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/* -*- 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_GFX_SYNCHRONOUSTASK_H
#define MOZILLA_GFX_SYNCHRONOUSTASK_H
#include "mozilla/ReentrantMonitor.h" // for ReentrantMonitor, etc
namespace mozilla {
namespace layers {
// Helper that creates a monitor and a "done" flag, then enters the monitor.
class MOZ_STACK_CLASS SynchronousTask {
friend class AutoCompleteTask;
public:
explicit SynchronousTask(const char* name)
: mMonitor(name), mAutoEnter(mMonitor), mDone(false) {}
nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT) {
// For indefinite timeouts, wait in a while loop to handle spurious
// wakeups.
while (aInterval == PR_INTERVAL_NO_TIMEOUT && !mDone) {
mMonitor.Wait();
}
// For finite timeouts, we only check once for completion, and otherwise
// rely on the ReentrantMonitor to manage the interval. If the monitor
// returns too early, we'll never know, but we can check if the mDone
// flag was set to true, indicating that the task finished successfully.
if (!mDone) {
// We ignore the return value from ReentrantMonitor::Wait, because it's
// always NS_OK, even in the case of timeout.
mMonitor.Wait(aInterval);
if (!mDone) {
return NS_ERROR_ABORT;
}
}
return NS_OK;
}
private:
void Complete() {
mDone = true;
mMonitor.NotifyAll();
}
private:
ReentrantMonitor mMonitor MOZ_UNANNOTATED;
ReentrantMonitorAutoEnter mAutoEnter;
bool mDone;
};
class MOZ_STACK_CLASS AutoCompleteTask final {
public:
explicit AutoCompleteTask(SynchronousTask* aTask)
: mTask(aTask), mAutoEnter(aTask->mMonitor) {}
~AutoCompleteTask() { mTask->Complete(); }
private:
SynchronousTask* mTask;
ReentrantMonitorAutoEnter mAutoEnter;
};
} // namespace layers
} // namespace mozilla
#endif
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