Eagerly destroy CommandBuffer commands after submission

Command buffers hold references to all encoded objects. Freeing them
eagerly significantly reduces the amount memory held before the JS GC
clears the command buffers.

Bug: dawn:262, dawn:372
Change-Id: I68dfa973f980fba8d94611ed1de3c593bdb91a63
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/26562
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Rafael Cintron <rafael.cintron@microsoft.com>
Commit-Queue: Austin Eng <enga@chromium.org>

src/dawn_native/CommandAllocator.cpp

@@ -30,13 +30,7 @@ namespace dawn_native {
     }
 
     CommandIterator::~CommandIterator() {
-        ASSERT(mDataWasDestroyed);
+        ASSERT(IsEmpty());
-
-        if (!IsEmpty()) {
-            for (auto& block : mBlocks) {
-                free(block.block);
-            }
-        }
     }
 
     CommandIterator::CommandIterator(CommandIterator&& other) {
@@ -44,18 +38,13 @@ namespace dawn_native {
             mBlocks = std::move(other.mBlocks);
             other.Reset();
         }
-        other.DataWasDestroyed();
         Reset();
     }
 
     CommandIterator& CommandIterator::operator=(CommandIterator&& other) {
-        if (!other.IsEmpty()) {
+        ASSERT(IsEmpty());
-            mBlocks = std::move(other.mBlocks);
+        mBlocks = std::move(other.mBlocks);
-            other.Reset();
+        other.Reset();
-        } else {
-            mBlocks.clear();
-        }
-        other.DataWasDestroyed();
         Reset();
         return *this;
     }
@@ -66,6 +55,7 @@ namespace dawn_native {
     }
 
     CommandIterator& CommandIterator::operator=(CommandAllocator&& allocator) {
+        ASSERT(IsEmpty());
         mBlocks = allocator.AcquireBlocks();
         Reset();
         return *this;
@@ -97,8 +87,17 @@ namespace dawn_native {
         }
     }
 
-    void CommandIterator::DataWasDestroyed() {
+    void CommandIterator::MakeEmptyAsDataWasDestroyed() {
-        mDataWasDestroyed = true;
+        if (IsEmpty()) {
+            return;
+        }
+
+        for (auto& block : mBlocks) {
+            free(block.block);
+        }
+        mBlocks.clear();
+        Reset();
+        ASSERT(IsEmpty());
     }
 
     bool CommandIterator::IsEmpty() const {

src/dawn_native/CommandAllocator.h

@@ -91,10 +91,13 @@ namespace dawn_native {
             return static_cast<T*>(NextData(sizeof(T) * count, alignof(T)));
         }
 
-        // Needs to be called if iteration was stopped early.
+        // Sets iterator to the beginning of the commands without emptying the list. This method can
+        // be used if iteration was stopped early and the iterator needs to be restarted.
         void Reset();
 
-        void DataWasDestroyed();
+        // This method must to be called after commands have been deleted. This indicates that the
+        // commands have been submitted and they are no longer valid.
+        void MakeEmptyAsDataWasDestroyed();
 
       private:
         bool IsEmpty() const;
@@ -139,7 +142,6 @@ namespace dawn_native {
         size_t mCurrentBlock = 0;
         // Used to avoid a special case for empty iterators.
         uint32_t mEndOfBlock = detail::kEndOfBlock;
-        bool mDataWasDestroyed = false;
     };
 
     class CommandAllocator {

src/dawn_native/CommandBuffer.cpp

@@ -24,18 +24,39 @@
 namespace dawn_native {
 
     CommandBufferBase::CommandBufferBase(CommandEncoder* encoder, const CommandBufferDescriptor*)
-        : ObjectBase(encoder->GetDevice()), mResourceUsages(encoder->AcquireResourceUsages()) {
+        : ObjectBase(encoder->GetDevice()),
+          mCommands(encoder->AcquireCommands()),
+          mResourceUsages(encoder->AcquireResourceUsages()) {
     }
 
     CommandBufferBase::CommandBufferBase(DeviceBase* device, ObjectBase::ErrorTag tag)
         : ObjectBase(device, tag) {
     }
 
+    CommandBufferBase::~CommandBufferBase() {
+        Destroy();
+    }
+
     // static
     CommandBufferBase* CommandBufferBase::MakeError(DeviceBase* device) {
         return new CommandBufferBase(device, ObjectBase::kError);
     }
 
