2 * Copyright (c) 1991, 1993
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29 * @(#)queue.h 8.5 (Berkeley) 8/20/94
36 #include <sys/cdefs.h>
39 * This file defines four types of data structures: singly-linked lists,
40 * singly-linked tail queues, lists and tail queues.
42 * A singly-linked list is headed by a single forward pointer. The elements
43 * are singly linked for minimum space and pointer manipulation overhead at
44 * the expense of O(n) removal for arbitrary elements. New elements can be
45 * added to the list after an existing element or at the head of the list.
46 * Elements being removed from the head of the list should use the explicit
47 * macro for this purpose for optimum efficiency. A singly-linked list may
48 * only be traversed in the forward direction. Singly-linked lists are ideal
49 * for applications with large datasets and few or no removals or for
50 * implementing a LIFO queue.
52 * A singly-linked tail queue is headed by a pair of pointers, one to the
53 * head of the list and the other to the tail of the list. The elements are
54 * singly linked for minimum space and pointer manipulation overhead at the
55 * expense of O(n) removal for arbitrary elements. New elements can be added
56 * to the list after an existing element, at the head of the list, or at the
57 * end of the list. Elements being removed from the head of the tail queue
58 * should use the explicit macro for this purpose for optimum efficiency.
59 * A singly-linked tail queue may only be traversed in the forward direction.
60 * Singly-linked tail queues are ideal for applications with large datasets
61 * and few or no removals or for implementing a FIFO queue.
63 * A list is headed by a single forward pointer (or an array of forward
64 * pointers for a hash table header). The elements are doubly linked
65 * so that an arbitrary element can be removed without a need to
66 * traverse the list. New elements can be added to the list before
67 * or after an existing element or at the head of the list. A list
68 * may be traversed in either direction.
70 * A tail queue is headed by a pair of pointers, one to the head of the
71 * list and the other to the tail of the list. The elements are doubly
72 * linked so that an arbitrary element can be removed without a need to
73 * traverse the list. New elements can be added to the list before or
74 * after an existing element, at the head of the list, or at the end of
75 * the list. A tail queue may be traversed in either direction.
77 * For details on the use of these macros, see the queue(3) manual page.
80 * SLIST LIST STAILQ TAILQ
82 * _HEAD_INITIALIZER + + + +
91 * _FOREACH_SAFE + + + +
92 * _FOREACH_REVERSE - - - +
93 * _FOREACH_REVERSE_SAFE - - - +
94 * _INSERT_HEAD + + + +
95 * _INSERT_BEFORE - + - +
96 * _INSERT_AFTER + + + +
97 * _INSERT_TAIL - - + +
99 * _REMOVE_AFTER + - + -
100 * _REMOVE_HEAD + - + -
105 #ifdef QUEUE_MACRO_DEBUG
106 /* Store the last 2 places the queue element or head was altered */
114 #define TRACEBUF struct qm_trace trace;
115 #define TRASHIT(x) do {(x) = (void *)-1;} while (0)
116 #define QMD_SAVELINK(name, link) void **name = (void *)&(link)
118 #define QMD_TRACE_HEAD(head) do { \
119 (head)->trace.prevline = (head)->trace.lastline; \
120 (head)->trace.prevfile = (head)->trace.lastfile; \
121 (head)->trace.lastline = __LINE__; \
122 (head)->trace.lastfile = __FILE__; \
125 #define QMD_TRACE_ELEM(elem) do { \
126 (elem)->trace.prevline = (elem)->trace.lastline; \
127 (elem)->trace.prevfile = (elem)->trace.lastfile; \
128 (elem)->trace.lastline = __LINE__; \
129 (elem)->trace.lastfile = __FILE__; \
133 #define QMD_TRACE_ELEM(elem)
134 #define QMD_TRACE_HEAD(head)
135 #define QMD_SAVELINK(name, link)
138 #endif /* QUEUE_MACRO_DEBUG */
141 * Singly-linked List declarations.
143 #define SLIST_HEAD(name, type) \
145 struct type *slh_first; /* first element */ \
148 #define SLIST_HEAD_INITIALIZER(head) \
151 #define SLIST_ENTRY(type) \
153 struct type *sle_next; /* next element */ \
157 * Singly-linked List functions.
