/*  Esta clase encapsula las funciones para la utilizacion de variables de condición
 *
 *  Autor: Programacion Paralela y Concurrente
 *  Fecha: 2020/Set/03
 *
**/

#include <stdio.h>
#include <unistd.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <string.h>

#include "Condition.h"

/*
 *  Creates a new condition variable
 *
 *  Uses an internal structure to make workers wait for resources
 *
**/
Condition::Condition() {

   this->waitingWorkers = 0;

}


/**
 * Destroys our condition variable
**/
Condition::~Condition() {

}


/**
 *  Wait for the condition controlled by our variable
 *
**/
void Condition::Wait( Lock & affectedLock ) {

   this->waitingWorkers++;
//printf( "process %d is waiting on lock 0x%x waiting %d\n", getpid(), this, this->waitingWorkers );
   affectedLock.Release();
   this->internalWaitMechanism.Acquire();
   affectedLock.Acquire();

} 

  
/**
 *  Notify one worker from the queue, if empty has no effect
 *
**/
void Condition::NotifyOne() {

//printf( "process %d Condition 0x%x waitingWorkers %d\n", getpid(), this, this->waitingWorkers );
   if ( this->waitingWorkers > 0 ) {
      this->waitingWorkers--;	// One
      this->internalWaitMechanism.Release();
//printf( "Releasing lock 0x%x\n", this );
   }

}


/**
 *  Same method as notify one, declared for compatibility with many examples
 *
**/
void Condition::Signal() {

   this->NotifyOne();

}


/**
 *  Signal all workers from the queue, if empty has no effect
 *
**/
void Condition::NotifyAll() {

   while ( this->waitingWorkers > 0 ) {
      this->waitingWorkers--;
      this->internalWaitMechanism.Release();
   }

}