gecko-dev/xpcom/glue/Mutex.h

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4.5 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: sw=4 ts=4 et :
* 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_Mutex_h
#define mozilla_Mutex_h
#include "prlock.h"
#include "mozilla/BlockingResourceBase.h"
#include "mozilla/GuardObjects.h"
//
// Provides:
//
// - Mutex, a non-recursive mutex
// - MutexAutoLock, an RAII class for ensuring that Mutexes are properly
// locked and unlocked
// - MutexAutoUnlock, complementary sibling to MutexAutoLock
//
// Using MutexAutoLock/MutexAutoUnlock is MUCH preferred to making bare
// calls to Mutex.Lock and Unlock.
//
namespace mozilla {
/**
* Mutex
* When possible, use MutexAutoLock/MutexAutoUnlock to lock/unlock this
* mutex within a scope, instead of calling Lock/Unlock directly.
**/
class NS_COM_GLUE Mutex : BlockingResourceBase
{
public:
/**
* Mutex
* @param name A name which can reference this lock
* @returns If failure, nullptr
* If success, a valid Mutex* which must be destroyed
* by Mutex::DestroyMutex()
**/
Mutex(const char* name) :
BlockingResourceBase(name, eMutex)
{
MOZ_COUNT_CTOR(Mutex);
mLock = PR_NewLock();
if (!mLock)
NS_RUNTIMEABORT("Can't allocate mozilla::Mutex");
}
/**
* ~Mutex
**/
~Mutex()
{
NS_ASSERTION(mLock,
"improperly constructed Lock or double free");
// NSPR does consistency checks for us
PR_DestroyLock(mLock);
mLock = 0;
MOZ_COUNT_DTOR(Mutex);
}
#ifndef DEBUG
/**
* Lock
* @see prlock.h
**/
void Lock()
{
PR_Lock(mLock);
}
/**
* Unlock
* @see prlock.h
**/
void Unlock()
{
PR_Unlock(mLock);
}
/**
* AssertCurrentThreadOwns
* @see prlock.h
**/
void AssertCurrentThreadOwns () const
{
}
/**
* AssertNotCurrentThreadOwns
* @see prlock.h
**/
void AssertNotCurrentThreadOwns () const
{
}
#else
void Lock();
void Unlock();
void AssertCurrentThreadOwns () const
{
PR_ASSERT_CURRENT_THREAD_OWNS_LOCK(mLock);
}
void AssertNotCurrentThreadOwns () const
{
// FIXME bug 476536
}
#endif // ifndef DEBUG
private:
Mutex();
Mutex(const Mutex&);
Mutex& operator=(const Mutex&);
PRLock* mLock;
friend class CondVar;
};
/**
* MutexAutoLock
* Acquires the Mutex when it enters scope, and releases it when it leaves
* scope.
*
* MUCH PREFERRED to bare calls to Mutex.Lock and Unlock.
*/
template<typename T>
class NS_COM_GLUE NS_STACK_CLASS BaseAutoLock
{
public:
/**
* Constructor
* The constructor aquires the given lock. The destructor
* releases the lock.
*
* @param aLock A valid mozilla::Mutex* returned by
* mozilla::Mutex::NewMutex.
**/
BaseAutoLock(T& aLock MOZ_GUARD_OBJECT_NOTIFIER_PARAM) :
mLock(&aLock)
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
NS_ASSERTION(mLock, "null mutex");
mLock->Lock();
}
~BaseAutoLock(void) {
mLock->Unlock();
}
private:
BaseAutoLock();
BaseAutoLock(BaseAutoLock&);
BaseAutoLock& operator=(BaseAutoLock&);
static void* operator new(size_t) CPP_THROW_NEW;
static void operator delete(void*);
T* mLock;
MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
};
typedef BaseAutoLock<Mutex> MutexAutoLock;
/**
* MutexAutoUnlock
* Releases the Mutex when it enters scope, and re-acquires it when it leaves
* scope.
*
* MUCH PREFERRED to bare calls to Mutex.Unlock and Lock.
*/
template<typename T>
class NS_COM_GLUE NS_STACK_CLASS BaseAutoUnlock
{
public:
BaseAutoUnlock(T& aLock MOZ_GUARD_OBJECT_NOTIFIER_PARAM) :
mLock(&aLock)
{
MOZ_GUARD_OBJECT_NOTIFIER_INIT;
NS_ASSERTION(mLock, "null lock");
mLock->Unlock();
}
~BaseAutoUnlock()
{
mLock->Lock();
}
private:
BaseAutoUnlock();
BaseAutoUnlock(BaseAutoUnlock&);
BaseAutoUnlock& operator =(BaseAutoUnlock&);
static void* operator new(size_t) CPP_THROW_NEW;
static void operator delete(void*);
T* mLock;
MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
};
typedef BaseAutoUnlock<Mutex> MutexAutoUnlock;
} // namespace mozilla
#endif // ifndef mozilla_Mutex_h