159 #define SLIST_EMPTY(head) ((head)->slh_first == NULL)
161 #define SLIST_FIRST(head) ((head)->slh_first)
163 #define SLIST_FOREACH(var, head, field) \
164 for ((var) = SLIST_FIRST((head)); \
166 (var) = SLIST_NEXT((var), field))
168 #define SLIST_FOREACH_SAFE(var, head, field, tvar) \
169 for ((var) = SLIST_FIRST((head)); \
170 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \
173 #define SLIST_FOREACH_PREVPTR(var, varp, head, field) \
174 for ((varp) = &SLIST_FIRST((head)); \
175 ((var) = *(varp)) != NULL; \
176 (varp) = &SLIST_NEXT((var), field))
178 #define SLIST_INIT(head) do { \
179 SLIST_FIRST((head)) = NULL; \
182 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
183 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \
184 SLIST_NEXT((slistelm), field) = (elm); \
187 #define SLIST_INSERT_HEAD(head, elm, field) do { \
188 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \
189 SLIST_FIRST((head)) = (elm); \
192 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
194 #define SLIST_REMOVE(head, elm, type, field) do { \
195 QMD_SAVELINK(oldnext, (elm)->field.sle_next); \
196 if (SLIST_FIRST((head)) == (elm)) { \
197 SLIST_REMOVE_HEAD((head), field); \
200 struct type *curelm = SLIST_FIRST((head)); \
201 while (SLIST_NEXT(curelm, field) != (elm)) \
202 curelm = SLIST_NEXT(curelm, field); \
203 SLIST_REMOVE_AFTER(curelm, field); \
208 #define SLIST_REMOVE_AFTER(elm, field) do { \
209 SLIST_NEXT(elm, field) = \
210 SLIST_NEXT(SLIST_NEXT(elm, field), field); \
213 #define SLIST_REMOVE_HEAD(head, field) do { \
214 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
217 #define SLIST_SWAP(head1, head2, type) do { \
218 struct type *swap_first = SLIST_FIRST(head1); \
219 SLIST_FIRST(head1) = SLIST_FIRST(head2); \
220 SLIST_FIRST(head2) = swap_first; \
224 * Singly-linked Tail queue declarations.
226 #define STAILQ_HEAD(name, type) \
228 struct type *stqh_first;/* first element */ \
229 struct type **stqh_last;/* addr of last next element */ \
232 #define STAILQ_HEAD_INITIALIZER(head) \
233 { NULL, &(head).stqh_first }
235 #define STAILQ_ENTRY(type) \
237 struct type *stqe_next; /* next element */ \
241 * Singly-linked Tail queue functions.
243 #define STAILQ_CONCAT(head1, head2) do { \
244 if (!STAILQ_EMPTY((head2))) { \
245 *(head1)->stqh_last = (head2)->stqh_first; \
246 (head1)->stqh_last = (head2)->stqh_last; \
247 STAILQ_INIT((head2)); \
251 #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
253 #define STAILQ_FIRST(head) ((head)->stqh_first)
255 #define STAILQ_FOREACH(var, head, field) \
256 for((var) = STAILQ_FIRST((head)); \
258 (var) = STAILQ_NEXT((var), field))
261 #define STAILQ_FOREACH_SAFE(var, head, field, tvar) \
262 for ((var) = STAILQ_FIRST((head)); \
263 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \
266 #define STAILQ_INIT(head) do { \
267 STAILQ_FIRST((head)) = NULL; \
268 (head)->stqh_last = &STAILQ_FIRST((head)); \
271 #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \
272 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
273 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
274 STAILQ_NEXT((tqelm), field) = (elm); \
277 #define STAILQ_INSERT_HEAD(head, elm, field) do { \
278 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
279 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
280 STAILQ_FIRST((head)) = (elm); \
283 #define STAILQ_INSERT_TAIL(head, elm, field) do { \
284 STAILQ_NEXT((elm), field) = NULL; \
285 *(head)->stqh_last = (elm); \
286 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
289 #define STAILQ_LAST(head, type, field) \