+    MaybeError CommandBufferBase::ValidateCanUseInSubmitNow() const {
+        ASSERT(!IsError());
+
+        if (mDestroyed) {
+            return DAWN_VALIDATION_ERROR("Command buffer reused in submit");
+        }
+        return {};
+    }
+
+    void CommandBufferBase::Destroy() {
+        FreeCommands(&mCommands);
+        mResourceUsages = {};
+        mDestroyed = true;
+    }
+
     const CommandBufferResourceUsage& CommandBufferBase::GetResourceUsages() const {
         return mResourceUsages;
     }

src/dawn_native/CommandBuffer.h

@@ -17,6 +17,8 @@
 
 #include "dawn_native/dawn_platform.h"
 
+#include "dawn_native/CommandAllocator.h"
+#include "dawn_native/Error.h"
 #include "dawn_native/Forward.h"
 #include "dawn_native/ObjectBase.h"
 #include "dawn_native/PassResourceUsage.h"
@@ -31,14 +33,24 @@ namespace dawn_native {
     class CommandBufferBase : public ObjectBase {
       public:
         CommandBufferBase(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor);
+
         static CommandBufferBase* MakeError(DeviceBase* device);
 
+        MaybeError ValidateCanUseInSubmitNow() const;
+        void Destroy();
+
         const CommandBufferResourceUsage& GetResourceUsages() const;
 
+      protected:
+        ~CommandBufferBase();
+
+        CommandIterator mCommands;
+
       private:
         CommandBufferBase(DeviceBase* device, ObjectBase::ErrorTag tag);
 
         CommandBufferResourceUsage mResourceUsages;
+        bool mDestroyed = false;
     };
 
     bool IsCompleteSubresourceCopiedTo(const TextureBase* texture,

src/dawn_native/Commands.cpp

@@ -188,7 +188,8 @@ namespace dawn_native {
                 }
             }
         }
-        commands->DataWasDestroyed();
+
+        commands->MakeEmptyAsDataWasDestroyed();
     }
 
     void SkipCommand(CommandIterator* commands, Command type) {

src/dawn_native/Queue.cpp

@@ -51,24 +51,11 @@ namespace dawn_native {
     }
 
     void QueueBase::Submit(uint32_t commandCount, CommandBufferBase* const* commands) {
-        DeviceBase* device = GetDevice();
+        SubmitInternal(commandCount, commands);
-        if (device->ConsumedError(device->ValidateIsAlive())) {
-            // If device is lost, don't let any commands be submitted
-            return;
-        }
 
-        TRACE_EVENT0(device->GetPlatform(), General, "Queue::Submit");
+        for (uint32_t i = 0; i < commandCount; ++i) {
-        if (device->IsValidationEnabled() &&
+            commands[i]->Destroy();
-            device->ConsumedError(ValidateSubmit(commandCount, commands))) {
-            return;
         }
-        ASSERT(!IsError());
-
-        if (device->ConsumedError(SubmitImpl(commandCount, commands))) {
-            return;
-        }
-        device->GetErrorScopeTracker()->TrackUntilLastSubmitComplete(
-            device->GetCurrentErrorScope());
     }
 
     void QueueBase::Signal(Fence* fence, uint64_t signalValue) {
@@ -170,6 +157,7 @@ namespace dawn_native {
 
         for (uint32_t i = 0; i < commandCount; ++i) {
             DAWN_TRY(GetDevice()->ValidateObject(commands[i]));
+            DAWN_TRY(commands[i]->ValidateCanUseInSubmitNow());
 
             const CommandBufferResourceUsage& usages = commands[i]->GetResourceUsages();
 
@@ -286,6 +274,28 @@ namespace dawn_native {
         return {};
     }
 
+    void QueueBase::SubmitInternal(uint32_t commandCount, CommandBufferBase* const* commands) {
+        DeviceBase* device = GetDevice();
+        if (device->ConsumedError(device->ValidateIsAlive())) {
+            // If device is lost, don't let any commands be submitted
+            return;
+        }
+
+        TRACE_EVENT0(device->GetPlatform(), General, "Queue::Submit");
+        if (device->IsValidationEnabled() &&
+            device->ConsumedError(ValidateSubmit(commandCount, commands))) {
+            return;
+        }
+        ASSERT(!IsError());
+
+        if (device->ConsumedError(SubmitImpl(commandCount, commands))) {
+            return;
+        }
+
+        device->GetErrorScopeTracker()->TrackUntilLastSubmitComplete(
+            device->GetCurrentErrorScope());
+    }
+
     void CopyTextureData(uint8_t* dstPointer,
                          const uint8_t* srcPointer,
                          uint32_t depth,

src/dawn_native/Queue.h

@@ -73,6 +73,8 @@ namespace dawn_native {
                                         size_t dataSize,
                                         const TextureDataLayout* dataLayout,
                                         const Extent3D* writeSize) const;
+
+        void SubmitInternal(uint32_t commandCount, CommandBufferBase* const* commands);
     };
 
