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/**
* @file llmutex.h
* @brief Base classes for mutex and condition handling.
*
* $LicenseInfo:firstyear=2004&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2012, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#ifndef LL_LLMUTEX_H
#define LL_LLMUTEX_H
#include "stdtypes.h"
#include "llthread.h"
#include <boost/noncopyable.hpp>
#include "mutex.h"
#include <condition_variable>
//============================================================================
//#define MUTEX_DEBUG (LL_DEBUG || LL_RELEASE_WITH_DEBUG_INFO)
#define MUTEX_DEBUG 0 //disable mutex debugging as it's interfering with profiles
#if MUTEX_DEBUG
#include <map>
#endif
class LL_COMMON_API LLMutex
{
public:
LLMutex();
virtual ~LLMutex();
void lock(); // blocks
bool trylock(); // non-blocking, returns true if lock held.
void unlock(); // undefined behavior when called on mutex not being held
bool isLocked(); // non-blocking, but does do a lock/unlock so not free
bool isSelfLocked(); //return true if locked in a same thread
LLThread::id_t lockingThread() const; //get ID of locking thread
protected:
std::mutex mMutex;
mutable U32 mCount;
mutable LLThread::id_t mLockingThread;
#if MUTEX_DEBUG
std::unordered_map<LLThread::id_t, BOOL> mIsLocked;
#endif
};
// Actually a condition/mutex pair (since each condition needs to be associated with a mutex).
class LL_COMMON_API LLCondition : public LLMutex
{
public:
LLCondition();
~LLCondition();
void wait(); // blocks
void signal();
void broadcast();
protected:
std::condition_variable mCond;
};
class LLMutexLock
{
public:
LLMutexLock(LLMutex* mutex)
{
mMutex = mutex;
if(mMutex)
mMutex->lock();
}
~LLMutexLock()
{
if(mMutex)
mMutex->unlock();
}
private:
LLMutex* mMutex;
};
//============================================================================
// Scoped locking class similar in function to LLMutexLock but uses
// the trylock() method to conditionally acquire lock without
// blocking. Caller resolves the resulting condition by calling
// the isLocked() method and either punts or continues as indicated.
//
// Mostly of interest to callers needing to avoid stalls who can
// guarantee another attempt at a later time.
class LLMutexTrylock
{
public:
LLMutexTrylock(LLMutex* mutex);
LLMutexTrylock(LLMutex* mutex, U32 aTries, U32 delay_ms = 10);
~LLMutexTrylock();
bool isLocked() const
{
return mLocked;
}
private:
LLMutex* mMutex;
bool mLocked;
};
/**
* @class LLScopedLock
* @brief Small class to help lock and unlock mutexes.
*
* The constructor handles the lock, and the destructor handles
* the unlock. Instances of this class are <b>not</b> thread safe.
*/
class LL_COMMON_API LLScopedLock : private boost::noncopyable
{
public:
/**
* @brief Constructor which accepts a mutex, and locks it.
*
* @param mutex An allocated mutex. If you pass in NULL,
* this wrapper will not lock.
*/
LLScopedLock(std::mutex* mutex);
/**
* @brief Destructor which unlocks the mutex if still locked.
*/
~LLScopedLock();
/**
* @brief Check lock.
*/
bool isLocked() const { return mLocked; }
/**
* @brief This method unlocks the mutex.
*/
void unlock();
protected:
bool mLocked;
std::mutex* mMutex;
};
#endif // LL_LLMUTEX_H
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