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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_StaticMonitor_h
#define mozilla_StaticMonitor_h
#include "mozilla/Atomics.h"
#include "mozilla/CondVar.h"
namespace mozilla {
class MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS StaticMonitor {
public:
// In debug builds, check that mMutex is initialized for us as we expect by
// the compiler. In non-debug builds, don't declare a constructor so that
// the compiler can see that the constructor is trivial.
#ifdef DEBUG
StaticMonitor() { MOZ_ASSERT(!mMutex); }
#endif
void Lock() { Mutex()->Lock(); }
void Unlock() { Mutex()->Unlock(); }
void Wait() { CondVar()->Wait(); }
CVStatus Wait(TimeDuration aDuration) { return CondVar()->Wait(aDuration); }
void Notify() { CondVar()->Notify(); }
void NotifyAll() { CondVar()->NotifyAll(); }
void AssertCurrentThreadOwns() {
#ifdef DEBUG
Mutex()->AssertCurrentThreadOwns();
#endif
}
private:
OffTheBooksMutex* Mutex() {
if (mMutex) {
return mMutex;
}
OffTheBooksMutex* mutex = new OffTheBooksMutex("StaticMutex");
if (!mMutex.compareExchange(nullptr, mutex)) {
delete mutex;
}
return mMutex;
}
OffTheBooksCondVar* CondVar() {
if (mCondVar) {
return mCondVar;
}
OffTheBooksCondVar* condvar =
new OffTheBooksCondVar(*Mutex(), "StaticCondVar");
if (!mCondVar.compareExchange(nullptr, condvar)) {
delete condvar;
}
return mCondVar;
}
Atomic<OffTheBooksMutex*> mMutex;
Atomic<OffTheBooksCondVar*> mCondVar;
// Disallow copy constructor, but only in debug mode. We only define
// a default constructor in debug mode (see above); if we declared
// this constructor always, the compiler wouldn't generate a trivial
// default constructor for us in non-debug mode.
#ifdef DEBUG
StaticMonitor(const StaticMonitor& aOther);
#endif
// Disallow these operators.
StaticMonitor& operator=(const StaticMonitor& aRhs);
static void* operator new(size_t) noexcept(true);
static void operator delete(void*);
};
class MOZ_STACK_CLASS StaticMonitorAutoLock {
public:
explicit StaticMonitorAutoLock(StaticMonitor& aMonitor)
: mMonitor(&aMonitor) {
mMonitor->Lock();
}
~StaticMonitorAutoLock() { mMonitor->Unlock(); }
void Wait() { mMonitor->Wait(); }
CVStatus Wait(TimeDuration aDuration) { return mMonitor->Wait(aDuration); }
void Notify() { mMonitor->Notify(); }
void NotifyAll() { mMonitor->NotifyAll(); }
private:
StaticMonitorAutoLock();
StaticMonitorAutoLock(const StaticMonitorAutoLock&);
StaticMonitorAutoLock& operator=(const StaticMonitorAutoLock&);
static void* operator new(size_t) noexcept(true);
StaticMonitor* mMonitor;
};
} // namespace mozilla
#endif
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