| 1 | /* Locking in multithreaded situations.
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| 2 | Copyright (C) 2005-2021 Free Software Foundation, Inc.
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| 3 |
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| 4 | This file is free software: you can redistribute it and/or modify
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| 5 | it under the terms of the GNU Lesser General Public License as
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| 6 | published by the Free Software Foundation; either version 2.1 of the
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| 7 | License, or (at your option) any later version.
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| 8 |
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| 9 | This file is distributed in the hope that it will be useful,
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 12 | GNU Lesser General Public License for more details.
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| 13 |
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| 14 | You should have received a copy of the GNU Lesser General Public License
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| 15 | along with this program. If not, see <https://www.gnu.org/licenses/>. */
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| 16 |
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| 17 | /* Written by Bruno Haible <bruno@clisp.org>, 2005.
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| 18 | Based on GCC's gthr-posix.h, gthr-posix95.h. */
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| 19 |
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| 20 | #include <config.h>
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| 21 |
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| 22 | #include "glthread/lock.h"
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| 23 |
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| 24 | /* ========================================================================= */
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| 25 |
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| 26 | #if USE_ISOC_THREADS || USE_ISOC_AND_POSIX_THREADS
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| 27 |
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| 28 | /* -------------------------- gl_lock_t datatype -------------------------- */
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| 29 |
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| 30 | int
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| 31 | glthread_lock_init (gl_lock_t *lock)
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| 32 | {
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| 33 | if (mtx_init (&lock->mutex, mtx_plain) != thrd_success)
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| 34 | return ENOMEM;
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| 35 | lock->init_needed = 0;
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| 36 | return 0;
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| 37 | }
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| 38 |
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| 39 | int
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| 40 | glthread_lock_lock (gl_lock_t *lock)
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| 41 | {
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| 42 | if (lock->init_needed)
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| 43 | call_once (&lock->init_once, lock->init_func);
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| 44 | if (mtx_lock (&lock->mutex) != thrd_success)
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| 45 | return EAGAIN;
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| 46 | return 0;
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| 47 | }
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| 48 |
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| 49 | int
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| 50 | glthread_lock_unlock (gl_lock_t *lock)
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| 51 | {
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| 52 | if (lock->init_needed)
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| 53 | call_once (&lock->init_once, lock->init_func);
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| 54 | if (mtx_unlock (&lock->mutex) != thrd_success)
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| 55 | return EINVAL;
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| 56 | return 0;
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| 57 | }
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| 58 |
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| 59 | int
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| 60 | glthread_lock_destroy (gl_lock_t *lock)
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| 61 | {
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| 62 | if (lock->init_needed)
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| 63 | call_once (&lock->init_once, lock->init_func);
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| 64 | mtx_destroy (&lock->mutex);
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| 65 | return 0;
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| 66 | }
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| 67 |
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| 68 | /* ------------------------- gl_rwlock_t datatype ------------------------- */
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| 69 |
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| 70 | int
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| 71 | glthread_rwlock_init (gl_rwlock_t *lock)
