gecko-dev/xpcom/glue/Mutex.h

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: sw=4 ts=4 et :
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef mozilla_Mutex_h
#define mozilla_Mutex_h
#include "prlock.h"
#include "mozilla/AutoRestore.h"
#include "mozilla/BlockingResourceBase.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, nsnull
* If success, a valid Mutex* which must be destroyed
* by Mutex::DestroyMutex()
**/
Mutex(const char* name) :
BlockingResourceBase(name, eMutex)
{
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;
}
#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.
*/
class NS_COM_GLUE NS_STACK_CLASS MutexAutoLock
{
public:
/**
* Constructor
* The constructor aquires the given lock. The destructor
* releases the lock.
*
* @param aLock A valid mozilla::Mutex* returned by
* mozilla::Mutex::NewMutex.
**/
MutexAutoLock(mozilla::Mutex& aLock MOZILLA_GUARD_OBJECT_NOTIFIER_PARAM) :
mLock(&aLock)
{
MOZILLA_GUARD_OBJECT_NOTIFIER_INIT;
NS_ASSERTION(mLock, "null mutex");
mLock->Lock();
}
~MutexAutoLock(void) {
mLock->Unlock();
}
private:
MutexAutoLock();
MutexAutoLock(MutexAutoLock&);
MutexAutoLock& operator=(MutexAutoLock&);
static void* operator new(size_t) CPP_THROW_NEW;
static void operator delete(void*);
mozilla::Mutex* mLock;
MOZILLA_DECL_USE_GUARD_OBJECT_NOTIFIER
};
/**
* 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.
*/
class NS_COM_GLUE NS_STACK_CLASS MutexAutoUnlock
{
public:
MutexAutoUnlock(mozilla::Mutex& aLock MOZILLA_GUARD_OBJECT_NOTIFIER_PARAM) :
mLock(&aLock)
{
MOZILLA_GUARD_OBJECT_NOTIFIER_INIT;
NS_ASSERTION(mLock, "null lock");
mLock->Unlock();
}
~MutexAutoUnlock()
{
mLock->Lock();
}
private:
MutexAutoUnlock();
MutexAutoUnlock(MutexAutoUnlock&);
MutexAutoUnlock& operator =(MutexAutoUnlock&);
static void* operator new(size_t) CPP_THROW_NEW;
static void operator delete(void*);
mozilla::Mutex* mLock;
MOZILLA_DECL_USE_GUARD_OBJECT_NOTIFIER
};
} // namespace mozilla
#endif // ifndef mozilla_Mutex_h