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#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
#include <semaphore.h>
#include "types.h"
#include "fifoqueue.h"
Fifo_q *
init_queue(int size)
{
Fifo_q * q = (Fifo_q *) malloc(sizeof(Fifo_q));
q->head = NULL;
q->tail = NULL;
q->maxSize = size;
q->currentSize = 0;
q->droppedValues = 0;
q->largestBufferSize = 0;
q->valuesReceived = 0;
q->valuesReleased = 0;
/*Queue empty from the beginning (block)*/
sem_init(&q->bufferEmptyBlock, 0, 0);
sem_init(&q->lock, 0, 1);
return q;
}
boolean
is_full(Fifo_q * q)
{
if(q->currentSize < q->maxSize)
return false;
else
return true;
}
boolean
is_empty(Fifo_q * q)
{
if(q->head==NULL)
return true;
else
return false;
}
int
add_to_queue(Fifo_q * q, Sensor_t * sensor)
{
if(q == NULL){
printf("Error: Queue not initialized\n");
free(sensor); //free if not appended
return -1;
}
else if(is_full(q)){
/* Drop Least Recently or Drop Most Recently */
#ifdef DLR
pop_from_queue(q);
#endif
q->droppedValues++;
free(sensor); //free if not appended
return 0;
}
sem_wait(&q->lock);
Queue_t * new_elem = (Queue_t *) malloc(sizeof(Queue_t));
new_elem->next = NULL;
new_elem->sensor = sensor;
if(is_empty(q)){
q->head = new_elem;
sem_post(&q->bufferEmptyBlock);
}else
q->tail->next = new_elem;
q->tail = new_elem;
q->currentSize++;
q->valuesReceived++;
if(q->currentSize > q->largestBufferSize)
q->largestBufferSize = q->currentSize;
sem_post(&q->lock);
return 1;
}
Sensor_t *
pop_from_queue(Fifo_q * q)
{
int semStat;
if(is_empty(q)){
#ifdef DEBUG
printf("Waiting for sensor data\n");
#endif
sem_wait(&q->bufferEmptyBlock);
}
sem_wait(&q->lock);
Queue_t * head = q->head;
Sensor_t * sensor = head->sensor;
/* If dequeue the last element */
if(q->currentSize == 1){
q->head = NULL;
q->tail = NULL;
/* Read current semaphore value */
sem_getvalue(&q->bufferEmptyBlock, &semStat);
if(semStat == 1) /* Mark buffer as empty if last elem */
sem_wait(&q->bufferEmptyBlock);
}else{
q->head = head->next;
}
free(head);
q->currentSize--;
#ifndef DLR
q->valuesReleased++;
#endif
sem_post(&q->lock);
return sensor;
}
Sensor_t *
create_sensor_object(int value, int uid)
{
Sensor_t * sensor = (Sensor_t *) malloc(sizeof(Sensor_t));
sensor->value = value;
sensor->uid = uid;
return sensor;
}
void
print_queue(Fifo_q * q)
{
sem_wait(&q->lock);
Queue_t * current = q->head;
printf("\nContent of the queue with size=%d\n",q->currentSize);
if(current == NULL){
printf("The queue is empty!\n");
sem_post(&q->lock);
return;
}
while(current != NULL){
printf("sensor value=%d, sensor uid=%d\n",
current->sensor->value, current->sensor->uid);
current = current->next;
}
sem_post(&q->lock);
}
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