .unregister_locked(bind_group_layout_id, &mut *bind_group_layout_guard);
                    return;
                }
            }
        };

        let (device_guard, mut token) = hub.devices.read(&mut token);
        device_guard[device_id]
            .lock_life(&mut token)
            .suspected_resources
            .bind_group_layouts
            .push(id::Valid(bind_group_layout_id));
    }

    pub fn device_create_pipeline_layout<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        desc: &binding_model::PipelineLayoutDescriptor,
        id_in: Input<G, id::PipelineLayoutId>,
    ) -> Result<id::PipelineLayoutId, CreatePipelineLayoutError> {
        span!(_guard, INFO, "Device::create_pipeline_layout");

        let hub = B::hub(self);
        let mut token = Token::root();

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;

        let layout = {
            let (bgl_guard, _) = hub.bind_group_layouts.read(&mut token);
            device.create_pipeline_layout(device_id, desc, &*bgl_guard)?
        };

        let id = hub
            .pipeline_layouts
            .register_identity(id_in, layout, &mut token);
        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => trace
                .lock()
                .add(trace::Action::CreatePipelineLayout(id.0, desc.clone())),
            None => (),
        };
        Ok(id.0)
    }

    pub fn pipeline_layout_error<B: GfxBackend>(
        &self,
        id_in: Input<G, id::PipelineLayoutId>,
    ) -> id::PipelineLayoutId {
        B::hub(self)
            .pipeline_layouts
            .register_error(id_in, &mut Token::root())
    }

    pub fn pipeline_layout_drop<B: GfxBackend>(&self, pipeline_layout_id: id::PipelineLayoutId) {
        span!(_guard, INFO, "PipelineLayout::drop");

        let hub = B::hub(self);
        let mut token = Token::root();
        let (device_id, ref_count) = {
            let (mut pipeline_layout_guard, _) = hub.pipeline_layouts.write(&mut token);
            match pipeline_layout_guard.get_mut(pipeline_layout_id) {
                Ok(layout) => (
                    layout.device_id.value,
                    layout.life_guard.ref_count.take().unwrap(),
                ),
                Err(InvalidId) => {
                    hub.pipeline_layouts
                        .unregister_locked(pipeline_layout_id, &mut *pipeline_layout_guard);
                    return;
                }
            }
        };

        let (device_guard, mut token) = hub.devices.read(&mut token);
        device_guard[device_id]
            .lock_life(&mut token)
            .suspected_resources
            .pipeline_layouts
            .push(Stored {
                value: id::Valid(pipeline_layout_id),
                ref_count,
            });
    }

    fn derive_pipeline_layout<B: GfxBackend>(
        &self,
        device: &Device<B>,
        device_id: id::DeviceId,
        implicit_pipeline_ids: Option<ImplicitPipelineIds<G>>,
        mut derived_group_layouts: ArrayVec<[binding_model::BindEntryMap; MAX_BIND_GROUPS]>,
        bgl_guard: &mut Storage<binding_model::BindGroupLayout<B>, id::BindGroupLayoutId>,
        pipeline_layout_guard: &mut Storage<binding_model::PipelineLayout<B>, id::PipelineLayoutId>,
    ) -> Result<
        (id::PipelineLayoutId, pipeline::ImplicitBindGroupCount),
        pipeline::ImplicitLayoutError,
    > {
        let hub = B::hub(self);
        let derived_bind_group_count =
            derived_group_layouts.len() as pipeline::ImplicitBindGroupCount;

        while derived_group_layouts
            .last()
            .map_or(false, |map| map.is_empty())
        {
            derived_group_layouts.pop();
        }
        let ids = implicit_pipeline_ids
            .as_ref()
            .ok_or(pipeline::ImplicitLayoutError::MissingIds(0))?;
        if ids.group_ids.len() < derived_group_layouts.len() {
            tracing::error!(
                "Not enough bind group IDs ({}) specified for the implicit layout ({})",
                ids.group_ids.len(),
                derived_group_layouts.len()
            );
            return Err(pipeline::ImplicitLayoutError::MissingIds(
                derived_bind_group_count,
            ));
        }

        let mut derived_group_layout_ids =
            ArrayVec::<[id::BindGroupLayoutId; MAX_BIND_GROUPS]>::new();
        for (bgl_id, map) in ids.group_ids.iter().zip(derived_group_layouts) {
            let processed_id =
                match Device::deduplicate_bind_group_layout(device_id, &map, bgl_guard) {
                    Some(dedup_id) => dedup_id,
                    None => {
                        #[cfg(feature = "trace")]
                        let bgl_desc = binding_model::BindGroupLayoutDescriptor {
                            label: None,
                            entries: if device.trace.is_some() {
                                Cow::Owned(map.values().cloned().collect())
                            } else {
                                Cow::Borrowed(&[])
                            },
                        };
                        let bgl = device.create_bind_group_layout(device_id, None, map)?;
                        let out_id = hub.bind_group_layouts.register_identity_locked(
                            bgl_id.clone(),
                            bgl,
                            bgl_guard,
                        );
                        #[cfg(feature = "trace")]
                        match device.trace {
                            Some(ref trace) => trace
                                .lock()
                                .add(trace::Action::CreateBindGroupLayout(out_id.0, bgl_desc)),
                            None => (),
                        };
                        out_id.0
                    }
                };
            derived_group_layout_ids.push(processed_id);
        }

        let layout_desc = binding_model::PipelineLayoutDescriptor {
            label: None,
            bind_group_layouts: Cow::Borrowed(&derived_group_layout_ids),
            push_constant_ranges: Cow::Borrowed(&[]), //TODO?
        };
        let layout = device.create_pipeline_layout(device_id, &layout_desc, bgl_guard)?;
        let layout_id = hub.pipeline_layouts.register_identity_locked(
            ids.root_id.clone(),
            layout,
            pipeline_layout_guard,
        );
        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => trace.lock().add(trace::Action::CreatePipelineLayout(
                layout_id.0,
                layout_desc,
            )),
            None => (),
        };
        Ok((layout_id.0, derived_bind_group_count))
    }

    pub fn device_create_bind_group<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        desc: &binding_model::BindGroupDescriptor,
        id_in: Input<G, id::BindGroupId>,
    ) -> Result<id::BindGroupId, CreateBindGroupError> {
        use crate::binding_model::BindingResource as Br;

        span!(_guard, INFO, "Device::create_bind_group");

        let hub = B::hub(self);
        let mut token = Token::root();

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;
        let (bind_group_layout_guard, mut token) = hub.bind_group_layouts.read(&mut token);
        let bind_group_layout = bind_group_layout_guard
            .get(desc.layout)
            .map_err(|_| CreateBindGroupError::InvalidLayout)?;

        // Check that the number of entries in the descriptor matches
        // the number of entries in the layout.
        let actual = desc.entries.len();
        let expected = bind_group_layout.entries.len();
        if actual != expected {
            return Err(CreateBindGroupError::BindingsNumMismatch { expected, actual });
        }

        let mut desc_set = {
            let mut desc_sets = ArrayVec::<[_; 1]>::new();
            device
                .desc_allocator
                .lock()
                .allocate(
                    &device.raw,
                    &bind_group_layout.raw,
                    &bind_group_layout.desc_counts,
                    1,
                    &mut desc_sets,
                )
                .expect("failed to allocate descriptor set");
            desc_sets.pop().unwrap()
        };

        // Set the descriptor set's label for easier debugging.
        if let Some(label) = desc.label.as_ref() {
            unsafe {
                device
                    .raw
                    .set_descriptor_set_name(desc_set.raw_mut(), &label);
            }
        }

        // Rebind `desc_set` as immutable
        let desc_set = desc_set;

        // TODO: arrayvec/smallvec
        // Record binding info for dynamic offset validation
        let mut dynamic_binding_info = Vec::new();

        // fill out the descriptors
        let mut used = TrackerSet::new(B::VARIANT);
        {
            let (buffer_guard, mut token) = hub.buffers.read(&mut token);
            let (texture_guard, mut token) = hub.textures.read(&mut token); //skip token
            let (texture_view_guard, mut token) = hub.texture_views.read(&mut token);
            let (sampler_guard, _) = hub.samplers.read(&mut token);

