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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"
#include "llmutex.h"
class LL_COMMON_API LLThread
{
private:
friend class LLMutex;
static U32 sIDIter;
#if LL_DARWIN
// statically allocated thread local storage not supported in Darwin executable formats
#elif LL_WINDOWS
static U32 __declspec(thread) LLThread::sThreadIndex;
#elif LL_LINUX
static U32 __thread LLThread::sThreadID ;
#endif
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; }
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;
class LLCondition* mRunCondition;
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 mRunCondition 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:
// mRunCondition->lock();
// if(!shouldSleep())
// mRunCondition->signal();
// mRunCondition->unlock();
};
void LLThread::lockData()
{
mRunCondition->lock();
}
void LLThread::unlockData()
{
mRunCondition->unlock();
}
//============================================================================
#endif // LL_LLTHREAD_H
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