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/*
* Copyright © 2016 Mozilla Foundation
*
* This program is made available under an ISC-style license. See the
* accompanying file LICENSE for details.
*/
#ifndef CUBEB_ARRAY_QUEUE_H
#define CUBEB_ARRAY_QUEUE_H
#include <assert.h>
#include <pthread.h>
#include <unistd.h>
#if defined(__cplusplus)
extern "C" {
#endif
typedef struct {
void ** buf;
size_t num;
size_t writePos;
size_t readPos;
pthread_mutex_t mutex;
} array_queue;
array_queue *
array_queue_create(size_t num)
{
assert(num != 0);
array_queue * new_queue = (array_queue *)calloc(1, sizeof(array_queue));
new_queue->buf = (void **)calloc(1, sizeof(void *) * num);
new_queue->readPos = 0;
new_queue->writePos = 0;
new_queue->num = num;
pthread_mutex_init(&new_queue->mutex, NULL);
return new_queue;
}
void
array_queue_destroy(array_queue * aq)
{
assert(aq);
free(aq->buf);
pthread_mutex_destroy(&aq->mutex);
free(aq);
}
int
array_queue_push(array_queue * aq, void * item)
{
assert(item);
pthread_mutex_lock(&aq->mutex);
int ret = -1;
if (aq->buf[aq->writePos % aq->num] == NULL) {
aq->buf[aq->writePos % aq->num] = item;
aq->writePos = (aq->writePos + 1) % aq->num;
ret = 0;
}
// else queue is full
pthread_mutex_unlock(&aq->mutex);
return ret;
}
void *
array_queue_pop(array_queue * aq)
{
pthread_mutex_lock(&aq->mutex);
void * value = aq->buf[aq->readPos % aq->num];
if (value) {
aq->buf[aq->readPos % aq->num] = NULL;
aq->readPos = (aq->readPos + 1) % aq->num;
}
pthread_mutex_unlock(&aq->mutex);
return value;
}
size_t
array_queue_get_size(array_queue * aq)
{
pthread_mutex_lock(&aq->mutex);
ssize_t r = aq->writePos - aq->readPos;
if (r < 0) {
r = aq->num + r;
assert(r >= 0);
}
pthread_mutex_unlock(&aq->mutex);
return (size_t)r;
}
#if defined(__cplusplus)
}
#endif
#endif // CUBE_ARRAY_QUEUE_H