            //TODO: group writes into contiguous sections
            let mut writes = Vec::new();
            for entry in desc.entries.iter() {
                let binding = entry.binding;
                // Find the corresponding declaration in the layout
                let decl = bind_group_layout
                    .entries
                    .get(&binding)
                    .ok_or(CreateBindGroupError::MissingBindingDeclaration(binding))?;
                let descriptors: SmallVec<[_; 1]> = match entry.resource {
                    Br::Buffer(ref bb) => {
                        let (pub_usage, internal_use, min_size, dynamic) = match decl.ty {
                            wgt::BindingType::UniformBuffer {
                                dynamic,
                                min_binding_size,
                            } => (
                                wgt::BufferUsage::UNIFORM,
                                resource::BufferUse::UNIFORM,
                                min_binding_size,
                                dynamic,
                            ),
                            wgt::BindingType::StorageBuffer {
                                dynamic,
                                min_binding_size,
                                readonly,
                            } => (
                                wgt::BufferUsage::STORAGE,
                                if readonly {
                                    resource::BufferUse::STORAGE_LOAD
                                } else {
                                    resource::BufferUse::STORAGE_STORE
                                },
                                min_binding_size,
                                dynamic,
                            ),
                            _ => {
                                return Err(CreateBindGroupError::WrongBindingType {
                                    binding,
                                    actual: decl.ty.clone(),
                                    expected:
                                        "UniformBuffer, StorageBuffer or ReadonlyStorageBuffer",
                                })
                            }
                        };

                        if bb.offset % wgt::BIND_BUFFER_ALIGNMENT != 0 {
                            return Err(CreateBindGroupError::UnalignedBufferOffset(bb.offset));
                        }

                        let buffer = used
                            .buffers
                            .use_extend(&*buffer_guard, bb.buffer_id, (), internal_use)
                            .unwrap();
                        check_buffer_usage(buffer.usage, pub_usage)?;
                        let (bind_size, bind_end) = match bb.size {
                            Some(size) => {
                                let end = bb.offset + size.get();
                                if end > buffer.size {
                                    return Err(CreateBindGroupError::BindingRangeTooLarge {
                                        range: bb.offset..end,
                                        size: buffer.size,
                                    });
                                }
                                (size.get(), end)
                            }
                            None => (buffer.size - bb.offset, buffer.size),
                        };

                        if pub_usage == wgt::BufferUsage::UNIFORM
                            && (device.limits.max_uniform_buffer_binding_size as u64) < bind_size
                        {
                            return Err(CreateBindGroupError::UniformBufferRangeTooLarge);
                        }

                        // Record binding info for validating dynamic offsets
                        if dynamic {
                            dynamic_binding_info.push(binding_model::BindGroupDynamicBindingData {
                                maximum_dynamic_offset: buffer.size - bind_end,
                            });
                        }

                        if let Some(non_zero) = min_size {
                            let min_size = non_zero.get();
                            if min_size > bind_size {
                                return Err(CreateBindGroupError::BindingSizeTooSmall {
                                    actual: bind_size,
                                    min: min_size,
                                });
                            }
                        }

                        let sub_range = hal::buffer::SubRange {
                            offset: bb.offset,
                            size: Some(bind_size),
                        };
                        SmallVec::from([hal::pso::Descriptor::Buffer(&buffer.raw, sub_range)])
                    }
                    Br::Sampler(id) => {
                        match decl.ty {
                            wgt::BindingType::Sampler { comparison } => {
                                let sampler = used
                                    .samplers
                                    .use_extend(&*sampler_guard, id, (), ())
                                    .unwrap();

                                // Check the actual sampler to also (not) be a comparison sampler
                                if sampler.comparison != comparison {
                                    return Err(CreateBindGroupError::WrongSamplerComparison);
                                }

                                SmallVec::from([hal::pso::Descriptor::Sampler(&sampler.raw)])
                            }
                            _ => {
                                return Err(CreateBindGroupError::WrongBindingType {
                                    binding,
                                    actual: decl.ty.clone(),
                                    expected: "Sampler",
                                })
                            }
                        }
                    }
                    Br::TextureView(id) => {
                        let view = used
                            .views
                            .use_extend(&*texture_view_guard, id, (), ())
                            .unwrap();
                        let (pub_usage, internal_use) = match decl.ty {
                            wgt::BindingType::SampledTexture { .. } => (
                                wgt::TextureUsage::SAMPLED,
                                resource::TextureUse::SAMPLED,
                            ),
                            wgt::BindingType::StorageTexture { readonly, .. } => (
                                wgt::TextureUsage::STORAGE,
                                if readonly {
                                    resource::TextureUse::STORAGE_LOAD
                                } else {
                                    resource::TextureUse::STORAGE_STORE
                                },
                            ),
                            _ => return Err(CreateBindGroupError::WrongBindingType {
                                binding,
                                actual: decl.ty.clone(),
                                expected: "SampledTexture, ReadonlyStorageTexture or WriteonlyStorageTexture"
                            })
                        };
                        if view
                            .aspects
                            .contains(hal::format::Aspects::DEPTH | hal::format::Aspects::STENCIL)
                        {
                            return Err(CreateBindGroupError::DepthStencilAspect);
                        }
                        match view.inner {
                            resource::TextureViewInner::Native {
                                ref raw,
                                ref source_id,
                            } => {
                                // Careful here: the texture may no longer have its own ref count,
                                // if it was deleted by the user.
                                let texture = &texture_guard[source_id.value];
                                used.textures
                                    .change_extend(
                                        source_id.value,
                                        &source_id.ref_count,
                                        view.selector.clone(),
                                        internal_use,
                                    )
                                    .unwrap();
                                check_texture_usage(texture.usage, pub_usage)?;
                                let image_layout =
                                    conv::map_texture_state(internal_use, view.aspects).1;
                                SmallVec::from([hal::pso::Descriptor::Image(raw, image_layout)])
                            }
                            resource::TextureViewInner::SwapChain { .. } => {
                                return Err(CreateBindGroupError::SwapChainImage);
                            }
                        }
                    }
                    Br::TextureViewArray(ref bindings_array) => {
                        let required_feats = wgt::Features::SAMPLED_TEXTURE_BINDING_ARRAY;
                        if !device.features.contains(required_feats) {
                            return Err(CreateBindGroupError::MissingFeatures(required_feats));
                        }

                        if let Some(count) = decl.count {
                            let count = count.get() as usize;
                            let num_bindings = bindings_array.len();
                            if count != num_bindings {
                                return Err(CreateBindGroupError::BindingArrayLengthMismatch {
                                    actual: num_bindings,
                                    expected: count,
                                });
                            }
                        } else {
                            return Err(CreateBindGroupError::SingleBindingExpected);
                        }

                        let (pub_usage, internal_use) = match decl.ty {
                            wgt::BindingType::SampledTexture { .. } => {
                                (wgt::TextureUsage::SAMPLED, resource::TextureUse::SAMPLED)
                            }
                            _ => {
                                return Err(CreateBindGroupError::WrongBindingType {
                                    binding,
                                    actual: decl.ty.clone(),
                                    expected: "SampledTextureArray",
                                })
                            }
                        };
                        bindings_array
                            .iter()
                            .map(|&id| {
                                let view = used
                                    .views
                                    .use_extend(&*texture_view_guard, id, (), ())
                                    .unwrap();
                                match view.inner {
                                    resource::TextureViewInner::Native {
                                        ref raw,
                                        ref source_id,
                                    } => {
                                        // Careful here: the texture may no longer have its own ref count,
                                        // if it was deleted by the user.
                                        let texture = &texture_guard[source_id.value];
                                        used.textures
                                            .change_extend(
                                                source_id.value,
                                                &source_id.ref_count,
                                                view.selector.clone(),
                                                internal_use,
                                            )
                                            .unwrap();
                                        check_texture_usage(texture.usage, pub_usage)?;
                                        let image_layout =
                                            conv::map_texture_state(internal_use, view.aspects).1;
                                        Ok(hal::pso::Descriptor::Image(raw, image_layout))
                                    }
                                    resource::TextureViewInner::SwapChain { .. } => {
                                        return Err(CreateBindGroupError::SwapChainImage)
                                    }
                                }
                            })
                            .collect::<Result<_, _>>()?
                    }
                };
                writes.alloc().init(hal::pso::DescriptorSetWrite {
                    set: desc_set.raw(),
                    binding,
                    array_offset: 0, //TODO
                    descriptors,
                });
            }

            unsafe {
                device.raw.write_descriptor_sets(writes);
            }
        }

