1 files changed, 365 insertions, 0 deletions
diff --git a/gfx/layers/ipc/CompositorVsyncScheduler.cpp b/gfx/layers/ipc/CompositorVsyncScheduler.cpp
new file mode 100644
index 0000000000..4662a1e3ae
--- /dev/null
+++ b/gfx/layers/ipc/CompositorVsyncScheduler.cpp
@@ -0,0 +1,365 @@
+/* -*- 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 "mozilla/layers/CompositorVsyncScheduler.h"
+
+#include <stdio.h>        // for fprintf, stdout
+#include <stdint.h>       // for uint64_t
+#include "base/task.h"    // for CancelableTask, etc
+#include "base/thread.h"  // for Thread
+#include "gfxPlatform.h"  // for gfxPlatform
+#ifdef MOZ_WIDGET_GTK
+#  include "gfxPlatformGtk.h"  // for gfxPlatform
+#endif
+#include "mozilla/AutoRestore.h"  // for AutoRestore
+#include "mozilla/DebugOnly.h"    // for DebugOnly
+#include "mozilla/StaticPrefs_gfx.h"
+#include "mozilla/StaticPrefs_layers.h"
+#include "mozilla/gfx/2D.h"     // for DrawTarget
+#include "mozilla/gfx/Point.h"  // for IntSize
+#include "mozilla/gfx/Rect.h"   // for IntSize
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/layers/CompositorVsyncSchedulerOwner.h"
+#include "mozilla/mozalloc.h"  // for operator new, etc
+#include "nsCOMPtr.h"          // for already_AddRefed
+#include "nsDebug.h"           // for NS_ASSERTION, etc
+#include "nsISupportsImpl.h"   // for MOZ_COUNT_CTOR, etc
+#include "nsIWidget.h"         // for nsIWidget
+#include "nsThreadUtils.h"     // for NS_IsMainThread
+#include "mozilla/Telemetry.h"
+#include "mozilla/VsyncDispatcher.h"
+#if defined(XP_WIN) || defined(MOZ_WIDGET_GTK)
+#  include "VsyncSource.h"
+#endif
+#include "mozilla/widget/CompositorWidget.h"
+#include "VRManager.h"
+
+namespace mozilla {
+
+namespace layers {
+
+using namespace mozilla::gfx;
+
+CompositorVsyncScheduler::Observer::Observer(CompositorVsyncScheduler* aOwner)
+    : mMutex("CompositorVsyncScheduler.Observer.Mutex"), mOwner(aOwner) {}
+
+CompositorVsyncScheduler::Observer::~Observer() { MOZ_ASSERT(!mOwner); }
+
+bool CompositorVsyncScheduler::Observer::NotifyVsync(const VsyncEvent& aVsync) {
+  MutexAutoLock lock(mMutex);
+  if (!mOwner) {
+    return false;
+  }
+  return mOwner->NotifyVsync(aVsync);
+}
+
+void CompositorVsyncScheduler::Observer::Destroy() {
+  MutexAutoLock lock(mMutex);
+  mOwner = nullptr;
+}
+
+CompositorVsyncScheduler::CompositorVsyncScheduler(
+    CompositorVsyncSchedulerOwner* aVsyncSchedulerOwner,
+    widget::CompositorWidget* aWidget)
+    : mVsyncSchedulerOwner(aVsyncSchedulerOwner),
+      mLastComposeTime(SampleTime::FromNow()),
+      mLastVsyncTime(TimeStamp::Now()),
+      mLastVsyncOutputTime(TimeStamp::Now()),
+      mIsObservingVsync(false),
+      mVsyncNotificationsSkipped(0),
+      mWidget(aWidget),
+      mCurrentCompositeTaskMonitor("CurrentCompositeTaskMonitor"),
+      mCurrentCompositeTask(nullptr),
+      mCurrentVRTaskMonitor("CurrentVRTaskMonitor"),
+      mCurrentVRTask(nullptr) {
+  mVsyncObserver = new Observer(this);
+
+  // mAsapScheduling is set on the main thread during init,
+  // but is only accessed after on the compositor thread.
