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/*
* CDDL HEADER START
*
* This file and its contents are supplied under the terms of the
* Common Development and Distribution License ("CDDL"), version 1.0.
* You may only use this file in accordance with the terms of version
* 1.0 of the CDDL.
*
* A full copy of the text of the CDDL should have accompanied this
* source. A copy of the CDDL is also available via the Internet at
* http://www.illumos.org/license/CDDL.
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2014 by Delphix. All rights reserved.
*/
#include <sys/bqueue.h>
#include <sys/zfs_context.h>
static inline bqueue_node_t *
obj2node(bqueue_t *q, void *data)
{
return ((bqueue_node_t *)((char *)data + q->bq_node_offset));
}
/*
* Initialize a blocking queue The maximum capacity of the queue is set to
* size. Types that want to be stored in a bqueue must contain a bqueue_node_t,
* and offset should give its offset from the start of the struct. Return 0 on
* success, or -1 on failure.
*/
int
bqueue_init(bqueue_t *q, uint64_t size, size_t node_offset)
{
list_create(&q->bq_list, node_offset + sizeof (bqueue_node_t),
node_offset + offsetof(bqueue_node_t, bqn_node));
cv_init(&q->bq_add_cv, NULL, CV_DEFAULT, NULL);
cv_init(&q->bq_pop_cv, NULL, CV_DEFAULT, NULL);
mutex_init(&q->bq_lock, NULL, MUTEX_DEFAULT, NULL);
q->bq_node_offset = node_offset;
q->bq_size = 0;
q->bq_maxsize = size;
return (0);
}
/*
* Destroy a blocking queue. This function asserts that there are no
* elements in the queue, and no one is blocked on the condition
* variables.
*/
void
bqueue_destroy(bqueue_t *q)
{
ASSERT0(q->bq_size);
cv_destroy(&q->bq_add_cv);
cv_destroy(&q->bq_pop_cv);
mutex_destroy(&q->bq_lock);
list_destroy(&q->bq_list);
}
/*
* Add data to q, consuming size units of capacity. If there is insufficient
* capacity to consume size units, block until capacity exists. Asserts size is
* > 0.
*/
void
bqueue_enqueue(bqueue_t *q, void *data, uint64_t item_size)
{
ASSERT3U(item_size, >, 0);
ASSERT3U(item_size, <=, q->bq_maxsize);
mutex_enter(&q->bq_lock);
obj2node(q, data)->bqn_size = item_size;
while (q->bq_size + item_size > q->bq_maxsize) {
cv_wait(&q->bq_add_cv, &q->bq_lock);
}
q->bq_size += item_size;
list_insert_tail(&q->bq_list, data);
cv_signal(&q->bq_pop_cv);
mutex_exit(&q->bq_lock);
}
/*
* Take the first element off of q. If there are no elements on the queue, wait
* until one is put there. Return the removed element.
*/
void *
bqueue_dequeue(bqueue_t *q)
{
void *ret;
uint64_t item_size;
mutex_enter(&q->bq_lock);
while (q->bq_size == 0) {
cv_wait(&q->bq_pop_cv, &q->bq_lock);
}
ret = list_remove_head(&q->bq_list);
item_size = obj2node(q, ret)->bqn_size;
q->bq_size -= item_size;
mutex_exit(&q->bq_lock);
cv_signal(&q->bq_add_cv);
return (ret);
}
/*
* Returns true if the space used is 0.
*/
boolean_t
bqueue_empty(bqueue_t *q)
{
return (q->bq_size == 0);
}
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