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Annotation of src/usr.bin/tmux/cmd-wait-for.c, Revision 1.19

1.19    ! nicm        1: /* $OpenBSD: cmd-wait-for.c,v 1.18 2019/06/18 11:08:42 nicm Exp $ */
1.1       nicm        2:
                      3: /*
1.13      nicm        4:  * Copyright (c) 2013 Nicholas Marriott <nicholas.marriott@gmail.com>
1.1       nicm        5:  * Copyright (c) 2013 Thiago de Arruda <tpadilha84@gmail.com>
                      6:  *
                      7:  * Permission to use, copy, modify, and distribute this software for any
                      8:  * purpose with or without fee is hereby granted, provided that the above
                      9:  * copyright notice and this permission notice appear in all copies.
                     10:  *
                     11:  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
                     12:  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
                     13:  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
                     14:  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
                     15:  * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
                     16:  * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
                     17:  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
                     18:  */
                     19:
                     20: #include <sys/types.h>
                     21:
                     22: #include <stdlib.h>
                     23: #include <string.h>
                     24:
                     25: #include "tmux.h"
                     26:
                     27: /*
                     28:  * Block or wake a client on a named wait channel.
                     29:  */
                     30:
1.16      nicm       31: static enum cmd_retval cmd_wait_for_exec(struct cmd *, struct cmdq_item *);
1.1       nicm       32:
                     33: const struct cmd_entry cmd_wait_for_entry = {
1.12      nicm       34:        .name = "wait-for",
                     35:        .alias = "wait",
                     36:
                     37:        .args = { "LSU", 1, 1 },
                     38:        .usage = "[-L|-S|-U] channel",
                     39:
                     40:        .flags = 0,
                     41:        .exec = cmd_wait_for_exec
1.1       nicm       42: };
                     43:
1.15      nicm       44: struct wait_item {
1.16      nicm       45:        struct cmdq_item        *item;
1.15      nicm       46:        TAILQ_ENTRY(wait_item)   entry;
                     47: };
                     48:
1.1       nicm       49: struct wait_channel {
                     50:        const char             *name;
1.2       nicm       51:        int                     locked;
1.8       nicm       52:        int                     woken;
1.2       nicm       53:
1.15      nicm       54:        TAILQ_HEAD(, wait_item) waiters;
                     55:        TAILQ_HEAD(, wait_item) lockers;
1.1       nicm       56:
                     57:        RB_ENTRY(wait_channel)  entry;
                     58: };
                     59: RB_HEAD(wait_channels, wait_channel);
1.14      nicm       60: static struct wait_channels wait_channels = RB_INITIALIZER(wait_channels);
1.1       nicm       61:
1.14      nicm       62: static int wait_channel_cmp(struct wait_channel *, struct wait_channel *);
                     63: RB_GENERATE_STATIC(wait_channels, wait_channel, entry, wait_channel_cmp);
1.1       nicm       64:
1.14      nicm       65: static int
1.1       nicm       66: wait_channel_cmp(struct wait_channel *wc1, struct wait_channel *wc2)
                     67: {
                     68:        return (strcmp(wc1->name, wc2->name));
                     69: }
                     70:
1.16      nicm       71: static enum cmd_retval cmd_wait_for_signal(struct cmdq_item *, const char *,
1.14      nicm       72:                            struct wait_channel *);
1.16      nicm       73: static enum cmd_retval cmd_wait_for_wait(struct cmdq_item *, const char *,
1.14      nicm       74:                            struct wait_channel *);
1.16      nicm       75: static enum cmd_retval cmd_wait_for_lock(struct cmdq_item *, const char *,
1.14      nicm       76:                            struct wait_channel *);
1.16      nicm       77: static enum cmd_retval cmd_wait_for_unlock(struct cmdq_item *, const char *,
1.14      nicm       78:                            struct wait_channel *);
1.1       nicm       79:
1.14      nicm       80: static struct wait_channel     *cmd_wait_for_add(const char *);
1.16      nicm       81: static void                     cmd_wait_for_remove(struct wait_channel *);
