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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"
//============================================================================
#define MUTEX_DEBUG (LL_DEBUG || LL_RELEASE_WITH_DEBUG_INFO)
struct apr_thread_mutex_t;
struct apr_pool_t;
struct apr_thread_cond_t;
class LL_COMMON_API LLMutex
{
public:
typedef enum
{
NO_THREAD = 0xFFFFFFFF
} e_locking_thread;
LLMutex(apr_pool_t *apr_poolp = NULL); // NULL pool constructs a new pool for the mutex
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
U32 lockingThread() const; //get ID of locking thread
protected:
apr_thread_mutex_t *mAPRMutexp;
mutable U32 mCount;
mutable U32 mLockingThread;
apr_pool_t *mAPRPoolp;
BOOL mIsLocalPool;
#if MUTEX_DEBUG
std::map<U32, 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(apr_pool_t* apr_poolp); // Defaults to global pool, could use the thread pool as well.
~LLCondition();
void wait(); // blocks
void signal();
void broadcast();
protected:
apr_thread_cond_t* mAPRCondp;
};
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)
: mMutex(mutex),
mLocked(false)
{
if (mMutex)
mLocked = mMutex->trylock();
}
~LLMutexTrylock()
{
if (mMutex && mLocked)
mMutex->unlock();
}
bool isLocked() const
{
return mLocked;
}
private:
LLMutex* mMutex;
bool mLocked;
};
#endif // LL_LLTHREAD_H
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