     // A helper function used in Queue::WriteTexture. The destination data layout must not

src/dawn_native/d3d12/CommandBufferD3D12.cpp

@@ -535,11 +535,7 @@ namespace dawn_native { namespace d3d12 {
     }  // anonymous namespace
 
     CommandBuffer::CommandBuffer(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor)
-        : CommandBufferBase(encoder, descriptor), mCommands(encoder->AcquireCommands()) {
+        : CommandBufferBase(encoder, descriptor) {
-    }
-
-    CommandBuffer::~CommandBuffer() {
-        FreeCommands(&mCommands);
     }
 
     MaybeError CommandBuffer::RecordCommands(CommandRecordingContext* commandContext) {

src/dawn_native/d3d12/CommandBufferD3D12.h

@@ -16,7 +16,6 @@
 #define DAWNNATIVE_D3D12_COMMANDBUFFERD3D12_H_
 
 #include "common/Constants.h"
-#include "dawn_native/CommandAllocator.h"
 #include "dawn_native/CommandBuffer.h"
 #include "dawn_native/Error.h"
 #include "dawn_native/d3d12/Forward.h"
@@ -43,7 +42,6 @@ namespace dawn_native { namespace d3d12 {
         MaybeError RecordCommands(CommandRecordingContext* commandContext);
 
       private:
-        ~CommandBuffer() override;
         MaybeError RecordComputePass(CommandRecordingContext* commandContext,
                                      BindGroupStateTracker* bindingTracker);
         MaybeError RecordRenderPass(CommandRecordingContext* commandContext,
@@ -55,8 +53,6 @@ namespace dawn_native { namespace d3d12 {
                                    RenderPassBuilder* renderPassBuilder);
         void EmulateBeginRenderPass(CommandRecordingContext* commandContext,
                                     const RenderPassBuilder* renderPassBuilder) const;
-
-        CommandIterator mCommands;
     };
 
 }}  // namespace dawn_native::d3d12

src/dawn_native/metal/CommandBufferMTL.h

@@ -15,7 +15,6 @@
 #ifndef DAWNNATIVE_METAL_COMMANDBUFFERMTL_H_
 #define DAWNNATIVE_METAL_COMMANDBUFFERMTL_H_
 
-#include "dawn_native/CommandAllocator.h"
 #include "dawn_native/CommandBuffer.h"
 #include "dawn_native/Error.h"
 
@@ -37,7 +36,6 @@ namespace dawn_native { namespace metal {
         MaybeError FillCommands(CommandRecordingContext* commandContext);
 
       private:
-        ~CommandBuffer() override;
         MaybeError EncodeComputePass(CommandRecordingContext* commandContext);
         MaybeError EncodeRenderPass(CommandRecordingContext* commandContext,
                                     MTLRenderPassDescriptor* mtlRenderPass,
@@ -48,8 +46,6 @@ namespace dawn_native { namespace metal {
                                             MTLRenderPassDescriptor* mtlRenderPass,
                                             uint32_t width,
                                             uint32_t height);
-
-        CommandIterator mCommands;
     };
 
 }}  // namespace dawn_native::metal

src/dawn_native/metal/CommandBufferMTL.mm

@@ -524,11 +524,7 @@ namespace dawn_native { namespace metal {
     }  // anonymous namespace
 
     CommandBuffer::CommandBuffer(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor)
-        : CommandBufferBase(encoder, descriptor), mCommands(encoder->AcquireCommands()) {
+        : CommandBufferBase(encoder, descriptor) {
-    }
-
-    CommandBuffer::~CommandBuffer() {
-        FreeCommands(&mCommands);
     }
 