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| 72 | {
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| 73 | if (mtx_init (&lock->lock, mtx_plain) != thrd_success
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| 74 | || cnd_init (&lock->waiting_readers) != thrd_success
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| 75 | || cnd_init (&lock->waiting_writers) != thrd_success)
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| 76 | return ENOMEM;
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| 77 | lock->waiting_writers_count = 0;
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| 78 | lock->runcount = 0;
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| 79 | lock->init_needed = 0;
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| 80 | return 0;
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| 81 | }
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| 82 |
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| 83 | int
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| 84 | glthread_rwlock_rdlock (gl_rwlock_t *lock)
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| 85 | {
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| 86 | if (lock->init_needed)
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| 87 | call_once (&lock->init_once, lock->init_func);
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| 88 | if (mtx_lock (&lock->lock) != thrd_success)
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| 89 | return EAGAIN;
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| 90 | /* Test whether only readers are currently running, and whether the runcount
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| 91 | field will not overflow, and whether no writer is waiting. The latter
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| 92 | condition is because POSIX recommends that "write locks shall take
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| 93 | precedence over read locks", to avoid "writer starvation". */
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| 94 | while (!(lock->runcount + 1 > 0 && lock->waiting_writers_count == 0))
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| 95 | {
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| 96 | /* This thread has to wait for a while. Enqueue it among the
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| 97 | waiting_readers. */
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| 98 | if (cnd_wait (&lock->waiting_readers, &lock->lock) != thrd_success)
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| 99 | {
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| 100 | mtx_unlock (&lock->lock);
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| 101 | return EINVAL;
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| 102 | }
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| 103 | }
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| 104 | lock->runcount++;
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| 105 | if (mtx_unlock (&lock->lock) != thrd_success)
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| 106 | return EINVAL;
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| 107 | return 0;
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| 108 | }
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| 109 |
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| 110 | int
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| 111 | glthread_rwlock_wrlock (gl_rwlock_t *lock)
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| 112 | {
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| 113 | if (lock->init_needed)
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| 114 | call_once (&lock->init_once, lock->init_func);
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| 115 | if (mtx_lock (&lock->lock) != thrd_success)
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| 116 | return EAGAIN;
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| 117 | /* Test whether no readers or writers are currently running. */
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| 118 | while (!(lock->runcount == 0))
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| 119 | {
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| 120 | /* This thread has to wait for a while. Enqueue it among the
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| 121 | waiting_writers. */
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| 122 | lock->waiting_writers_count++;
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| 123 | if (cnd_wait (&lock->waiting_writers, &lock->lock) != thrd_success)
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| 124 | {
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| 125 | lock->waiting_writers_count--;
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| 126 | mtx_unlock (&lock->lock);
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| 127 | return EINVAL;
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| 128 | }
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| 129 | lock->waiting_writers_count--;
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| 130 | }
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| 131 | lock->runcount--; /* runcount becomes -1 */
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| 132 | if (mtx_unlock (&lock->lock) != thrd_success)
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| 133 | return EINVAL;
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| 134 | return 0;
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| 135 | }
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| 136 |
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| 137 | int
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| 138 | glthread_rwlock_unlock (gl_rwlock_t *lock)
