xpcom/threads/EventQueue.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_EventQueue_h
   8 #define mozilla_EventQueue_h
   9
  10 #include "mozilla/Mutex.h"
  11 #include "mozilla/Queue.h"
  12 #include "mozilla/TimeStamp.h"
  13 #include "nsCOMPtr.h"
  14 #include "nsIRunnable.h"
  15
  16 namespace mozilla {
  17
  18 #define EVENT_QUEUE_PRIORITY_LIST(EVENT_PRIORITY) \
  19   EVENT_PRIORITY(Idle, 0)                         \
  20   EVENT_PRIORITY(DeferredTimers, 1)               \
  21   EVENT_PRIORITY(Low, 2)                          \
  22   EVENT_PRIORITY(InputLow, 3)                     \
  23   EVENT_PRIORITY(Normal, 4)                       \
  24   EVENT_PRIORITY(MediumHigh, 5)                   \
  25   EVENT_PRIORITY(InputHigh, 6)                    \
  26   EVENT_PRIORITY(Vsync, 7)                        \
  27   EVENT_PRIORITY(InputHighest, 8)                 \
  28   EVENT_PRIORITY(RenderBlocking, 9)               \
  29   EVENT_PRIORITY(Control, 10)
  30
  31 enum class EventQueuePriority {
  32 #define EVENT_PRIORITY(NAME, VALUE) NAME = VALUE,
  33   EVENT_QUEUE_PRIORITY_LIST(EVENT_PRIORITY)
  34 #undef EVENT_PRIORITY
  35       Invalid
  36 };
  37
  38 class IdlePeriodState;
  39
  40 namespace detail {
  41
  42 // EventQueue is our unsynchronized event queue implementation. It is a queue
  43 // of runnables used for non-main thread, as well as optionally providing
  44 // forwarding to TaskController.
  45 //
  46 // Since EventQueue is unsynchronized, it should be wrapped in an outer
  47 // SynchronizedEventQueue implementation (like ThreadEventQueue).
  48 template <size_t ItemsPerPage>
  49 class EventQueueInternal {
  50  public:
  51   explicit EventQueueInternal(bool aForwardToTC) : mForwardToTC(aForwardToTC) {}
  52
  53   // Add an event to the end of the queue. Implementors are free to use
  54   // aPriority however they wish.  If the runnable supports
  55   // nsIRunnablePriority and the implementing class supports
  56   // prioritization, aPriority represents the result of calling
  57   // nsIRunnablePriority::GetPriority().  *aDelay is time the event has
  58   // already been delayed (used when moving an event from one queue to
  59   // another)
  60   void PutEvent(already_AddRefed<nsIRunnable>&& aEvent,
  61                 EventQueuePriority aPriority, const MutexAutoLock& aProofOfLock,
  62                 mozilla::TimeDuration* aDelay = nullptr);
  63
  64   // Get an event from the front of the queue. This should return null if the
  65   // queue is non-empty but the event in front is not ready to run.
  66   // *aLastEventDelay is the time the event spent in queues before being
  67   // retrieved.
  68   already_AddRefed<nsIRunnable> GetEvent(
  69       const MutexAutoLock& aProofOfLock,
  70       mozilla::TimeDuration* aLastEventDelay = nullptr);
  71
  72   // Returns true if the queue is empty. Implies !HasReadyEvent().
  73   bool IsEmpty(const MutexAutoLock& aProofOfLock);
  74
  75   // Returns true if the queue is non-empty and if the event in front is ready
  76   // to run. Implies !IsEmpty(). This should return true iff GetEvent returns a
  77   // non-null value.
  78   bool HasReadyEvent(const MutexAutoLock& aProofOfLock);
  79
  80   // Returns the number of events in the queue.
  81   size_t Count(const MutexAutoLock& aProofOfLock) const;
  82   // For some reason, if we put this in the .cpp file the linker can't find it
  83   already_AddRefed<nsIRunnable> PeekEvent(const MutexAutoLock& aProofOfLock) {
  84     if (mQueue.IsEmpty()) {
  85       return nullptr;
  86     }
  87
  88     nsCOMPtr<nsIRunnable> result = mQueue.FirstElement();
  89     return result.forget();
  90   }
  91
  92   void EnableInputEventPrioritization(const MutexAutoLock& aProofOfLock) {}
  93   void FlushInputEventPrioritization(const MutexAutoLock& aProofOfLock) {}
  94   void SuspendInputEventPrioritization(const MutexAutoLock& aProofOfLock) {}
  95   void ResumeInputEventPrioritization(const MutexAutoLock& aProofOfLock) {}
  96
  97   size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
  98     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
  99   }
 100
 101   size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
 102     size_t size = mQueue.ShallowSizeOfExcludingThis(aMallocSizeOf);
 103     size += mDispatchTimes.ShallowSizeOfExcludingThis(aMallocSizeOf);
 104     return size;
 105   }
 106
 107  private:
 108   mozilla::Queue<nsCOMPtr<nsIRunnable>, ItemsPerPage> mQueue;
 109   // This queue is only populated when the profiler is turned on.
 110   mozilla::Queue<mozilla::TimeStamp, ItemsPerPage> mDispatchTimes;
 111   TimeDuration mLastEventDelay;
 112   // This indicates PutEvent forwards runnables to the TaskController. This
 113   // should be true for the top level event queue on the main thread.
 114   bool mForwardToTC;
 115 };
 116
 117 }  // namespace detail
 118
 119 class EventQueue final : public mozilla::detail::EventQueueInternal<16> {
 120  public:
 121   explicit EventQueue(bool aForwardToTC = false)
 122       : mozilla::detail::EventQueueInternal<16>(aForwardToTC) {}
 123 };
 124
 125 template <size_t ItemsPerPage = 16>
 126 class EventQueueSized final
 127     : public mozilla::detail::EventQueueInternal<ItemsPerPage> {
 128  public:
 129   explicit EventQueueSized(bool aForwardToTC = false)
 130       : mozilla::detail::EventQueueInternal<ItemsPerPage>(aForwardToTC) {}
 131 };
 132
 133 }  // namespace mozilla
 134
 135 #endif  // mozilla_EventQueue_h