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/**
* @file llthread.h
* @brief Base classes for thread, mutex and condition handling.
*
* $LicenseInfo:firstyear=2004&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2010, 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_LLTHREAD_H
#define LL_LLTHREAD_H
#include "llapp.h"
#include "llapr.h"
#include "apr_thread_cond.h"
class LLThread;
class LLMutex;
class LLCondition;
#if LL_WINDOWS
#define ll_thread_local __declspec(thread)
#else
#define ll_thread_local __thread
#endif
class LL_COMMON_API LLThread
{
private:
static U32 sIDIter;
public:
typedef enum e_thread_status
{
STOPPED = 0, // The thread is not running. Not started, or has exited its run function
RUNNING = 1, // The thread is currently running
QUITTING= 2 // Someone wants this thread to quit
} EThreadStatus;
LLThread(const std::string& name, apr_pool_t *poolp = NULL);
virtual ~LLThread(); // Warning! You almost NEVER want to destroy a thread unless it's in the STOPPED state.
virtual void shutdown(); // stops the thread
bool isQuitting() const { return (QUITTING == mStatus); }
bool isStopped() const { return (STOPPED == mStatus); }
static U32 currentID(); // Return ID of current thread
static void yield(); // Static because it can be called by the main thread, which doesn't have an LLThread data structure.
public:
// PAUSE / RESUME functionality. See source code for important usage notes.
// Called from MAIN THREAD.
void pause();
void unpause();
bool isPaused() { return isStopped() || mPaused == TRUE; }
// Cause the thread to wake up and check its condition
void wake();
// Same as above, but to be used when the condition is already locked.
void wakeLocked();
// Called from run() (CHILD THREAD). Pause the thread if requested until unpaused.
void checkPause();
// this kicks off the apr thread
void start(void);
apr_pool_t *getAPRPool() { return mAPRPoolp; }
LLVolatileAPRPool* getLocalAPRFilePool() { return mLocalAPRFilePoolp ; }
U32 getID() const { return mID; }
// Called by threads *not* created via LLThread to register some
// internal state used by LLMutex. You must call this once early
// in the running thread to prevent collisions with the main thread.
static void registerThreadID();
private:
BOOL mPaused;
// static function passed to APR thread creation routine
static void *APR_THREAD_FUNC staticRun(apr_thread_t *apr_threadp, void *datap);
protected:
std::string mName;
LLCondition* mRunCondition;
LLMutex* mDataLock;
apr_thread_t *mAPRThreadp;
apr_pool_t *mAPRPoolp;
BOOL mIsLocalPool;
EThreadStatus mStatus;
U32 mID;
//a local apr_pool for APRFile operations in this thread. If it exists, LLAPRFile::sAPRFilePoolp should not be used.
//Note: this pool is used by APRFile ONLY, do NOT use it for any other purposes.
// otherwise it will cause severe memory leaking!!! --bao
LLVolatileAPRPool *mLocalAPRFilePoolp ;
void setQuitting();
// virtual function overridden by subclass -- this will be called when the thread runs
virtual void run(void) = 0;
// virtual predicate function -- returns true if the thread should wake up, false if it should sleep.
virtual bool runCondition(void);
// Lock/Unlock Run Condition -- use around modification of any variable used in runCondition()
inline void lockData();
inline void unlockData();
// This is the predicate that decides whether the thread should sleep.
// It should only be called with mDataLock locked, since the virtual runCondition() function may need to access
// data structures that are thread-unsafe.
bool shouldSleep(void) { return (mStatus == RUNNING) && (isPaused() || (!runCondition())); }
// To avoid spurious signals (and the associated context switches) when the condition may or may not have changed, you can do the following:
// mDataLock->lock();
// if(!shouldSleep())
// mRunCondition->signal();
// mDataLock->unlock();
};
//============================================================================
#define MUTEX_DEBUG (LL_DEBUG || LL_RELEASE_WITH_DEBUG_INFO)
class LL_COMMON_API LLMutex
{
public:
typedef enum
{
NO_THREAD = 0xFFFFFFFF
} e_locking_thread;
LLMutex(apr_pool_t *apr_poolp); // NULL pool constructs a new pool for the mutex
virtual ~LLMutex();
void lock(); // blocks
void unlock();
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;
};
//============================================================================
void LLThread::lockData()
{
mDataLock->lock();
}
void LLThread::unlockData()
{
mDataLock->unlock();
}
//============================================================================
// see llmemory.h for LLPointer<> definition
class LL_COMMON_API LLThreadSafeRefCount
{
public:
static void initThreadSafeRefCount(); // creates sMutex
static void cleanupThreadSafeRefCount(); // destroys sMutex
private:
static LLMutex* sMutex;
protected:
virtual ~LLThreadSafeRefCount(); // use unref()
public:
LLThreadSafeRefCount();
LLThreadSafeRefCount(const LLThreadSafeRefCount&);
LLThreadSafeRefCount& operator=(const LLThreadSafeRefCount& ref)
{
mRef = 0;
return *this;
}
void ref()
{
mRef++;
}
S32 unref()
{
llassert(mRef >= 1);
bool time_to_die = (mRef == 1);
if (time_to_die)
{
if (sMutex) sMutex->lock();
// Looks redundant, but is very much not
// We need to check again once we've acquired the lock
// so that two threads who get into the if in parallel
// don't both attempt to the delete.
//
mRef--;
if (mRef == 0)
delete this;
if (sMutex) sMutex->unlock();
return 0;
}
return --mRef;
}
S32 getNumRefs() const
{
const S32 currentVal = mRef.CurrentValue();
return currentVal;
}
private:
LLAtomic32< S32 > mRef;
};
//============================================================================
// Simple responder for self destructing callbacks
// Pure virtual class
class LL_COMMON_API LLResponder : public LLThreadSafeRefCount
{
protected:
virtual ~LLResponder();
public:
virtual void completed(bool success) = 0;
};
//============================================================================
#endif // LL_LLTHREAD_H
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