1.8       nicm       82:
1.14      nicm       83: static struct wait_channel *
1.8       nicm       84: cmd_wait_for_add(const char *name)
                     85: {
                     86:        struct wait_channel *wc;
                     87:
                     88:        wc = xmalloc(sizeof *wc);
                     89:        wc->name = xstrdup(name);
                     90:
                     91:        wc->locked = 0;
                     92:        wc->woken = 0;
                     93:
                     94:        TAILQ_INIT(&wc->waiters);
                     95:        TAILQ_INIT(&wc->lockers);
                     96:
                     97:        RB_INSERT(wait_channels, &wait_channels, wc);
                     98:
                     99:        log_debug("add wait channel %s", wc->name);
                    100:
                    101:        return (wc);
                    102: }
                    103:
1.14      nicm      104: static void
1.8       nicm      105: cmd_wait_for_remove(struct wait_channel *wc)
                    106: {
                    107:        if (wc->locked)
                    108:                return;
                    109:        if (!TAILQ_EMPTY(&wc->waiters) || !wc->woken)
                    110:                return;
                    111:
                    112:        log_debug("remove wait channel %s", wc->name);
                    113:
                    114:        RB_REMOVE(wait_channels, &wait_channels, wc);
                    115:
                    116:        free((void *)wc->name);
                    117:        free(wc);
                    118: }
                    119:
1.14      nicm      120: static enum cmd_retval
1.16      nicm      121: cmd_wait_for_exec(struct cmd *self, struct cmdq_item *item)
1.1       nicm      122: {
1.19    ! nicm      123:        struct args             *args = cmd_get_args(self);
1.1       nicm      124:        const char              *name = args->argv[0];
                    125:        struct wait_channel     *wc, wc0;
                    126:
                    127:        wc0.name = name;
                    128:        wc = RB_FIND(wait_channels, &wait_channels, &wc0);
                    129:
                    130:        if (args_has(args, 'S'))
1.16      nicm      131:                return (cmd_wait_for_signal(item, name, wc));
1.2       nicm      132:        if (args_has(args, 'L'))
1.16      nicm      133:                return (cmd_wait_for_lock(item, name, wc));
1.2       nicm      134:        if (args_has(args, 'U'))
1.16      nicm      135:                return (cmd_wait_for_unlock(item, name, wc));
                    136:        return (cmd_wait_for_wait(item, name, wc));
1.1       nicm      137: }
                    138:
1.14      nicm      139: static enum cmd_retval
1.16      nicm      140: cmd_wait_for_signal(__unused struct cmdq_item *item, const char *name,
1.1       nicm      141:     struct wait_channel *wc)
                    142: {
1.15      nicm      143:        struct wait_item        *wi, *wi1;
1.1       nicm      144:
1.8       nicm      145:        if (wc == NULL)
                    146:                wc = cmd_wait_for_add(name);
                    147:
                    148:        if (TAILQ_EMPTY(&wc->waiters) && !wc->woken) {
                    149:                log_debug("signal wait channel %s, no waiters", wc->name);
                    150:                wc->woken = 1;
                    151:                return (CMD_RETURN_NORMAL);
1.1       nicm      152:        }
1.8       nicm      153:        log_debug("signal wait channel %s, with waiters", wc->name);
1.1       nicm      154:
1.15      nicm      155:        TAILQ_FOREACH_SAFE(wi, &wc->waiters, entry, wi1) {
1.18      nicm      156:                cmdq_continue(wi->item);
1.15      nicm      157:
                    158:                TAILQ_REMOVE(&wc->waiters, wi, entry);
                    159:                free(wi);
1.1       nicm      160:        }
1.2       nicm      161:
1.8       nicm      162:        cmd_wait_for_remove(wc);
1.1       nicm      163:        return (CMD_RETURN_NORMAL);
                    164: }
                    165:
1.14      nicm      166: static enum cmd_retval
1.16      nicm      167: cmd_wait_for_wait(struct cmdq_item *item, const char *name,
                    168:     struct wait_channel *wc)
1.1       nicm      169: {
1.16      nicm      170:        struct client           *c = item->client;
1.15      nicm      171:        struct wait_item        *wi;
1.8       nicm      172:
1.17      nicm      173:        if (c == NULL) {
1.16      nicm      174:                cmdq_error(item, "not able to wait");
