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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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
//
// - OffTheBooksMutex, a non-recursive mutex that doesn't do leak checking
// - OffTheBooksMutexAuto{Lock,Unlock} - Like MutexAuto{Lock,Unlock}, but for
// an OffTheBooksMutex.
//
// Using MutexAutoLock/MutexAutoUnlock etc. is MUCH preferred to making bare
// calls to Lock and Unlock.
//
namespace mozilla {
/**
* OffTheBooksMutex is identical to Mutex, except that OffTheBooksMutex doesn't
* include leak checking. Sometimes you want to intentionally "leak" a mutex
* until shutdown; in these cases, OffTheBooksMutex is for you.
*/
class OffTheBooksMutex : BlockingResourceBase
{
public:
/**
* @param aName A name which can reference this lock
* @returns If failure, nullptr
* If success, a valid Mutex* which must be destroyed
* by Mutex::DestroyMutex()
**/
explicit OffTheBooksMutex(const char* aName)
: BlockingResourceBase(aName, eMutex)
{
mLock = PR_NewLock();
if (!mLock) {
NS_RUNTIMEABORT("Can't allocate mozilla::Mutex");
}
}
~OffTheBooksMutex()
{
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:
OffTheBooksMutex();
OffTheBooksMutex(const OffTheBooksMutex&);
OffTheBooksMutex& operator=(const OffTheBooksMutex&);
PRLock* mLock;
friend class CondVar;
// MozPromise needs to access mLock for debugging purpose.
template<typename, typename, bool>
friend class MozPromise;
};
/**
* Mutex
* When possible, use MutexAutoLock/MutexAutoUnlock to lock/unlock this
* mutex within a scope, instead of calling Lock/Unlock directly.
*/
class Mutex : public OffTheBooksMutex
{
public:
explicit Mutex(const char* aName)
: OffTheBooksMutex(aName)
{
MOZ_COUNT_CTOR(Mutex);
}
~Mutex()
{
MOZ_COUNT_DTOR(Mutex);
}
private:
Mutex();
Mutex(const Mutex&);
Mutex& operator=(const Mutex&);
};
/**
* 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 MOZ_RAII 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.
**/
explicit 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;
T* mLock;
MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
};
typedef BaseAutoLock<Mutex> MutexAutoLock;
typedef BaseAutoLock<OffTheBooksMutex> OffTheBooksMutexAutoLock;
/**
* 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 MOZ_RAII BaseAutoUnlock
{
public:
explicit 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;
T* mLock;
MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
};
typedef BaseAutoUnlock<Mutex> MutexAutoUnlock;
typedef BaseAutoUnlock<OffTheBooksMutex> OffTheBooksMutexAutoUnlock;
} // namespace mozilla
#endif // ifndef mozilla_Mutex_h
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