        let bind_group = binding_model::BindGroup {
            raw: desc_set,
            device_id: Stored {
                value: id::Valid(device_id),
                ref_count: device.life_guard.add_ref(),
            },
            layout_id: id::Valid(desc.layout),
            life_guard: LifeGuard::new(),
            used,
            dynamic_binding_info,
        };
        let ref_count = bind_group.life_guard.add_ref();

        let id = hub
            .bind_groups
            .register_identity(id_in, bind_group, &mut token);
        tracing::debug!(
            "Bind group {:?} {:#?}",
            id,
            hub.bind_groups.read(&mut token).0[id].used
        );
        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => trace
                .lock()
                .add(trace::Action::CreateBindGroup(id.0, desc.clone())),
            None => (),
        };

        device
            .trackers
            .lock()
            .bind_groups
            .init(id, ref_count, PhantomData)
            .unwrap();
        Ok(id.0)
    }

    pub fn bind_group_error<B: GfxBackend>(
        &self,
        id_in: Input<G, id::BindGroupId>,
    ) -> id::BindGroupId {
        B::hub(self)
            .bind_groups
            .register_error(id_in, &mut Token::root())
    }

    pub fn bind_group_drop<B: GfxBackend>(&self, bind_group_id: id::BindGroupId) {
        span!(_guard, INFO, "BindGroup::drop");

        let hub = B::hub(self);
        let mut token = Token::root();

        let device_id = {
            let (mut bind_group_guard, _) = hub.bind_groups.write(&mut token);
            match bind_group_guard.get_mut(bind_group_id) {
                Ok(bind_group) => {
                    bind_group.life_guard.ref_count.take();
                    bind_group.device_id.value
                }
                Err(InvalidId) => {
                    hub.bind_groups
                        .unregister_locked(bind_group_id, &mut *bind_group_guard);
                    return;
                }
            }
        };

        let (device_guard, mut token) = hub.devices.read(&mut token);
        device_guard[device_id]
            .lock_life(&mut token)
            .suspected_resources
            .bind_groups
            .push(id::Valid(bind_group_id));
    }

    pub fn device_create_shader_module<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        source: pipeline::ShaderModuleSource,
        id_in: Input<G, id::ShaderModuleId>,
    ) -> Result<id::ShaderModuleId, pipeline::CreateShaderModuleError> {
        span!(_guard, INFO, "Device::create_shader_module");

        let hub = B::hub(self);
        let mut token = Token::root();
        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;
        let spv_flags = if cfg!(debug_assertions) {
            naga::back::spv::WriterFlags::DEBUG
        } else {
            naga::back::spv::WriterFlags::empty()
        };

        let (spv, naga) = match source {
            pipeline::ShaderModuleSource::SpirV(spv) => {
                let module = if device.private_features.shader_validation {
                    // Parse the given shader code and store its representation.
                    let spv_iter = spv.into_iter().cloned();
                    naga::front::spv::Parser::new(spv_iter)
                        .parse()
                        .map_err(|err| {
                            // TODO: eventually, when Naga gets support for all features,
                            // we want to convert these to a hard error,
                            tracing::warn!("Failed to parse shader SPIR-V code: {:?}", err);
                            tracing::warn!("Shader module will not be validated");
                        })
                        .ok()
                } else {
                    None
                };
                (spv, module)
            }
            pipeline::ShaderModuleSource::Wgsl(code) => {
                // TODO: refactor the corresponding Naga error to be owned, and then
                // display it instead of unwrapping
                let module = naga::front::wgsl::parse_str(&code).unwrap();
                let spv = naga::back::spv::Writer::new(&module.header, spv_flags).write(&module);
                (
                    Cow::Owned(spv),
                    if device.private_features.shader_validation {
                        Some(module)
                    } else {
                        None
                    },
                )
            }
            pipeline::ShaderModuleSource::Naga(module) => {
                let spv = naga::back::spv::Writer::new(&module.header, spv_flags).write(&module);
                (
                    Cow::Owned(spv),
                    if device.private_features.shader_validation {
                        Some(module)
                    } else {
                        None
                    },
                )
            }
        };

        if let Some(ref module) = naga {
            naga::proc::Validator::new().validate(module)?;
        }

        let raw = unsafe {
            device
                .raw
                .create_shader_module(&spv)
                .map_err(|err| match err {
                    hal::device::ShaderError::OutOfMemory(_) => DeviceError::OutOfMemory,
                    _ => panic!("failed to create shader module: {}", err),
                })?
        };
        let shader = pipeline::ShaderModule {
            raw,
            device_id: Stored {
                value: id::Valid(device_id),
                ref_count: device.life_guard.add_ref(),
            },
            module: naga,
        };

        let id = hub
            .shader_modules
            .register_identity(id_in, shader, &mut token);
        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => {
                let mut trace = trace.lock();
                let data = trace.make_binary("spv", unsafe {
                    std::slice::from_raw_parts(spv.as_ptr() as *const u8, spv.len() * 4)
                });
                trace.add(trace::Action::CreateShaderModule { id: id.0, data });
            }
            None => {}
        };
        Ok(id.0)
    }

    pub fn shader_module_error<B: GfxBackend>(
        &self,
        id_in: Input<G, id::ShaderModuleId>,
    ) -> id::ShaderModuleId {
        let hub = B::hub(self);
        let mut token = Token::root();
        let (_, mut token) = hub.devices.read(&mut token);
        hub.shader_modules.register_error(id_in, &mut token)
    }

    pub fn shader_module_drop<B: GfxBackend>(&self, shader_module_id: id::ShaderModuleId) {
        span!(_guard, INFO, "ShaderModule::drop");

        let hub = B::hub(self);
        let mut token = Token::root();
        let (device_guard, mut token) = hub.devices.read(&mut token);
        let (module, _) = hub.shader_modules.unregister(shader_module_id, &mut token);

        let device = &device_guard[module.device_id.value];
        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => trace
                .lock()
                .add(trace::Action::DestroyShaderModule(shader_module_id)),
            None => (),
        };
        unsafe {
            device.raw.destroy_shader_module(module.raw);
        }
    }

    pub fn device_create_command_encoder<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        desc: &wgt::CommandEncoderDescriptor<Label>,
        id_in: Input<G, id::CommandEncoderId>,
    ) -> Result<id::CommandEncoderId, command::CommandAllocatorError> {
        span!(_guard, INFO, "Device::create_command_encoder");

        let hub = B::hub(self);
        let mut token = Token::root();

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;

        let dev_stored = Stored {
            value: id::Valid(device_id),
            ref_count: device.life_guard.add_ref(),
        };

        let mut command_buffer = device.cmd_allocator.allocate(
            dev_stored,
            &device.raw,
            device.limits.clone(),
            device.private_features,
            #[cfg(feature = "trace")]
            device.trace.is_some(),
        )?;

        unsafe {
            let raw_command_buffer = command_buffer.raw.last_mut().unwrap();
            if let Some(ref label) = desc.label {
                device
                    .raw
                    .set_command_buffer_name(raw_command_buffer, label);
            }
            raw_command_buffer.begin_primary(hal::command::CommandBufferFlags::ONE_TIME_SUBMIT);
        }

        let id = hub
            .command_buffers
            .register_identity(id_in, command_buffer, &mut token);

