Bug 1780792 - Move the buffer creation code in Buffer.cpp. r=jimb

No funcitonal change here, I like to have the code maintaining and depending on the same invariants to be in the same place.

Depends on D151616

Differential Revision: https://phabricator.services.mozilla.com/D151617

dom/webgpu/Buffer.cpp

@@ -53,6 +53,53 @@ Buffer::~Buffer() {
   mozilla::DropJSObjects(this);
 }
 
+already_AddRefed<Buffer> Buffer::Create(Device* aDevice, RawId aDeviceId,
+                                        const dom::GPUBufferDescriptor& aDesc,
+                                        ErrorResult& aRv) {
+  if (aDevice->IsLost()) {
+    RefPtr<Buffer> buffer =
+        new Buffer(aDevice, 0, aDesc.mSize, 0, ipc::Shmem());
+    return buffer.forget();
+  }
+
+  RefPtr<WebGPUChild> actor = aDevice->GetBridge();
+
+  ipc::Shmem shmem;
+  bool hasMapFlags = aDesc.mUsage & (dom::GPUBufferUsage_Binding::MAP_WRITE |
+                                     dom::GPUBufferUsage_Binding::MAP_READ);
+  if (hasMapFlags || aDesc.mMappedAtCreation) {
+    const auto checked = CheckedInt<size_t>(aDesc.mSize);
+    if (!checked.isValid()) {
+      aRv.ThrowRangeError("Mappable size is too large");
+      return nullptr;
+    }
+    const auto& size = checked.value();
+
+    if (!actor->AllocUnsafeShmem(size, &shmem)) {
+      aRv.ThrowAbortError(
+          nsPrintfCString("Unable to allocate shmem of size %" PRIuPTR, size));
+      return nullptr;
+    }
+
+    // zero out memory
+    memset(shmem.get<uint8_t>(), 0, size);
+  }
+
+  MaybeShmem maybeShmem = mozilla::null_t();
+  if (shmem.IsReadable()) {
+    maybeShmem = shmem;
+  }
+  RawId id = actor->DeviceCreateBuffer(aDeviceId, aDesc, std::move(maybeShmem));
+
+  RefPtr<Buffer> buffer =
+      new Buffer(aDevice, id, aDesc.mSize, aDesc.mUsage, std::move(shmem));
+  if (aDesc.mMappedAtCreation) {
+    buffer->SetMapped(!(aDesc.mUsage & dom::GPUBufferUsage_Binding::MAP_READ));
+  }
+
+  return buffer.forget();
+}
+
 bool Buffer::Mappable() const {
   return (mUsage & (dom::GPUBufferUsage_Binding::MAP_WRITE |
                     dom::GPUBufferUsage_Binding::MAP_READ)) != 0;

dom/webgpu/Buffer.h

@@ -17,9 +17,10 @@ namespace mozilla {
 class ErrorResult;
 
 namespace dom {
+struct GPUBufferDescriptor;
 template <typename T>
 class Optional;
-}
+}  // namespace dom
 
 namespace ipc {
 class Shmem;
@@ -43,13 +44,17 @@ class Buffer final : public ObjectBase, public ChildOf<Device> {
   GPU_DECL_CYCLE_COLLECTION(Buffer)
   GPU_DECL_JS_WRAP(Buffer)
 
-  Buffer(Device* const aParent, RawId aId, BufferAddress aSize, uint32_t aUsage,
-         ipc::Shmem&& aShmem);
+  static already_AddRefed<Buffer> Create(Device* aDevice, RawId aDeviceId,
+                                         const dom::GPUBufferDescriptor& aDesc,
+                                         ErrorResult& aRv);
+
   void SetMapped(bool aWritable);
 
   const RawId mId;
 
  private:
+  Buffer(Device* const aParent, RawId aId, BufferAddress aSize, uint32_t aUsage,
+         ipc::Shmem&& aShmem);
   virtual ~Buffer();
   void Cleanup();
   void UnmapArrayBuffers(JSContext* aCx, ErrorResult& aRv);

dom/webgpu/Device.cpp

@@ -95,6 +95,8 @@ void Device::CleanupUnregisteredInParent() {
   mValid = false;
 }
 
+bool Device::IsLost() const { return !mBridge || !mBridge->CanSend(); }
+
 // Generate an error on the Device timeline for this device.
 //
 // aMessage is interpreted as UTF-8.
@@ -121,45 +123,7 @@ dom::Promise* Device::GetLost(ErrorResult& aRv) {
 
 already_AddRefed<Buffer> Device::CreateBuffer(
     const dom::GPUBufferDescriptor& aDesc, ErrorResult& aRv) {
-  if (!mBridge->CanSend()) {
-    RefPtr<Buffer> buffer = new Buffer(this, 0, aDesc.mSize, 0, ipc::Shmem());
-    return buffer.forget();
-  }
-
-  ipc::Shmem shmem;
-  bool hasMapFlags = aDesc.mUsage & (dom::GPUBufferUsage_Binding::MAP_WRITE |
-                                     dom::GPUBufferUsage_Binding::MAP_READ);
-  if (hasMapFlags || aDesc.mMappedAtCreation) {
-    const auto checked = CheckedInt<size_t>(aDesc.mSize);
-    if (!checked.isValid()) {
-      aRv.ThrowRangeError("Mappable size is too large");
-      return nullptr;
-    }
-    const auto& size = checked.value();
-
-    if (!mBridge->AllocUnsafeShmem(size, &shmem)) {
-      aRv.ThrowAbortError(
-          nsPrintfCString("Unable to allocate shmem of size %" PRIuPTR, size));
-      return nullptr;
-    }
-
-    // zero out memory
-    memset(shmem.get<uint8_t>(), 0, size);
-  }
-
-  MaybeShmem maybeShmem = mozilla::null_t();
-  if (shmem.IsReadable()) {
-    maybeShmem = shmem;
-  }
-  RawId id = mBridge->DeviceCreateBuffer(mId, aDesc, std::move(maybeShmem));
-
-  RefPtr<Buffer> buffer =
-      new Buffer(this, id, aDesc.mSize, aDesc.mUsage, std::move(shmem));
-  if (aDesc.mMappedAtCreation) {
-    buffer->SetMapped(!(aDesc.mUsage & dom::GPUBufferUsage_Binding::MAP_READ));
-  }
-
-  return buffer.forget();
+  return Buffer::Create(this, mId, aDesc, aRv);
 }
 
 RefPtr<MappingPromise> Device::MapBufferAsync(RawId aId, uint32_t aMode,

dom/webgpu/Device.h

@@ -114,6 +114,8 @@ class Device final : public DOMEventTargetHelper, public SupportsWeakPtr {
 
   void GenerateError(const nsCString& aMessage);
 
+  bool IsLost() const;
+
  private:
   ~Device();
   void Cleanup();