+  mAsapScheduling =
+      StaticPrefs::layers_offmainthreadcomposition_frame_rate() == 0 ||
+      gfxPlatform::IsInLayoutAsapMode();
+}
+
+CompositorVsyncScheduler::~CompositorVsyncScheduler() {
+  MOZ_ASSERT(!mIsObservingVsync);
+  MOZ_ASSERT(!mVsyncObserver);
+  // The CompositorVsyncDispatcher is cleaned up before this in the
+  // nsBaseWidget, which stops vsync listeners
+  mVsyncSchedulerOwner = nullptr;
+}
+
+void CompositorVsyncScheduler::Destroy() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+
+  if (!mVsyncObserver) {
+    // Destroy was already called on this object.
+    return;
+  }
+  UnobserveVsync();
+  mVsyncObserver->Destroy();
+  mVsyncObserver = nullptr;
+
+  mCompositeRequestedAt = TimeStamp();
+  CancelCurrentCompositeTask();
+  CancelCurrentVRTask();
+}
+
+void CompositorVsyncScheduler::PostCompositeTask(
+    const VsyncEvent& aVsyncEvent) {
+  MonitorAutoLock lock(mCurrentCompositeTaskMonitor);
+  if (mCurrentCompositeTask == nullptr && CompositorThread()) {
+    RefPtr<CancelableRunnable> task = NewCancelableRunnableMethod<VsyncEvent>(
+        "layers::CompositorVsyncScheduler::Composite", this,
+        &CompositorVsyncScheduler::Composite, aVsyncEvent);
+    mCurrentCompositeTask = task;
+    CompositorThread()->Dispatch(task.forget());
+  }
+}
+
+void CompositorVsyncScheduler::PostVRTask(TimeStamp aTimestamp) {
+  MonitorAutoLock lockVR(mCurrentVRTaskMonitor);
+  if (mCurrentVRTask == nullptr && CompositorThread()) {
+    RefPtr<CancelableRunnable> task = NewCancelableRunnableMethod<TimeStamp>(
+        "layers::CompositorVsyncScheduler::DispatchVREvents", this,
+        &CompositorVsyncScheduler::DispatchVREvents, aTimestamp);
+    mCurrentVRTask = task;
+    CompositorThread()->Dispatch(task.forget());
+  }
+}
+
+void CompositorVsyncScheduler::ScheduleComposition() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  if (!mVsyncObserver) {
+    // Destroy was already called on this object.
+    return;
+  }
+
+  // Make a synthetic vsync event for the calls to PostCompositeTask below.
+  TimeStamp vsyncTime = TimeStamp::Now();
+  TimeStamp outputTime = vsyncTime + mVsyncSchedulerOwner->GetVsyncInterval();
+  VsyncEvent vsyncEvent(VsyncId(), vsyncTime, outputTime);
+
+  if (mAsapScheduling) {
+    // Used only for performance testing purposes, and when recording/replaying
+    // to ensure that graphics are up to date.
+    PostCompositeTask(vsyncEvent);
+  } else {
+    if (!mCompositeRequestedAt) {
+      mCompositeRequestedAt = TimeStamp::Now();
+    }
+    if (!mIsObservingVsync && mCompositeRequestedAt) {
+      ObserveVsync();
+      // Starting to observe vsync is an async operation that goes
+      // through the main thread of the UI process. It's possible that
+      // we're blocking there waiting on a composite, so schedule an initial
+      // one now to get things started.
+      PostCompositeTask(vsyncEvent);
+    }
+  }
+}
+
+bool CompositorVsyncScheduler::NotifyVsync(const VsyncEvent& aVsync) {
+  // Called from the vsync dispatch thread. When in the GPU Process, that's
+  // the same as the compositor thread.
