1 files changed, 103 insertions, 0 deletions
diff --git a/dom/ipc/VsyncParent.cpp b/dom/ipc/VsyncParent.cpp
new file mode 100644
index 0000000000..617e054cd3
--- /dev/null
+++ b/dom/ipc/VsyncParent.cpp
@@ -0,0 +1,103 @@
+/* -*- 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 "VsyncParent.h"
+
+#include "mozilla/Unused.h"
+#include "nsThreadUtils.h"
+#include "nsIThread.h"
+
+namespace mozilla::dom {
+
+VsyncParent::VsyncParent()
+    : mObservingVsync(false),
+      mDestroyed(false),
+      mInitialThread(NS_GetCurrentThread()) {}
+
+void VsyncParent::UpdateVsyncDispatcher(
+    const RefPtr<VsyncDispatcher>& aVsyncDispatcher) {
+  if (aVsyncDispatcher == mVsyncDispatcher) {
+    return;
+  }
+
+  if (mObservingVsync && mVsyncDispatcher) {
+    mVsyncDispatcher->RemoveVsyncObserver(this);
+  }
+  mVsyncDispatcher = aVsyncDispatcher;
+  if (mObservingVsync) {
+    mVsyncDispatcher->AddVsyncObserver(this);
+  }
+}
+
+void VsyncParent::NotifyVsync(const VsyncEvent& aVsync) {
+  if (IsOnInitialThread()) {
+    DispatchVsyncEvent(aVsync);
+    return;
+  }
+
+  // Called on hardware vsync thread. We should post to current ipc thread.
+  nsCOMPtr<nsIRunnable> vsyncEvent = NewRunnableMethod<VsyncEvent>(
+      "dom::VsyncParent::DispatchVsyncEvent", this,
+      &VsyncParent::DispatchVsyncEvent, aVsync);
+  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToThreadQueue(
+      vsyncEvent.forget(), mInitialThread, EventQueuePriority::Vsync));
+}
+
+void VsyncParent::DispatchVsyncEvent(const VsyncEvent& aVsync) {
+  AssertIsOnInitialThread();
+
+  // If we call NotifyVsync() when we handle ActorDestroy() message, we might
+  // still call DispatchVsyncEvent().
+  // Similarly, we might also receive RecvUnobserveVsync() when call
+  // NotifyVsync(). We use mObservingVsync and mDestroyed flags to skip this
+  // notification.
+  if (mObservingVsync && !mDestroyed) {
+    TimeDuration vsyncRate = mVsyncDispatcher->GetVsyncRate();
+    Unused << SendNotify(aVsync, vsyncRate.ToMilliseconds());
+  }
+}
+
+mozilla::ipc::IPCResult VsyncParent::RecvObserve() {
+  AssertIsOnInitialThread();
+  if (!mObservingVsync) {
+    if (mVsyncDispatcher) {
+      mVsyncDispatcher->AddVsyncObserver(this);
+    }
+    mObservingVsync = true;
+    return IPC_OK();
+  }
+  return IPC_FAIL_NO_REASON(this);
+}
+
+mozilla::ipc::IPCResult VsyncParent::RecvUnobserve() {
+  AssertIsOnInitialThread();
+  if (mObservingVsync) {
+    if (mVsyncDispatcher) {
+      mVsyncDispatcher->RemoveVsyncObserver(this);
+    }
+    mObservingVsync = false;
+    return IPC_OK();
+  }
+  return IPC_FAIL_NO_REASON(this);
+}
+
+void VsyncParent::ActorDestroy(ActorDestroyReason aActorDestroyReason) {
+  MOZ_ASSERT(!mDestroyed);
+  AssertIsOnInitialThread();
+  if (mObservingVsync && mVsyncDispatcher) {
+    mVsyncDispatcher->RemoveVsyncObserver(this);
+  }
+  mVsyncDispatcher = nullptr;
+  mDestroyed = true;
+}
+
+bool VsyncParent::IsOnInitialThread() {
+  return NS_GetCurrentThread() == mInitialThread;
+}
+
+void VsyncParent::AssertIsOnInitialThread() { MOZ_ASSERT(IsOnInitialThread()); }
+
+}  // namespace mozilla::dom