290 (STAILQ_EMPTY((head)) ? \
292 __member2struct(type, field, (head)->stqh_last))
294 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
296 #define STAILQ_REMOVE(head, elm, type, field) do { \
297 QMD_SAVELINK(oldnext, (elm)->field.stqe_next); \
298 if (STAILQ_FIRST((head)) == (elm)) { \
299 STAILQ_REMOVE_HEAD((head), field); \
302 struct type *curelm = STAILQ_FIRST((head)); \
303 while (STAILQ_NEXT(curelm, field) != (elm)) \
304 curelm = STAILQ_NEXT(curelm, field); \
305 STAILQ_REMOVE_AFTER(head, curelm, field); \
310 #define STAILQ_REMOVE_AFTER(head, elm, field) do { \
311 if ((STAILQ_NEXT(elm, field) = \
312 STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL) \
313 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
316 #define STAILQ_REMOVE_HEAD(head, field) do { \
317 if ((STAILQ_FIRST((head)) = \
318 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
319 (head)->stqh_last = &STAILQ_FIRST((head)); \
322 #define STAILQ_SWAP(head1, head2, type) do { \
323 struct type *swap_first = STAILQ_FIRST(head1); \
324 struct type **swap_last = (head1)->stqh_last; \
325 STAILQ_FIRST(head1) = STAILQ_FIRST(head2); \
326 (head1)->stqh_last = (head2)->stqh_last; \
327 STAILQ_FIRST(head2) = swap_first; \
328 (head2)->stqh_last = swap_last; \
329 if (STAILQ_EMPTY(head1)) \
330 (head1)->stqh_last = &STAILQ_FIRST(head1); \
331 if (STAILQ_EMPTY(head2)) \
332 (head2)->stqh_last = &STAILQ_FIRST(head2); \
339 #define LIST_HEAD(name, type) \
341 struct type *lh_first; /* first element */ \
344 #define LIST_HEAD_INITIALIZER(head) \
347 #define LIST_ENTRY(type) \
349 struct type *le_next; /* next element */ \
350 struct type **le_prev; /* address of previous next element */ \
357 #if (defined(_KERNEL) && defined(INVARIANTS))
358 #define QMD_LIST_CHECK_HEAD(head, field) do { \
359 if (LIST_FIRST((head)) != NULL && \
360 LIST_FIRST((head))->field.le_prev != \
361 &LIST_FIRST((head))) \
362 panic("Bad list head %p first->prev != head", (head)); \
365 #define QMD_LIST_CHECK_NEXT(elm, field) do { \
366 if (LIST_NEXT((elm), field) != NULL && \
367 LIST_NEXT((elm), field)->field.le_prev != \
368 &((elm)->field.le_next)) \
369 panic("Bad link elm %p next->prev != elm", (elm)); \
372 #define QMD_LIST_CHECK_PREV(elm, field) do { \
373 if (*(elm)->field.le_prev != (elm)) \
374 panic("Bad link elm %p prev->next != elm", (elm)); \
377 #define QMD_LIST_CHECK_HEAD(head, field)
378 #define QMD_LIST_CHECK_NEXT(elm, field)
379 #define QMD_LIST_CHECK_PREV(elm, field)
380 #endif /* (_KERNEL && INVARIANTS) */
382 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
384 #define LIST_FIRST(head) ((head)->lh_first)
386 #define LIST_FOREACH(var, head, field) \
387 for ((var) = LIST_FIRST((head)); \
389 (var) = LIST_NEXT((var), field))
391 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
392 for ((var) = LIST_FIRST((head)); \
393 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
396 #define LIST_INIT(head) do { \
397 LIST_FIRST((head)) = NULL; \
400 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
401 QMD_LIST_CHECK_NEXT(listelm, field); \
402 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
403 LIST_NEXT((listelm), field)->field.le_prev = \
404 &LIST_NEXT((elm), field); \
405 LIST_NEXT((listelm), field) = (elm); \
406 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
409 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
410 QMD_LIST_CHECK_PREV(listelm, field); \
411 (elm)->field.le_prev = (listelm)->field.le_prev; \
412 LIST_NEXT((elm), field) = (listelm); \
413 *(listelm)->field.le_prev = (elm); \
