summaryrefslogtreecommitdiff
path: root/tests/pthread-rwlock.c
diff options
context:
space:
mode:
Diffstat (limited to 'tests/pthread-rwlock.c')
-rw-r--r--tests/pthread-rwlock.c624
1 files changed, 624 insertions, 0 deletions
diff --git a/tests/pthread-rwlock.c b/tests/pthread-rwlock.c
new file mode 100644
index 00000000..46681538
--- /dev/null
+++ b/tests/pthread-rwlock.c
@@ -0,0 +1,624 @@
+/* POSIX read-write locks.
+ Copyright (C) 2019-2024 Free Software Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2019. */
+
+#include <config.h>
+
+/* Specification. */
+#include <pthread.h>
+
+#if (defined _WIN32 && ! defined __CYGWIN__) && USE_WINDOWS_THREADS
+# include "windows-timedrwlock.h"
+#else
+# include <errno.h>
+# include <limits.h>
+# include <sys/time.h>
+# include <time.h>
+#endif
+
+#ifndef MIN
+# define MIN(a, b) ((a) < (b) ? (a) : (b))
+#endif
+
+#if ((defined _WIN32 && ! defined __CYGWIN__) && USE_WINDOWS_THREADS) || !HAVE_PTHREAD_H
+
+int
+pthread_rwlockattr_init (pthread_rwlockattr_t *attr)
+{
+ *attr = 0;
+ return 0;
+}
+
+int
+pthread_rwlockattr_destroy (_GL_UNUSED pthread_rwlockattr_t *attr)
+{
+ return 0;
+}
+
+#elif PTHREAD_RWLOCK_BAD_WAITQUEUE
+
+/* Override pthread_rwlockattr_init, to use the kind PREFER_WRITER_NONRECURSIVE
+ (or possibly PREFER_WRITER) instead of the kind DEFAULT. */
+int
+pthread_rwlockattr_init (pthread_rwlockattr_t *attr)
+# undef pthread_rwlockattr_init
+{
+ int err;
+
+ err = pthread_rwlockattr_init (attr);
+ if (err != 0)
+ return err;
+ err = pthread_rwlockattr_setkind_np (attr,
+ PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
+ if (err != 0)
+ {
+ pthread_rwlockattr_destroy (attr);
+ return err;
+ }
+ return 0;
+}
+
+#endif
+
+#if (defined _WIN32 && ! defined __CYGWIN__) && USE_WINDOWS_THREADS
+/* Use Windows threads. */
+
+int
+pthread_rwlock_init (pthread_rwlock_t *lock,
+ _GL_UNUSED const pthread_rwlockattr_t *attr)
+{
+ glwthread_timedrwlock_init (lock);
+ return 0;
+}
+
+int
+pthread_rwlock_rdlock (pthread_rwlock_t *lock)
+{
+ return glwthread_timedrwlock_rdlock (lock);
+}
+
+int
+pthread_rwlock_wrlock (pthread_rwlock_t *lock)
+{
+ return glwthread_timedrwlock_wrlock (lock);
+}
+
+int
+pthread_rwlock_tryrdlock (pthread_rwlock_t *lock)
+{
+ return glwthread_timedrwlock_tryrdlock (lock);
+}
+
+int
+pthread_rwlock_trywrlock (pthread_rwlock_t *lock)
+{
+ return glwthread_timedrwlock_trywrlock (lock);
+}
+
+int
+pthread_rwlock_timedrdlock (pthread_rwlock_t *lock,
+ const struct timespec *abstime)
+{
+ return glwthread_timedrwlock_timedrdlock (lock, abstime);
+}
+
+int
+pthread_rwlock_timedwrlock (pthread_rwlock_t *lock,
+ const struct timespec *abstime)
+{
+ return glwthread_timedrwlock_timedwrlock (lock, abstime);
+}
+
+int
+pthread_rwlock_unlock (pthread_rwlock_t *lock)
+{
+ return glwthread_timedrwlock_unlock (lock);
+}
+
+int
+pthread_rwlock_destroy (pthread_rwlock_t *lock)
+{
+ return glwthread_timedrwlock_destroy (lock);
+}
+
+#elif HAVE_PTHREAD_H
+/* Provide workarounds for POSIX threads. */
+
+# if PTHREAD_RWLOCK_UNIMPLEMENTED
+
+int
+pthread_rwlock_init (pthread_rwlock_t *lock,
+ _GL_UNUSED const pthread_rwlockattr_t *attr)
+{
+ int err;
+
+ err = pthread_mutex_init (&lock->lock, NULL);
+ if (err != 0)
+ return err;
+ err = pthread_cond_init (&lock->waiting_readers, NULL);
+ if (err != 0)
+ return err;
+ err = pthread_cond_init (&lock->waiting_writers, NULL);
+ if (err != 0)
+ return err;
+ lock->waiting_writers_count = 0;
