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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 only be traversed in the forward 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 ((struct type *)(void *) \
293 ((char *)((head)->stqh_last) - __offsetof(struct type, field))))
295 #define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
297 #define STAILQ_REMOVE(head, elm, type, field) do { \
298 QMD_SAVELINK(oldnext, (elm)->field.stqe_next); \
299 if (STAILQ_FIRST((head)) == (elm)) { \
300 STAILQ_REMOVE_HEAD((head), field); \
303 struct type *curelm = STAILQ_FIRST((head)); \
304 while (STAILQ_NEXT(curelm, field) != (elm)) \
305 curelm = STAILQ_NEXT(curelm, field); \
306 STAILQ_REMOVE_AFTER(head, curelm, field); \
311 #define STAILQ_REMOVE_AFTER(head, elm, field) do { \
312 if ((STAILQ_NEXT(elm, field) = \
313 STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL) \
314 (head)->stqh_last = &STAILQ_NEXT((elm), field); \
317 #define STAILQ_REMOVE_HEAD(head, field) do { \
318 if ((STAILQ_FIRST((head)) = \
319 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \
320 (head)->stqh_last = &STAILQ_FIRST((head)); \
323 #define STAILQ_SWAP(head1, head2, type) do { \
324 struct type *swap_first = STAILQ_FIRST(head1); \
325 struct type **swap_last = (head1)->stqh_last; \
326 STAILQ_FIRST(head1) = STAILQ_FIRST(head2); \
327 (head1)->stqh_last = (head2)->stqh_last; \
328 STAILQ_FIRST(head2) = swap_first; \
329 (head2)->stqh_last = swap_last; \
330 if (STAILQ_EMPTY(head1)) \
331 (head1)->stqh_last = &STAILQ_FIRST(head1); \
332 if (STAILQ_EMPTY(head2)) \
333 (head2)->stqh_last = &STAILQ_FIRST(head2); \
340 #define LIST_HEAD(name, type) \
342 struct type *lh_first; /* first element */ \
345 #define LIST_HEAD_INITIALIZER(head) \
348 #define LIST_ENTRY(type) \
350 struct type *le_next; /* next element */ \
351 struct type **le_prev; /* address of previous next element */ \
358 #if (defined(_KERNEL) && defined(INVARIANTS))
359 #define QMD_LIST_CHECK_HEAD(head, field) do { \
360 if (LIST_FIRST((head)) != NULL && \
361 LIST_FIRST((head))->field.le_prev != \
362 &LIST_FIRST((head))) \
363 panic("Bad list head %p first->prev != head", (head)); \
366 #define QMD_LIST_CHECK_NEXT(elm, field) do { \
367 if (LIST_NEXT((elm), field) != NULL && \
368 LIST_NEXT((elm), field)->field.le_prev != \
369 &((elm)->field.le_next)) \
370 panic("Bad link elm %p next->prev != elm", (elm)); \
373 #define QMD_LIST_CHECK_PREV(elm, field) do { \
374 if (*(elm)->field.le_prev != (elm)) \
375 panic("Bad link elm %p prev->next != elm", (elm)); \
378 #define QMD_LIST_CHECK_HEAD(head, field)
379 #define QMD_LIST_CHECK_NEXT(elm, field)
380 #define QMD_LIST_CHECK_PREV(elm, field)
381 #endif /* (_KERNEL && INVARIANTS) */
383 #define LIST_EMPTY(head) ((head)->lh_first == NULL)
385 #define LIST_FIRST(head) ((head)->lh_first)
387 #define LIST_FOREACH(var, head, field) \
388 for ((var) = LIST_FIRST((head)); \
390 (var) = LIST_NEXT((var), field))
392 #define LIST_FOREACH_SAFE(var, head, field, tvar) \
393 for ((var) = LIST_FIRST((head)); \
394 (var) && ((tvar) = LIST_NEXT((var), field), 1); \
397 #define LIST_INIT(head) do { \
398 LIST_FIRST((head)) = NULL; \
401 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
402 QMD_LIST_CHECK_NEXT(listelm, field); \
403 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
404 LIST_NEXT((listelm), field)->field.le_prev = \
405 &LIST_NEXT((elm), field); \
406 LIST_NEXT((listelm), field) = (elm); \
407 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \
410 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
