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/*
* Copyright (C) Igor Sysoev
* Copyright (C) NGINX, Inc.
*/
#ifndef _NXT_QUEUE_H_INCLUDED_
#define _NXT_QUEUE_H_INCLUDED_
typedef struct nxt_queue_link_s nxt_queue_link_t;
struct nxt_queue_link_s {
nxt_queue_link_t *prev;
nxt_queue_link_t *next;
};
typedef struct {
nxt_queue_link_t head;
} nxt_queue_t;
#define nxt_queue_init(queue) \
do { \
(queue)->head.prev = &(queue)->head; \
(queue)->head.next = &(queue)->head; \
} while (0)
#define nxt_queue_sentinel(link) \
do { \
(link)->prev = (link); \
(link)->next = (link); \
} while (0)
/*
* Short-circuit a queue link to itself to allow once remove safely it
* using nxt_queue_remove().
*/
#define nxt_queue_self(link) \
nxt_queue_sentinel(link)
#define nxt_queue_is_empty(queue) \
(&(queue)->head == (queue)->head.prev)
/*
* A loop to iterate all queue links starting from head:
*
* nxt_queue_link_t link;
* } nxt_type_t *tp;
*
*
* for (lnk = nxt_queue_first(queue);
* lnk != nxt_queue_tail(queue);
* lnk = nxt_queue_next(lnk))
* {
* tp = nxt_queue_link_data(lnk, nxt_type_t, link);
*
* or starting from tail:
*
* for (lnk = nxt_queue_last(queue);
* lnk != nxt_queue_head(queue);
* lnk = nxt_queue_next(lnk))
* {
* tp = nxt_queue_link_data(lnk, nxt_type_t, link);
*/
#define nxt_queue_first(queue) \
(queue)->head.next
#define nxt_queue_last(queue) \
(queue)->head.prev
#define nxt_queue_head(queue) \
(&(queue)->head)
#define nxt_queue_tail(queue) \
(&(queue)->head)
#define nxt_queue_next(link) \
(link)->next
#define nxt_queue_prev(link) \
(link)->prev
#define nxt_queue_insert_head(queue, link) \
do { \
(link)->next = (queue)->head.next; \
(link)->next->prev = (link); \
(link)->prev = &(queue)->head; \
(queue)->head.next = (link); \
} while (0)
#define nxt_queue_insert_tail(queue, link) \
do { \
(link)->prev = (queue)->head.prev; \
(link)->prev->next = (link); \
(link)->next = &(queue)->head; \
(queue)->head.prev = (link); \
} while (0)
#define nxt_queue_insert_after(target, link) \
do { \
(link)->next = (target)->next; \
(link)->next->prev = (link); \
(link)->prev = (target); \
(target)->next = (link); \
} while (0)
#define nxt_queue_insert_before(target, link) \
do { \
(link)->next = (target); \
(link)->prev = (target)->prev; \
(target)->prev = (link); \
(link)->prev->next = (link); \
} while (0)
#if (NXT_DEBUG)
#define nxt_queue_remove(link) \
do { \
(link)->next->prev = (link)->prev; \
(link)->prev->next = (link)->next; \
(link)->prev = NULL; \
(link)->next = NULL; \
} while (0)
#else
#define nxt_queue_remove(link) \
do { \
(link)->next->prev = (link)->prev; \
(link)->prev->next = (link)->next; \
} while (0)
#endif
/*
* Split the queue "queue" starting at the element "link",
* the "tail" is the new tail queue.
*/
#define nxt_queue_split(queue, link, tail) \
do { \
(tail)->head.prev = (queue)->head.prev; \
(tail)->head.prev->next = &(tail)->head; \
(tail)->head.next = (link); \
(queue)->head.prev = (link)->prev; \
(queue)->head.prev->next = &(queue)->head; \
(link)->prev = &(tail)->head; \
} while (0)
/* Truncate the queue "queue" starting at element "link". */
#define nxt_queue_truncate(queue, link) \
do { \
(queue)->head.prev = (link)->prev; \
(queue)->head.prev->next = &(queue)->head; \
} while (0)
/* Add the queue "tail" to the queue "queue". */
#define nxt_queue_add(queue, tail) \
do { \
(queue)->head.prev->next = (tail)->head.next; \
(tail)->head.next->prev = (queue)->head.prev; \
(queue)->head.prev = (tail)->head.prev; \
(queue)->head.prev->next = &(queue)->head; \
} while (0)
#define nxt_queue_link_data(lnk, type, link) \
nxt_container_of(lnk, type, link)
NXT_EXPORT nxt_queue_link_t *nxt_queue_middle(nxt_queue_t *queue);
NXT_EXPORT void nxt_queue_sort(nxt_queue_t *queue,
nxt_int_t (*compare)(const void *, const nxt_queue_link_t *,
const nxt_queue_link_t *), const void *data);
#endif /* _NXT_QUEUE_H_INCLUDED_ */