| /* ==================================================================== |
| * The Apache Software License, Version 1.1 |
| * |
| * Copyright (c) 2000 The Apache Software Foundation. All rights |
| * reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * 3. The end-user documentation included with the redistribution, |
| * if any, must include the following acknowledgment: |
| * "This product includes software developed by the |
| * Apache Software Foundation (http://www.apache.org/)." |
| * Alternately, this acknowledgment may appear in the software itself, |
| * if and wherever such third-party acknowledgments normally appear. |
| * |
| * 4. The names "Apache" and "Apache Software Foundation" must |
| * not be used to endorse or promote products derived from this |
| * software without prior written permission. For written |
| * permission, please contact apache@apache.org. |
| * |
| * 5. Products derived from this software may not be called "Apache", |
| * nor may "Apache" appear in their name, without prior written |
| * permission of the Apache Software Foundation. |
| * |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
| * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR |
| * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
| * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * ==================================================================== |
| * |
| * This software consists of voluntary contributions made by many |
| * individuals on behalf of the Apache Software Foundation. For more |
| * information on the Apache Software Foundation, please see |
| * <http://www.apache.org/>. |
| */ |
| |
| /* |
| * This code draws heavily from the 4.4BSD <sys/queue.h> macros |
| * and Dean Gaudet's "splim/ring.h". |
| * <http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/sys/queue.h> |
| * <http://www.arctic.org/~dean/splim/> |
| * |
| * We'd use Dean's code directly if we could guarantee the |
| * availability of inline functions. |
| */ |
| |
| #ifndef AP_RING_H |
| #define AP_RING_H |
| |
| /* |
| * for offsetof() |
| */ |
| #include <stddef.h> |
| |
| /* |
| * A ring is a kind of doubly-linked list that can be manipulated |
| * without knowing where its head is. |
| */ |
| |
| /* |
| * A struct on a ring contains a field linking it to the other |
| * elements in the ring, e.g. |
| * |
| * struct my_item_t { |
| * AP_RING_ENTRY(my_item_t) link; |
| * int foo; |
| * char *bar; |
| * }; |
| * |
| * A struct may be put on more than one ring if it has more than one |
| * AP_RING_ENTRY field. |
| */ |
| #define AP_RING_ENTRY(elem) \ |
| struct { \ |
| struct elem *next; \ |
| struct elem *prev; \ |
| } |
| |
| /* |
| * Each ring is managed via its head, which is a struct declared like this: |
| * |
| * AP_RING_HEAD(my_ring_t, my_item_t); |
| * struct my_ring_t ring, *ringp; |
| * |
| * This struct looks just like the element link struct so that we can |
| * be sure that the typecasting games will work as expected. |
| * |
| * The first element in the ring is next after the head, and the last |
| * element is just before the head. |
| */ |
| #define AP_RING_HEAD(head, elem) \ |
| struct head { \ |
| struct elem *next; \ |
| struct elem *prev; \ |
| } |
| |
| /* |
| * The head itself isn't an element, but in order to get rid of all |
| * the special cases when dealing with the ends of the ring, we play |
| * typecasting games to make it look like one. The sentinel is the |
| * magic pointer value that occurs before the first and after the last |
| * elements in the ring, computed from the address of the ring's head. |
| * |
| * Note that for strict C standards compliance you should put the |
| * AP_RING_ENTRY first in struct elem unless the head is always part |
| * of a larger object with enough earlier fields to accommodate the |
| * offsetof() computed below. You can usually ignore this caveat. |
| */ |
| #define AP_RING_SENTINEL(hp, elem, link) \ |
| (struct elem *)((char *)(hp) - offsetof(struct elem, link)) |
| |
| /* |
| * Accessor macros. Use these rather than footling inside the |
| * structures directly so that you can more easily change to a |
| * different flavour of list from BSD's <sys/queue.h>. |
| */ |
| #define AP_RING_FIRST(hp) (hp)->next |
| #define AP_RING_LAST(hp) (hp)->prev |
| #define AP_RING_NEXT(ep, link) (ep)->link.next |
| #define AP_RING_PREV(ep, link) (ep)->link.prev |
| |
| /* |
| * Empty rings and singleton elements. |
| */ |
| #define AP_RING_INIT(hp, elem, link) do { \ |
| AP_RING_FIRST((hp)) = AP_RING_SENTINEL((hp), elem, link); \ |