411 QMD_LIST_CHECK_PREV(listelm, field); \
412 (elm)->field.le_prev = (listelm)->field.le_prev; \
413 LIST_NEXT((elm), field) = (listelm); \
414 *(listelm)->field.le_prev = (elm); \
415 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \
418 #define LIST_INSERT_HEAD(head, elm, field) do { \
419 QMD_LIST_CHECK_HEAD((head), field); \
420 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \
421 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
422 LIST_FIRST((head)) = (elm); \
423 (elm)->field.le_prev = &LIST_FIRST((head)); \
426 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
428 #define LIST_REMOVE(elm, field) do { \
429 QMD_SAVELINK(oldnext, (elm)->field.le_next); \
430 QMD_SAVELINK(oldprev, (elm)->field.le_prev); \
431 QMD_LIST_CHECK_NEXT(elm, field); \
432 QMD_LIST_CHECK_PREV(elm, field); \
433 if (LIST_NEXT((elm), field) != NULL) \
434 LIST_NEXT((elm), field)->field.le_prev = \
435 (elm)->field.le_prev; \
436 *(elm)->field.le_prev = LIST_NEXT((elm), field); \
441 #define LIST_SWAP(head1, head2, type, field) do { \
442 struct type *swap_tmp = LIST_FIRST((head1)); \
443 LIST_FIRST((head1)) = LIST_FIRST((head2)); \
444 LIST_FIRST((head2)) = swap_tmp; \
445 if ((swap_tmp = LIST_FIRST((head1))) != NULL) \
446 swap_tmp->field.le_prev = &LIST_FIRST((head1)); \
447 if ((swap_tmp = LIST_FIRST((head2))) != NULL) \
448 swap_tmp->field.le_prev = &LIST_FIRST((head2)); \
452 * Tail queue declarations.
454 #define TAILQ_HEAD(name, type) \
456 struct type *tqh_first; /* first element */ \
457 struct type **tqh_last; /* addr of last next element */ \
461 #define TAILQ_HEAD_INITIALIZER(head) \
462 { NULL, &(head).tqh_first }
464 #define TAILQ_ENTRY(type) \
466 struct type *tqe_next; /* next element */ \
467 struct type **tqe_prev; /* address of previous next element */ \
472 * Tail queue functions.
474 #if (defined(_KERNEL) && defined(INVARIANTS))
475 #define QMD_TAILQ_CHECK_HEAD(head, field) do { \
476 if (!TAILQ_EMPTY(head) && \
477 TAILQ_FIRST((head))->field.tqe_prev != \
478 &TAILQ_FIRST((head))) \
479 panic("Bad tailq head %p first->prev != head", (head)); \
482 #define QMD_TAILQ_CHECK_TAIL(head, field) do { \
483 if (*(head)->tqh_last != NULL) \
484 panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head)); \
487 #define QMD_TAILQ_CHECK_NEXT(elm, field) do { \
488 if (TAILQ_NEXT((elm), field) != NULL && \
489 TAILQ_NEXT((elm), field)->field.tqe_prev != \
490 &((elm)->field.tqe_next)) \
491 panic("Bad link elm %p next->prev != elm", (elm)); \
494 #define QMD_TAILQ_CHECK_PREV(elm, field) do { \
495 if (*(elm)->field.tqe_prev != (elm)) \
496 panic("Bad link elm %p prev->next != elm", (elm)); \
499 #define QMD_TAILQ_CHECK_HEAD(head, field)
500 #define QMD_TAILQ_CHECK_TAIL(head, headname)
501 #define QMD_TAILQ_CHECK_NEXT(elm, field)
502 #define QMD_TAILQ_CHECK_PREV(elm, field)
503 #endif /* (_KERNEL && INVARIANTS) */
505 #define TAILQ_CONCAT(head1, head2, field) do { \
506 if (!TAILQ_EMPTY(head2)) { \
507 *(head1)->tqh_last = (head2)->tqh_first; \
508 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
509 (head1)->tqh_last = (head2)->tqh_last; \
510 TAILQ_INIT((head2)); \
511 QMD_TRACE_HEAD(head1); \
512 QMD_TRACE_HEAD(head2); \
516 #define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
518 #define TAILQ_FIRST(head) ((head)->tqh_first)
520 #define TAILQ_FOREACH(var, head, field) \
521 for ((var) = TAILQ_FIRST((head)); \
523 (var) = TAILQ_NEXT((var), field))
525 #define TAILQ_FOREACH_SAFE(var, head, field, tvar) \
526 for ((var) = TAILQ_FIRST((head)); \
527 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \
