queue.h revision 126891
1/* 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)queue.h 8.5 (Berkeley) 8/20/94 34 * $FreeBSD: head/sys/sys/queue.h 126891 2004-03-12 21:45:33Z trhodes $ 35 */ 36 37#ifndef _SYS_QUEUE_H_ 38#define _SYS_QUEUE_H_ 39 40#include <sys/cdefs.h> 41 42/* 43 * This file defines four types of data structures: singly-linked lists, 44 * singly-linked tail queues, lists and tail queues. 45 * 46 * A singly-linked list is headed by a single forward pointer. The elements 47 * are singly linked for minimum space and pointer manipulation overhead at 48 * the expense of O(n) removal for arbitrary elements. New elements can be 49 * added to the list after an existing element or at the head of the list. 50 * Elements being removed from the head of the list should use the explicit 51 * macro for this purpose for optimum efficiency. A singly-linked list may 52 * only be traversed in the forward direction. Singly-linked lists are ideal 53 * for applications with large datasets and few or no removals or for 54 * implementing a LIFO queue. 55 * 56 * A singly-linked tail queue is headed by a pair of pointers, one to the 57 * head of the list and the other to the tail of the list. The elements are 58 * singly linked for minimum space and pointer manipulation overhead at the 59 * expense of O(n) removal for arbitrary elements. New elements can be added 60 * to the list after an existing element, at the head of the list, or at the 61 * end of the list. Elements being removed from the head of the tail queue 62 * should use the explicit macro for this purpose for optimum efficiency. 63 * A singly-linked tail queue may only be traversed in the forward direction. 64 * Singly-linked tail queues are ideal for applications with large datasets 65 * and few or no removals or for implementing a FIFO queue. 66 * 67 * A list is headed by a single forward pointer (or an array of forward 68 * pointers for a hash table header). The elements are doubly linked 69 * so that an arbitrary element can be removed without a need to 70 * traverse the list. New elements can be added to the list before 71 * or after an existing element or at the head of the list. A list 72 * may only be traversed in the forward direction. 73 * 74 * A tail queue is headed by a pair of pointers, one to the head of the 75 * list and the other to the tail of the list. The elements are doubly 76 * linked so that an arbitrary element can be removed without a need to 77 * traverse the list. New elements can be added to the list before or 78 * after an existing element, at the head of the list, or at the end of 79 * the list. A tail queue may be traversed in either direction. 80 * 81 * For details on the use of these macros, see the queue(3) manual page. 82 * 83 * 84 * SLIST LIST STAILQ TAILQ 85 * _HEAD + + + + 86 * _HEAD_INITIALIZER + + + + 87 * _ENTRY + + + + 88 * _INIT + + + + 89 * _EMPTY + + + + 90 * _FIRST + + + + 91 * _NEXT + + + + 92 * _PREV - - - + 93 * _LAST - - + + 94 * _FOREACH + + + + 95 * _FOREACH_SAFE + + + + 96 * _FOREACH_REVERSE - - - + 97 * _FOREACH_REVERSE_SAFE - - - + 98 * _INSERT_HEAD + + + + 99 * _INSERT_BEFORE - + - + 100 * _INSERT_AFTER + + + + 101 * _INSERT_TAIL - - + + 102 * _CONCAT - - + + 103 * _REMOVE_HEAD + - + - 104 * _REMOVE + + + + 105 * 106 */ 107#define QUEUE_MACRO_DEBUG 0 108#if QUEUE_MACRO_DEBUG 109/* Store the last 2 places