        Ok(id.0)
    }

    pub fn command_encoder_error<B: GfxBackend>(
        &self,
        id_in: Input<G, id::CommandEncoderId>,
    ) -> id::CommandEncoderId {
        B::hub(self)
            .command_buffers
            .register_error(id_in, &mut Token::root())
    }

    pub fn command_buffer_error<B: GfxBackend>(
        &self,
        id_in: Input<G, id::CommandBufferId>,
    ) -> id::CommandBufferId {
        B::hub(self)
            .command_buffers
            .register_error(id_in, &mut Token::root())
    }

    pub fn command_encoder_drop<B: GfxBackend>(&self, command_encoder_id: id::CommandEncoderId) {
        span!(_guard, INFO, "CommandEncoder::drop");

        let hub = B::hub(self);
        let mut token = Token::root();

        let (mut device_guard, mut token) = hub.devices.write(&mut token);
        let (cmdbuf, _) = hub
            .command_buffers
            .unregister(command_encoder_id, &mut token);

        let device = &mut device_guard[cmdbuf.device_id.value];
        device.untrack::<G>(&hub, &cmdbuf.trackers, &mut token);
        device.cmd_allocator.discard(cmdbuf);
    }

    pub fn command_buffer_drop<B: GfxBackend>(&self, command_buffer_id: id::CommandBufferId) {
        span!(_guard, INFO, "CommandBuffer::drop");
        self.command_encoder_drop::<B>(command_buffer_id)
    }

    pub fn device_create_render_bundle_encoder(
        &self,
        device_id: id::DeviceId,
        desc: &command::RenderBundleEncoderDescriptor,
    ) -> Result<id::RenderBundleEncoderId, command::CreateRenderBundleError> {
        span!(_guard, INFO, "Device::create_render_bundle_encoder");
        let encoder = command::RenderBundleEncoder::new(desc, device_id, None);
        encoder.map(|encoder| Box::into_raw(Box::new(encoder)))
    }

    pub fn render_bundle_error<B: GfxBackend>(
        &self,
        id_in: Input<G, id::RenderBundleId>,
    ) -> id::RenderBundleId {
        let hub = B::hub(self);
        let mut token = Token::root();
        let (_, mut token) = hub.devices.read(&mut token);
        hub.render_bundles.register_error(id_in, &mut token)
    }

    pub fn render_bundle_drop<B: GfxBackend>(&self, render_bundle_id: id::RenderBundleId) {
        span!(_guard, INFO, "RenderBundle::drop");
        let hub = B::hub(self);
        let mut token = Token::root();

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device_id = {
            let (mut bundle_guard, _) = hub.render_bundles.write(&mut token);
            match bundle_guard.get_mut(render_bundle_id) {
                Ok(bundle) => {
                    bundle.life_guard.ref_count.take();
                    bundle.device_id.value
                }
                Err(InvalidId) => {
                    hub.render_bundles
                        .unregister_locked(render_bundle_id, &mut *bundle_guard);
                    return;
                }
            }
        };

        device_guard[device_id]
            .lock_life(&mut token)
            .suspected_resources
            .render_bundles
            .push(id::Valid(render_bundle_id));
    }

    pub fn device_create_render_pipeline<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        desc: &pipeline::RenderPipelineDescriptor,
        id_in: Input<G, id::RenderPipelineId>,
        implicit_pipeline_ids: Option<ImplicitPipelineIds<G>>,
    ) -> Result<
        (id::RenderPipelineId, pipeline::ImplicitBindGroupCount),
        pipeline::CreateRenderPipelineError,
    > {
        span!(_guard, INFO, "Device::create_render_pipeline");

        let hub = B::hub(self);
        let mut token = Token::root();

        let samples = {
            let sc = desc.sample_count;
            if sc == 0 || sc > 32 || !conv::is_power_of_two(sc) {
                return Err(pipeline::CreateRenderPipelineError::InvalidSampleCount(sc));
            }
            sc as u8
        };

        let color_states = &desc.color_states;
        let depth_stencil_state = desc.depth_stencil_state.as_ref();

        let rasterization_state = desc
            .rasterization_state
            .as_ref()
            .cloned()
            .unwrap_or_default();
        let rasterizer = conv::map_rasterization_state_descriptor(&rasterization_state);

        let mut interface = validation::StageInterface::default();
        let mut validated_stages = wgt::ShaderStage::empty();

        let desc_vbs = &desc.vertex_state.vertex_buffers;
        let mut vertex_strides = Vec::with_capacity(desc_vbs.len());
        let mut vertex_buffers = Vec::with_capacity(desc_vbs.len());
        let mut attributes = Vec::new();
        for (i, vb_state) in desc_vbs.iter().enumerate() {
            vertex_strides
                .alloc()
                .init((vb_state.stride, vb_state.step_mode));
            if vb_state.attributes.is_empty() {
                continue;
            }
            if vb_state.stride % wgt::VERTEX_STRIDE_ALIGNMENT != 0 {
                return Err(pipeline::CreateRenderPipelineError::UnalignedVertexStride {
                    index: i as u32,
                    stride: vb_state.stride,
                });
            }
            vertex_buffers.alloc().init(hal::pso::VertexBufferDesc {
                binding: i as u32,
                stride: vb_state.stride as u32,
                rate: match vb_state.step_mode {
                    InputStepMode::Vertex => hal::pso::VertexInputRate::Vertex,
                    InputStepMode::Instance => hal::pso::VertexInputRate::Instance(1),
                },
            });
            let desc_atts = &vb_state.attributes;
            for attribute in desc_atts.iter() {
                if attribute.offset >= 0x10000000 {
                    return Err(
                        pipeline::CreateRenderPipelineError::InvalidVertexAttributeOffset {
                            location: attribute.shader_location,
                            offset: attribute.offset,
                        },
                    );
                }
                attributes.alloc().init(hal::pso::AttributeDesc {
                    location: attribute.shader_location,
                    binding: i as u32,
                    element: hal::pso::Element {
                        format: conv::map_vertex_format(attribute.format),
                        offset: attribute.offset as u32,
                    },
                });
                interface.insert(
                    attribute.shader_location,
                    validation::MaybeOwned::Owned(validation::map_vertex_format(attribute.format)),
                );
            }
        }

        let input_assembler = hal::pso::InputAssemblerDesc {
            primitive: conv::map_primitive_topology(desc.primitive_topology),
            with_adjacency: false,
            restart_index: None, //TODO
        };

        let blender = hal::pso::BlendDesc {
            logic_op: None, // TODO
            targets: color_states
                .iter()
                .map(conv::map_color_state_descriptor)
                .collect(),
        };
        let depth_stencil = depth_stencil_state
            .map(conv::map_depth_stencil_state_descriptor)
            .unwrap_or_default();

        let multisampling: Option<hal::pso::Multisampling> = if samples == 1 {
            None
        } else {
            Some(hal::pso::Multisampling {
                rasterization_samples: samples,
                sample_shading: None,
                sample_mask: desc.sample_mask as u64,
                alpha_coverage: desc.alpha_to_coverage_enabled,
                alpha_to_one: false,
            })
        };

        // TODO
        let baked_states = hal::pso::BakedStates {
            viewport: None,
            scissor: None,
            blend_color: None,
            depth_bounds: None,
        };

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;
        if rasterization_state.clamp_depth
            && !device.features.contains(wgt::Features::DEPTH_CLAMPING)
        {
            return Err(pipeline::CreateRenderPipelineError::MissingFeature(
                wgt::Features::DEPTH_CLAMPING,
            ));
        }

        let (raw_pipeline, layout_id, layout_ref_count, derived_bind_group_count) = {
            //TODO: only lock mutable if the layout is derived
            let (mut pipeline_layout_guard, mut token) = hub.pipeline_layouts.write(&mut token);
            let (mut bgl_guard, mut token) = hub.bind_group_layouts.write(&mut token);

            let mut derived_group_layouts =
                ArrayVec::<[binding_model::BindEntryMap; MAX_BIND_GROUPS]>::new();
            if desc.layout.is_none() {
                for _ in 0..device.limits.max_bind_groups {
                    derived_group_layouts.push(binding_model::BindEntryMap::default());
                }
            }

            let (shader_module_guard, _) = hub.shader_modules.read(&mut token);

            let rp_key = RenderPassKey {
                colors: color_states
                    .iter()
                    .map(|state| {
                        let at = hal::pass::Attachment {
                            format: Some(conv::map_texture_format(
                                state.format,
                                device.private_features,
                            )),
                            samples,
                            ops: hal::pass::AttachmentOps::PRESERVE,
                            stencil_ops: hal::pass::AttachmentOps::DONT_CARE,
                            layouts: hal::image::Layout::General..hal::image::Layout::General,
                        };
                        (at, hal::image::Layout::ColorAttachmentOptimal)
                    })
                    .collect(),
                // We can ignore the resolves as the vulkan specs says:
                // As an additional special case, if two render passes have a single subpass,
                // they are compatible even if they have different resolve attachment references
                // or depth/stencil resolve modes but satisfy the other compatibility conditions.
                resolves: ArrayVec::new(),
                depth_stencil: depth_stencil_state.map(|state| {
                    let at = hal::pass::Attachment {
                        format: Some(conv::map_texture_format(
                            state.format,
                            device.private_features,
                        )),
                        samples,
                        ops: hal::pass::AttachmentOps::PRESERVE,
                        stencil_ops: hal::pass::AttachmentOps::PRESERVE,
                        layouts: hal::image::Layout::General..hal::image::Layout::General,
                    };
                    (at, hal::image::Layout::DepthStencilAttachmentOptimal)
                }),
            };

