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-rw-r--r--lib/glthread/lock.c749
1 files changed, 749 insertions, 0 deletions
diff --git a/lib/glthread/lock.c b/lib/glthread/lock.c
new file mode 100644
index 0000000..10af6f2
--- /dev/null
+++ b/lib/glthread/lock.c
@@ -0,0 +1,749 @@
+/* Locking in multithreaded situations.
+ Copyright (C) 2005-2020 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3, or (at your option)
+ any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, see <https://www.gnu.org/licenses/>. */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2005.
+ Based on GCC's gthr-posix.h, gthr-posix95.h. */
+
+#include <config.h>
+
+#include "glthread/lock.h"
+
+/* ========================================================================= */
+
+#if USE_ISOC_THREADS || USE_ISOC_AND_POSIX_THREADS
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+int
+glthread_lock_init (gl_lock_t *lock)
+{
+ if (mtx_init (&lock->mutex, mtx_plain) != thrd_success)
+ return ENOMEM;
+ lock->init_needed = 0;
+ return 0;
+}
+
+int
+glthread_lock_lock (gl_lock_t *lock)
+{
+ if (lock->init_needed)
+ call_once (&lock->init_once, lock->init_func);
+ if (mtx_lock (&lock->mutex) != thrd_success)
+ return EAGAIN;
+ return 0;
+}
+
+int
+glthread_lock_unlock (gl_lock_t *lock)
+{
+ if (lock->init_needed)
+ call_once (&lock->init_once, lock->init_func);
+ if (mtx_unlock (&lock->mutex) != thrd_success)
+ return EINVAL;
+ return 0;
+}
+
+int
+glthread_lock_destroy (gl_lock_t *lock)
+{
+ if (lock->init_needed)
+ call_once (&lock->init_once, lock->init_func);
+ mtx_destroy (&lock->mutex);
+ return 0;
+}
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+int
+glthread_rwlock_init (gl_rwlock_t *lock)
+{
+ if (mtx_init (&lock->lock, mtx_plain) != thrd_success
+ || cnd_init (&lock->waiting_readers) != thrd_success
+ || cnd_init (&lock->waiting_writers) != thrd_success)
+ return ENOMEM;
+ lock->waiting_writers_count = 0;
+ lock->runcount = 0;
+ lock->init_needed = 0;
+ return 0;
+}
+
+int
+glthread_rwlock_rdlock (gl_rwlock_t *lock)
+{
+ if (lock->init_needed)
+ call_once (&lock->init_once, lock->init_func);
+ if (mtx_lock (&lock->lock) != thrd_success)
+ return EAGAIN;
+ /* 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. */
+ if (cnd_wait (&lock->waiting_readers, &lock->lock) != thrd_success)
+ {
+ mtx_unlock (&lock->lock);
+ return EINVAL;
+ }
+ }
+ lock->runcount++;
+ if (mtx_unlock (&lock->lock) != thrd_success)
+ return EINVAL;
+ return 0;
+}
+
+int
+glthread_rwlock_wrlock (gl_rwlock_t *lock)
+{
+ if (lock->init_needed)
+ call_once (&lock->init_once, lock->init_func);
+ if (mtx_lock (&lock->lock) != thrd_success)
+ return EAGAIN;
+ /* 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++;
+ if (cnd_wait (&lock->waiting_writers, &lock->lock) != thrd_success)
+ {
+ lock->waiting_writers_count--;
+ mtx_unlock (&lock->lock);
+ return EINVAL;
+ }
+ lock->waiting_writers_count--;
+ }
+ lock->runcount--; /* runcount becomes -1 */
+ if (mtx_unlock (&lock->lock) != thrd_success)
+ return EINVAL;
+ return 0;
+}
+
+int
+glthread_rwlock_unlock (gl_rwlock_t *lock)
+{
+ if (lock->init_needed)
+ call_once (&lock->init_once, lock->init_func);
+ if (mtx_lock (&lock->lock) != thrd_success)
+ return EAGAIN;
+ if (lock->runcount < 0)
+ {
+ /* Drop a writer lock. */
+ if (!(lock->runcount == -1))
+ {
+ mtx_unlock (&lock->lock);
+ return EINVAL;
+ }
+ lock->runcount = 0;
+ }
+ else
+ {
+ /* Drop a reader lock. */