+ lock->runcount = 0;
+ return 0;
+}
+
+int
+pthread_rwlock_rdlock (pthread_rwlock_t *lock)
+{
+ int err;
+
+ err = pthread_mutex_lock (&lock->lock);
+ if (err != 0)
+ return err;
+ /* Test whether only readers are currently running, and whether the runcount
+ field will not overflow, and whether no writer is waiting. The latter
+ condition is because POSIX recommends that "write locks shall take
+ precedence over read locks", to avoid "writer starvation". */
+ while (!(lock->runcount + 1 > 0 && lock->waiting_writers_count == 0))
+ {
+ /* This thread has to wait for a while. Enqueue it among the
+ waiting_readers. */
+ err = pthread_cond_wait (&lock->waiting_readers, &lock->lock);
+ if (err != 0)
+ {
+ pthread_mutex_unlock (&lock->lock);
+ return err;
+ }
+ }
+ lock->runcount++;
+ return pthread_mutex_unlock (&lock->lock);
+}
+
+int
+pthread_rwlock_wrlock (pthread_rwlock_t *lock)
+{
+ int err;
+
+ err = pthread_mutex_lock (&lock->lock);
+ if (err != 0)
+ return err;
+ /* Test whether no readers or writers are currently running. */
+ while (!(lock->runcount == 0))
+ {
+ /* This thread has to wait for a while. Enqueue it among the
+ waiting_writers. */
+ lock->waiting_writers_count++;
+ err = pthread_cond_wait (&lock->waiting_writers, &lock->lock);
+ if (err != 0)
+ {
+ lock->waiting_writers_count--;
+ pthread_mutex_unlock (&lock->lock);
+ return err;
+ }
+ lock->waiting_writers_count--;
+ }
+ lock->runcount--; /* runcount becomes -1 */
+ return pthread_mutex_unlock (&lock->lock);
+}
+
+int
+pthread_rwlock_tryrdlock (pthread_rwlock_t *lock)
+{
+ int err;
+
+ err = pthread_mutex_lock (&lock->lock);
+ if (err != 0)
+ return err;
+ /* Test whether only readers are currently running, and whether the runcount
+ field will not overflow, and whether no writer is waiting. The latter
+ condition is because POSIX recommends that "write locks shall take
+ precedence over read locks", to avoid "writer starvation". */
+ if (!(lock->runcount + 1 > 0 && lock->waiting_writers_count == 0))
+ {
+ /* This thread would have to wait for a while. Return instead. */
+ pthread_mutex_unlock (&lock->lock);
+ return EBUSY;
+ }
+ lock->runcount++;
+ return pthread_mutex_unlock (&lock->lock);
+}
+
+int
+pthread_rwlock_trywrlock (pthread_rwlock_t *lock)
+{
+ int err;
+
+ err = pthread_mutex_lock (&lock->lock);
+ if (err != 0)
+ return err;
+ /* Test whether no readers or writers are currently running. */
+ if (!(lock->runcount == 0))
+ {
+ /* This thread would have to wait for a while. Return instead. */
+ pthread_mutex_unlock (&lock->lock);
+ return EBUSY;
+ }
+ lock->runcount--; /* runcount becomes -1 */
+ return pthread_mutex_unlock (&lock->lock);
+}
+
+int
+pthread_rwlock_timedrdlock (pthread_rwlock_t *lock,
+ const struct timespec *abstime)
+{
+ int err;
+
+ err = pthread_mutex_lock (&lock->lock);
+ if (err != 0)
+ return err;
+ /* Test whether only readers are currently running, and whether the runcount
+ field will not overflow, and whether no writer is waiting. The latter
+ condition is because POSIX recommends that "write locks shall take
+ precedence over read locks", to avoid "writer starvation". */
+ while (!(lock->runcount + 1 > 0 && lock->waiting_writers_count == 0))
+ {
+ /* This thread has to wait for a while. Enqueue it among the
+ waiting_readers. */
+ err = pthread_cond_timedwait (&lock->waiting_readers, &lock->lock,
+ abstime);
+ if (err != 0)
+ {
+ pthread_mutex_unlock (&lock->lock);