+#ifdef DEBUG
+#  ifdef MOZ_WAYLAND
+  // On Wayland, we dispatch vsync from the main thread, without a GPU process.
+  // To allow this, we skip the following asserts if we're currently utilizing
+  // the Wayland backend. The IsParentProcess guard is needed to ensure that
+  // we don't accidentally attempt to initialize the gfxPlatform in the GPU
+  // process on X11.
+  if (!XRE_IsParentProcess() ||
+      !gfxPlatformGtk::GetPlatform()->IsWaylandDisplay())
+#  endif  // MOZ_WAYLAND
+  {
+    MOZ_ASSERT_IF(XRE_IsParentProcess(),
+                  !CompositorThreadHolder::IsInCompositorThread());
+    MOZ_ASSERT(!NS_IsMainThread());
+  }
+
+  MOZ_ASSERT_IF(XRE_GetProcessType() == GeckoProcessType_GPU,
+                CompositorThreadHolder::IsInCompositorThread());
+#endif  // DEBUG
+
+#if defined(MOZ_WIDGET_ANDROID)
+  gfx::VRManager* vm = gfx::VRManager::Get();
+  if (!vm->IsPresenting()) {
+    PostCompositeTask(aVsync);
+  }
+#else
+  PostCompositeTask(aVsync);
+#endif  // defined(MOZ_WIDGET_ANDROID)
+
+  PostVRTask(aVsync.mTime);
+  return true;
+}
+
+void CompositorVsyncScheduler::CancelCurrentVRTask() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread() ||
+             NS_IsMainThread());
+  MonitorAutoLock lock(mCurrentVRTaskMonitor);
+  if (mCurrentVRTask) {
+    mCurrentVRTask->Cancel();
+    mCurrentVRTask = nullptr;
+  }
+}
+
+void CompositorVsyncScheduler::CancelCurrentCompositeTask() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread() ||
+             NS_IsMainThread());
+  MonitorAutoLock lock(mCurrentCompositeTaskMonitor);
+  if (mCurrentCompositeTask) {
+    mCurrentCompositeTask->Cancel();
+    mCurrentCompositeTask = nullptr;
+  }
+}
+
+void CompositorVsyncScheduler::Composite(const VsyncEvent& aVsyncEvent) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  MOZ_ASSERT(mVsyncSchedulerOwner);
+
+  {  // scope lock
+    MonitorAutoLock lock(mCurrentCompositeTaskMonitor);
+    mCurrentCompositeTask = nullptr;
+  }
+
+  mLastVsyncTime = aVsyncEvent.mTime;
+  mLastVsyncOutputTime = aVsyncEvent.mOutputTime;
+  mLastVsyncId = aVsyncEvent.mId;
+
+  if (!mAsapScheduling) {
+    // Some early exit conditions if we're not in ASAP mode
+    if (aVsyncEvent.mTime < mLastComposeTime.Time()) {
+      // We can sometimes get vsync timestamps that are in the past
+      // compared to the last compose with force composites.
+      // In those cases, wait until the next vsync;
+      return;
+    }
+
+    if (mVsyncSchedulerOwner->IsPendingComposite()) {
+      // If previous composite is still on going, finish it and wait for the
+      // next vsync.