            let vertex = {
                let entry_point_name = &desc.vertex_stage.entry_point;
                let flag = wgt::ShaderStage::VERTEX;

                let shader_module =
                    shader_module_guard
                        .get(desc.vertex_stage.module)
                        .map_err(|_| pipeline::CreateRenderPipelineError::Stage {
                            flag,
                            error: validation::StageError::InvalidModule,
                        })?;

                if let Some(ref module) = shader_module.module {
                    let group_layouts = match desc.layout {
                        Some(pipeline_layout_id) => Device::get_introspection_bind_group_layouts(
                            pipeline_layout_guard
                                .get(pipeline_layout_id)
                                .map_err(|_| pipeline::CreateRenderPipelineError::InvalidLayout)?,
                            &*bgl_guard,
                        ),
                        None => validation::IntrospectionBindGroupLayouts::Derived(
                            &mut derived_group_layouts,
                        ),
                    };

                    interface = validation::check_stage(
                        module,
                        group_layouts,
                        &entry_point_name,
                        naga::ShaderStage::Vertex,
                        interface,
                    )
                    .map_err(|error| pipeline::CreateRenderPipelineError::Stage { flag, error })?;
                    validated_stages |= flag;
                }

                hal::pso::EntryPoint::<B> {
                    entry: &entry_point_name, // TODO
                    module: &shader_module.raw,
                    specialization: hal::pso::Specialization::EMPTY,
                }
            };

            let fragment = match &desc.fragment_stage {
                Some(stage) => {
                    let entry_point_name = &stage.entry_point;
                    let flag = wgt::ShaderStage::FRAGMENT;

                    let shader_module = shader_module_guard.get(stage.module).map_err(|_| {
                        pipeline::CreateRenderPipelineError::Stage {
                            flag,
                            error: validation::StageError::InvalidModule,
                        }
                    })?;

                    let group_layouts = match desc.layout {
                        Some(pipeline_layout_id) => Device::get_introspection_bind_group_layouts(
                            pipeline_layout_guard
                                .get(pipeline_layout_id)
                                .map_err(|_| pipeline::CreateRenderPipelineError::InvalidLayout)?,
                            &*bgl_guard,
                        ),
                        None => validation::IntrospectionBindGroupLayouts::Derived(
                            &mut derived_group_layouts,
                        ),
                    };

                    if validated_stages == wgt::ShaderStage::VERTEX {
                        if let Some(ref module) = shader_module.module {
                            interface = validation::check_stage(
                                module,
                                group_layouts,
                                &entry_point_name,
                                naga::ShaderStage::Fragment,
                                interface,
                            )
                            .map_err(|error| {
                                pipeline::CreateRenderPipelineError::Stage { flag, error }
                            })?;
                            validated_stages |= flag;
                        }
                    }

                    Some(hal::pso::EntryPoint::<B> {
                        entry: &entry_point_name,
                        module: &shader_module.raw,
                        specialization: hal::pso::Specialization::EMPTY,
                    })
                }
                None => None,
            };

            if validated_stages.contains(wgt::ShaderStage::FRAGMENT) {
                for (i, state) in color_states.iter().enumerate() {
                    let output = &interface[&(i as wgt::ShaderLocation)];
                    if !validation::check_texture_format(state.format, output) {
                        tracing::warn!(
                            "Incompatible fragment output[{}]. Shader: {:?}. Expected: {:?}",
                            i,
                            state.format,
                            &**output
                        );
                        return Err(
                            pipeline::CreateRenderPipelineError::IncompatibleOutputFormat {
                                index: i as u8,
                            },
                        );
                    }
                }
            }
            let last_stage = match desc.fragment_stage {
                Some(_) => wgt::ShaderStage::FRAGMENT,
                None => wgt::ShaderStage::VERTEX,
            };
            if desc.layout.is_none() && !validated_stages.contains(last_stage) {
                Err(pipeline::ImplicitLayoutError::ReflectionError(last_stage))?
            }

            let primitive_assembler = hal::pso::PrimitiveAssemblerDesc::Vertex {
                buffers: &vertex_buffers,
                attributes: &attributes,
                input_assembler,
                vertex,
                tessellation: None,
                geometry: None,
            };

            // TODO
            let flags = hal::pso::PipelineCreationFlags::empty();
            // TODO
            let parent = hal::pso::BasePipeline::None;

            let (pipeline_layout_id, derived_bind_group_count) = match desc.layout {
                Some(id) => (id, 0),
                None => self.derive_pipeline_layout(
                    device,
                    device_id,
                    implicit_pipeline_ids,
                    derived_group_layouts,
                    &mut *bgl_guard,
                    &mut *pipeline_layout_guard,
                )?,
            };
            let layout = pipeline_layout_guard
                .get(pipeline_layout_id)
                .map_err(|_| pipeline::CreateRenderPipelineError::InvalidLayout)?;

            let mut render_pass_cache = device.render_passes.lock();
            let pipeline_desc = hal::pso::GraphicsPipelineDesc {
                primitive_assembler,
                rasterizer,
                fragment,
                blender,
                depth_stencil,
                multisampling,
                baked_states,
                layout: &layout.raw,
                subpass: hal::pass::Subpass {
                    index: 0,
                    main_pass: match render_pass_cache.entry(rp_key) {
                        Entry::Occupied(e) => e.into_mut(),
                        Entry::Vacant(e) => {
                            let pass = device
                                .create_compatible_render_pass(e.key())
                                .or(Err(DeviceError::OutOfMemory))?;
                            e.insert(pass)
                        }
                    },
                },
                flags,
                parent,
            };
            // TODO: cache
            let raw = unsafe {
                device
                    .raw
                    .create_graphics_pipeline(&pipeline_desc, None)
                    .map_err(|err| match err {
                        hal::pso::CreationError::OutOfMemory(_) => DeviceError::OutOfMemory,
                        _ => panic!("failed to create graphics pipeline: {}", err),
                    })?
            };
            if let Some(_) = desc.label {
                //TODO-0.6: device.set_graphics_pipeline_name(&mut raw, label)
            }

            (
                raw,
                pipeline_layout_id,
                layout.life_guard.add_ref(),
                derived_bind_group_count,
            )
        };

        let pass_context = RenderPassContext {
            attachments: AttachmentData {
                colors: color_states.iter().map(|state| state.format).collect(),
                resolves: ArrayVec::new(),
                depth_stencil: depth_stencil_state
                    .as_ref()
                    .map(|state| state.format.clone()),
            },
            sample_count: samples,
        };

        let mut flags = pipeline::PipelineFlags::empty();
        for state in color_states.iter() {
            if state.color_blend.uses_color() | state.alpha_blend.uses_color() {
                flags |= pipeline::PipelineFlags::BLEND_COLOR;
            }
        }
        if let Some(ds) = depth_stencil_state.as_ref() {
            if ds.stencil.needs_ref_value() {
                flags |= pipeline::PipelineFlags::STENCIL_REFERENCE;
            }
            if !ds.is_read_only() {
                flags |= pipeline::PipelineFlags::WRITES_DEPTH_STENCIL;
            }
        }

        let pipeline = pipeline::RenderPipeline {
            raw: raw_pipeline,
            layout_id: Stored {
                value: id::Valid(layout_id),
                ref_count: layout_ref_count,
            },
            device_id: Stored {
                value: id::Valid(device_id),
                ref_count: device.life_guard.add_ref(),
            },
            pass_context,
            flags,
            index_format: desc.vertex_state.index_format,
            vertex_strides,
            life_guard: LifeGuard::new(),
        };

        let id = hub
            .render_pipelines
            .register_identity(id_in, pipeline, &mut token);

        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => trace.lock().add(trace::Action::CreateRenderPipeline(
                id.0,
                pipeline::RenderPipelineDescriptor {
                    layout: Some(layout_id),
                    ..desc.clone()
                },
            )),
            None => (),
        };
        Ok((id.0, derived_bind_group_count))
    }