+ return err;
+ }
+ }
+ lock->runcount++;
+ return pthread_mutex_unlock (&lock->lock);
+}
+
+int
+pthread_rwlock_timedwrlock (pthread_rwlock_t *lock,
+ const struct timespec *abstime)
+{
+ int err;
+
+ err = pthread_mutex_lock (&lock->lock);
+ if (err != 0)
+ return err;
+ /* Test whether no readers or writers are currently running. */
+ while (!(lock->runcount == 0))
+ {
+ /* This thread has to wait for a while. Enqueue it among the
+ waiting_writers. */
+ lock->waiting_writers_count++;
+ err = pthread_cond_timedwait (&lock->waiting_writers, &lock->lock,
+ abstime);
+ if (err != 0)
+ {
+ lock->waiting_writers_count--;
+ pthread_mutex_unlock (&lock->lock);
+ return err;
+ }
+ lock->waiting_writers_count--;
+ }
+ lock->runcount--; /* runcount becomes -1 */
+ return pthread_mutex_unlock (&lock->lock);
+}
+
+int
+pthread_rwlock_unlock (pthread_rwlock_t *lock)
+{
+ int err;
+
+ err = pthread_mutex_lock (&lock->lock);
+ if (err != 0)
+ return err;
+ if (lock->runcount < 0)
+ {
+ /* Drop a writer lock. */
+ if (!(lock->runcount == -1))
+ {
+ pthread_mutex_unlock (&lock->lock);
+ return EINVAL;
+ }
+ lock->runcount = 0;
+ }
+ else
+ {
+ /* Drop a reader lock. */
+ if (!(lock->runcount > 0))
+ {
+ pthread_mutex_unlock (&lock->lock);
+ return EINVAL;
+ }
+ lock->runcount--;
+ }
+ if (lock->runcount == 0)
+ {
+ /* POSIX recommends that "write locks shall take precedence over read
+ locks", to avoid "writer starvation". */
+ if (lock->waiting_writers_count > 0)
+ {
+ /* Wake up one of the waiting writers. */
+ err = pthread_cond_signal (&lock->waiting_writers);
+ if (err != 0)
+ {
+ pthread_mutex_unlock (&lock->lock);
+ return err;
+ }
+ }
+ else
+ {
+ /* Wake up all waiting readers. */
+ err = pthread_cond_broadcast (&lock->waiting_readers);
+ if (err != 0)
+ {
+ pthread_mutex_unlock (&lock->lock);
+ return err;
+ }
+ }
+ }
+ return pthread_mutex_unlock (&lock->lock);
+}
+
+int
+pthread_rwlock_destroy (pthread_rwlock_t *lock)
+{
+ int err;
+
+ err = pthread_mutex_destroy (&lock->lock);
+ if (err != 0)
+ return err;
+ err = pthread_cond_destroy (&lock->waiting_readers);
+ if (err != 0)
+ return err;
+ err = pthread_cond_destroy (&lock->waiting_writers);
+ if (err != 0)
+ return err;
+ return 0;
+}
+
+# else
+
+# if PTHREAD_RWLOCK_BAD_WAITQUEUE
+
+/* Override pthread_rwlock_init, to use the kind PREFER_WRITER_NONRECURSIVE
+ (or possibly PREFER_WRITER) instead of the default, when no
+ pthread_rwlockattr_t object is specified. */
+int
+pthread_rwlock_init (pthread_rwlock_t *lock, const pthread_rwlockattr_t *attr)
+# undef pthread_rwlock_init
+{
+ int err;
+
+ if (attr != NULL)
+ err = pthread_rwlock_init (lock, attr);
+ else
+ {
+ pthread_rwlockattr_t replacement_attr;
+
+ err = pthread_rwlockattr_init (&replacement_attr);
+ if (err != 0)
+ return err;
+ err = pthread_rwlockattr_setkind_np (&replacement_attr,
+ PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
+ if (err != 0)
+ {
+ pthread_rwlockattr_destroy (&replacement_attr);
+ return err;
+ }
+ err = pthread_rwlock_init (lock, &replacement_attr);
+ pthread_rwlockattr_destroy (&replacement_attr);
+ }
+ return err;
+}
+
+# endif
+
+# if PTHREAD_RWLOCK_LACKS_TIMEOUT
+
+int
+pthread_rwlock_timedrdlock (pthread_rwlock_t *lock,
+ const struct timespec *abstime)
+{
+ /* Poll the lock's state in regular intervals. Ugh. */
+ for (;;)
+ {
+ int err;
+ struct timeval currtime;
+ unsigned long remaining;
+