530 #define TAILQ_FOREACH_REVERSE(var, head, headname, field) \
531 for ((var) = TAILQ_LAST((head), headname); \
533 (var) = TAILQ_PREV((var), headname, field))
535 #define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \
536 for ((var) = TAILQ_LAST((head), headname); \
537 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \
540 #define TAILQ_INIT(head) do { \
541 TAILQ_FIRST((head)) = NULL; \
542 (head)->tqh_last = &TAILQ_FIRST((head)); \
543 QMD_TRACE_HEAD(head); \
546 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
547 QMD_TAILQ_CHECK_NEXT(listelm, field); \
548 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
549 TAILQ_NEXT((elm), field)->field.tqe_prev = \
550 &TAILQ_NEXT((elm), field); \
552 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
553 QMD_TRACE_HEAD(head); \
555 TAILQ_NEXT((listelm), field) = (elm); \
556 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \
557 QMD_TRACE_ELEM(&(elm)->field); \
558 QMD_TRACE_ELEM(&listelm->field); \
561 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
562 QMD_TAILQ_CHECK_PREV(listelm, field); \
563 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
564 TAILQ_NEXT((elm), field) = (listelm); \
565 *(listelm)->field.tqe_prev = (elm); \
566 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \
567 QMD_TRACE_ELEM(&(elm)->field); \
568 QMD_TRACE_ELEM(&listelm->field); \
571 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
572 QMD_TAILQ_CHECK_HEAD(head, field); \
573 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \
574 TAILQ_FIRST((head))->field.tqe_prev = \
575 &TAILQ_NEXT((elm), field); \
577 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
578 TAILQ_FIRST((head)) = (elm); \
579 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \
580 QMD_TRACE_HEAD(head); \
581 QMD_TRACE_ELEM(&(elm)->field); \
584 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
585 QMD_TAILQ_CHECK_TAIL(head, field); \
586 TAILQ_NEXT((elm), field) = NULL; \
587 (elm)->field.tqe_prev = (head)->tqh_last; \
588 *(head)->tqh_last = (elm); \
589 (head)->tqh_last = &TAILQ_NEXT((elm), field); \
590 QMD_TRACE_HEAD(head); \
591 QMD_TRACE_ELEM(&(elm)->field); \
594 #define TAILQ_LAST(head, headname) \
595 (*(((struct headname *)((head)->tqh_last))->tqh_last))
597 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
599 #define TAILQ_PREV(elm, headname, field) \
600 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
602 #define TAILQ_REMOVE(head, elm, field) do { \
603 QMD_SAVELINK(oldnext, (elm)->field.tqe_next); \
604 QMD_SAVELINK(oldprev, (elm)->field.tqe_prev); \
605 QMD_TAILQ_CHECK_NEXT(elm, field); \
606 QMD_TAILQ_CHECK_PREV(elm, field); \
607 if ((TAILQ_NEXT((elm), field)) != NULL) \
608 TAILQ_NEXT((elm), field)->field.tqe_prev = \
609 (elm)->field.tqe_prev; \
611 (head)->tqh_last = (elm)->field.tqe_prev; \
612 QMD_TRACE_HEAD(head); \
614 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \
617 QMD_TRACE_ELEM(&(elm)->field); \
620 #define TAILQ_SWAP(head1, head2, type, field) do { \
621 struct type *swap_first = (head1)->tqh_first; \
622 struct type **swap_last = (head1)->tqh_last; \
623 (head1)->tqh_first = (head2)->tqh_first; \
624 (head1)->tqh_last = (head2)->tqh_last; \
625 (head2)->tqh_first = swap_first; \
626 (head2)->tqh_last = swap_last; \
627 if ((swap_first = (head1)->tqh_first) != NULL) \
628 swap_first->field.tqe_prev = &(head1)->tqh_first; \
630 (head1)->tqh_last = &(head1)->tqh_first; \
631 if ((swap_first = (head2)->tqh_first) != NULL) \
632 swap_first->field.tqe_prev = &(head2)->tqh_first; \
634 (head2)->tqh_last = &(head2)->tqh_first; \
637 #endif /* !_SYS_QUEUE_H_ */