1 files changed, 97 insertions, 0 deletions
diff --git a/xpcom/threads/InputTaskManager.h b/xpcom/threads/InputTaskManager.h
new file mode 100644
index 0000000000..ac3e44b516
--- /dev/null
+++ b/xpcom/threads/InputTaskManager.h
@@ -0,0 +1,97 @@
+/* -*- 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/. */
+
+#ifndef mozilla_InputTaskManager_h
+#define mozilla_InputTaskManager_h
+
+#include "TaskController.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/StaticPrefs_dom.h"
+
+namespace mozilla {
+
+class InputTaskManager : public TaskManager {
+ public:
+  int32_t GetPriorityModifierForEventLoopTurn(
+      const MutexAutoLock& aProofOfLock) final;
+  void WillRunTask() final;
+  void DidRunTask() final;
+
+  enum InputEventQueueState {
+    STATE_DISABLED,
+    STATE_FLUSHING,
+    STATE_SUSPEND,
+    STATE_ENABLED
+  };
+
+  void EnableInputEventPrioritization();
+  void FlushInputEventPrioritization();
+  void SuspendInputEventPrioritization();
+  void ResumeInputEventPrioritization();
+
+  InputEventQueueState State() { return mInputQueueState; }
+
+  void SetState(InputEventQueueState aState) { mInputQueueState = aState; }
+
+  TimeStamp InputHandlingStartTime() { return mInputHandlingStartTime; }
+
+  void SetInputHandlingStartTime(TimeStamp aStartTime) {
+    mInputHandlingStartTime = aStartTime;
+  }
+
+  static InputTaskManager* Get() { return gInputTaskManager.get(); }
+  static void Cleanup() { gInputTaskManager = nullptr; }
+  static void Init();
+
+  bool IsSuspended(const MutexAutoLock& aProofOfLock) override {
+    MOZ_ASSERT(NS_IsMainThread());
+    return mSuspensionLevel > 0;
+  }
+
+  bool IsSuspended() {
+    MOZ_ASSERT(NS_IsMainThread());
+    return mSuspensionLevel > 0;
+  }
+
+  void IncSuspensionLevel() {
+    MOZ_ASSERT(NS_IsMainThread());
+    ++mSuspensionLevel;
+  }
+
+  void DecSuspensionLevel() {
+    MOZ_ASSERT(NS_IsMainThread());
+    --mSuspensionLevel;
+  }
+
+  static bool CanSuspendInputEvent() {
+    // Ensure it's content process because InputTaskManager only
+    // works in e10s.
+    //
+    // Input tasks will have nullptr as their task manager when the
+    // event queue state is STATE_DISABLED, so we can't suspend
+    // input events.
+    return XRE_IsContentProcess() &&
+           StaticPrefs::dom_input_events_canSuspendInBCG_enabled() &&
+           InputTaskManager::Get()->State() !=
+               InputEventQueueState::STATE_DISABLED;
+  }
+
+ private:
+  InputTaskManager() : mInputQueueState(STATE_DISABLED) {}
+
+  TimeStamp mInputHandlingStartTime;
+  Atomic<InputEventQueueState> mInputQueueState;
+  AutoTArray<TimeStamp, 4> mStartTimes;
+
+  static StaticRefPtr<InputTaskManager> gInputTaskManager;
+
+  // Number of BCGs have asked InputTaskManager to suspend input events
+  uint32_t mSuspensionLevel = 0;
+};
+
+}  // namespace mozilla
+
+#endif  // mozilla_InputTaskManager_h