+ err = pthread_rwlock_tryrdlock (lock);
+ if (err != EBUSY)
+ return err;
+
+ gettimeofday (&currtime, NULL);
+
+ if (currtime.tv_sec > abstime->tv_sec)
+ remaining = 0;
+ else
+ {
+ unsigned long seconds = abstime->tv_sec - currtime.tv_sec;
+ remaining = seconds * 1000000000;
+ if (remaining / 1000000000 != seconds) /* overflow? */
+ remaining = ULONG_MAX;
+ else
+ {
+ long nanoseconds =
+ abstime->tv_nsec - currtime.tv_usec * 1000;
+ if (nanoseconds >= 0)
+ {
+ remaining += nanoseconds;
+ if (remaining < nanoseconds) /* overflow? */
+ remaining = ULONG_MAX;
+ }
+ else
+ {
+ if (remaining >= - nanoseconds)
+ remaining -= (- nanoseconds);
+ else
+ remaining = 0;
+ }
+ }
+ }
+ if (remaining == 0)
+ return ETIMEDOUT;
+
+ /* Sleep 1 ms. */
+ struct timespec duration =
+ {
+ .tv_sec = 0,
+ .tv_nsec = MIN (1000000, remaining)
+ };
+ nanosleep (&duration, NULL);
+ }
+}
+
+int
+pthread_rwlock_timedwrlock (pthread_rwlock_t *lock,
+ const struct timespec *abstime)
+{
+ /* Poll the lock's state in regular intervals. Ugh. */
+ for (;;)
+ {
+ int err;
+ struct timeval currtime;
+ unsigned long remaining;
+
+ err = pthread_rwlock_trywrlock (lock);
+ if (err != EBUSY)
+ return err;
+
+ gettimeofday (&currtime, NULL);
+
+ if (currtime.tv_sec > abstime->tv_sec)
+ remaining = 0;
+ else
+ {
+ unsigned long seconds = abstime->tv_sec - currtime.tv_sec;
+ remaining = seconds * 1000000000;
+ if (remaining / 1000000000 != seconds) /* overflow? */
+ remaining = ULONG_MAX;
+ else
+ {
+ long nanoseconds =
+ abstime->tv_nsec - currtime.tv_usec * 1000;
+ if (nanoseconds >= 0)
+ {
+ remaining += nanoseconds;
+ if (remaining < nanoseconds) /* overflow? */
+ remaining = ULONG_MAX;
+ }
+ else
+ {
+ if (remaining >= - nanoseconds)
+ remaining -= (- nanoseconds);
+ else
+ remaining = 0;
+ }
+ }
+ }
+ if (remaining == 0)
+ return ETIMEDOUT;
+
+ /* Sleep 1 ms. */
+ struct timespec duration =
+ {
+ .tv_sec = 0,
+ .tv_nsec = MIN (1000000, remaining)
+ };
+ nanosleep (&duration, NULL);
+ }
+}
+
+# endif
+
+# endif
+
+#else
+/* Provide a dummy implementation for single-threaded applications. */
+
+/* The pthread_rwlock_t is an 'int', representing the number of readers running,
+ or -1 when a writer runs. */
+
+int
+pthread_rwlock_init (pthread_rwlock_t *lock,
+ _GL_UNUSED const pthread_rwlockattr_t *attr)
+{
+ *lock = 0;
+ return 0;
+}
+
+int
+pthread_rwlock_rdlock (pthread_rwlock_t *lock)
+{
+ if (*lock < 0)
+ return EDEADLK;
+ (*lock)++;
+ return 0;
+}
+
+int
+pthread_rwlock_wrlock (pthread_rwlock_t *lock)
+{
+ if (*lock != 0)
+ return EDEADLK;
+ *lock = -1;
+ return 0;
+}
+
+int
+pthread_rwlock_tryrdlock (pthread_rwlock_t *lock)
+{
+ return pthread_rwlock_rdlock (lock);
+}
+
+int
+pthread_rwlock_trywrlock (pthread_rwlock_t *lock)
+{
+ return pthread_rwlock_wrlock (lock);
+}
+
+int
+pthread_rwlock_timedrdlock (pthread_rwlock_t *lock,
+ _GL_UNUSED const struct timespec *abstime)
+{
+ return pthread_rwlock_rdlock (lock);
+}
+
+int
+pthread_rwlock_timedwrlock (pthread_rwlock_t *lock,
+ _GL_UNUSED const struct timespec *abstime)
+{
+ return pthread_rwlock_wrlock (lock);
+}
+
+int
+pthread_rwlock_unlock (pthread_rwlock_t *lock)
+{
+ if (*lock == 0)
+ return EPERM;
+ if (*lock < 0)
+ *lock = 0;
+ else /* *lock > 0 */
+ (*lock)--;
+ return 0;
+}
+
+int
+pthread_rwlock_destroy (pthread_rwlock_t *lock)
+{
+ if (*lock)
+ return EBUSY;
+ return 0;
+}
+
+#endif
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-26 07:00:10 +0000