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| 139 | {
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| 140 | if (lock->init_needed)
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| 141 | call_once (&lock->init_once, lock->init_func);
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| 142 | if (mtx_lock (&lock->lock) != thrd_success)
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| 143 | return EAGAIN;
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| 144 | if (lock->runcount < 0)
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| 145 | {
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| 146 | /* Drop a writer lock. */
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| 147 | if (!(lock->runcount == -1))
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| 148 | {
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| 149 | mtx_unlock (&lock->lock);
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| 150 | return EINVAL;
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| 151 | }
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| 152 | lock->runcount = 0;
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| 153 | }
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| 154 | else
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| 155 | {
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| 156 | /* Drop a reader lock. */
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| 157 | if (!(lock->runcount > 0))
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| 158 | {
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| 159 | mtx_unlock (&lock->lock);
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| 160 | return EINVAL;
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| 161 | }
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| 162 | lock->runcount--;
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| 163 | }
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| 164 | if (lock->runcount == 0)
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| 165 | {
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| 166 | /* POSIX recommends that "write locks shall take precedence over read
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| 167 | locks", to avoid "writer starvation". */
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| 168 | if (lock->waiting_writers_count > 0)
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| 169 | {
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| 170 | /* Wake up one of the waiting writers. */
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| 171 | if (cnd_signal (&lock->waiting_writers) != thrd_success)
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| 172 | {
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| 173 | mtx_unlock (&lock->lock);
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| 174 | return EINVAL;
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| 175 | }
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| 176 | }
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| 177 | else
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| 178 | {
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| 179 | /* Wake up all waiting readers. */
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| 180 | if (cnd_broadcast (&lock->waiting_readers) != thrd_success)
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| 181 | {
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| 182 | mtx_unlock (&lock->lock);
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| 183 | return EINVAL;
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| 184 | }
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| 185 | }
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| 186 | }
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| 187 | if (mtx_unlock (&lock->lock) != thrd_success)
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| 188 | return EINVAL;
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| 189 | return 0;
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| 190 | }
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| 191 |
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| 192 | int
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| 193 | glthread_rwlock_destroy (gl_rwlock_t *lock)
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| 194 | {
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| 195 | if (lock->init_needed)
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| 196 | call_once (&lock->init_once, lock->init_func);
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| 197 | mtx_destroy (&lock->lock);
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| 198 | cnd_destroy (&lock->waiting_readers);
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| 199 | cnd_destroy (&lock->waiting_writers);
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| 200 | return 0;
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| 201 | }
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| 202 |
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| 203 | /* --------------------- gl_recursive_lock_t datatype --------------------- */
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| 204 |
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| 205 | int
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| 206 | glthread_recursive_lock_init (gl_recursive_lock_t *lock)
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| 207 | {
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| 208 | if (mtx_init (&lock->mutex, mtx_plain | mtx_recursive) != thrd_success)
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| 209 | return ENOMEM;
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| 210 | lock->init_needed = 0;
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| 211 | return 0;