+      mVsyncSchedulerOwner->FinishPendingComposite();
+      return;
+    }
+  }
+
+  if (mCompositeRequestedAt || mAsapScheduling) {
+    mCompositeRequestedAt = TimeStamp();
+    mLastComposeTime = SampleTime::FromVsync(aVsyncEvent.mTime);
+
+    // Tell the owner to do a composite
+    mVsyncSchedulerOwner->CompositeToTarget(aVsyncEvent.mId, nullptr, nullptr);
+
+    mVsyncNotificationsSkipped = 0;
+
+    TimeDuration compositeFrameTotal = TimeStamp::Now() - aVsyncEvent.mTime;
+    mozilla::Telemetry::Accumulate(
+        mozilla::Telemetry::COMPOSITE_FRAME_ROUNDTRIP_TIME,
+        compositeFrameTotal.ToMilliseconds());
+  } else if (mVsyncNotificationsSkipped++ >
+             StaticPrefs::gfx_vsync_compositor_unobserve_count_AtStartup()) {
+    UnobserveVsync();
+  }
+}
+
+void CompositorVsyncScheduler::ForceComposeToTarget(gfx::DrawTarget* aTarget,
+                                                    const IntRect* aRect) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+
+  /**
+   * bug 1138502 - There are cases such as during long-running window resizing
+   * events where we receive many force-composites. We also continue to get
+   * vsync notifications. Because the force-composites trigger compositing and
+   * clear the mCompositeRequestedAt timestamp, the vsync notifications will not
+   * need to do anything and so will increment the mVsyncNotificationsSkipped
+   * counter to indicate the vsync was ignored. If this happens enough times, we
+   * will disable listening for vsync entirely. On the next force-composite we
+   * will enable listening for vsync again, and continued force-composites and
+   * vsyncs will cause oscillation between observing vsync and not. On some
+   * platforms, enabling/disabling vsync is not free and this oscillating
+   * behavior causes a performance hit. In order to avoid this problem, we reset
+   * the mVsyncNotificationsSkipped counter to keep vsync enabled.
+   */
+  mVsyncNotificationsSkipped = 0;
+
+  mLastComposeTime = SampleTime::FromNow();
+  MOZ_ASSERT(mVsyncSchedulerOwner);
+  mVsyncSchedulerOwner->CompositeToTarget(VsyncId(), aTarget, aRect);
+}
+
+bool CompositorVsyncScheduler::NeedsComposite() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  return (bool)mCompositeRequestedAt;
+}
+
+bool CompositorVsyncScheduler::FlushPendingComposite() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  if (mCompositeRequestedAt) {
+    CancelCurrentCompositeTask();
+    ForceComposeToTarget(nullptr, nullptr);
+    return true;
+  }
+  return false;
+}
+
+void CompositorVsyncScheduler::ObserveVsync() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  mWidget->ObserveVsync(mVsyncObserver);
+  mIsObservingVsync = true;
+}
+
+void CompositorVsyncScheduler::UnobserveVsync() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  mWidget->ObserveVsync(nullptr);
+  mIsObservingVsync = false;
+}
+
+void CompositorVsyncScheduler::DispatchVREvents(TimeStamp aVsyncTimestamp) {
+  {
+    MonitorAutoLock lock(mCurrentVRTaskMonitor);
+    mCurrentVRTask = nullptr;
+  }
+  // This only allows to be called by CompositorVsyncScheduler::PostVRTask()
+  // When the process is going to shutdown, the runnable has chance to be
+  // executed by other threads, we only want it to be run in the compositor
+  // thread.
+  if (!CompositorThreadHolder::IsInCompositorThread()) {
+    return;
+  }
+
+  VRManager* vm = VRManager::Get();
+  vm->NotifyVsync(aVsyncTimestamp);
+}
+
+const SampleTime& CompositorVsyncScheduler::GetLastComposeTime() const {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  return mLastComposeTime;
+}
+
+const TimeStamp& CompositorVsyncScheduler::GetLastVsyncTime() const {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  return mLastVsyncTime;
+}
+
+const TimeStamp& CompositorVsyncScheduler::GetLastVsyncOutputTime() const {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  return mLastVsyncOutputTime;
+}
+
+const VsyncId& CompositorVsyncScheduler::GetLastVsyncId() const {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  return mLastVsyncId;
+}
+
+void CompositorVsyncScheduler::UpdateLastComposeTime() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  mLastComposeTime = SampleTime::FromNow();
+}
+
+}  // namespace layers
+}  // namespace mozilla