     MaybeError CommandBuffer::FillCommands(CommandRecordingContext* commandContext) {

src/dawn_native/null/DeviceNull.cpp

@@ -329,11 +329,7 @@ namespace dawn_native { namespace null {
     // CommandBuffer
 
     CommandBuffer::CommandBuffer(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor)
-        : CommandBufferBase(encoder, descriptor), mCommands(encoder->AcquireCommands()) {
+        : CommandBufferBase(encoder, descriptor) {
-    }
-
-    CommandBuffer::~CommandBuffer() {
-        FreeCommands(&mCommands);
     }
 
     // QuerySet

src/dawn_native/null/DeviceNull.h

@@ -216,10 +216,6 @@ namespace dawn_native { namespace null {
       public:
         CommandBuffer(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor);
 
-      private:
-        ~CommandBuffer() override;
-
-        CommandIterator mCommands;
     };
 
     class QuerySet final : public QuerySetBase {

src/dawn_native/opengl/CommandBufferGL.cpp

@@ -442,11 +442,7 @@ namespace dawn_native { namespace opengl {
     }  // namespace
 
     CommandBuffer::CommandBuffer(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor)
-        : CommandBufferBase(encoder, descriptor), mCommands(encoder->AcquireCommands()) {
+        : CommandBufferBase(encoder, descriptor) {
-    }
-
-    CommandBuffer::~CommandBuffer() {
-        FreeCommands(&mCommands);
     }
 
     void CommandBuffer::Execute() {

src/dawn_native/opengl/CommandBufferGL.h

@@ -15,7 +15,6 @@
 #ifndef DAWNNATIVE_OPENGL_COMMANDBUFFERGL_H_
 #define DAWNNATIVE_OPENGL_COMMANDBUFFERGL_H_
 
-#include "dawn_native/CommandAllocator.h"
 #include "dawn_native/CommandBuffer.h"
 
 namespace dawn_native {
@@ -33,11 +32,8 @@ namespace dawn_native { namespace opengl {
         void Execute();
 
       private:
-        ~CommandBuffer() override;
         void ExecuteComputePass();
         void ExecuteRenderPass(BeginRenderPassCmd* renderPass);
-
-        CommandIterator mCommands;
     };
 
 }}  // namespace dawn_native::opengl

src/dawn_native/vulkan/CommandBufferVk.cpp

@@ -330,11 +330,7 @@ namespace dawn_native { namespace vulkan {
     }
 
     CommandBuffer::CommandBuffer(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor)
-        : CommandBufferBase(encoder, descriptor), mCommands(encoder->AcquireCommands()) {
+        : CommandBufferBase(encoder, descriptor) {
-    }
-
-    CommandBuffer::~CommandBuffer() {
-        FreeCommands(&mCommands);
     }
 
     void CommandBuffer::RecordCopyImageWithTemporaryBuffer(

src/dawn_native/vulkan/CommandBufferVk.h

@@ -15,7 +15,6 @@
 #ifndef DAWNNATIVE_VULKAN_COMMANDBUFFERVK_H_
 #define DAWNNATIVE_VULKAN_COMMANDBUFFERVK_H_
 
-#include "dawn_native/CommandAllocator.h"
 #include "dawn_native/CommandBuffer.h"
 #include "dawn_native/Error.h"
 
@@ -40,7 +39,6 @@ namespace dawn_native { namespace vulkan {
 
       private:
         CommandBuffer(CommandEncoder* encoder, const CommandBufferDescriptor* descriptor);
-        ~CommandBuffer() override;
 
         MaybeError RecordComputePass(CommandRecordingContext* recordingContext);
         MaybeError RecordRenderPass(CommandRecordingContext* recordingContext,
@@ -49,8 +47,6 @@ namespace dawn_native { namespace vulkan {
                                                 const TextureCopy& srcCopy,
                                                 const TextureCopy& dstCopy,
                                                 const Extent3D& copySize);
-
-        CommandIterator mCommands;
     };
 
 }}  // namespace dawn_native::vulkan

src/tests/unittests/CommandAllocatorTests.cpp

@@ -63,7 +63,7 @@ TEST(CommandAllocator, DoNothingAllocator) {
 TEST(CommandAllocator, DoNothingAllocatorWithIterator) {
     CommandAllocator allocator;
     CommandIterator iterator(std::move(allocator));
-    iterator.DataWasDestroyed();
+    iterator.MakeEmptyAsDataWasDestroyed();
 }
 
