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84 lines
2.2 KiB
C++
84 lines
2.2 KiB
C++
/* -*- Mode: C++; tab-width: 12; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_SyncRunnable_h
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#define mozilla_SyncRunnable_h
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#include "nsThreadUtils.h"
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#include "mozilla/Monitor.h"
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namespace mozilla {
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/**
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* This class will wrap a nsIRunnable and dispatch it to the main thread
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* synchronously. This is different from nsIEventTarget.DISPATCH_SYNC:
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* this class does not spin the event loop waiting for the event to be
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* dispatched. This means that you don't risk reentrance from pending
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* messages, but you must be sure that the target thread does not ever block
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* on this thread, or else you will deadlock.
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*
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* Typical usage:
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* nsRefPtr<SyncRunnable> sr = new SyncRunnable(new myrunnable...());
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* sr->DispatchToThread(t);
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*
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* We also provide a convenience wrapper:
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* SyncRunnable::DispatchToThread(new myrunnable...());
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*
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*/
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class SyncRunnable : public nsRunnable
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{
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public:
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SyncRunnable(nsIRunnable* r)
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: mRunnable(r)
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, mMonitor("SyncRunnable")
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{ }
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void DispatchToThread(nsIEventTarget* thread,
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bool forceDispatch = false)
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{
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nsresult rv;
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bool on;
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if (!forceDispatch) {
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rv = thread->IsOnCurrentThread(&on);
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MOZ_ASSERT(NS_SUCCEEDED(rv));
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if (NS_SUCCEEDED(rv) && on) {
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mRunnable->Run();
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return;
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}
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}
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mozilla::MonitorAutoLock lock(mMonitor);
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rv = thread->Dispatch(this, NS_DISPATCH_NORMAL);
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if (NS_SUCCEEDED(rv)) {
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lock.Wait();
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}
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}
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static void DispatchToThread(nsIEventTarget* thread,
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nsIRunnable* r,
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bool forceDispatch = false)
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{
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nsRefPtr<SyncRunnable> s(new SyncRunnable(r));
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s->DispatchToThread(thread, forceDispatch);
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}
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protected:
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NS_IMETHODIMP Run()
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{
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mRunnable->Run();
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mozilla::MonitorAutoLock(mMonitor).Notify();
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return NS_OK;
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}
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private:
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nsCOMPtr<nsIRunnable> mRunnable;
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mozilla::Monitor mMonitor;
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};
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} // namespace mozilla
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#endif // mozilla_SyncRunnable_h
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