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| 212 | }
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| 213 |
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| 214 | int
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| 215 | glthread_recursive_lock_lock (gl_recursive_lock_t *lock)
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| 216 | {
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| 217 | if (lock->init_needed)
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| 218 | call_once (&lock->init_once, lock->init_func);
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| 219 | if (mtx_lock (&lock->mutex) != thrd_success)
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| 220 | return EAGAIN;
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| 221 | return 0;
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| 222 | }
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| 223 |
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| 224 | int
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| 225 | glthread_recursive_lock_unlock (gl_recursive_lock_t *lock)
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| 226 | {
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| 227 | if (lock->init_needed)
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| 228 | call_once (&lock->init_once, lock->init_func);
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| 229 | if (mtx_unlock (&lock->mutex) != thrd_success)
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| 230 | return EINVAL;
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| 231 | return 0;
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| 232 | }
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| 233 |
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| 234 | int
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| 235 | glthread_recursive_lock_destroy (gl_recursive_lock_t *lock)
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| 236 | {
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| 237 | if (lock->init_needed)
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| 238 | call_once (&lock->init_once, lock->init_func);
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| 239 | mtx_destroy (&lock->mutex);
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| 240 | return 0;
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| 241 | }
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| 242 |
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| 243 | /* -------------------------- gl_once_t datatype -------------------------- */
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| 244 |
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| 245 | #endif
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| 246 |
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| 247 | /* ========================================================================= */
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| 248 |
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| 249 | #if USE_POSIX_THREADS
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| 250 |
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| 251 | /* -------------------------- gl_lock_t datatype -------------------------- */
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| 252 |
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| 253 | /* ------------------------- gl_rwlock_t datatype ------------------------- */
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| 254 |
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| 255 | # if HAVE_PTHREAD_RWLOCK && (HAVE_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER || (defined PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP && (__GNU_LIBRARY__ > 1)))
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| 256 |
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| 257 | # if defined PTHREAD_RWLOCK_INITIALIZER || defined PTHREAD_RWLOCK_INITIALIZER_NP
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| 258 |
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| 259 | # if !HAVE_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER
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| 260 | /* glibc with bug https://sourceware.org/bugzilla/show_bug.cgi?id=13701 */
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| 261 |
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| 262 | int
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| 263 | glthread_rwlock_init_for_glibc (pthread_rwlock_t *lock)
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| 264 | {
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| 265 | pthread_rwlockattr_t attributes;
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| 266 | int err;
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| 267 |
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| 268 | err = pthread_rwlockattr_init (&attributes);
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| 269 | if (err != 0)
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| 270 | return err;
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| 271 | /* Note: PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP is the only value that
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| 272 | causes the writer to be preferred. PTHREAD_RWLOCK_PREFER_WRITER_NP does not
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| 273 | do this; see
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| 274 | http://man7.org/linux/man-pages/man3/pthread_rwlockattr_setkind_np.3.html */
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| 275 | err = pthread_rwlockattr_setkind_np (&attributes,
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| 276 | PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