 // Test basic usage of allocator + iterator
@@ -108,7 +108,7 @@ TEST(CommandAllocator, Basic) {
         hasNext = iterator.NextCommandId(&type);
         ASSERT_FALSE(hasNext);
 
-        iterator.DataWasDestroyed();
+        iterator.MakeEmptyAsDataWasDestroyed();
     }
 }
 
@@ -152,7 +152,7 @@ TEST(CommandAllocator, BasicWithData) {
         hasNext = iterator.NextCommandId(&type);
         ASSERT_FALSE(hasNext);
 
-        iterator.DataWasDestroyed();
+        iterator.MakeEmptyAsDataWasDestroyed();
     }
 }
 
@@ -197,7 +197,7 @@ TEST(CommandAllocator, MultipleIterations) {
         hasNext = iterator.NextCommandId(&type);
         ASSERT_FALSE(hasNext);
 
-        iterator.DataWasDestroyed();
+        iterator.MakeEmptyAsDataWasDestroyed();
     }
 }
 // Test large commands work
@@ -230,7 +230,7 @@ TEST(CommandAllocator, LargeCommands) {
     }
     ASSERT_EQ(numCommands, kCommandCount);
 
-    iterator.DataWasDestroyed();
+    iterator.MakeEmptyAsDataWasDestroyed();
 }
 
 // Test many small commands work
@@ -260,7 +260,7 @@ TEST(CommandAllocator, ManySmallCommands) {
     }
     ASSERT_EQ(numCommands, kCommandCount);
 
-    iterator.DataWasDestroyed();
+    iterator.MakeEmptyAsDataWasDestroyed();
 }
 
 /*        ________
@@ -325,7 +325,7 @@ TEST(CommandAllocator, IteratorReset) {
         hasNext = iterator.NextCommandId(&type);
         ASSERT_FALSE(hasNext);
 
-        iterator.DataWasDestroyed();
+        iterator.MakeEmptyAsDataWasDestroyed();
     }
 }
 
@@ -339,7 +339,7 @@ TEST(CommandAllocator, EmptyIterator) {
         bool hasNext = iterator.NextCommandId(&type);
         ASSERT_FALSE(hasNext);
 
-        iterator.DataWasDestroyed();
+        iterator.MakeEmptyAsDataWasDestroyed();
     }
     {
         CommandAllocator allocator;
@@ -350,8 +350,8 @@ TEST(CommandAllocator, EmptyIterator) {
         bool hasNext = iterator2.NextCommandId(&type);
         ASSERT_FALSE(hasNext);
 
-        iterator1.DataWasDestroyed();
+        iterator1.MakeEmptyAsDataWasDestroyed();
-        iterator2.DataWasDestroyed();
+        iterator2.MakeEmptyAsDataWasDestroyed();
     }
     {
         CommandIterator iterator1;
@@ -361,8 +361,8 @@ TEST(CommandAllocator, EmptyIterator) {
         bool hasNext = iterator2.NextCommandId(&type);
         ASSERT_FALSE(hasNext);
 
-        iterator1.DataWasDestroyed();
+        iterator1.MakeEmptyAsDataWasDestroyed();
-        iterator2.DataWasDestroyed();
+        iterator2.MakeEmptyAsDataWasDestroyed();
     }
 }
 
@@ -425,7 +425,7 @@ TEST(CommandAllocator, AllocateDefaultInitializes) {
     ASSERT_EQ(int44->value, 44);
 
     CommandIterator iterator(std::move(allocator));
-    iterator.DataWasDestroyed();
+    iterator.MakeEmptyAsDataWasDestroyed();
 }
 
 // Test that the allcator correctly defaults initalizes data for AllocateData
@@ -445,5 +445,5 @@ TEST(CommandAllocator, AllocateDataDefaultInitializes) {
     ASSERT_EQ(int35[2].value, 35);
 
     CommandIterator iterator(std::move(allocator));
-    iterator.DataWasDestroyed();
+    iterator.MakeEmptyAsDataWasDestroyed();
 }

src/tests/unittests/ToBackendTests.cpp

@@ -19,17 +19,17 @@
 
 #include <type_traits>
 
-// Make our own Base - Backend object pair, reusing the CommandBuffer name
+// Make our own Base - Backend object pair, reusing the AdapterBase name
 namespace dawn_native {
-    class CommandBufferBase : public RefCounted {};
+    class AdapterBase : public RefCounted {};
 }  // namespace dawn_native
 
 using namespace dawn_native;
 