+ if (!(lock->runcount > 0))
+ {
+ mtx_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. */
+ if (cnd_signal (&lock->waiting_writers) != thrd_success)
+ {
+ mtx_unlock (&lock->lock);
+ return EINVAL;
+ }
+ }
+ else
+ {
+ /* Wake up all waiting readers. */
+ if (cnd_broadcast (&lock->waiting_readers) != thrd_success)
+ {
+ mtx_unlock (&lock->lock);
+ return EINVAL;
+ }
+ }
+ }
+ if (mtx_unlock (&lock->lock) != thrd_success)
+ return EINVAL;
+ return 0;
+}
+
+int
+glthread_rwlock_destroy (gl_rwlock_t *lock)
+{
+ if (lock->init_needed)
+ call_once (&lock->init_once, lock->init_func);
+ mtx_destroy (&lock->lock);
+ cnd_destroy (&lock->waiting_readers);
+ cnd_destroy (&lock->waiting_writers);
+ return 0;
+}
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+int
+glthread_recursive_lock_init (gl_recursive_lock_t *lock)
+{
+ if (mtx_init (&lock->mutex, mtx_plain | mtx_recursive) != thrd_success)
+ return ENOMEM;
+ lock->init_needed = 0;
+ return 0;
+}
+
+int
+glthread_recursive_lock_lock (gl_recursive_lock_t *lock)
+{
+ if (lock->init_needed)
+ call_once (&lock->init_once, lock->init_func);
+ if (mtx_lock (&lock->mutex) != thrd_success)
+ return EAGAIN;
+ return 0;
+}
+
+int
+glthread_recursive_lock_unlock (gl_recursive_lock_t *lock)
+{
+ if (lock->init_needed)
+ call_once (&lock->init_once, lock->init_func);
+ if (mtx_unlock (&lock->mutex) != thrd_success)
+ return EINVAL;
+ return 0;
+}
+
+int
+glthread_recursive_lock_destroy (gl_recursive_lock_t *lock)
+{
+ if (lock->init_needed)
+ call_once (&lock->init_once, lock->init_func);
+ mtx_destroy (&lock->mutex);
+ return 0;
+}
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_POSIX_THREADS
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+# if HAVE_PTHREAD_RWLOCK && (HAVE_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER || (defined PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP && (__GNU_LIBRARY__ > 1)))
+
+# if defined PTHREAD_RWLOCK_INITIALIZER || defined PTHREAD_RWLOCK_INITIALIZER_NP
+
+# if !HAVE_PTHREAD_RWLOCK_RDLOCK_PREFER_WRITER
+ /* glibc with bug https://sourceware.org/bugzilla/show_bug.cgi?id=13701 */
+
+int
+glthread_rwlock_init_for_glibc (pthread_rwlock_t *lock)
+{
+ pthread_rwlockattr_t attributes;
+ int err;
+
+ err = pthread_rwlockattr_init (&attributes);
+ if (err != 0)
+ return err;
+ /* Note: PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP is the only value that
+ causes the writer to be preferred. PTHREAD_RWLOCK_PREFER_WRITER_NP does not
+ do this; see
+ http://man7.org/linux/man-pages/man3/pthread_rwlockattr_setkind_np.3.html */
+ err = pthread_rwlockattr_setkind_np (&attributes,
+ PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
+ if (err == 0)
+ err = pthread_rwlock_init(lock, &attributes);
+ /* pthread_rwlockattr_destroy always returns 0. It cannot influence the
+ return value. */
+ pthread_rwlockattr_destroy (&attributes);
+ return err;
+}
+
+# endif
+# else
+
+int
+glthread_rwlock_init_multithreaded (gl_rwlock_t *lock)
+{
+ int err;
+
+ err = pthread_rwlock_init (&lock->rwlock, NULL);
+ if (err != 0)
+ return err;
+ lock->initialized = 1;
+ return 0;
+}
+
+int
+glthread_rwlock_rdlock_multithreaded (gl_rwlock_t *lock)
+{
+ if (!lock->initialized)
+ {
+ int err;
+
+ err = pthread_mutex_lock (&lock->guard);
+ if (err != 0)
+ return err;
+ if (!lock->initialized)
+ {
+ err = glthread_rwlock_init_multithreaded (lock);
+ if (err != 0)
+ {
+ pthread_mutex_unlock (&lock->guard);
+ return err;
+ }