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| 277 | if (err == 0)
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| 278 | err = pthread_rwlock_init(lock, &attributes);
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| 279 | /* pthread_rwlockattr_destroy always returns 0. It cannot influence the
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| 280 | return value. */
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| 281 | pthread_rwlockattr_destroy (&attributes);
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| 282 | return err;
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| 283 | }
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| 284 |
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| 285 | # endif
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| 286 | # else
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| 287 |
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| 288 | int
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| 289 | glthread_rwlock_init_multithreaded (gl_rwlock_t *lock)
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| 290 | {
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| 291 | int err;
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| 292 |
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| 293 | err = pthread_rwlock_init (&lock->rwlock, NULL);
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| 294 | if (err != 0)
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| 295 | return err;
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| 296 | lock->initialized = 1;
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| 297 | return 0;
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| 298 | }
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| 299 |
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| 300 | int
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| 301 | glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock)
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| 302 | {
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| 303 | if (!lock->initialized)
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| 304 | {
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| 305 | int err;
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| 306 |
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| 307 | err = pthread_mutex_lock (&lock->guard);
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| 308 | if (err != 0)
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| 309 | return err;
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| 310 | if (!lock->initialized)
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| 311 | {
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| 312 | err = glthread_rwlock_init_multithreaded (lock);
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| 313 | if (err != 0)
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| 314 | {
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| 315 | pthread_mutex_unlock (&lock->guard);
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| 316 | return err;
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| 317 | }
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| 318 | }
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| 319 | err = pthread_mutex_unlock (&lock->guard);
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| 320 | if (err != 0)
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| 321 | return err;
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| 322 | }
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| 323 | return pthread_rwlock_rdlock (&lock->rwlock);
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| 324 | }
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| 325 |
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| 326 | int
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| 327 | glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock)
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| 328 | {
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| 329 | if (!lock->initialized)
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| 330 | {
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| 331 | int err;
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| 332 |
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| 333 | err = pthread_mutex_lock (&lock->guard);
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| 334 | if (err != 0)
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| 335 | return err;
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| 336 | if (!lock->initialized)
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| 337 | {
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| 338 | err = glthread_rwlock_init_multithreaded (lock);
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| 339 | if (err != 0)
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| 340 | {
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| 341 | pthread_mutex_unlock (&lock->guard);
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| 342 | return err;
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| 343 | }
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| 344 | }
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| 345 | err = pthread_mutex_unlock (&lock->guard);
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| 346 | if (err != 0)
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| 347 | return err;
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| 348 | }
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| 349 | return pthread_rwlock_wrlock (&lock->rwlock);
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| 350 | }
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| 351 |
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| 352 | int