414 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
417 #define LIST_INSERT_HEAD(head, elm, field) do { \
418 QMD_LIST_CHECK_HEAD((head), field); \
419 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
420 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
421 LIST_FIRST((head)) = (elm); \
422 (elm)->field.le_prev = &LIST_FIRST((head)); \
425 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
427 #define LIST_PREV(elm, head, type, field) \
428 ((elm)->field.le_prev == &LIST_FIRST((head)) ? \
430 __member2struct(type, field, (elm)->field.le_prev))
432 #define LIST_REMOVE(elm, field) do { \
433 QMD_SAVELINK(oldnext, (elm)->field.le_next); \
434 QMD_SAVELINK(oldprev, (elm)->field.le_prev); \
435 QMD_LIST_CHECK_NEXT(elm, field); \
436 QMD_LIST_CHECK_PREV(elm, field); \
437 if (LIST_NEXT((elm), field) != NULL) \
438 LIST_NEXT((elm), field)->field.le_prev = \
439 (elm)->field.le_prev; \
440 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
445 #define LIST_SWAP(head1, head2, type, field) do { \
446 struct type *swap_tmp = LIST_FIRST((head1)); \
447 LIST_FIRST((head1)) = LIST_FIRST((head2)); \
448 LIST_FIRST((head2)) = swap_tmp; \
449 if ((swap_tmp = LIST_FIRST((head1))) != NULL) \
450 swap_tmp->field.le_prev = &LIST_FIRST((head1)); \
451 if ((swap_tmp = LIST_FIRST((head2))) != NULL) \
452 swap_tmp->field.le_prev = &LIST_FIRST((head2)); \
456 * Tail queue declarations.
458 #define TAILQ_HEAD(name, type) \
460 struct type *tqh_first; /* first element */ \
461 struct type **tqh_last; /* addr of last next element */ \
465 #define TAILQ_HEAD_INITIALIZER(head) \
466 { NULL, &(head).tqh_first }
468 #define TAILQ_ENTRY(type) \
470 struct type *tqe_next; /* next element */ \
471 struct type **tqe_prev; /* address of previous next element */ \
476 * Tail queue functions.
478 #if (defined(_KERNEL) && defined(INVARIANTS))
479 #define QMD_TAILQ_CHECK_HEAD(head, field) do { \
480 if (!TAILQ_EMPTY(head) && \
481 TAILQ_FIRST((head))->field.tqe_prev != \
482 &TAILQ_FIRST((head))) \
483 panic("Bad tailq head %p first->prev != head", (head)); \
486 #define QMD_TAILQ_CHECK_TAIL(head, field) do { \
487 if (*(head)->tqh_last != NULL) \
488 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); \
491 #define QMD_TAILQ_CHECK_NEXT(elm, field) do { \
492 if (TAILQ_NEXT((elm), field) != NULL && \
493 TAILQ_NEXT((elm), field)->field.tqe_prev != \
494 &((elm)->field.tqe_next)) \
495 panic("Bad link elm %p next->prev != elm", (elm)); \
498 #define QMD_TAILQ_CHECK_PREV(elm, field) do { \
499 if (*(elm)->field.tqe_prev != (elm)) \
500 panic("Bad link elm %p prev->next != elm", (elm)); \
503 #define QMD_TAILQ_CHECK_HEAD(head, field)
504 #define QMD_TAILQ_CHECK_TAIL(head, headname)
505 #define QMD_TAILQ_CHECK_NEXT(elm, field)
506 #define QMD_TAILQ_CHECK_PREV(elm, field)
507 #endif /* (_KERNEL && INVARIANTS) */
509 #define TAILQ_CONCAT(head1, head2, field) do { \
510 if (!TAILQ_EMPTY(head2)) { \
511 *(head1)->tqh_last = (head2)->tqh_first; \
512 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
513 (head1)->tqh_last = (head2)->tqh_last; \
514 TAILQ_INIT((head2)); \
515 QMD_TRACE_HEAD(head1); \
516 QMD_TRACE_HEAD(head2); \
520 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
522 #define TAILQ_FIRST(head) ((head)->tqh_first)
524 #define TAILQ_FOREACH(var, head, field) \
525 for ((var) = TAILQ_FIRST((head)); \
527 (var) = TAILQ_NEXT((var), field))
529 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
530 for ((var) = TAILQ_FIRST((head)); \
531 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
534 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
