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comparison: xpcom/threads/SyncRunnable.h
xpcom/threads/SyncRunnable.h
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| 1 /* -*- Mode: C++; tab-width: 12; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ | |
| 2 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 3 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 5 | |
| 6 #ifndef mozilla_SyncRunnable_h | |
| 7 #define mozilla_SyncRunnable_h | |
| 8 | |
| 9 #include "nsThreadUtils.h" | |
| 10 #include "mozilla/Monitor.h" | |
| 11 | |
| 12 namespace mozilla { | |
| 13 | |
| 14 /** | |
| 15 * This class will wrap a nsIRunnable and dispatch it to the main thread | |
| 16 * synchronously. This is different from nsIEventTarget.DISPATCH_SYNC: | |
| 17 * this class does not spin the event loop waiting for the event to be | |
| 18 * dispatched. This means that you don't risk reentrance from pending | |
| 19 * messages, but you must be sure that the target thread does not ever block | |
| 20 * on this thread, or else you will deadlock. | |
| 21 * | |
| 22 * Typical usage: | |
| 23 * nsRefPtr<SyncRunnable> sr = new SyncRunnable(new myrunnable...()); | |
| 24 * sr->DispatchToThread(t); | |
| 25 * | |
| 26 * We also provide a convenience wrapper: | |
| 27 * SyncRunnable::DispatchToThread(new myrunnable...()); | |
| 28 * | |
| 29 */ | |
| 30 class SyncRunnable : public nsRunnable | |
| 31 { | |
| 32 public: | |
| 33 SyncRunnable(nsIRunnable* r) | |
| 34 : mRunnable(r) | |
| 35 , mMonitor("SyncRunnable") | |
| 36 , mDone(false) | |
| 37 { } | |
| 38 | |
| 39 void DispatchToThread(nsIEventTarget* thread, | |
| 40 bool forceDispatch = false) | |
| 41 { | |
| 42 nsresult rv; | |
| 43 bool on; | |
| 44 | |
| 45 if (!forceDispatch) { | |
| 46 rv = thread->IsOnCurrentThread(&on); | |
| 47 MOZ_ASSERT(NS_SUCCEEDED(rv)); | |
| 48 if (NS_SUCCEEDED(rv) && on) { | |
| 49 mRunnable->Run(); | |
| 50 return; | |
| 51 } | |
| 52 } | |
| 53 | |
| 54 rv = thread->Dispatch(this, NS_DISPATCH_NORMAL); | |
| 55 if (NS_SUCCEEDED(rv)) { | |
| 56 mozilla::MonitorAutoLock lock(mMonitor); | |
| 57 while (!mDone) { | |
| 58 lock.Wait(); | |
| 59 } | |
| 60 } | |
| 61 } | |
| 62 | |
| 63 static void DispatchToThread(nsIEventTarget* thread, | |
| 64 nsIRunnable* r, | |
| 65 bool forceDispatch = false) | |
| 66 { | |
| 67 nsRefPtr<SyncRunnable> s(new SyncRunnable(r)); | |
| 68 s->DispatchToThread(thread, forceDispatch); | |
| 69 } | |
| 70 | |
| 71 protected: | |
| 72 NS_IMETHODIMP Run() | |
| 73 { | |
| 74 mRunnable->Run(); | |
| 75 | |
| 76 mozilla::MonitorAutoLock lock(mMonitor); | |
| 77 MOZ_ASSERT(!mDone); | |
| 78 | |
| 79 mDone = true; | |
| 80 mMonitor.Notify(); | |
| 81 | |
| 82 return NS_OK; | |
| 83 } | |
| 84 | |
| 85 private: | |
| 86 nsCOMPtr<nsIRunnable> mRunnable; | |
| 87 mozilla::Monitor mMonitor; | |
| 88 bool mDone; | |
| 89 }; | |
| 90 | |
| 91 } // namespace mozilla | |
| 92 | |
| 93 #endif // mozilla_SyncRunnable_h |