1.1       nicm      175:                return (CMD_RETURN_ERROR);
                    176:        }
                    177:
1.8       nicm      178:        if (wc == NULL)
                    179:                wc = cmd_wait_for_add(name);
                    180:
                    181:        if (wc->woken) {
1.10      nicm      182:                log_debug("wait channel %s already woken (%p)", wc->name, c);
1.8       nicm      183:                cmd_wait_for_remove(wc);
                    184:                return (CMD_RETURN_NORMAL);
1.1       nicm      185:        }
1.10      nicm      186:        log_debug("wait channel %s not woken (%p)", wc->name, c);
1.2       nicm      187:
1.15      nicm      188:        wi = xcalloc(1, sizeof *wi);
1.16      nicm      189:        wi->item = item;
1.15      nicm      190:        TAILQ_INSERT_TAIL(&wc->waiters, wi, entry);
1.1       nicm      191:
                    192:        return (CMD_RETURN_WAIT);
                    193: }
1.2       nicm      194:
1.14      nicm      195: static enum cmd_retval
1.16      nicm      196: cmd_wait_for_lock(struct cmdq_item *item, const char *name,
                    197:     struct wait_channel *wc)
1.2       nicm      198: {
1.15      nicm      199:        struct wait_item        *wi;
                    200:
1.17      nicm      201:        if (item->client == NULL) {
1.16      nicm      202:                cmdq_error(item, "not able to lock");
1.2       nicm      203:                return (CMD_RETURN_ERROR);
                    204:        }
                    205:
1.8       nicm      206:        if (wc == NULL)
                    207:                wc = cmd_wait_for_add(name);
1.2       nicm      208:
                    209:        if (wc->locked) {
1.15      nicm      210:                wi = xcalloc(1, sizeof *wi);
1.16      nicm      211:                wi->item = item;
1.15      nicm      212:                TAILQ_INSERT_TAIL(&wc->lockers, wi, entry);
1.2       nicm      213:                return (CMD_RETURN_WAIT);
                    214:        }
                    215:        wc->locked = 1;
                    216:
                    217:        return (CMD_RETURN_NORMAL);
                    218: }
                    219:
1.14      nicm      220: static enum cmd_retval
1.16      nicm      221: cmd_wait_for_unlock(struct cmdq_item *item, const char *name,
1.2       nicm      222:     struct wait_channel *wc)
                    223: {
1.15      nicm      224:        struct wait_item        *wi;
1.2       nicm      225:
                    226:        if (wc == NULL || !wc->locked) {
1.16      nicm      227:                cmdq_error(item, "channel %s not locked", name);
1.2       nicm      228:                return (CMD_RETURN_ERROR);
                    229:        }
                    230:
1.15      nicm      231:        if ((wi = TAILQ_FIRST(&wc->lockers)) != NULL) {
1.18      nicm      232:                cmdq_continue(wi->item);
1.15      nicm      233:                TAILQ_REMOVE(&wc->lockers, wi, entry);
                    234:                free(wi);
1.2       nicm      235:        } else {
                    236:                wc->locked = 0;
1.8       nicm      237:                cmd_wait_for_remove(wc);
1.2       nicm      238:        }
                    239:
                    240:        return (CMD_RETURN_NORMAL);
                    241: }
                    242:
1.6       nicm      243: void
                    244: cmd_wait_for_flush(void)
                    245: {
                    246:        struct wait_channel     *wc, *wc1;
1.15      nicm      247:        struct wait_item        *wi, *wi1;
1.6       nicm      248:
                    249:        RB_FOREACH_SAFE(wc, wait_channels, &wait_channels, wc1) {
1.15      nicm      250:                TAILQ_FOREACH_SAFE(wi, &wc->waiters, entry, wi1) {
1.18      nicm      251:                        cmdq_continue(wi->item);
1.15      nicm      252:                        TAILQ_REMOVE(&wc->waiters, wi, entry);
                    253:                        free(wi);
1.6       nicm      254:                }
1.9       nicm      255:                wc->woken = 1;
1.15      nicm      256:                TAILQ_FOREACH_SAFE(wi, &wc->lockers, entry, wi1) {
1.18      nicm      257:                        cmdq_continue(wi->item);
1.15      nicm      258:                        TAILQ_REMOVE(&wc->lockers, wi, entry);
                    259:                        free(wi);
1.6       nicm      260:                }
1.8       nicm      261:                wc->locked = 0;
                    262:                cmd_wait_for_remove(wc);
1.6       nicm      263:        }
                    264: }