#ifndef BU_ITO_CONDITION_H #define BU_ITO_CONDITION_H #include <pthread.h> #include "itomutex.h" namespace Bu { /** * Ito condition. This is a fairly simple condition mechanism. As you may * notice this class inherits from the ItoMutex 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> * ItoCondition 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. *@author Mike Buland */ class ItoCondition : public ItoMutex { public: /** * Create a condition. */ ItoCondition(); /** * Destroy a condition. */ ~ItoCondition(); /** * 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