GpuVSyncProvider with unit test

gpu/ipc/service/gpu_vsync_provider_win.cc

+// Copyright (c) 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "gpu/ipc/service/gpu_vsync_provider.h"
+
+#include "base/atomicops.h"
+#include "base/strings/stringprintf.h"
+#include "base/threading/thread.h"
+#include "base/trace_event/trace_event.h"
+
+#include <windows.h>
+
+namespace gpu {
+
+namespace {
+// from <D3dkmthk.h>
+typedef LONG NTSTATUS;
+typedef UINT D3DKMT_HANDLE;
+typedef UINT D3DDDI_VIDEO_PRESENT_SOURCE_ID;
+
+#define STATUS_SUCCESS ((NTSTATUS)0x00000000L)
+
+typedef struct _D3DKMT_OPENADAPTERFROMHDC {
+  HDC hDc;
+  D3DKMT_HANDLE hAdapter;
+  LUID AdapterLuid;
+  D3DDDI_VIDEO_PRESENT_SOURCE_ID VidPnSourceId;
+} D3DKMT_OPENADAPTERFROMHDC;
+
+typedef struct _D3DKMT_CLOSEADAPTER {
+  D3DKMT_HANDLE hAdapter;
+} D3DKMT_CLOSEADAPTER;
+
+typedef struct _D3DKMT_WAITFORVERTICALBLANKEVENT {
+  D3DKMT_HANDLE hAdapter;
+  D3DKMT_HANDLE hDevice;
+  D3DDDI_VIDEO_PRESENT_SOURCE_ID VidPnSourceId;
+} D3DKMT_WAITFORVERTICALBLANKEVENT;
+
+typedef NTSTATUS(APIENTRY* PFND3DKMTOPENADAPTERFROMHDC)(
+    D3DKMT_OPENADAPTERFROMHDC*);
+typedef NTSTATUS(APIENTRY* PFND3DKMTCLOSEADAPTER)(D3DKMT_CLOSEADAPTER*);
+typedef NTSTATUS(APIENTRY* PFND3DKMTWAITFORVERTICALBLANKEVENT)(
+    D3DKMT_WAITFORVERTICALBLANKEVENT*);
+}  // namespace
+
+// The actual implementation of background tasks plus any state that might be
+// needed on the worker thread.
+class GpuVSyncWorker : public base::Thread {
+ public:
+  GpuVSyncWorker(const GpuVSyncProvider::VSyncCallback& callback,
+                 SurfaceHandle surface_handle);
+  ~GpuVSyncWorker() override;
+
+  void Enable(bool enabled);
+  void StartRunningVSyncOnThread();
+  void WaitForVSyncOnThread();
+  void SendVSyncUpdate(base::TimeTicks timestamp);
+  void Reschedule();
+
+ private:
+  // Specifies whether background tasks are running.
+  // This can be set on background thread only.
+  bool running_ = false;
+
+  // Specified whether the worker is enabled.  This is accessed from both
+  // threads but can be changed on the main thread only.
+  base::subtle::AtomicWord enabled_ = false;
+
+  const GpuVSyncProvider::VSyncCallback callback_;
+  const SurfaceHandle surface_handle_;
+
+  PFND3DKMTOPENADAPTERFROMHDC open_adapter_from_hdc_ptr_;
+  PFND3DKMTCLOSEADAPTER close_adapter_ptr_;
+  PFND3DKMTWAITFORVERTICALBLANKEVENT wait_for_vertical_blank_event_ptr_;
+};
+
+GpuVSyncWorker::GpuVSyncWorker(const GpuVSyncProvider::VSyncCallback& callback,
+                               SurfaceHandle surface_handle)
+    : base::Thread(base::StringPrintf("VSync-%d", surface_handle)),
+      callback_(callback),
+      surface_handle_(surface_handle) {
+  HMODULE gdi32 = GetModuleHandle(L"gdi32");
+  if (!gdi32) {
+    NOTREACHED() << "Can't open gdi32.dll";
+    return;
+  }
+
+  open_adapter_from_hdc_ptr_ = reinterpret_cast<PFND3DKMTOPENADAPTERFROMHDC>(
+      ::GetProcAddress(gdi32, "D3DKMTOpenAdapterFromHdc"));
+  if (!open_adapter_from_hdc_ptr_) {
+    NOTREACHED() << "Can't find D3DKMTOpenAdapterFromHdc in gdi32.dll";
+    return;
+  }
+
+  close_adapter_ptr_ = reinterpret_cast<PFND3DKMTCLOSEADAPTER>(
+      ::GetProcAddress(gdi32, "D3DKMTCloseAdapter"));
+  if (!close_adapter_ptr_) {
+    NOTREACHED() << "Can't find D3DKMTCloseAdapter in gdi32.dll";
+    return;
+  }
+
+  wait_for_vertical_blank_event_ptr_ =
+      reinterpret_cast<PFND3DKMTWAITFORVERTICALBLANKEVENT>(
+          ::GetProcAddress(gdi32, "D3DKMTWaitForVerticalBlankEvent"));
+  if (!wait_for_vertical_blank_event_ptr_) {
+    NOTREACHED() << "Can't find D3DKMTWaitForVerticalBlankEvent in gdi32.dll";
+    return;
+  }
+}
+
+GpuVSyncWorker::~GpuVSyncWorker() {
+  Stop();
+}
+
+void GpuVSyncWorker::Enable(bool enabled) {
+  auto was_enabled = base::subtle::NoBarrier_AtomicExchange(&enabled_, enabled);
+
+  if (enabled && !was_enabled)
+    task_runner()->PostTask(
+        FROM_HERE, base::Bind(&GpuVSyncWorker::StartRunningVSyncOnThread,
+                              base::Unretained(this)));
+}
+
+void GpuVSyncWorker::StartRunningVSyncOnThread() {
+  DCHECK(base::PlatformThread::CurrentId() == GetThreadId());
+
+  if (!running_) {
+    running_ = true;
+    WaitForVSyncOnThread();
+  }
+}
+
+void GpuVSyncWorker::WaitForVSyncOnThread() {
+  DCHECK(base::PlatformThread::CurrentId() == GetThreadId());
+
+  TRACE_EVENT0("gpu", "GpuVSyncWorker::WaitForVSyncOnThread");
+
+  HMONITOR monitor =
+      MonitorFromWindow(surface_handle_, MONITOR_DEFAULTTONEAREST);
+  MONITORINFOEX monitor_info;
+  monitor_info.cbSize = sizeof(MONITORINFOEX);
+  BOOL success = GetMonitorInfo(monitor, &monitor_info);
+  CHECK(success);
+
+  HDC hdc = CreateDC(NULL, monitor_info.szDevice, NULL, NULL);
+
+  D3DKMT_OPENADAPTERFROMHDC open_adapter_data;
+  open_adapter_data.hDc = hdc;
+
+  NTSTATUS result = open_adapter_from_hdc_ptr_(&open_adapter_data);

