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/*
* Copyright (C) 2007-2011 Xagasoft, All rights reserved.
*
* This file is part of the libbu++ library and is released under the
* terms of the license contained in the file LICENSE.
*/
#ifndef BU_CONDITION_H
#define BU_CONDITION_H
#include <pthread.h>
#include "bu/mutex.h"
namespace Bu
{
/**
* Ito condition. This is a fairly simple condition mechanism. As you may
* notice this class inherits from the Mutex class, this is because all
* conditions must be within a locked block. The standard usage of a
* condition is to pause one thread, perhaps indefinately, until another
* thread signals that it is alright to procede.
* <br>
* Standard usage for the thread that wants to wait is as follows:
* <pre>
* Condition cond;
* ... // Perform setup and enter your run loop
* cond.lock();
* while( !isFinished() ) // Could be anything you're waiting for
* cond.wait();
* ... // Take care of what you have to.
* cond.unlock();
* </pre>
* The usage for the triggering thread is much simpler, when it needs to
* tell the others that it's time to grab some data it calls either signal
* or broadcast. See both of those functions for the difference.
*@ingroup Threading
*/
class Condition : public Mutex
{
public:
/**
* Create a condition.
*/
Condition();
/**
* Destroy a condition.
*/
~Condition();
/**
* Wait forever, or until signalled. This has to be called from within
* a locked section, i.e. before calling this this object's lock
* function should be called.
*/
int wait();
/**
* Wait for a maximum of nSec seconds and nUSec micro-seconds or until
* signalled. This is a little more friendly function if you want to
* perform other operations in the thrad loop that calls this function.
* Like the other wait function, this must be inside a locked section.
*@param nSec The seconds to wait.
*@param nUSec the micro-seconds to wait.
*/
int wait( int nSec, int nUSec );
/**
* Notify the next thread waiting on this condition that they can go
* ahead. This only signals one thread, the next one in the condition
* queue, that it is safe to procede with whatever operation was being
* waited on.
*/
int signal();
/**
* Notify all threads waiting on this condition that they can go ahead
* now. This function is slower than signal, but more effective in
* certain situations where you may not know how many threads should be
* activated.
*/
int broadcast();
private:
pthread_cond_t cond; /**< Internal condition reference. */
};
}
#endif
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