    /// Get an ID of one of the bind group layouts. The ID adds a refcount,
    /// which needs to be released by calling `bind_group_layout_drop`.
    pub fn render_pipeline_get_bind_group_layout<B: GfxBackend>(
        &self,
        pipeline_id: id::RenderPipelineId,
        index: u32,
    ) -> Result<id::BindGroupLayoutId, binding_model::GetBindGroupLayoutError> {
        let hub = B::hub(self);
        let mut token = Token::root();
        let (pipeline_layout_guard, mut token) = hub.pipeline_layouts.read(&mut token);
        let (bgl_guard, mut token) = hub.bind_group_layouts.read(&mut token);
        let (_, mut token) = hub.bind_groups.read(&mut token);
        let (pipeline_guard, _) = hub.render_pipelines.read(&mut token);

        let pipeline = pipeline_guard
            .get(pipeline_id)
            .map_err(|_| binding_model::GetBindGroupLayoutError::InvalidPipeline)?;
        let id = pipeline_layout_guard[pipeline.layout_id.value]
            .bind_group_layout_ids
            .get(index as usize)
            .ok_or(binding_model::GetBindGroupLayoutError::InvalidGroupIndex(
                index,
            ))?;
        bgl_guard[*id].multi_ref_count.inc();
        Ok(id.0)
    }

    pub fn render_pipeline_error<B: GfxBackend>(
        &self,
        id_in: Input<G, id::RenderPipelineId>,
    ) -> id::RenderPipelineId {
        let hub = B::hub(self);
        let mut token = Token::root();
        let (_, mut token) = hub.devices.read(&mut token);
        hub.render_pipelines.register_error(id_in, &mut token)
    }

    pub fn render_pipeline_drop<B: GfxBackend>(&self, render_pipeline_id: id::RenderPipelineId) {
        span!(_guard, INFO, "RenderPipeline::drop");
        let hub = B::hub(self);
        let mut token = Token::root();
        let (device_guard, mut token) = hub.devices.read(&mut token);

        let (device_id, layout_id) = {
            let (mut pipeline_guard, _) = hub.render_pipelines.write(&mut token);
            match pipeline_guard.get_mut(render_pipeline_id) {
                Ok(pipeline) => {
                    pipeline.life_guard.ref_count.take();
                    (pipeline.device_id.value, pipeline.layout_id.clone())
                }
                Err(InvalidId) => {
                    hub.render_pipelines
                        .unregister_locked(render_pipeline_id, &mut *pipeline_guard);
                    return;
                }
            }
        };

        let mut life_lock = device_guard[device_id].lock_life(&mut token);
        life_lock
            .suspected_resources
            .render_pipelines
            .push(id::Valid(render_pipeline_id));
        life_lock
            .suspected_resources
            .pipeline_layouts
            .push(layout_id);
    }

    pub fn device_create_compute_pipeline<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        desc: &pipeline::ComputePipelineDescriptor,
        id_in: Input<G, id::ComputePipelineId>,
        implicit_pipeline_ids: Option<ImplicitPipelineIds<G>>,
    ) -> Result<
        (id::ComputePipelineId, pipeline::ImplicitBindGroupCount),
        pipeline::CreateComputePipelineError,
    > {
        span!(_guard, INFO, "Device::create_compute_pipeline");

        let hub = B::hub(self);
        let mut token = Token::root();

        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;
        let (raw_pipeline, layout_id, layout_ref_count, derived_bind_group_count) = {
            //TODO: only lock mutable if the layout is derived
            let (mut pipeline_layout_guard, mut token) = hub.pipeline_layouts.write(&mut token);
            let (mut bgl_guard, mut token) = hub.bind_group_layouts.write(&mut token);

            let mut derived_group_layouts =
                ArrayVec::<[binding_model::BindEntryMap; MAX_BIND_GROUPS]>::new();

            let interface = validation::StageInterface::default();
            let pipeline_stage = &desc.compute_stage;
            let (shader_module_guard, _) = hub.shader_modules.read(&mut token);

            let entry_point_name = &pipeline_stage.entry_point;
            let shader_module = shader_module_guard
                .get(pipeline_stage.module)
                .map_err(|_| {
                    pipeline::CreateComputePipelineError::Stage(
                        validation::StageError::InvalidModule,
                    )
                })?;

            if let Some(ref module) = shader_module.module {
                let group_layouts = match desc.layout {
                    Some(pipeline_layout_id) => Device::get_introspection_bind_group_layouts(
                        pipeline_layout_guard
                            .get(pipeline_layout_id)
                            .map_err(|_| pipeline::CreateComputePipelineError::InvalidLayout)?,
                        &*bgl_guard,
                    ),
                    None => {
                        for _ in 0..device.limits.max_bind_groups {
                            derived_group_layouts.push(binding_model::BindEntryMap::default());
                        }
                        validation::IntrospectionBindGroupLayouts::Derived(
                            &mut derived_group_layouts,
                        )
                    }
                };
                let _ = validation::check_stage(
                    module,
                    group_layouts,
                    &entry_point_name,
                    naga::ShaderStage::Compute,
                    interface,
                )
                .map_err(pipeline::CreateComputePipelineError::Stage)?;
            } else if desc.layout.is_none() {
                Err(pipeline::ImplicitLayoutError::ReflectionError(
                    wgt::ShaderStage::COMPUTE,
                ))?
            }

            let shader = hal::pso::EntryPoint::<B> {
                entry: &entry_point_name, // TODO
                module: &shader_module.raw,
                specialization: hal::pso::Specialization::EMPTY,
            };

            // TODO
            let flags = hal::pso::PipelineCreationFlags::empty();
            // TODO
            let parent = hal::pso::BasePipeline::None;

            let (pipeline_layout_id, derived_bind_group_count) = match desc.layout {
                Some(id) => (id, 0),
                None => self.derive_pipeline_layout(
                    device,
                    device_id,
                    implicit_pipeline_ids,
                    derived_group_layouts,
                    &mut *bgl_guard,
                    &mut *pipeline_layout_guard,
                )?,
            };
            let layout = pipeline_layout_guard
                .get(pipeline_layout_id)
                .map_err(|_| pipeline::CreateComputePipelineError::InvalidLayout)?;

            let pipeline_desc = hal::pso::ComputePipelineDesc {
                shader,
                layout: &layout.raw,
                flags,
                parent,
            };

            let raw = match unsafe { device.raw.create_compute_pipeline(&pipeline_desc, None) } {
                Ok(pipeline) => pipeline,
                Err(hal::pso::CreationError::OutOfMemory(_)) => {
                    return Err(pipeline::CreateComputePipelineError::Device(
                        DeviceError::OutOfMemory,
                    ))
                }
                other => panic!("Compute pipeline creation error: {:?}", other),
            };
            if let Some(_) = desc.label {
                //TODO-0.6: device.raw.set_compute_pipeline_name(&mut raw, label);
            }
            (
                raw,
                pipeline_layout_id,
                layout.life_guard.add_ref(),
                derived_bind_group_count,
            )
        };

        let pipeline = pipeline::ComputePipeline {
            raw: raw_pipeline,
            layout_id: Stored {
                value: id::Valid(layout_id),
                ref_count: layout_ref_count,
            },
            device_id: Stored {
                value: id::Valid(device_id),
                ref_count: device.life_guard.add_ref(),
            },
            life_guard: LifeGuard::new(),
        };
        let id = hub
            .compute_pipelines
            .register_identity(id_in, pipeline, &mut token);

        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => trace.lock().add(trace::Action::CreateComputePipeline(
                id.0,
                pipeline::ComputePipelineDescriptor {
                    layout: Some(layout_id),
                    ..desc.clone()
                },
            )),
            None => (),
        };
        Ok((id.0, derived_bind_group_count))
    }

