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/**
* @file llthread.h
* @brief Base classes for thread, mutex and condition handling.
*
* Copyright (c) 2004-$CurrentYear$, Linden Research, Inc.
* $License$
*/
#ifndef LL_LLTHREAD_H
#define LL_LLTHREAD_H
#include "llapr.h"
#include "llapp.h"
#include "apr-1/apr_thread_cond.h"
class LLThread;
class LLMutex;
class LLCondition;
class LLThread
{
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.
static void yield(); // Static because it can be called by the main thread, which doesn't have an LLThread data structure.
bool isQuitting() const;
bool isStopped() const;
// PAUSE / RESUME functionality. See source code for important usage notes.
public:
// Called from MAIN THREAD.
void pause();
void unpause();
bool isPaused() { return mPaused ? true : false; }
// 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; }
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;
apr_thread_t *mAPRThreadp;
apr_pool_t *mAPRPoolp;
BOOL mIsLocalPool;
EThreadStatus mStatus;
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();
};
//============================================================================
class LLMutex
{
public:
LLMutex(apr_pool_t *apr_poolp); // Defaults to global pool, could use the thread pool as well.
~LLMutex();
void lock(); // blocks
void unlock();
bool isLocked(); // non-blocking, but does do a lock/unlock so not free
protected:
apr_thread_mutex_t *mAPRMutexp;
apr_pool_t *mAPRPoolp;
BOOL mIsLocalPool;
};
// Actually a condition/mutex pair (since each condition needs to be associated with a mutex).
class 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;
mMutex->lock();
}
~LLMutexLock()
{
mMutex->unlock();
}
private:
LLMutex* mMutex;
};
//============================================================================
void LLThread::lockData()
{
mRunCondition->lock();
}
void LLThread::unlockData()
{
mRunCondition->unlock();
}
//============================================================================
#endif // LL_LLTHREAD_H
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