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| 353 | glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock)
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| 354 | {
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| 355 | if (!lock->initialized)
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| 356 | return EINVAL;
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| 357 | return pthread_rwlock_unlock (&lock->rwlock);
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| 358 | }
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| 359 |
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| 360 | int
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| 361 | glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock)
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| 362 | {
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| 363 | int err;
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| 364 |
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| 365 | if (!lock->initialized)
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| 366 | return EINVAL;
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| 367 | err = pthread_rwlock_destroy (&lock->rwlock);
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| 368 | if (err != 0)
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| 369 | return err;
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| 370 | lock->initialized = 0;
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| 371 | return 0;
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| 372 | }
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| 373 |
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| 374 | # endif
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| 375 |
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| 376 | # else
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| 377 |
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| 378 | int
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| 379 | glthread_rwlock_init_multithreaded (gl_rwlock_t *lock)
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| 380 | {
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| 381 | int err;
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| 382 |
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| 383 | err = pthread_mutex_init (&lock->lock, NULL);
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| 384 | if (err != 0)
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| 385 | return err;
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| 386 | err = pthread_cond_init (&lock->waiting_readers, NULL);
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| 387 | if (err != 0)
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| 388 | return err;
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| 389 | err = pthread_cond_init (&lock->waiting_writers, NULL);
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| 390 | if (err != 0)
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| 391 | return err;
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| 392 | lock->waiting_writers_count = 0;
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| 393 | lock->runcount = 0;
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| 394 | return 0;
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| 395 | }
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| 396 |
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| 397 | int
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| 398 | glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock)
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| 399 | {
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| 400 | int err;
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| 401 |
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| 402 | err = pthread_mutex_lock (&lock->lock);
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| 403 | if (err != 0)
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| 404 | return err;
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| 405 | /* Test whether only readers are currently running, and whether the runcount
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| 406 | field will not overflow, and whether no writer is waiting. The latter
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| 407 | condition is because POSIX recommends that "write locks shall take
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| 408 | precedence over read locks", to avoid "writer starvation". */
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| 409 | while (!(lock->runcount + 1 > 0 && lock->waiting_writers_count == 0))
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| 410 | {
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| 411 | /* This thread has to wait for a while. Enqueue it among the
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| 412 | waiting_readers. */
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| 413 | err = pthread_cond_wait (&lock->waiting_readers, &lock->lock);
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| 414 | if (err != 0)
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| 415 | {
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| 416 | pthread_mutex_unlock (&lock->lock);
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| 417 | return err;
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| 418 | }
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| 419 | }
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| 420 | lock->runcount++;
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| 421 | return pthread_mutex_unlock (&lock->lock);
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| 422 | }
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| 423 |