    /// Get an ID of one of the bind group layouts. The ID adds a refcount,
    /// which needs to be released by calling `bind_group_layout_drop`.
    pub fn compute_pipeline_get_bind_group_layout<B: GfxBackend>(
        &self,
        pipeline_id: id::ComputePipelineId,
        index: u32,
    ) -> Result<id::BindGroupLayoutId, binding_model::GetBindGroupLayoutError> {
        let hub = B::hub(self);
        let mut token = Token::root();
        let (pipeline_layout_guard, mut token) = hub.pipeline_layouts.read(&mut token);
        let (bgl_guard, mut token) = hub.bind_group_layouts.read(&mut token);
        let (_, mut token) = hub.bind_groups.read(&mut token);
        let (pipeline_guard, _) = hub.compute_pipelines.read(&mut token);

        let pipeline = pipeline_guard
            .get(pipeline_id)
            .map_err(|_| binding_model::GetBindGroupLayoutError::InvalidPipeline)?;
        let id = pipeline_layout_guard[pipeline.layout_id.value]
            .bind_group_layout_ids
            .get(index as usize)
            .ok_or(binding_model::GetBindGroupLayoutError::InvalidGroupIndex(
                index,
            ))?;
        bgl_guard[*id].multi_ref_count.inc();
        Ok(id.0)
    }

    pub fn compute_pipeline_error<B: GfxBackend>(
        &self,
        id_in: Input<G, id::ComputePipelineId>,
    ) -> id::ComputePipelineId {
        let hub = B::hub(self);
        let mut token = Token::root();
        let (_, mut token) = hub.devices.read(&mut token);
        hub.compute_pipelines.register_error(id_in, &mut token)
    }

    pub fn compute_pipeline_drop<B: GfxBackend>(&self, compute_pipeline_id: id::ComputePipelineId) {
        span!(_guard, INFO, "ComputePipeline::drop");
        let hub = B::hub(self);
        let mut token = Token::root();
        let (device_guard, mut token) = hub.devices.read(&mut token);

        let (device_id, layout_id) = {
            let (mut pipeline_guard, _) = hub.compute_pipelines.write(&mut token);
            match pipeline_guard.get_mut(compute_pipeline_id) {
                Ok(pipeline) => {
                    pipeline.life_guard.ref_count.take();
                    (pipeline.device_id.value, pipeline.layout_id.clone())
                }
                Err(InvalidId) => {
                    hub.compute_pipelines
                        .unregister_locked(compute_pipeline_id, &mut *pipeline_guard);
                    return;
                }
            }
        };

        let mut life_lock = device_guard[device_id].lock_life(&mut token);
        life_lock
            .suspected_resources
            .compute_pipelines
            .push(id::Valid(compute_pipeline_id));
        life_lock
            .suspected_resources
            .pipeline_layouts
            .push(layout_id);
    }

    pub fn device_create_swap_chain<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        surface_id: id::SurfaceId,
        desc: &wgt::SwapChainDescriptor,
    ) -> Result<id::SwapChainId, swap_chain::CreateSwapChainError> {
        span!(_guard, INFO, "Device::create_swap_chain");

        fn validate_swap_chain_descriptor(
            config: &mut hal::window::SwapchainConfig,
            caps: &hal::window::SurfaceCapabilities,
        ) {
            let width = config.extent.width;
            let height = config.extent.height;
            if width < caps.extents.start().width
                || width > caps.extents.end().width
                || height < caps.extents.start().height
                || height > caps.extents.end().height
            {
                tracing::warn!(
                    "Requested size {}x{} is outside of the supported range: {:?}",
                    width,
                    height,
                    caps.extents
                );
            }
            if !caps.present_modes.contains(config.present_mode) {
                tracing::warn!(
                    "Surface does not support present mode: {:?}, falling back to {:?}",
                    config.present_mode,
                    hal::window::PresentMode::FIFO
                );
                config.present_mode = hal::window::PresentMode::FIFO;
            }
        }

        tracing::info!("creating swap chain {:?}", desc);
        let hub = B::hub(self);
        let mut token = Token::root();

        let (mut surface_guard, mut token) = self.surfaces.write(&mut token);
        let (adapter_guard, mut token) = hub.adapters.read(&mut token);
        let (device_guard, mut token) = hub.devices.read(&mut token);
        let (mut swap_chain_guard, _) = hub.swap_chains.write(&mut token);
        let device = device_guard
            .get(device_id)
            .map_err(|_| DeviceError::Invalid)?;
        let surface = surface_guard
            .get_mut(surface_id)
            .map_err(|_| swap_chain::CreateSwapChainError::InvalidSurface)?;

        let (caps, formats) = {
            let surface = B::get_surface_mut(surface);
            let adapter = &adapter_guard[device.adapter_id.value];
            let queue_family = &adapter.raw.queue_families[0];
            if !surface.supports_queue_family(queue_family) {
                return Err(swap_chain::CreateSwapChainError::UnsupportedQueueFamily);
            }
            let formats = surface.supported_formats(&adapter.raw.physical_device);
            let caps = surface.capabilities(&adapter.raw.physical_device);
            (caps, formats)
        };
        let num_frames = swap_chain::DESIRED_NUM_FRAMES
            .max(*caps.image_count.start())
            .min(*caps.image_count.end());
        let mut config =
            swap_chain::swap_chain_descriptor_to_hal(&desc, num_frames, device.private_features);
        if let Some(formats) = formats {
            if !formats.contains(&config.format) {
                return Err(swap_chain::CreateSwapChainError::UnsupportedFormat {
                    requested: config.format,
                    available: formats,
                });
            }
        }
        validate_swap_chain_descriptor(&mut config, &caps);

        unsafe {
            B::get_surface_mut(surface)
                .configure_swapchain(&device.raw, config)
                .map_err(|err| match err {
                    hal::window::CreationError::OutOfMemory(_) => DeviceError::OutOfMemory,
                    hal::window::CreationError::DeviceLost(_) => DeviceError::Lost,
                    _ => panic!("failed to configure swap chain on creation: {}", err),
                })?;
        }

        let sc_id = surface_id.to_swap_chain_id(B::VARIANT);
        if let Some(sc) = swap_chain_guard.remove(sc_id) {
            if !sc.acquired_view_id.is_none() {
                return Err(swap_chain::CreateSwapChainError::SwapChainOutputExists);
            }
            unsafe {
                device.raw.destroy_semaphore(sc.semaphore);
            }
        }
        #[cfg(feature = "trace")]
        match device.trace {
            Some(ref trace) => trace
                .lock()
                .add(Action::CreateSwapChain(sc_id, desc.clone())),
            None => (),
        };

        let swap_chain = swap_chain::SwapChain {
            life_guard: LifeGuard::new(),
            device_id: Stored {
                value: id::Valid(device_id),
                ref_count: device.life_guard.add_ref(),
            },
            desc: desc.clone(),
            num_frames,
            semaphore: device
                .raw
                .create_semaphore()
                .or(Err(DeviceError::OutOfMemory))?,
            acquired_view_id: None,
            acquired_framebuffers: Vec::new(),
            active_submission_index: 0,
        };
        swap_chain_guard.insert(sc_id, swap_chain);
        Ok(sc_id)
    }

    #[cfg(feature = "replay")]
    /// Only triange suspected resource IDs. This helps us to avoid ID collisions
    /// upon creating new resources when re-playing a trace.
    pub fn device_maintain_ids<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
    ) -> Result<(), InvalidDevice> {
        let hub = B::hub(self);
        let mut token = Token::root();
        let (device_guard, mut token) = hub.devices.read(&mut token);
        let device = device_guard.get(device_id).map_err(|_| InvalidDevice)?;
        device.lock_life(&mut token).triage_suspected(
            &hub,
            &device.trackers,
            #[cfg(feature = "trace")]
            None,
            &mut token,
        );
        Ok(())
    }

    pub fn device_poll<B: GfxBackend>(
        &self,
        device_id: id::DeviceId,
        force_wait: bool,
    ) -> Result<(), WaitIdleError> {
        span!(_guard, INFO, "Device::poll");

        let hub = B::hub(self);
        let mut token = Token::root();
        let callbacks = {
            let (device_guard, mut token) = hub.devices.read(&mut token);
            device_guard
                .get(device_id)
                .map_err(|_| DeviceError::Invalid)?
                .maintain(&hub, force_wait, &mut token)?
        };
        fire_map_callbacks(callbacks);
        Ok(())
    }

    fn poll_devices<B: GfxBackend>(
        &self,
        force_wait: bool,
        callbacks: &mut Vec<BufferMapPendingCallback>,
    ) -> Result<(), WaitIdleError> {
        span!(_guard, INFO, "Device::poll_devices");

        let hub = B::hub(self);
        let mut token = Token::root();
        let (device_guard, mut token) = hub.devices.read(&mut token);
        for (_, device) in device_guard.iter(B::VARIANT) {
            let cbs = device.maintain(&hub, force_wait, &mut token)?;
            callbacks.extend(cbs);
        }
        Ok(())
    }

    pub fn poll_all_devices(&self, force_wait: bool) -> Result<(), WaitIdleError> {
        use crate::backend;
        let mut callbacks = Vec::new();

        backends! {
            #[vulkan] {
                self.poll_devices::<backend::Vulkan>(force_wait, &mut callbacks)?;
            }
            #[metal] {
                self.poll_devices::<backend::Metal>(force_wait, &mut callbacks)?;
            }
            #[dx12] {
                self.poll_devices::<backend::Dx12>(force_wait, &mut callbacks)?;
            }
            #[dx11] {
                self.poll_devices::<backend::Dx11>(force_wait, &mut callbacks)?;
            }
        }

        fire_map_callbacks(callbacks);