the queue element or head was altered */ 110struct qm_trace { 111 char * lastfile; 112 int lastline; 113 char * prevfile; 114 int prevline; 115}; 116 117#define TRACEBUF struct qm_trace trace; 118#define TRASHIT(x) do {(x) = (void *)-1;} while (0) 119 120#define QMD_TRACE_HEAD(head) do { \ 121 (head)->trace.prevline = (head)->trace.lastline; \ 122 (head)->trace.prevfile = (head)->trace.lastfile; \ 123 (head)->trace.lastline = __LINE__; \ 124 (head)->trace.lastfile = __FILE__; \ 125} while (0) 126 127#define QMD_TRACE_ELEM(elem) do { \ 128 (elem)->trace.prevline = (elem)->trace.lastline; \ 129 (elem)->trace.prevfile = (elem)->trace.lastfile; \ 130 (elem)->trace.lastline = __LINE__; \ 131 (elem)->trace.lastfile = __FILE__; \ 132} while (0) 133 134#else 135#define QMD_TRACE_ELEM(elem) 136#define QMD_TRACE_HEAD(head) 137#define TRACEBUF 138#define TRASHIT(x) 139#endif /* QUEUE_MACRO_DEBUG */ 140 141/* 142 * Singly-linked List declarations. 143 */ 144#define SLIST_HEAD(name, type) \ 145struct name { \ 146 struct type *slh_first; /* first element */ \ 147} 148 149#define SLIST_HEAD_INITIALIZER(head) \ 150 { NULL } 151 152#define SLIST_ENTRY(type) \ 153struct { \ 154 struct type *sle_next; /* next element */ \ 155} 156 157/* 158 * Singly-linked List functions. 159 */ 160#define SLIST_EMPTY(head) ((head)->slh_first == NULL) 161 162#define SLIST_FIRST(head) ((head)->slh_first) 163 164#define SLIST_FOREACH(var, head, field) \ 165 for ((var) = SLIST_FIRST((head)); \ 166 (var); \ 167 (var) = SLIST_NEXT((var), field)) 168 169#define SLIST_FOREACH_SAFE(var, head, field, tvar) \ 170 for ((var) = SLIST_FIRST((head)); \ 171 (var) && ((tvar) = SLIST_NEXT((var), field), 1); \ 172 (var) = (tvar)) 173 174#define SLIST_FOREACH_PREVPTR(var, varp, head, field) \ 175 for ((varp) = &SLIST_FIRST((head)); \ 176 ((var) = *(varp)) != NULL; \ 177 (varp) = &SLIST_NEXT((var), field)) 178 179#define SLIST_INIT(head) do { \ 180 SLIST_FIRST((head)) = NULL; \ 181} while (0) 182 183#define SLIST_INSERT_AFTER(slistelm, elm, field) do { \ 184 SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field); \ 185 SLIST_NEXT((slistelm), field) = (elm); \ 186} while (0) 187 188#define SLIST_INSERT_HEAD(head, elm, field) do { \ 189 SLIST_NEXT((elm), field) = SLIST_FIRST((head)); \ 190 SLIST_FIRST((head)) = (elm); \ 191} while (0) 192 193#define SLIST_NEXT(elm, field) ((elm)->field.sle_next) 194 195#define SLIST_REMOVE(head, elm, type, field) do { \ 196 if (SLIST_FIRST((head)) == (elm)) { \ 197 SLIST_REMOVE_HEAD((head), field); \ 198 } \ 199 else { \ 200 struct type *curelm = SLIST_FIRST((head)); \ 201 while (SLIST_NEXT(curelm, field) != (elm)) \ 202 curelm = SLIST_NEXT(curelm, field); \ 203 SLIST_NEXT(curelm, field) = \ 204 SLIST_NEXT(SLIST_NEXT(curelm, field), field); \ 205 } \ 206} while (0) 207 208#define SLIST_REMOVE_HEAD(head, field) do { \ 209 SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \ 210} while (0) 211 212/* 213 * Singly-linked Tail queue declarations. 214 */ 215#define STAILQ_HEAD(name, type) \ 216struct name { \ 217 struct type *stqh_first;/* first element */ \ 218 struct type **stqh_last;/* addr of last next element */ \ 219} 220 221#define STAILQ_HEAD_INITIALIZER(head) \ 222 { NULL, &(head).stqh_first } 223 224#define STAILQ_ENTRY(type) \ 225struct { \ 226 struct type *stqe_next; /* next element */ \ 227} 228 229/* 230 * Singly-linked Tail queue functions. 