1 files changed, 156 insertions, 0 deletions
diff --git a/xpcom/threads/InputTaskManager.cpp b/xpcom/threads/InputTaskManager.cpp
new file mode 100644
index 0000000000..42b2814290
--- /dev/null
+++ b/xpcom/threads/InputTaskManager.cpp
@@ -0,0 +1,156 @@
+/* -*- 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 "InputTaskManager.h"
+#include "VsyncTaskManager.h"
+#include "nsRefreshDriver.h"
+
+namespace mozilla {
+
+StaticRefPtr<InputTaskManager> InputTaskManager::gInputTaskManager;
+
+void InputTaskManager::EnableInputEventPrioritization() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mInputQueueState == STATE_DISABLED);
+  mInputQueueState = STATE_ENABLED;
+}
+
+void InputTaskManager::FlushInputEventPrioritization() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mInputQueueState == STATE_ENABLED ||
+             mInputQueueState == STATE_SUSPEND);
+  mInputQueueState =
+      mInputQueueState == STATE_ENABLED ? STATE_FLUSHING : STATE_SUSPEND;
+}
+
+void InputTaskManager::SuspendInputEventPrioritization() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mInputQueueState == STATE_ENABLED ||
+             mInputQueueState == STATE_FLUSHING);
+  mInputQueueState = STATE_SUSPEND;
+}
+
+void InputTaskManager::ResumeInputEventPrioritization() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mInputQueueState == STATE_SUSPEND);
+  mInputQueueState = STATE_ENABLED;
+}
+
+int32_t InputTaskManager::GetPriorityModifierForEventLoopTurn(
+    const MutexAutoLock& aProofOfLock) {
+  // When the state is disabled, the input task that we have is
+  // very likely SuspendInputEventQueue, so here we also use
+  // normal priority as ResumeInputEventQueue, FlushInputEventQueue and
+  // SetInputEventQueueEnabled all uses normal priority, to
+  // ensure the ordering is correct.
+  if (State() == InputTaskManager::STATE_DISABLED) {
+    return static_cast<int32_t>(EventQueuePriority::Normal) -
+           static_cast<int32_t>(EventQueuePriority::InputHigh);
+  }
+
+  return GetPriorityModifierForEventLoopTurnForStrictVsyncAlignment();
+}
+
+void InputTaskManager::WillRunTask() {
+  TaskManager::WillRunTask();
+  mInputPriorityController.WillRunTask();
+}
+
+int32_t
+InputTaskManager::GetPriorityModifierForEventLoopTurnForStrictVsyncAlignment() {
+  MOZ_ASSERT(!IsSuspended());
+
+  size_t inputCount = PendingTaskCount();
+  if (inputCount > 0 &&
+      mInputPriorityController.ShouldUseHighestPriority(this)) {
+    return static_cast<int32_t>(EventQueuePriority::InputHighest) -
+           static_cast<int32_t>(EventQueuePriority::InputHigh);
+  }
+
+  if (State() == STATE_FLUSHING ||
+      nsRefreshDriver::GetNextTickHint().isNothing()) {
+    return 0;
+  }
+
+  return static_cast<int32_t>(EventQueuePriority::InputLow) -
+         static_cast<int32_t>(EventQueuePriority::InputHigh);
+}
+
+InputTaskManager::InputPriorityController::InputPriorityController()
+    : mInputVsyncState(InputVsyncState::NoPendingVsync) {}
+
+bool InputTaskManager::InputPriorityController::ShouldUseHighestPriority(
+    InputTaskManager* aInputTaskManager) {
+  if (mInputVsyncState == InputVsyncState::HasPendingVsync) {
+    return true;
+  }
+
+  if (mInputVsyncState == InputVsyncState::RunVsync) {
+    return false;
+  }
+
+  if (mInputVsyncState == InputVsyncState::NoPendingVsync &&
+      VsyncTaskManager::Get()->PendingTaskCount()) {
+    EnterPendingVsyncState(aInputTaskManager->PendingTaskCount());
+    return true;
+  }
+
+  return false;
+}
+
+void InputTaskManager::InputPriorityController::EnterPendingVsyncState(
+    uint32_t aNumPendingTasks) {
+  MOZ_ASSERT(mInputVsyncState == InputVsyncState::NoPendingVsync);
+
+  mInputVsyncState = InputVsyncState::HasPendingVsync;
+  mMaxInputTasksToRun = aNumPendingTasks;
+  mRunInputStartTime = TimeStamp::Now();
+}
+
+void InputTaskManager::InputPriorityController::WillRunVsync() {
+  if (mInputVsyncState == InputVsyncState::RunVsync ||
+      mInputVsyncState == InputVsyncState::HasPendingVsync) {
+    LeavePendingVsyncState(false);
+  }
+}
+
+void InputTaskManager::InputPriorityController::LeavePendingVsyncState(
+    bool aRunVsync) {
+  if (aRunVsync) {
+    MOZ_ASSERT(mInputVsyncState == InputVsyncState::HasPendingVsync);
+    mInputVsyncState = InputVsyncState::RunVsync;
+  } else {
+    mInputVsyncState = InputVsyncState::NoPendingVsync;
+  }
+
+  mMaxInputTasksToRun = 0;
+}
+
+void InputTaskManager::InputPriorityController::WillRunTask() {
+  switch (mInputVsyncState) {
+    case InputVsyncState::NoPendingVsync:
+      return;
+    case InputVsyncState::HasPendingVsync:
+      MOZ_ASSERT(mMaxInputTasksToRun > 0);
+      --mMaxInputTasksToRun;
+      if (!mMaxInputTasksToRun ||
+          TimeStamp::Now() - mRunInputStartTime >=
+              TimeDuration::FromMilliseconds(
+                  StaticPrefs::dom_input_event_queue_duration_max())) {
+        LeavePendingVsyncState(true);
+      }
+      return;
+    default:
+      MOZ_DIAGNOSTIC_ASSERT(
+          false, "Shouldn't run this input task when we suppose to run vsync");
+      return;
+  }
+}
+
+// static
+void InputTaskManager::Init() { gInputTaskManager = new InputTaskManager(); }
+
+}  // namespace mozilla