queue.c

#include "queue.h"
#include <pthread.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

typedef struct queue {
  int in;
  int out;
  int num_elem;
  int size;
  void **arr;
  pthread_mutex_t mutex;
  pthread_cond_t not_empty;
  pthread_cond_t not_full;
} queue;
queue_t *queue_new(int size)
{
  queue_t *Q;
  Q = calloc(1, sizeof(queue_t));
  Q->arr = calloc(size, sizeof(void *));
  Q->in = 0;
  Q->out = 0;
  Q->num_elem = 0;
  Q->size = size;
  pthread_mutex_init(&Q->mutex, NULL);
  pthread_cond_init(&Q->not_empty, NULL);
  pthread_cond_init(&Q->not_full, NULL);
  return Q;
}
void queue_delete(queue_t **q)
{
  if (q != NULL && *q != NULL) {
    if ((*q)->arr != NULL) {
      free((*q)->arr);
    }
    free(*q);
    *q = NULL;
  }
}
bool queue_push(queue_t *q, void *elem)
{
  if (q != NULL) {
    pthread_mutex_lock(&q->mutex);
    while (q->num_elem == q->size) {
      pthread_cond_wait(&q->not_full, &q->mutex);
    }
    q->arr[q->in] = elem;
    q->in = (q->in + 1) % q->size;
    q->num_elem++;
    pthread_cond_signal(&q->not_empty);
    pthread_mutex_unlock(&q->mutex);
    return true;
  } else {
    return false;
  }
}
bool queue_pop(queue_t *q, void **elem)
{
  if (q != NULL) {
    pthread_mutex_lock(&q->mutex);
    while (q->num_elem == 0) {
      pthread_cond_wait(&q->not_empty, &q->mutex);
    }
    *elem = q->arr[q->out];
    q->out = (q->out + 1) % q->size;
    q->num_elem--;
    pthread_cond_signal(&q->not_full);
    pthread_mutex_unlock(&q->mutex);
    return true;
  } else {
    return false;
  }
}