231 */ 232#define STAILQ_CONCAT(head1, head2) do { \ 233 if (!STAILQ_EMPTY((head2))) { \ 234 *(head1)->stqh_last = (head2)->stqh_first; \ 235 (head1)->stqh_last = (head2)->stqh_last; \ 236 STAILQ_INIT((head2)); \ 237 } \ 238} while (0) 239 240#define STAILQ_EMPTY(head) ((head)->stqh_first == NULL) 241 242#define STAILQ_FIRST(head) ((head)->stqh_first) 243 244#define STAILQ_FOREACH(var, head, field) \ 245 for((var) = STAILQ_FIRST((head)); \ 246 (var); \ 247 (var) = STAILQ_NEXT((var), field)) 248 249 250#define STAILQ_FOREACH_SAFE(var, head, field, tvar) \ 251 for ((var) = STAILQ_FIRST((head)); \ 252 (var) && ((tvar) = STAILQ_NEXT((var), field), 1); \ 253 (var) = (tvar)) 254 255#define STAILQ_INIT(head) do { \ 256 STAILQ_FIRST((head)) = NULL; \ 257 (head)->stqh_last = &STAILQ_FIRST((head)); \ 258} while (0) 259 260#define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do { \ 261 if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\ 262 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 263 STAILQ_NEXT((tqelm), field) = (elm); \ 264} while (0) 265 266#define STAILQ_INSERT_HEAD(head, elm, field) do { \ 267 if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \ 268 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 269 STAILQ_FIRST((head)) = (elm); \ 270} while (0) 271 272#define STAILQ_INSERT_TAIL(head, elm, field) do { \ 273 STAILQ_NEXT((elm), field) = NULL; \ 274 *(head)->stqh_last = (elm); \ 275 (head)->stqh_last = &STAILQ_NEXT((elm), field); \ 276} while (0) 277 278#define STAILQ_LAST(head, type, field) \ 279 (STAILQ_EMPTY((head)) ? \ 280 NULL : \ 281 ((struct type *) \ 282 ((char *)((head)->stqh_last) - __offsetof(struct type, field)))) 283 284#define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next) 285 286#define STAILQ_REMOVE(head, elm, type, field) do { \ 287 if (STAILQ_FIRST((head)) == (elm)) { \ 288 STAILQ_REMOVE_HEAD((head), field); \ 289 } \ 290 else { \ 291 struct type *curelm = STAILQ_FIRST((head)); \ 292 while (STAILQ_NEXT(curelm, field) != (elm)) \ 293 curelm = STAILQ_NEXT(curelm, field); \ 294 if ((STAILQ_NEXT(curelm, field) = \ 295 STAILQ_NEXT(STAILQ_NEXT(curelm, field), field)) == NULL)\ 296 (head)->stqh_last = &STAILQ_NEXT((curelm), field);\ 297 } \ 298} while (0) 299 300#define STAILQ_REMOVE_HEAD(head, field) do { \ 301 if ((STAILQ_FIRST((head)) = \ 302 STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL) \ 303 (head)->stqh_last = &STAILQ_FIRST((head)); \ 304} while (0) 305 306#define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do { \ 307 if ((STAILQ_FIRST((head)) = STAILQ_NEXT((elm), field)) == NULL) \ 308 (head)->stqh_last = &STAILQ_FIRST((head)); \ 309} while (0) 310 311/* 312 * List declarations. 313 */ 314#define LIST_HEAD(name, type) \ 315struct name { \ 316 struct type *lh_first; /* first element */ \ 317} 318 319#define LIST_HEAD_INITIALIZER(head) \ 320 { NULL } 321 322#define LIST_ENTRY(type) \ 323struct { \ 324 struct type *le_next; /* next element */ \ 325 struct type **le_prev; /* address of previous next element */ \ 326} 327 328/* 329 * List functions. 