535 for ((var) = TAILQ_LAST((head), headname); \
537 (var) = TAILQ_PREV((var), headname, field))
539 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
540 for ((var) = TAILQ_LAST((head), headname); \
541 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
544 #define TAILQ_INIT(head) do { \
545 TAILQ_FIRST((head)) = NULL; \
546 (head)->tqh_last = &TAILQ_FIRST((head)); \
547 QMD_TRACE_HEAD(head); \
550 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
551 QMD_TAILQ_CHECK_NEXT(listelm, field); \
552 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
553 TAILQ_NEXT((elm), field)->field.tqe_prev = \
554 &TAILQ_NEXT((elm), field); \
556 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
557 QMD_TRACE_HEAD(head); \
559 TAILQ_NEXT((listelm), field) = (elm); \
560 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
561 QMD_TRACE_ELEM(&(elm)->field); \
562 QMD_TRACE_ELEM(&listelm->field); \
565 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
566 QMD_TAILQ_CHECK_PREV(listelm, field); \
567 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
568 TAILQ_NEXT((elm), field) = (listelm); \
569 *(listelm)->field.tqe_prev = (elm); \
570 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
571 QMD_TRACE_ELEM(&(elm)->field); \
572 QMD_TRACE_ELEM(&listelm->field); \
575 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
576 QMD_TAILQ_CHECK_HEAD(head, field); \
577 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
578 TAILQ_FIRST((head))->field.tqe_prev = \
579 &TAILQ_NEXT((elm), field); \
581 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
582 TAILQ_FIRST((head)) = (elm); \
583 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
584 QMD_TRACE_HEAD(head); \
585 QMD_TRACE_ELEM(&(elm)->field); \
588 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
589 QMD_TAILQ_CHECK_TAIL(head, field); \
590 TAILQ_NEXT((elm), field) = NULL; \
591 (elm)->field.tqe_prev = (head)->tqh_last; \
592 *(head)->tqh_last = (elm); \
593 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
594 QMD_TRACE_HEAD(head); \
595 QMD_TRACE_ELEM(&(elm)->field); \
598 #define TAILQ_LAST(head, headname) \
599 (*(((struct headname *)((head)->tqh_last))->tqh_last))
601 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
603 #define TAILQ_PREV(elm, headname, field) \
604 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
606 #define TAILQ_REMOVE(head, elm, field) do { \
607 QMD_SAVELINK(oldnext, (elm)->field.tqe_next); \
608 QMD_SAVELINK(oldprev, (elm)->field.tqe_prev); \
609 QMD_TAILQ_CHECK_NEXT(elm, field); \
610 QMD_TAILQ_CHECK_PREV(elm, field); \
611 if ((TAILQ_NEXT((elm), field)) != NULL) \
612 TAILQ_NEXT((elm), field)->field.tqe_prev = \
613 (elm)->field.tqe_prev; \
615 (head)->tqh_last = (elm)->field.tqe_prev; \
616 QMD_TRACE_HEAD(head); \
618 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
621 QMD_TRACE_ELEM(&(elm)->field); \
624 #define TAILQ_SWAP(head1, head2, type, field) do { \
625 struct type *swap_first = (head1)->tqh_first; \
626 struct type **swap_last = (head1)->tqh_last; \
627 (head1)->tqh_first = (head2)->tqh_first; \
628 (head1)->tqh_last = (head2)->tqh_last; \
629 (head2)->tqh_first = swap_first; \
630 (head2)->tqh_last = swap_last; \
631 if ((swap_first = (head1)->tqh_first) != NULL) \
632 swap_first->field.tqe_prev = &(head1)->tqh_first; \
634 (head1)->tqh_last = &(head1)->tqh_first; \
635 if ((swap_first = (head2)->tqh_first) != NULL) \
636 swap_first->field.tqe_prev = &(head2)->tqh_first; \
638 (head2)->tqh_last = &(head2)->tqh_first; \
641 #endif /* !_SYS_QUEUE_H_ */