1 files changed, 89 insertions, 0 deletions
diff --git a/dom/base/TimeoutExecutor.h b/dom/base/TimeoutExecutor.h
new file mode 100644
index 0000000000..991ff8fe7f
--- /dev/null
+++ b/dom/base/TimeoutExecutor.h
@@ -0,0 +1,89 @@
+/* -*- 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_dom_timeoutexecutor_h
+#define mozilla_dom_timeoutexecutor_h
+
+#include "mozilla/TimeStamp.h"
+#include "nsCOMPtr.h"
+#include "nsIRunnable.h"
+#include "nsITimer.h"
+#include "nsINamed.h"
+
+namespace mozilla::dom {
+
+class TimeoutManager;
+
+class TimeoutExecutor final : public nsIRunnable,
+                              public nsITimerCallback,
+                              public nsINamed {
+  TimeoutManager* mOwner;
+  bool mIsIdleQueue;
+  nsCOMPtr<nsITimer> mTimer;
+  TimeStamp mDeadline;
+  uint32_t mMaxIdleDeferMS;
+
+  // Limits how far we allow timers to fire into the future from their
+  // deadline.  Starts off at zero, but is then adjusted when we start
+  // using nsITimer.  The nsITimer implementation may sometimes fire
+  // early and we should allow that to minimize additional wakeups.
+  TimeDuration mAllowedEarlyFiringTime;
+
+  // The TimeoutExecutor is repeatedly scheduled by the TimeoutManager
+  // to fire for the next soonest Timeout.  Since the executor is re-used
+  // it needs to handle switching between a few states.
+  enum class Mode {
+    // None indicates the executor is idle.  It may be scheduled or shutdown.
+    None,
+    // Immediate means the executor is scheduled to run a Timeout with a
+    // deadline that has already expired.
+    Immediate,
+    // Delayed means the executor is scheduled to run a Timeout with a
+    // deadline in the future.
+    Delayed,
+    // Shutdown means the TimeoutManager has been destroyed.  Once this
+    // state is reached the executor cannot be scheduled again.  If the
+    // executor is already dispatched as a runnable or held by a timer then
+    // we may still get a Run()/Notify() call which will be ignored.
+    Shutdown
+  };
+
+  Mode mMode;
+
+  ~TimeoutExecutor();
+
+  nsresult ScheduleImmediate(const TimeStamp& aDeadline, const TimeStamp& aNow);
+
+  nsresult ScheduleDelayed(const TimeStamp& aDeadline, const TimeStamp& aNow,
+                           const TimeDuration& aMinDelay);
+
+  nsresult Schedule(const TimeStamp& aDeadline, const TimeDuration& aMinDelay);
+
+  nsresult MaybeReschedule(const TimeStamp& aDeadline,
+                           const TimeDuration& aMinDelay);
+
+  MOZ_CAN_RUN_SCRIPT void MaybeExecute();
+
+ public:
+  TimeoutExecutor(TimeoutManager* aOwner, bool aIsIdleQueue,
+                  uint32_t aMaxIdleDeferMS);
+
+  void Shutdown();
+
+  nsresult MaybeSchedule(const TimeStamp& aDeadline,
+                         const TimeDuration& aMinDelay);
+
+  void Cancel();
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIRUNNABLE
+  NS_DECL_NSITIMERCALLBACK
+  NS_DECL_NSINAMED
+};
+
+}  // namespace mozilla::dom
+
+#endif  // mozilla_dom_timeoutexecutor_h