330 */ 331 332#define LIST_EMPTY(head) ((head)->lh_first == NULL) 333 334#define LIST_FIRST(head) ((head)->lh_first) 335 336#define LIST_FOREACH(var, head, field) \ 337 for ((var) = LIST_FIRST((head)); \ 338 (var); \ 339 (var) = LIST_NEXT((var), field)) 340 341#define LIST_FOREACH_SAFE(var, head, field, tvar) \ 342 for ((var) = LIST_FIRST((head)); \ 343 (var) && ((tvar) = LIST_NEXT((var), field), 1); \ 344 (var) = (tvar)) 345 346#define LIST_INIT(head) do { \ 347 LIST_FIRST((head)) = NULL; \ 348} while (0) 349 350#define LIST_INSERT_AFTER(listelm, elm, field) do { \ 351 if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\ 352 LIST_NEXT((listelm), field)->field.le_prev = \ 353 &LIST_NEXT((elm), field); \ 354 LIST_NEXT((listelm), field) = (elm); \ 355 (elm)->field.le_prev = &LIST_NEXT((listelm), field); \ 356} while (0) 357 358#define LIST_INSERT_BEFORE(listelm, elm, field) do { \ 359 (elm)->field.le_prev = (listelm)->field.le_prev; \ 360 LIST_NEXT((elm), field) = (listelm); \ 361 *(listelm)->field.le_prev = (elm); \ 362 (listelm)->field.le_prev = &LIST_NEXT((elm), field); \ 363} while (0) 364 365#define LIST_INSERT_HEAD(head, elm, field) do { \ 366 if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL) \ 367 LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\ 368 LIST_FIRST((head)) = (elm); \ 369 (elm)->field.le_prev = &LIST_FIRST((head)); \ 370} while (0) 371 372#define LIST_NEXT(elm, field) ((elm)->field.le_next) 373 374#define LIST_REMOVE(elm, field) do { \ 375 if (LIST_NEXT((elm), field) != NULL) \ 376 LIST_NEXT((elm), field)->field.le_prev = \ 377 (elm)->field.le_prev; \ 378 *(elm)->field.le_prev = LIST_NEXT((elm), field); \ 379} while (0) 380 381/* 382 * Tail queue declarations. 383 */ 384#define TAILQ_HEAD(name, type) \ 385struct name { \ 386 struct type *tqh_first; /* first element */ \ 387 struct type **tqh_last; /* addr of last next element */ \ 388 TRACEBUF \ 389} 390 391#define TAILQ_HEAD_INITIALIZER(head) \ 392 { NULL, &(head).tqh_first } 393 394#define TAILQ_ENTRY(type) \ 395struct { \ 396 struct type *tqe_next; /* next element */ \ 397 struct type **tqe_prev; /* address of previous next element */ \ 398 TRACEBUF \ 399} 400 401/* 402 * Tail queue functions. 403 */ 404#define TAILQ_CONCAT(head1, head2, field) do { \ 405 if (!TAILQ_EMPTY(head2)) { \ 406 *(head1)->tqh_last = (head2)->tqh_first; \ 407 (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \ 408 (head1)->tqh_last = (head2)->tqh_last; \ 409 TAILQ_INIT((head2)); \ 410 QMD_TRACE_HEAD(head); \ 411 QMD_TRACE_HEAD(head2); \ 412 } \ 413} while (0) 414 415#define TAILQ_EMPTY(head) ((head)->tqh_first == NULL) 416 417#define TAILQ_FIRST(head) ((head)->tqh_first) 418 419#define TAILQ_FOREACH(var, head, field) \ 420 for ((var) = TAILQ_FIRST((head)); \ 421 (var); \ 422 (var) = TAILQ_NEXT((var), field)) 423 424#define TAILQ_FOREACH_SAFE(var, head, field, tvar) \ 425 for ((var) = TAILQ_FIRST((head)); \ 426 (var) && ((tvar) = TAILQ_NEXT((var), field), 1); \ 427 (var) = (tvar)) 428 429#define TAILQ_FOREACH_REVERSE(var, head, headname, field) \ 430 for ((var) = TAILQ_LAST((head), headname); \ 431 (var); \ 432 (var) = TAILQ_PREV((var), headname, field)) 433 434#define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar) \ 435 for ((var) = TAILQ_LAST((head), headname); \ 436 (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1); \ 437 (var) = (tvar)) 438 439#define TAILQ_INIT(head) do { \ 440 TAILQ_FIRST((head)) = NULL; \ 441 (head)->tqh_last = &TAILQ_FIRST((head)); \ 442 QMD_TRACE_HEAD(head); \ 443} while (0) 444 445#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \ 446 if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\ 