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| 424 | int
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| 425 | glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock)
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| 426 | {
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| 427 | int err;
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| 428 |
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| 429 | err = pthread_mutex_lock (&lock->lock);
|
|---|
| 430 | if (err != 0)
|
|---|
| 431 | return err;
|
|---|
| 432 | /* Test whether no readers or writers are currently running. */
|
|---|
| 433 | while (!(lock->runcount == 0))
|
|---|
| 434 | {
|
|---|
| 435 | /* This thread has to wait for a while. Enqueue it among the
|
|---|
| 436 | waiting_writers. */
|
|---|
| 437 | lock->waiting_writers_count++;
|
|---|
| 438 | err = pthread_cond_wait (&lock->waiting_writers, &lock->lock);
|
|---|
| 439 | if (err != 0)
|
|---|
| 440 | {
|
|---|
| 441 | lock->waiting_writers_count--;
|
|---|
| 442 | pthread_mutex_unlock (&lock->lock);
|
|---|
| 443 | return err;
|
|---|
| 444 | }
|
|---|
| 445 | lock->waiting_writers_count--;
|
|---|
| 446 | }
|
|---|
| 447 | lock->runcount--; /* runcount becomes -1 */
|
|---|
| 448 | return pthread_mutex_unlock (&lock->lock);
|
|---|
| 449 | }
|
|---|
| 450 |
|
|---|
| 451 | int
|
|---|
| 452 | glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock)
|
|---|
| 453 | {
|
|---|
| 454 | int err;
|
|---|
| 455 |
|
|---|
| 456 | err = pthread_mutex_lock (&lock->lock);
|
|---|
| 457 | if (err != 0)
|
|---|
| 458 | return err;
|
|---|
| 459 | if (lock->runcount < 0)
|
|---|
| 460 | {
|
|---|
| 461 | /* Drop a writer lock. */
|
|---|
| 462 | if (!(lock->runcount == -1))
|
|---|
| 463 | {
|
|---|
| 464 | pthread_mutex_unlock (&lock->lock);
|
|---|
| 465 | return EINVAL;
|
|---|
| 466 | }
|
|---|
| 467 | lock->runcount = 0;
|
|---|
| 468 | }
|
|---|
| 469 | else
|
|---|
| 470 | {
|
|---|
| 471 | /* Drop a reader lock. */
|
|---|
| 472 | if (!(lock->runcount > 0))
|
|---|
| 473 | {
|
|---|
| 474 | pthread_mutex_unlock (&lock->lock);
|
|---|
| 475 | return EINVAL;
|
|---|
| 476 | }
|
|---|
| 477 | lock->runcount--;
|
|---|
| 478 | }
|
|---|
| 479 | if (lock->runcount == 0)
|
|---|
| 480 | {
|
|---|
| 481 | /* POSIX recommends that "write locks shall take precedence over read
|
|---|
| 482 | locks", to avoid "writer starvation". */
|
|---|
| 483 | if (lock->waiting_writers_count > 0)
|
|---|
| 484 | {
|
|---|
| 485 | /* Wake up one of the waiting writers. */
|
|---|
| 486 | err = pthread_cond_signal (&lock->waiting_writers);
|
|---|
| 487 | if (err != 0)
|
|---|
| 488 | {
|
|---|
| 489 | pthread_mutex_unlock (&lock->lock);
|
|---|
| 490 | return err;
|
|---|
| 491 | }
|
|---|
| 492 | }
|
|---|
| 493 | else
|
|---|
| 494 | {
|
|---|
| 495 | /* Wake up all waiting readers. */
|
|---|
| 496 | err = pthread_cond_broadcast (&lock->waiting_readers);
|
|---|
| 497 | if (err != 0)
|
|---|
| 498 | {
|
|---|
| 499 | pthread_mutex_unlock (&lock->lock);
|
|---|
| 500 | return err;
|
|---|
| 501 | }
|
|---|
| 502 | }
|
|---|
| 503 | }
|
|---|
| 504 | return pthread_mutex_unlock (&lock->lock);
|
|---|
| 505 | }
|
|---|
| 506 |
|
|---|
| 507 | int
|
|---|
| 508 | glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock)
|
|---|
| 509 | {
|
|---|
| 510 | int err;
|
|---|
| 511 |
|
|---|
| 512 | err = pthread_mutex_destroy (&lock->lock);
|
|---|
| 513 | if (err != 0)
|
|---|
| 514 | return err;
|
|---|
| 515 | err = pthread_cond_destroy (&lock->waiting_readers);
|
|---|
| 516 | if (err != 0)
|
|---|
| 517 | return err;
|
|---|
| 518 | err = pthread_cond_destroy (&lock->waiting_writers);
|
|---|
| 519 | if (err != 0)
|
|---|
| 520 | return err;
|
|---|
| 521 | return 0;
|
|---|
| 522 | }
|
|---|
| 523 |
|
|---|
| 524 | # endif
|
|---|
| 525 |
|
|---|
| 526 | /* --------------------- gl_recursive_lock_t datatype --------------------- */
|
|---|
| 527 |
|
|---|
| 528 | # if HAVE_PTHREAD_MUTEX_RECURSIVE
|
|---|
| 529 |
|
|---|
| 530 | # if defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER || defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
|
|---|
| 531 |
|
|---|
| 532 | int
|
|---|
| 533 | glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock)
|
|---|
| 534 | {
|
|---|
| 535 | pthread_mutexattr_t attributes;
|
|---|
| 536 | int err;
|
|---|
| 537 |
|
|---|
| 538 | err = pthread_mutexattr_init (&attributes);
|
|---|
| 539 | if (err != 0)
|
|---|
| 540 | return err;
|
|---|
| 541 | err = pthread_mutexattr_settype (&attributes, PTHREAD_MUTEX_RECURSIVE);
|
|---|
| 542 | if (err != 0)
|
|---|
| 543 | {
|
|---|
| 544 | pthread_mutexattr_destroy (&attributes);
|
|---|
| 545 | return err;
|
|---|
| 546 | }
|
|---|
| 547 | err = pthread_mutex_init (lock, &attributes);
|
|---|
| 548 | if (err != 0)
|
|---|
| 549 | {
|
|---|
| 550 | pthread_mutexattr_destroy (&attributes);
|
|---|
| 551 | return err;
|
|---|
| 552 | }
|
|---|
| 553 | err = pthread_mutexattr_destroy (&attributes);
|
|---|
| 554 | if (err != 0)
|
|---|
| 555 | return err;
|
|---|
| 556 | return 0;
|
|---|
| 557 | }
|
|---|
| 558 |
|
|---|
| 559 | # else
|
|---|
| 560 |
|
|---|
| 561 | int
|
|---|
| 562 | glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock)
|
|---|
| 563 | {
|
|---|
| 564 | pthread_mutexattr_t attributes;
|
|---|
| 565 | int err;
|
|---|
| 566 |
|
|---|
| 567 | err = pthread_mutexattr_init (&attributes);
|
|---|
| 568 | if (err != 0)
|
|---|
| 569 | return err;
|
|---|
| 570 | err = pthread_mutexattr_settype (&attributes, PTHREAD_MUTEX_RECURSIVE);
|
|---|
| 571 | if (err != 0)
|
|---|
| 572 | {
|
|---|
| 573 | pthread_mutexattr_destroy (&attributes);
|
|---|
| 574 | return err;
|
|---|
| 575 | }
|
|---|
| 576 | err = pthread_mutex_init (&lock->recmutex, &attributes);
|
|---|
| 577 | if (err != 0)
|
|---|
| 578 | {