        Ok(())
    }

    pub fn device_error<B: GfxBackend>(&self, id_in: Input<G, id::DeviceId>) -> id::DeviceId {
        B::hub(self)
            .devices
            .register_error(id_in, &mut Token::root())
    }

    pub fn device_drop<B: GfxBackend>(&self, device_id: id::DeviceId) {
        span!(_guard, INFO, "Device::drop");

        let hub = B::hub(self);
        let mut token = Token::root();
        let device = {
            let (mut device, _) = hub.devices.unregister(device_id, &mut token);
            device.prepare_to_die();
            device
        };

        // Adapter is only referenced by the device and itself.
        // This isn't a robust way to destroy them, we should find a better one.
        if device.adapter_id.ref_count.load() == 1 {
            let (_adapter, _) = hub
                .adapters
                .unregister(device.adapter_id.value.0, &mut token);
        }

        device.dispose();
    }

    pub fn buffer_map_async<B: GfxBackend>(
        &self,
        buffer_id: id::BufferId,
        range: Range<BufferAddress>,
        op: resource::BufferMapOperation,
    ) -> Result<(), resource::BufferAccessError> {
        span!(_guard, INFO, "Device::buffer_map_async");

        let hub = B::hub(self);
        let mut token = Token::root();
        let (device_guard, mut token) = hub.devices.read(&mut token);
        let (pub_usage, internal_use) = match op.host {
            HostMap::Read => (wgt::BufferUsage::MAP_READ, resource::BufferUse::MAP_READ),
            HostMap::Write => (wgt::BufferUsage::MAP_WRITE, resource::BufferUse::MAP_WRITE),
        };

        if range.start % wgt::COPY_BUFFER_ALIGNMENT != 0
            || range.end % wgt::COPY_BUFFER_ALIGNMENT != 0
        {
            return Err(resource::BufferAccessError::UnalignedRange);
        }

        let (device_id, ref_count) = {
            let (mut buffer_guard, _) = hub.buffers.write(&mut token);
            let buffer = buffer_guard
                .get_mut(buffer_id)
                .map_err(|_| resource::BufferAccessError::InvalidBuffer)?;

            check_buffer_usage(buffer.usage, pub_usage)?;
            buffer.map_state = match buffer.map_state {
                resource::BufferMapState::Init { .. } | resource::BufferMapState::Active { .. } => {
                    return Err(resource::BufferAccessError::AlreadyMapped);
                }
                resource::BufferMapState::Waiting(_) => {
                    op.call_error();
                    return Ok(());
                }
                resource::BufferMapState::Idle => {
                    resource::BufferMapState::Waiting(resource::BufferPendingMapping {
                        sub_range: hal::buffer::SubRange {
                            offset: range.start,
                            size: Some(range.end - range.start),
                        },
                        op,
                        parent_ref_count: buffer.life_guard.add_ref(),
                    })
                }
            };
            tracing::debug!("Buffer {:?} map state -> Waiting", buffer_id);

            (buffer.device_id.value, buffer.life_guard.add_ref())
        };

        let device = &device_guard[device_id];
        device.trackers.lock().buffers.change_replace(
            id::Valid(buffer_id),
            &ref_count,
            (),
            internal_use,
        );

        device
            .lock_life(&mut token)
            .map(id::Valid(buffer_id), ref_count);

        Ok(())
    }

    pub fn buffer_get_mapped_range<B: GfxBackend>(
        &self,
        buffer_id: id::BufferId,
        offset: BufferAddress,
        _size: Option<BufferSize>,
    ) -> Result<*mut u8, resource::BufferAccessError> {
        span!(_guard, INFO, "Device::buffer_get_mapped_range");

        let hub = B::hub(self);
        let mut token = Token::root();
        let (buffer_guard, _) = hub.buffers.read(&mut token);
        let buffer = buffer_guard
            .get(buffer_id)
            .map_err(|_| resource::BufferAccessError::InvalidBuffer)?;

        match buffer.map_state {
            resource::BufferMapState::Init { ptr, .. }
            | resource::BufferMapState::Active { ptr, .. } => unsafe {
                Ok(ptr.as_ptr().offset(offset as isize))
            },
            resource::BufferMapState::Idle | resource::BufferMapState::Waiting(_) => {
                Err(resource::BufferAccessError::NotMapped)
            }
        }
    }

    pub fn buffer_unmap<B: GfxBackend>(
        &self,
        buffer_id: id::BufferId,
    ) -> Result<(), resource::BufferAccessError> {
        span!(_guard, INFO, "Device::buffer_unmap");

        let hub = B::hub(self);
        let mut token = Token::root();

        let (mut device_guard, mut token) = hub.devices.write(&mut token);
        let (mut buffer_guard, _) = hub.buffers.write(&mut token);
        let buffer = buffer_guard
            .get_mut(buffer_id)
            .map_err(|_| resource::BufferAccessError::InvalidBuffer)?;
        let device = &mut device_guard[buffer.device_id.value];

        tracing::debug!("Buffer {:?} map state -> Idle", buffer_id);
        match mem::replace(&mut buffer.map_state, resource::BufferMapState::Idle) {
            resource::BufferMapState::Init {
                ptr,
                stage_buffer,
                stage_memory,
                needs_flush,
            } => {
                #[cfg(feature = "trace")]
                match device.trace {
                    Some(ref trace) => {
                        let mut trace = trace.lock();
                        let data = trace.make_binary("bin", unsafe {
                            std::slice::from_raw_parts(ptr.as_ptr(), buffer.size as usize)
                        });
                        trace.add(trace::Action::WriteBuffer {
                            id: buffer_id,
                            data,
                            range: 0..buffer.size,
                            queued: true,
                        });
                    }
                    None => (),
                };
                let _ = ptr;

                if needs_flush {
                    let segment = hal::memory::Segment::default();
                    unsafe {
                        device
                            .raw
                            .flush_mapped_memory_ranges(iter::once((
                                stage_memory.memory(),
                                segment,
                            )))
                            .unwrap()
                    };
                }

                buffer.life_guard.use_at(device.active_submission_index + 1);
                let region = hal::command::BufferCopy {
                    src: 0,
                    dst: 0,
                    size: buffer.size,
                };
                let transition_src = hal::memory::Barrier::Buffer {
                    states: hal::buffer::Access::HOST_WRITE..hal::buffer::Access::TRANSFER_READ,
                    target: &stage_buffer,
                    range: hal::buffer::SubRange::WHOLE,
                    families: None,
                };
                let transition_dst = hal::memory::Barrier::Buffer {
                    states: hal::buffer::Access::empty()..hal::buffer::Access::TRANSFER_WRITE,
                    target: &buffer.raw,
                    range: hal::buffer::SubRange::WHOLE,
                    families: None,
                };
                unsafe {
                    let cmdbuf = device.borrow_pending_writes();
                    cmdbuf.pipeline_barrier(
                        hal::pso::PipelineStage::HOST..hal::pso::PipelineStage::TRANSFER,
                        hal::memory::Dependencies::empty(),
                        iter::once(transition_src).chain(iter::once(transition_dst)),
                    );
                    if buffer.size > 0 {
                        cmdbuf.copy_buffer(&stage_buffer, &buffer.raw, iter::once(region));
                    }
                }
                device
                    .pending_writes
                    .consume_temp(stage_buffer, stage_memory);
            }
            resource::BufferMapState::Idle => {
                return Err(resource::BufferAccessError::NotMapped);
            }
            resource::BufferMapState::Waiting(_) => {}
            resource::BufferMapState::Active {
                ptr,
                sub_range,
                host,
            } => {
                if host == HostMap::Write {
                    #[cfg(feature = "trace")]
                    match device.trace {
                        Some(ref trace) => {
                            let mut trace = trace.lock();
                            let size = sub_range.size_to(buffer.size);
                            let data = trace.make_binary("bin", unsafe {
                                std::slice::from_raw_parts(ptr.as_ptr(), size as usize)
                            });
                            trace.add(trace::Action::WriteBuffer {
                                id: buffer_id,
                                data,
                                range: sub_range.offset..sub_range.offset + size,
                                queued: false,
                            });
                        }
                        None => (),
                    };
                    let _ = (ptr, sub_range);
                }
                unmap_buffer(&device.raw, buffer)?;
            }
        }
        Ok(())
    }
}