| AP_RING_LAST((hp)) = AP_RING_SENTINEL((hp), elem, link); \ |
| } while (0) |
| |
| #define AP_RING_EMPTY(hp, elem, link) \ |
| (AP_RING_FIRST((hp)) == AP_RING_SENTINEL((hp), elem, link)) |
| |
| #define AP_RING_ELEM_INIT(ep, link) do { \ |
| AP_RING_NEXT((ep), link) = (ep); \ |
| AP_RING_PREV((ep), link) = (ep); \ |
| } while (0) |
| |
| /* |
| * Adding elements. |
| */ |
| #define AP_RING_SPLICE_BEFORE(lep, ep1, epN, link) do { \ |
| AP_RING_NEXT((epN), link) = (lep); \ |
| AP_RING_PREV((ep1), link) = AP_RING_PREV((lep), link); \ |
| AP_RING_NEXT(AP_RING_PREV((lep), link), link) = (ep1); \ |
| AP_RING_PREV((lep), link) = (epN); \ |
| } while (0) |
| |
| #define AP_RING_SPLICE_AFTER(lep, ep1, epN, link) do { \ |
| AP_RING_PREV((ep1), link) = (lep); \ |
| AP_RING_NEXT((epN), link) = AP_RING_NEXT((lep), link); \ |
| AP_RING_PREV(AP_RING_NEXT((lep), link), link) = (epN); \ |
| AP_RING_NEXT((lep), link) = (ep1); \ |
| } while (0) |
| |
| #define AP_RING_INSERT_BEFORE(lep, nep, link) \ |
| AP_RING_SPLICE_BEFORE((lep), (nep), (nep), link) |
| |
| #define AP_RING_INSERT_AFTER(lep, nep, link) \ |
| AP_RING_SPLICE_AFTER((lep), (nep), (nep), link) |
| |
| /* |
| * These macros work when the ring is empty: inserting before the head |
| * or after the tail of an empty ring using the macros above doesn't work. |
| */ |
| #define AP_RING_SPLICE_HEAD(hp, ep1, epN, elem, link) \ |
| AP_RING_SPLICE_AFTER(AP_RING_SENTINEL((hp), elem, link), \ |
| (ep1), (epN), link) |
| |
| #define AP_RING_SPLICE_TAIL(hp, ep1, epN, elem, link) \ |
| AP_RING_SPLICE_BEFORE(AP_RING_SENTINEL((hp), elem, link), \ |
| (ep1), (epN), link) |
| |
| #define AP_RING_INSERT_HEAD(hp, nep, elem, link) \ |
| AP_RING_SPLICE_HEAD((hp), (nep), (nep), elem, link) |
| |
| #define AP_RING_INSERT_TAIL(hp, nep, elem, link) \ |
| AP_RING_SPLICE_TAIL((hp), (nep), (nep), elem, link) |
| |
| /* |
| * Concatenating ring h2 onto the end of ring h1 leaves h2 empty. |
| */ |
| #define AP_RING_CONCAT(h1, h2, elem, link) do { \ |
| if (!AP_RING_EMPTY((h2), elem, link)) { \ |
| AP_RING_SPLICE_BEFORE(AP_RING_SENTINEL((h1), elem, link), \ |
| AP_RING_FIRST((h2)), \ |
| AP_RING_LAST((h2)), link); \ |
| AP_RING_INIT((h2), elem, link); \ |
| } \ |
| } while (0) |
| |
| /* |
| * Removing elements. Be warned that the unspliced elements are left |
| * with dangling pointers at either end! |
| */ |
| #define AP_RING_UNSPLICE(ep1, epN, link) do { \ |
| AP_RING_NEXT(AP_RING_PREV((ep1), link), link) = \ |
| AP_RING_NEXT((epN), link); \ |
| AP_RING_PREV(AP_RING_NEXT((epN), link), link) = \ |
| AP_RING_PREV((ep1), link); \ |
| } while (0) |
| |
| #define AP_RING_REMOVE(ep, link) \ |
| AP_RING_UNSPLICE((ep), (ep), link) |
| |
| /* |
| * Iteration. |
| */ |
| #define AP_RING_FOREACH(ep, hp, elem, link) \ |
| for ((ep) = AP_RING_FIRST((hp)); \ |
| (ep) != AP_RING_SENTINEL((hp), elem, link); \ |
| (ep) = AP_RING_NEXT((ep), link)) |
| |
| #define AP_RING_FOREACH_REVERSE(ep, hp, elem, link) \ |
| for ((ep) = AP_RING_LAST((hp)); \ |
| (ep) != AP_RING_SENTINEL((hp), elem, link); \ |
| (ep) = AP_RING_PREV((ep), link)) |
| |
| #ifdef AP_RING_DEBUG |
| #include <stdio.h> |
| #define AP_RING_CHECK_ONE(msg, ptr) \ |
| fprintf(stderr, "*** %s %p\n", msg, ptr) |
| #define AP_RING_CHECK(hp, elem, link, msg) \ |
| AP_RING_CHECK_ELEM(AP_RING_SENTINEL(hp, elem, link), elem, link, msg) |
| #define AP_RING_CHECK_ELEM(ep, elem, link, msg) do { \ |
| struct elem *start = (ep); \ |
| struct elem *this = start; \ |
| fprintf(stderr, "*** ring check start -- %s\n", msg); \ |
| do { \ |
| fprintf(stderr, "\telem %p\n", this); \ |
| fprintf(stderr, "\telem->next %p\n", \ |
| AP_RING_NEXT(this, link)); \ |
| fprintf(stderr, "\telem->prev %p\n", \ |
| AP_RING_PREV(this, link)); \ |
| fprintf(stderr, "\telem->next->prev %p\n", \ |
| AP_RING_PREV(AP_RING_NEXT(this, link), link)); \ |
| fprintf(stderr, "\telem->prev->next %p\n", \ |
| AP_RING_NEXT(AP_RING_PREV(this, link), link)); \ |
| if (AP_RING_PREV(AP_RING_NEXT(this, link), link) != this) { \ |
| fprintf(stderr, "\t*** this->next->prev != this\n"); \ |
| break; \ |
| } \ |
| if (AP_RING_NEXT(AP_RING_PREV(this, link), link) != this) { \ |
| fprintf(stderr, "\t*** this->prev->next != this\n"); \ |
| break; \ |
| } \ |
| this = AP_RING_NEXT(this, link); \ |
| } while (this != start); \ |
| fprintf(stderr, "*** ring check end\n"); \ |
| } while (0) |
| #else |
| #define AP_RING_CHECK_ONE(msg, ptr) |
| #define AP_RING_CHECK(hp, elem, link, msg) |
| #define AP_RING_CHECK_ELEM(ep, elem, link, msg) |
| #endif |
| |
| #endif /* !AP_RING_H */ |