[jbauman, 2017/01/06 03:25:50]

I guess we'll see how the performance of this looks. OpenAdapter definitely has
to do some driver work in the kernel but at least it's not as expensive as
creating a device.

[stanisc, 2017/01/06 21:35:51]

I did some tracing and this didn't look like a noticeable cost. I guess if this
becomes a problem I could add a logic where monitor_info.szDevice is compared to
the previous one and the adapter is opened/closed only when the device name
changes. 

[brucedawson, 2017/01/06 21:43:52]

Maybe do some timing measurements on a few machines and add a comment to
quantify what you're seeing, if only to save future readers from wondering what
counts as "noticeable cost". I guess the thing to measure would be the entire
init sequence, from the beginning of this function to where you call
wait_for_vertical_blank_event_ptr.

That is, add a comment saying the cost in microseconds you are seeing on one or
more machines.

+  DeleteDC(hdc);
+
+  CHECK(result == STATUS_SUCCESS);
+
+  D3DKMT_WAITFORVERTICALBLANKEVENT wait_for_vertical_blank_event_data;
+  wait_for_vertical_blank_event_data.hAdapter = open_adapter_data.hAdapter;
+  wait_for_vertical_blank_event_data.hDevice = 0;
+  wait_for_vertical_blank_event_data.VidPnSourceId =
+      open_adapter_data.VidPnSourceId;
+
+  result =
+      wait_for_vertical_blank_event_ptr_(&wait_for_vertical_blank_event_data);
+  if (result == STATUS_SUCCESS) {
+    // Note: this sends update on background thread which the callback is
+    // expected to handle.
+    SendVSyncUpdate(base::TimeTicks::Now());
+  }
+
+  D3DKMT_CLOSEADAPTER close_adapter_data;
+  close_adapter_data.hAdapter = open_adapter_data.hAdapter;
+
+  result = close_adapter_ptr_(&close_adapter_data);
+  CHECK(result == STATUS_SUCCESS);
+
+  Reschedule();
+}
+
+void GpuVSyncWorker::SendVSyncUpdate(base::TimeTicks timestamp) {
+  if (base::subtle::NoBarrier_Load(&enabled_)) {
+    TRACE_EVENT0("gpu", "GpuVSyncWorker::SendVSyncUpdate");
+    callback_.Run(timestamp);
+  }
+}
+
+void GpuVSyncWorker::Reschedule() {
+  // Restart the task if still enabled.
+  if (base::subtle::NoBarrier_Load(&enabled_)) {
+    task_runner()->PostTask(FROM_HERE,
+                            base::Bind(&GpuVSyncWorker::WaitForVSyncOnThread,
+                                       base::Unretained(this)));
+  } else {
+    running_ = false;
+  }
+}
+
+/* static */
+std::unique_ptr<GpuVSyncProvider> GpuVSyncProvider::Create(
+    const VSyncCallback& callback,
+    SurfaceHandle surface_handle) {
+  return std::unique_ptr<GpuVSyncProvider>(
+      new GpuVSyncProvider(callback, surface_handle));
+}
+
+GpuVSyncProvider::GpuVSyncProvider(const VSyncCallback& callback,
+                                   SurfaceHandle surface_handle)
+    : vsync_worker_(new GpuVSyncWorker(callback, surface_handle)) {
+  // Start the thread.
+  base::Thread::Options options;
+  // TODO(stanisc): might consider even higher priority - REALTIME_AUDIO.
+  options.priority = base::ThreadPriority::DISPLAY;
+  vsync_worker_->StartWithOptions(options);
+}
+
+GpuVSyncProvider::~GpuVSyncProvider() = default;
+
+void GpuVSyncProvider::EnableVSync(bool enabled) {
+  vsync_worker_->Enable(enabled);
+}
+
+}  // namespace gpu