aca-tasks/MonitorExample/monitor.cpp

#include "monitor.h"

template<typename T>
Monitor<T>::Monitor(int n) {
    buffer = new T[n];
    for(int i=0;i<n;i++)
        emptySpotsQ.push(&buffer[i]);	// Initialize emptySpotsQ with buffer places
}
//-----------------------------------------

template<typename T>
Monitor<T>::~Monitor() {
    delete []buffer;
}
//-----------------------------------------

//producer tries to put an item:
//  lock l
//  wait for spot in putting queue
//  get first spot in putting queue
template<typename T>
T* Monitor<T>::canPut() {
    QMutexLocker ml(&l);			// Lock entry controlling mutex l
    while (emptySpotsQ.size() == 0)	// If no free place in emptySpots queue:
        full.wait(&l);				// Block until condition variable full is given free by mutex l
    T *aux = emptySpotsQ.front();	// Get place in emptySpotsQ
    emptySpotsQ.pop();				// ?? Free one place in emptySpotsQ ?? (documentation of class queue currently not available)
    return aux;						// Return pointer to place in emptySpotsQ for item to be produced
}
//-----------------------------------------

//consumer tries to take an item:
//  lock l
//  wait until items are in itemq
//  take item
template<typename T>
T* Monitor<T>::canGet() {
    QMutexLocker ml(&l);		// Lock entry controlling mutex l
    while (itemQ.size() == 0)	// If no item in itemQ:
        empty.wait(&l);			// Block until condition variable empty is given free by mutex l
    T* temp = itemQ.front();	// Get item out of itemQ
    itemQ.pop();				// ?? Free one place in itemQ ?? (documentation of class queue currently not available)
    return temp;				// Return pointer to item in itemQ, which will be consumed
}
//-----------------------------------------

//producer is done with producing and wants to put that item:
//  lock l
//  push produced item to itemQ
//  wake waiting consumer
template<typename T>
void Monitor<T>::donePutting(T *x) {
    QMutexLocker ml(&l);	// Lock entry controlling mutex l
    itemQ.push(x);			// Push place with produced item into itemQ
    empty.wakeOne();		// Notify one consumer thread waiting for condition variable empty
}
//-----------------------------------------

//consumer is done with taking an item:
//  lock l
//  enlarge producer queue by one
//  notify a producer of new spot
template<typename T>
void Monitor<T>::doneGetting(T *x) {
    QMutexLocker ml(&l);	// Lock entry controlling mutex l
    emptySpotsQ.push(x);	// Give free the buffer place which had hold the consumed item by pushing in into emptySpotsQ
    full.wakeOne();			// Notify one producer thread waiting for condition variable empty
}
//************************************************************