-class MyCommandBuffer : public CommandBufferBase {};
+class MyAdapter : public AdapterBase {};
 
 struct MyBackendTraits {
-    using CommandBufferType = MyCommandBuffer;
+    using AdapterType = MyAdapter;
 };
 
 // Instanciate ToBackend for our "backend"
@@ -41,48 +41,47 @@ auto ToBackend(T&& common) -> decltype(ToBackendBase<MyBackendTraits>(common)) {
 // Test that ToBackend correctly converts pointers to base classes.
 TEST(ToBackend, Pointers) {
     {
-        MyCommandBuffer* cmdBuf = new MyCommandBuffer;
+        MyAdapter* adapter = new MyAdapter;
-        const CommandBufferBase* base = cmdBuf;
+        const AdapterBase* base = adapter;
 
-        auto backendCmdBuf = ToBackend(base);
+        auto backendAdapter = ToBackend(base);
-        static_assert(std::is_same<decltype(backendCmdBuf), const MyCommandBuffer*>::value, "");
+        static_assert(std::is_same<decltype(backendAdapter), const MyAdapter*>::value, "");
-        ASSERT_EQ(cmdBuf, backendCmdBuf);
+        ASSERT_EQ(adapter, backendAdapter);
 
-        cmdBuf->Release();
+        adapter->Release();
     }
     {
-        MyCommandBuffer* cmdBuf = new MyCommandBuffer;
+        MyAdapter* adapter = new MyAdapter;
-        CommandBufferBase* base = cmdBuf;
+        AdapterBase* base = adapter;
 
-        auto backendCmdBuf = ToBackend(base);
+        auto backendAdapter = ToBackend(base);
-        static_assert(std::is_same<decltype(backendCmdBuf), MyCommandBuffer*>::value, "");
+        static_assert(std::is_same<decltype(backendAdapter), MyAdapter*>::value, "");
-        ASSERT_EQ(cmdBuf, backendCmdBuf);
+        ASSERT_EQ(adapter, backendAdapter);
 
-        cmdBuf->Release();
+        adapter->Release();
     }
 }
 
 // Test that ToBackend correctly converts Refs to base classes.
 TEST(ToBackend, Ref) {
     {
-        MyCommandBuffer* cmdBuf = new MyCommandBuffer;
+        MyAdapter* adapter = new MyAdapter;
-        const Ref<CommandBufferBase> base(cmdBuf);
+        const Ref<AdapterBase> base(adapter);
 
-        const auto& backendCmdBuf = ToBackend(base);
+        const auto& backendAdapter = ToBackend(base);
-        static_assert(std::is_same<decltype(ToBackend(base)), const Ref<MyCommandBuffer>&>::value,
+        static_assert(std::is_same<decltype(ToBackend(base)), const Ref<MyAdapter>&>::value, "");
-                      "");
+        ASSERT_EQ(adapter, backendAdapter.Get());
-        ASSERT_EQ(cmdBuf, backendCmdBuf.Get());
 
-        cmdBuf->Release();
+        adapter->Release();
     }
     {
-        MyCommandBuffer* cmdBuf = new MyCommandBuffer;
+        MyAdapter* adapter = new MyAdapter;
-        Ref<CommandBufferBase> base(cmdBuf);
+        Ref<AdapterBase> base(adapter);
 
-        auto backendCmdBuf = ToBackend(base);
+        auto backendAdapter = ToBackend(base);
-        static_assert(std::is_same<decltype(ToBackend(base)), Ref<MyCommandBuffer>&>::value, "");
+        static_assert(std::is_same<decltype(ToBackend(base)), Ref<MyAdapter>&>::value, "");
-        ASSERT_EQ(cmdBuf, backendCmdBuf.Get());
+        ASSERT_EQ(adapter, backendAdapter.Get());
 
-        cmdBuf->Release();
+        adapter->Release();
     }
 }

src/tests/unittests/validation/QueueSubmitValidationTests.cpp

@@ -23,9 +23,10 @@ namespace {
     // Test submitting with a mapped buffer is disallowed
     TEST_F(QueueSubmitValidationTest, SubmitWithMappedBuffer) {
         // Create a map-write buffer.
+        const uint64_t kBufferSize = 4;
         wgpu::BufferDescriptor descriptor;
         descriptor.usage = wgpu::BufferUsage::MapWrite | wgpu::BufferUsage::CopySrc;
-        descriptor.size = 4;
+        descriptor.size = kBufferSize;
         wgpu::Buffer buffer = device.CreateBuffer(&descriptor);
 