|
|---|
| 579 | pthread_mutexattr_destroy (&attributes);
|
|---|
| 580 | return err;
|
|---|
| 581 | }
|
|---|
| 582 | err = pthread_mutexattr_destroy (&attributes);
|
|---|
| 583 | if (err != 0)
|
|---|
| 584 | return err;
|
|---|
| 585 | lock->initialized = 1;
|
|---|
| 586 | return 0;
|
|---|
| 587 | }
|
|---|
| 588 |
|
|---|
| 589 | int
|
|---|
| 590 | glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock)
|
|---|
| 591 | {
|
|---|
| 592 | if (!lock->initialized)
|
|---|
| 593 | {
|
|---|
| 594 | int err;
|
|---|
| 595 |
|
|---|
| 596 | err = pthread_mutex_lock (&lock->guard);
|
|---|
| 597 | if (err != 0)
|
|---|
| 598 | return err;
|
|---|
| 599 | if (!lock->initialized)
|
|---|
| 600 | {
|
|---|
| 601 | err = glthread_recursive_lock_init_multithreaded (lock);
|
|---|
| 602 | if (err != 0)
|
|---|
| 603 | {
|
|---|
| 604 | pthread_mutex_unlock (&lock->guard);
|
|---|
| 605 | return err;
|
|---|
| 606 | }
|
|---|
| 607 | }
|
|---|
| 608 | err = pthread_mutex_unlock (&lock->guard);
|
|---|
| 609 | if (err != 0)
|
|---|
| 610 | return err;
|
|---|
| 611 | }
|
|---|
| 612 | return pthread_mutex_lock (&lock->recmutex);
|
|---|
| 613 | }
|
|---|
| 614 |
|
|---|
| 615 | int
|
|---|
| 616 | glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock)
|
|---|
| 617 | {
|
|---|
| 618 | if (!lock->initialized)
|
|---|
| 619 | return EINVAL;
|
|---|
| 620 | return pthread_mutex_unlock (&lock->recmutex);
|
|---|
| 621 | }
|
|---|
| 622 |
|
|---|
| 623 | int
|
|---|
| 624 | glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock)
|
|---|
| 625 | {
|
|---|
| 626 | int err;
|
|---|
| 627 |
|
|---|
| 628 | if (!lock->initialized)
|
|---|
| 629 | return EINVAL;
|
|---|
| 630 | err = pthread_mutex_destroy (&lock->recmutex);
|
|---|
| 631 | if (err != 0)
|
|---|
| 632 | return err;
|
|---|
| 633 | lock->initialized = 0;
|
|---|
| 634 | return 0;
|
|---|
| 635 | }
|
|---|
| 636 |
|
|---|
| 637 | # endif
|
|---|
| 638 |
|
|---|
| 639 | # else
|
|---|
| 640 |
|
|---|
| 641 | int
|
|---|
| 642 | glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock)
|
|---|
| 643 | {
|
|---|
| 644 | int err;
|
|---|
| 645 |
|
|---|
| 646 | err = pthread_mutex_init (&lock->mutex, NULL);
|
|---|
| 647 | if (err != 0)
|
|---|
| 648 | return err;
|
|---|
| 649 | lock->owner = (pthread_t) 0;
|
|---|
| 650 | lock->depth = 0;
|
|---|
| 651 | return 0;
|
|---|
| 652 | }
|
|---|
| 653 |
|
|---|
| 654 | int
|
|---|
| 655 | glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock)
|
|---|
| 656 | {
|
|---|
| 657 | pthread_t self = pthread_self ();
|
|---|
| 658 | if (lock->owner != self)
|
|---|
| 659 | {
|
|---|
| 660 | int err;
|
|---|
| 661 |
|
|---|
| 662 | err = pthread_mutex_lock (&lock->mutex);
|
|---|
| 663 | if (err != 0)
|
|---|
| 664 | return err;
|
|---|
| 665 | lock->owner = self;
|
|---|
| 666 | }
|
|---|
| 667 | if (++(lock->depth) == 0) /* wraparound? */
|
|---|
| 668 | {
|
|---|
| 669 | lock->depth--;
|
|---|
| 670 | return EAGAIN;
|
|---|
| 671 | }
|
|---|
| 672 | return 0;
|
|---|
| 673 | }
|
|---|
| 674 |
|
|---|
| 675 | int
|
|---|
| 676 | glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock)
|
|---|
| 677 | {
|
|---|
| 678 | if (lock->owner != pthread_self ())
|
|---|
| 679 | return EPERM;
|
|---|
| 680 | if (lock->depth == 0)
|
|---|
| 681 | return EINVAL;
|
|---|
| 682 | if (--(lock->depth) == 0)
|
|---|
| 683 | {
|
|---|
| 684 | lock->owner = (pthread_t) 0;
|
|---|
| 685 | return pthread_mutex_unlock (&lock->mutex);
|
|---|
| 686 | }
|
|---|
| 687 | else
|
|---|
| 688 | return 0;
|
|---|
| 689 | }
|
|---|
| 690 |
|
|---|
| 691 | int
|
|---|
| 692 | glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock)
|
|---|
| 693 | {
|
|---|
| 694 | if (lock->owner != (pthread_t) 0)
|
|---|
| 695 | return EBUSY;
|
|---|
| 696 | return pthread_mutex_destroy (&lock->mutex);
|
|---|
| 697 | }
|
|---|
| 698 |
|
|---|
| 699 | # endif
|
|---|
| 700 |
|
|---|
| 701 | /* -------------------------- gl_once_t datatype -------------------------- */
|
|---|
| 702 |
|
|---|
| 703 | static const pthread_once_t fresh_once = PTHREAD_ONCE_INIT;
|
|---|
| 704 |
|
|---|
| 705 | int
|
|---|
| 706 | glthread_once_singlethreaded (pthread_once_t *once_control)
|
|---|
| 707 | {
|
|---|
| 708 | /* We don't know whether pthread_once_t is an integer type, a floating-point
|
|---|
| 709 | type, a pointer type, or a structure type. */
|
|---|
| 710 | char *firstbyte = (char *)once_control;
|
|---|
| 711 | if (*firstbyte == *(const char *)&fresh_once)
|
|---|
| 712 | {
|
|---|
| 713 | /* First time use of once_control. Invert the first byte. */
|
|---|
| 714 | *firstbyte = ~ *(const char *)&fresh_once;
|
|---|
| 715 | return 1;
|
|---|
| 716 | }
|
|---|
| 717 | else
|
|---|
| 718 | return 0;
|
|---|
| 719 | }
|
|---|
| 720 |
|
|---|
| 721 | # if !(PTHREAD_IN_USE_DETECTION_HARD || USE_POSIX_THREADS_WEAK)
|
|---|
| 722 |
|
|---|
| 723 | int
|
|---|
| 724 | glthread_once_multithreaded (pthread_once_t *once_control,
|
|---|
| 725 | void (*init_function) (void))
|
|---|
| 726 | {
|
|---|
| 727 | int err = pthread_once (once_control, init_function);
|
|---|
| 728 | if (err == ENOSYS)
|
|---|
| 729 | {
|
|---|
| 730 | /* This happens on FreeBSD 11: The pthread_once function in libc returns
|
|---|
| 731 | ENOSYS. */
|
|---|
| 732 | if (glthread_once_singlethreaded (once_control))
|
|---|
| 733 | init_function ();
|
|---|
| 734 | return 0;
|
|---|
| 735 | }
|
|---|
| 736 | return err;
|
|---|
| 737 | }
|
|---|
| 738 |
|
|---|
| 739 | # endif
|
|---|
| 740 |
|
|---|
| 741 | #endif
|
|---|
| 742 |
|
|---|
| 743 | /* ========================================================================= */
|
|---|
| 744 |
|
|---|
| 745 | #if USE_WINDOWS_THREADS
|
|---|
| 746 |
|
|---|
| 747 | #endif
|
|---|
| 748 |
|
|---|
| 749 | /* ========================================================================= */
|
|---|