447 TAILQ_NEXT((elm), field)->field.tqe_prev = \ 448 &TAILQ_NEXT((elm), field); \ 449 else { \ 450 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 451 QMD_TRACE_HEAD(head); \ 452 } \ 453 TAILQ_NEXT((listelm), field) = (elm); \ 454 (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field); \ 455 QMD_TRACE_ELEM(&(elm)->field); \ 456 QMD_TRACE_ELEM(&listelm->field); \ 457} while (0) 458 459#define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \ 460 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \ 461 TAILQ_NEXT((elm), field) = (listelm); \ 462 *(listelm)->field.tqe_prev = (elm); \ 463 (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field); \ 464 QMD_TRACE_ELEM(&(elm)->field); \ 465 QMD_TRACE_ELEM(&listelm->field); \ 466} while (0) 467 468#define TAILQ_INSERT_HEAD(head, elm, field) do { \ 469 if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL) \ 470 TAILQ_FIRST((head))->field.tqe_prev = \ 471 &TAILQ_NEXT((elm), field); \ 472 else \ 473 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 474 TAILQ_FIRST((head)) = (elm); \ 475 (elm)->field.tqe_prev = &TAILQ_FIRST((head)); \ 476 QMD_TRACE_HEAD(head); \ 477 QMD_TRACE_ELEM(&(elm)->field); \ 478} while (0) 479 480#define TAILQ_INSERT_TAIL(head, elm, field) do { \ 481 TAILQ_NEXT((elm), field) = NULL; \ 482 (elm)->field.tqe_prev = (head)->tqh_last; \ 483 *(head)->tqh_last = (elm); \ 484 (head)->tqh_last = &TAILQ_NEXT((elm), field); \ 485 QMD_TRACE_HEAD(head); \ 486 QMD_TRACE_ELEM(&(elm)->field); \ 487} while (0) 488 489#define TAILQ_LAST(head, headname) \ 490 (*(((struct headname *)((head)->tqh_last))->tqh_last)) 491 492#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next) 493 494#define TAILQ_PREV(elm, headname, field) \ 495 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last)) 496 497#define TAILQ_REMOVE(head, elm, field) do { \ 498 if ((TAILQ_NEXT((elm), field)) != NULL) \ 499 TAILQ_NEXT((elm), field)->field.tqe_prev = \ 500 (elm)->field.tqe_prev; \ 501 else { \ 502 (head)->tqh_last = (elm)->field.tqe_prev; \ 503 QMD_TRACE_HEAD(head); \ 504 } \ 505 *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field); \ 506 TRASHIT((elm)->field.tqe_next); \ 507 TRASHIT((elm)->field.tqe_prev); \ 508 QMD_TRACE_ELEM(&(elm)->field); \ 509} while (0) 510 511 512#ifdef _KERNEL 513 514/* 515 * XXX insque() and remque() are an old way of handling certain queues. 516 * They bogusly assumes that all queue heads look alike. 517 */ 518 519struct quehead { 520 struct quehead *qh_link; 521 struct quehead *qh_rlink; 522}; 523 524#if defined(__GNUC__) || defined(__INTEL_COMPILER) 525 526static __inline void 527insque(void *a, void *b) 528{ 529 struct quehead *element = (struct quehead *)a, 530 *head = (struct quehead *)b; 531 532 element->qh_link = head->qh_link; 533 element->qh_rlink = head; 534 head->qh_link = element; 535 element->qh_link->qh_rlink = element; 536} 537 538static __inline void 539remque(void *a) 540{ 541 struct quehead *element = (struct quehead *)a; 542 543 element->qh_link->qh_rlink = element->qh_rlink; 544 element->qh_rlink->qh_link = element->qh_link; 545 element->qh_rlink = 0; 546} 547 548#else /* !(__GNUC__ || __INTEL_COMPILER) */ 549 550void insque(void *a, void *b); 551void remque(void *a); 552 553#endif /* __GNUC__ || __INTEL_COMPILER */ 554 555#endif /* _KERNEL */ 556 557#endif /* !_SYS_QUEUE_H_ */ 558