         // Create a fake copy destination buffer
@@ -36,7 +37,7 @@ namespace {
         wgpu::CommandBuffer commands;
         {
             wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
-            encoder.CopyBufferToBuffer(buffer, 0, targetBuffer, 0, 4);
+            encoder.CopyBufferToBuffer(buffer, 0, targetBuffer, 0, kBufferSize);
             commands = encoder.Finish();
         }
 
@@ -45,17 +46,35 @@ namespace {
         // Submitting when the buffer has never been mapped should succeed
         queue.Submit(1, &commands);
 
+        {
+            wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
+            encoder.CopyBufferToBuffer(buffer, 0, targetBuffer, 0, kBufferSize);
+            commands = encoder.Finish();
+        }
+
         // Map the buffer, submitting when the buffer is mapped should fail
-        buffer.MapWriteAsync(nullptr, nullptr);
+        buffer.MapAsync(wgpu::MapMode::Write, 0, kBufferSize, nullptr, nullptr);
 
         // Try submitting before the callback is fired.
         ASSERT_DEVICE_ERROR(queue.Submit(1, &commands));
 
         WaitForAllOperations(device);
 
+        {
+            wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
+            encoder.CopyBufferToBuffer(buffer, 0, targetBuffer, 0, kBufferSize);
+            commands = encoder.Finish();
+        }
+
         // Try submitting after the callback is fired.
         ASSERT_DEVICE_ERROR(queue.Submit(1, &commands));
 
+        {
+            wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
+            encoder.CopyBufferToBuffer(buffer, 0, targetBuffer, 0, kBufferSize);
+            commands = encoder.Finish();
+        }
+
         // Unmap the buffer, queue submit should succeed
         buffer.Unmap();
         queue.Submit(1, &commands);
@@ -182,4 +201,53 @@ namespace {
         }
     }
 
+    // Test it is invalid to submit a command buffer twice
+    TEST_F(QueueSubmitValidationTest, CommandBufferSubmittedTwice) {
+        wgpu::CommandBuffer commandBuffer = device.CreateCommandEncoder().Finish();
+        wgpu::Queue queue = device.GetDefaultQueue();
+
+        // Should succeed
+        queue.Submit(1, &commandBuffer);
+
+        // Should fail because command buffer was already submitted
+        ASSERT_DEVICE_ERROR(queue.Submit(1, &commandBuffer));
+    }
+
+    // Test resubmitting failed command buffers
+    TEST_F(QueueSubmitValidationTest, CommandBufferSubmittedFailed) {
+        // Create a map-write buffer
+        const uint64_t kBufferSize = 4;
+        wgpu::BufferDescriptor descriptor;
+        descriptor.usage = wgpu::BufferUsage::MapWrite | wgpu::BufferUsage::CopySrc;
+        descriptor.size = kBufferSize;
+        wgpu::Buffer buffer = device.CreateBuffer(&descriptor);
+
+        // Create a destination buffer for the b2b copy
+        descriptor.usage = wgpu::BufferUsage::CopyDst;
+        descriptor.size = kBufferSize;
+        wgpu::Buffer targetBuffer = device.CreateBuffer(&descriptor);
+
+        // Create a command buffer that reads from the mappable buffer
+        wgpu::CommandBuffer commands;
+        {
+            wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
+            encoder.CopyBufferToBuffer(buffer, 0, targetBuffer, 0, kBufferSize);
+            commands = encoder.Finish();
+        }
+
+        wgpu::Queue queue = device.GetDefaultQueue();
+
+        // Map the source buffer to force a failure
+        buffer.MapAsync(wgpu::MapMode::Write, 0, kBufferSize, nullptr, nullptr);
+
+        // Submitting a command buffer with a mapped buffer should fail
+        ASSERT_DEVICE_ERROR(queue.Submit(1, &commands));
+
+        // Unmap buffer to fix the failure
+        buffer.Unmap();
+
+        // Resubmitting any command buffer, even if the problem was fixed, should fail
+        ASSERT_DEVICE_ERROR(queue.Submit(1, &commands));
+    }
+
 }  // anonymous namespace