1 files changed, 153 insertions, 0 deletions
diff --git a/gfx/layers/d3d11/ReadbackManagerD3D11.cpp b/gfx/layers/d3d11/ReadbackManagerD3D11.cpp
new file mode 100644
index 0000000000..bfe7c12af6
--- /dev/null
+++ b/gfx/layers/d3d11/ReadbackManagerD3D11.cpp
@@ -0,0 +1,153 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#include "ReadbackManagerD3D11.h"
+#include "ReadbackProcessor.h"
+#include "ReadbackLayer.h"
+#include "mozilla/layers/TextureClient.h"
+#include "mozilla/gfx/2D.h"
+
+#include "nsIThread.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+
+using namespace gfx;
+
+namespace layers {
+
+// Structure that contains the information required to execute a readback task,
+// the only member accessed off the main thread here is mReadbackTexture. Since
+// mSink may be released only on the main thread this object should always be
+// destroyed on the main thread!
+struct ReadbackTask {
+  // The texture that we copied the contents of the paintedlayer to.
+  RefPtr<ID3D10Texture2D> mReadbackTexture;
+  // The sink that we're trying to read back to.
+  RefPtr<TextureReadbackSink> mSink;
+};
+
+// This class is created and dispatched from the Readback thread but it must be
+// destroyed by the main thread.
+class ReadbackResultWriterD3D11 final : public nsIRunnable {
+  ~ReadbackResultWriterD3D11() {}
+  NS_DECL_THREADSAFE_ISUPPORTS
+ public:
+  explicit ReadbackResultWriterD3D11(UniquePtr<ReadbackTask>&& aTask)
+      : mTask(std::move(aTask)) {}
+
+  NS_IMETHOD Run() override {
+    D3D10_TEXTURE2D_DESC desc;
+    mTask->mReadbackTexture->GetDesc(&desc);
+
+    D3D10_MAPPED_TEXTURE2D mappedTex;
+    // Unless there is an error this map should succeed immediately, as we've
+    // recently mapped (and unmapped) this copied data on our task thread.
+    HRESULT hr = mTask->mReadbackTexture->Map(0, D3D10_MAP_READ, 0, &mappedTex);
+
+    if (FAILED(hr)) {
+      mTask->mSink->ProcessReadback(nullptr);
+      return NS_OK;
+    }
+
+    {
+      RefPtr<DataSourceSurface> surf = Factory::CreateWrappingDataSourceSurface(
+          (uint8_t*)mappedTex.pData, mappedTex.RowPitch,
+          IntSize(desc.Width, desc.Height), SurfaceFormat::B8G8R8A8);
+
+      mTask->mSink->ProcessReadback(surf);
+
+      MOZ_ASSERT(surf->hasOneRef());
+    }
+
+    mTask->mReadbackTexture->Unmap(0);
+
+    return NS_OK;
+  }
+
+ private:
+  UniquePtr<ReadbackTask> mTask;
+};
+
+NS_IMPL_ISUPPORTS(ReadbackResultWriterD3D11, nsIRunnable)
+
+DWORD WINAPI ReadbackManagerD3D11::StartTaskThread(void* aManager) {
+  static_cast<ReadbackManagerD3D11*>(aManager)->ProcessTasks();
+
+  return 0;
+}
+
+ReadbackManagerD3D11::ReadbackManagerD3D11() : mRefCnt(0) {
+  ::InitializeCriticalSection(&mTaskMutex);
+  mShutdownEvent = ::CreateEventA(nullptr, FALSE, FALSE, nullptr);
+  mTaskSemaphore = ::CreateSemaphoreA(nullptr, 0, 1000000, nullptr);
+  mTaskThread = ::CreateThread(nullptr, 0, StartTaskThread, this, 0, 0);
+}
+
+ReadbackManagerD3D11::~ReadbackManagerD3D11() {
+  ::SetEvent(mShutdownEvent);
+
+  // This shouldn't take longer than 5 seconds, if it does we're going to choose
+  // to leak the thread and its synchronisation in favor of crashing or freezing
+  DWORD result = ::WaitForSingleObject(mTaskThread, 5000);
+  if (result != WAIT_TIMEOUT) {
+    ::DeleteCriticalSection(&mTaskMutex);
+    ::CloseHandle(mShutdownEvent);
+    ::CloseHandle(mTaskSemaphore);
+    ::CloseHandle(mTaskThread);
+  } else {
+    MOZ_CRASH("ReadbackManager: Task thread did not shutdown in 5 seconds.");
+  }
+}
+
+void ReadbackManagerD3D11::PostTask(ID3D10Texture2D* aTexture,
+                                    TextureReadbackSink* aSink) {
+  auto task = MakeUnique<ReadbackTask>();
+  task->mReadbackTexture = aTexture;
+  task->mSink = aSink;
+
+  ::EnterCriticalSection(&mTaskMutex);
+  mPendingReadbackTasks.AppendElement(std::move(task));
+  ::LeaveCriticalSection(&mTaskMutex);
+
+  ::ReleaseSemaphore(mTaskSemaphore, 1, nullptr);
+}
+
+void ReadbackManagerD3D11::ProcessTasks() {
+  HANDLE handles[] = {mTaskSemaphore, mShutdownEvent};
+
+  while (true) {
+    DWORD result = ::WaitForMultipleObjects(2, handles, FALSE, INFINITE);
+    if (result != WAIT_OBJECT_0) {
+      return;
+    }
+
+    ::EnterCriticalSection(&mTaskMutex);
+    if (mPendingReadbackTasks.Length() == 0) {
+      MOZ_CRASH("Trying to read from an empty array, bad bad bad");
+    }
+    UniquePtr<ReadbackTask> nextReadbackTask =
+        std::move(mPendingReadbackTasks[0]);
+    mPendingReadbackTasks.RemoveElementAt(0);
+    ::LeaveCriticalSection(&mTaskMutex);
+
+    // We want to block here until the texture contents are available, the
+    // easiest thing is to simply map and unmap.
+    D3D10_MAPPED_TEXTURE2D mappedTex;
+    nextReadbackTask->mReadbackTexture->Map(0, D3D10_MAP_READ, 0, &mappedTex);
+    nextReadbackTask->mReadbackTexture->Unmap(0);
+
+    // We can only send the update to the sink on the main thread, so post an
+    // event there to do so. Ownership of the task is passed from
+    // mPendingReadbackTasks to ReadbackResultWriter here.
+    nsCOMPtr<nsIThread> thread = do_GetMainThread();
+    thread->Dispatch(new ReadbackResultWriterD3D11(std::move(nextReadbackTask)),
+                     nsIEventTarget::DISPATCH_NORMAL);
+  }
+}
+
+}  // namespace layers
+}  // namespace mozilla