dom/base/SameProcessMessageQueue.cpp

   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 file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "SameProcessMessageQueue.h"
   8 #include "nsThreadUtils.h"
   9
  10 using namespace mozilla;
  11 using namespace mozilla::dom;
  12
  13 SameProcessMessageQueue* SameProcessMessageQueue::sSingleton;
  14
  15 SameProcessMessageQueue::SameProcessMessageQueue() = default;
  16
  17 SameProcessMessageQueue::~SameProcessMessageQueue() {
  18   // This code should run during shutdown, and we should already have pumped the
  19   // event loop. So we should only see messages here if someone is sending
  20   // messages pretty late in shutdown.
  21   NS_WARNING_ASSERTION(mQueue.IsEmpty(),
  22                        "Shouldn't send messages during shutdown");
  23   sSingleton = nullptr;
  24 }
  25
  26 void SameProcessMessageQueue::Push(Runnable* aRunnable) {
  27   mQueue.AppendElement(aRunnable);
  28   NS_DispatchToCurrentThread(aRunnable);
  29 }
  30
  31 void SameProcessMessageQueue::Flush() {
  32   const nsTArray<RefPtr<Runnable>> queue = std::move(mQueue);
  33   for (size_t i = 0; i < queue.Length(); i++) {
  34     queue[i]->Run();
  35   }
  36 }
  37
  38 /* static */
  39 SameProcessMessageQueue* SameProcessMessageQueue::Get() {
  40   if (!sSingleton) {
  41     sSingleton = new SameProcessMessageQueue();
  42   }
  43   return sSingleton;
  44 }
  45
  46 SameProcessMessageQueue::Runnable::Runnable() : mDispatched(false) {}
  47
  48 NS_IMPL_ISUPPORTS(SameProcessMessageQueue::Runnable, nsIRunnable)
  49
  50 nsresult SameProcessMessageQueue::Runnable::Run() {
  51   if (mDispatched) {
  52     return NS_OK;
  53   }
  54
  55   SameProcessMessageQueue* queue = SameProcessMessageQueue::Get();
  56   queue->mQueue.RemoveElement(this);
  57
  58   mDispatched = true;
  59   return HandleMessage();
  60 }