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120 lines
3.2 KiB
C++
120 lines
3.2 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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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_Monitor_h
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#define mozilla_Monitor_h
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#include "mozilla/CondVar.h"
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#include "mozilla/Mutex.h"
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namespace mozilla {
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/**
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* Monitor provides a *non*-reentrant monitor: *not* a Java-style
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* monitor. If your code needs support for reentrancy, use
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* ReentrantMonitor instead. (Rarely should reentrancy be needed.)
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*
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* Instead of directly calling Monitor methods, it's safer and simpler
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* to instead use the RAII wrappers MonitorAutoLock and
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* MonitorAutoUnlock.
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*/
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class Monitor {
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public:
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explicit Monitor(const char* aName)
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: mMutex(aName), mCondVar(mMutex, "[Monitor.mCondVar]") {}
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~Monitor() = default;
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void Lock() { mMutex.Lock(); }
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[[nodiscard]] bool TryLock() { return mMutex.TryLock(); }
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void Unlock() { mMutex.Unlock(); }
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void Wait() { mCondVar.Wait(); }
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CVStatus Wait(TimeDuration aDuration) { return mCondVar.Wait(aDuration); }
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void Notify() { mCondVar.Notify(); }
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void NotifyAll() { mCondVar.NotifyAll(); }
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void AssertCurrentThreadOwns() const { mMutex.AssertCurrentThreadOwns(); }
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void AssertNotCurrentThreadOwns() const {
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mMutex.AssertNotCurrentThreadOwns();
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}
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private:
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Monitor();
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Monitor(const Monitor&);
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Monitor& operator=(const Monitor&);
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Mutex mMutex;
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CondVar mCondVar;
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};
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/**
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* Lock the monitor for the lexical scope instances of this class are
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* bound to (except for MonitorAutoUnlock in nested scopes).
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*
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* The monitor must be unlocked when instances of this class are
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* created.
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*/
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class MOZ_STACK_CLASS MonitorAutoLock {
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public:
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explicit MonitorAutoLock(Monitor& aMonitor) : mMonitor(&aMonitor) {
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mMonitor->Lock();
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}
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~MonitorAutoLock() { mMonitor->Unlock(); }
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void Wait() { mMonitor->Wait(); }
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CVStatus Wait(TimeDuration aDuration) { return mMonitor->Wait(aDuration); }
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void Notify() { mMonitor->Notify(); }
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void NotifyAll() { mMonitor->NotifyAll(); }
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private:
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MonitorAutoLock();
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MonitorAutoLock(const MonitorAutoLock&);
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MonitorAutoLock& operator=(const MonitorAutoLock&);
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static void* operator new(size_t) noexcept(true);
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friend class MonitorAutoUnlock;
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Monitor* mMonitor;
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};
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/**
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* Unlock the monitor for the lexical scope instances of this class
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* are bound to (except for MonitorAutoLock in nested scopes).
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*
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* The monitor must be locked by the current thread when instances of
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* this class are created.
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*/
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class MOZ_STACK_CLASS MonitorAutoUnlock {
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public:
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explicit MonitorAutoUnlock(Monitor& aMonitor) : mMonitor(&aMonitor) {
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mMonitor->Unlock();
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}
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explicit MonitorAutoUnlock(MonitorAutoLock& aMonitorLock)
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: mMonitor(aMonitorLock.mMonitor) {
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mMonitor->Unlock();
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}
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~MonitorAutoUnlock() { mMonitor->Lock(); }
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private:
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MonitorAutoUnlock();
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MonitorAutoUnlock(const MonitorAutoUnlock&);
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MonitorAutoUnlock& operator=(const MonitorAutoUnlock&);
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static void* operator new(size_t) noexcept(true);
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Monitor* mMonitor;
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};
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} // namespace mozilla
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#endif // mozilla_Monitor_h
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