+ }
+ err = pthread_mutex_unlock (&lock->guard);
+ if (err != 0)
+ return err;
+ }
+ return pthread_rwlock_rdlock (&lock->rwlock);
+}
+
+int
+glthread_rwlock_wrlock_multithreaded (gl_rwlock_t *lock)
+{
+ if (!lock->initialized)
+ {
+ int err;
+
+ err = pthread_mutex_lock (&lock->guard);
+ if (err != 0)
+ return err;
+ if (!lock->initialized)
+ {
+ err = glthread_rwlock_init_multithreaded (lock);
+ if (err != 0)
+ {
+ pthread_mutex_unlock (&lock->guard);
+ return err;
+ }
+ }
+ err = pthread_mutex_unlock (&lock->guard);
+ if (err != 0)
+ return err;
+ }
+ return pthread_rwlock_wrlock (&lock->rwlock);
+}
+
+int
+glthread_rwlock_unlock_multithreaded (gl_rwlock_t *lock)
+{
+ if (!lock->initialized)
+ return EINVAL;
+ return pthread_rwlock_unlock (&lock->rwlock);
+}
+
+int
+glthread_rwlock_destroy_multithreaded (gl_rwlock_t *lock)
+{
+ int err;
+
+ if (!lock->initialized)
+ return EINVAL;
+ err = pthread_rwlock_destroy (&lock->rwlock);
+ if (err != 0)
+ return err;
+ lock->initialized = 0;
+ return 0;
+}
+
+# endif
+
+# else
+
+int
+glthread_rwlock_init_multithreaded (gl_rwlock_t *lock)
+{
+ 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
+glthread_rwlock_rdlock_multithreaded (gl_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
+glthread_rwlock_wrlock_multithreaded (gl_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
+glthread_rwlock_unlock_multithreaded (gl_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
+glthread_rwlock_destroy_multithreaded (gl_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;
+}
+
+# endif
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+# if HAVE_PTHREAD_MUTEX_RECURSIVE
+
+# if defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER || defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
+
+int
+glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock)
+{
+ pthread_mutexattr_t attributes;
+ int err;
+
+ err = pthread_mutexattr_init (&attributes);
+ if (err != 0)
+ return err;
+ err = pthread_mutexattr_settype (&attributes, PTHREAD_MUTEX_RECURSIVE);
+ if (err != 0)
+ {
+ pthread_mutexattr_destroy (&attributes);
+ return err;
+ }
+ err = pthread_mutex_init (lock, &attributes);
+ if (err != 0)
+ {
+ pthread_mutexattr_destroy (&attributes);
+ return err;
+ }
+ err = pthread_mutexattr_destroy (&attributes);
+ if (err != 0)
+ return err;
+ return 0;
+}
+
+# else
+
+int
+glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock)
+{
+ pthread_mutexattr_t attributes;
+ int err;
+
+ err = pthread_mutexattr_init (&attributes);
+ if (err != 0)
+ return err;
+ err = pthread_mutexattr_settype (&attributes, PTHREAD_MUTEX_RECURSIVE);
+ if (err != 0)
+ {
+ pthread_mutexattr_destroy (&attributes);
+ return err;
+ }
+ err = pthread_mutex_init (&lock->recmutex, &attributes);
+ if (err != 0)
+ {
+ pthread_mutexattr_destroy (&attributes);
+ return err;
+ }
+ err = pthread_mutexattr_destroy (&attributes);
+ if (err != 0)
+ return err;
+ lock->initialized = 1;
+ return 0;
+}
+
+int
+glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock)
+{
+ if (!lock->initialized)
+ {
+ int err;
+
+ err = pthread_mutex_lock (&lock->guard);
+ if (err != 0)
+ return err;
+ if (!lock->initialized)
+ {
+ err = glthread_recursive_lock_init_multithreaded (lock);
+ if (err != 0)
+ {
+ pthread_mutex_unlock (&lock->guard);
+ return err;
+ }
+ }
+ err = pthread_mutex_unlock (&lock->guard);
+ if (err != 0)
+ return err;
+ }
+ return pthread_mutex_lock (&lock->recmutex);
+}
+
+int
+glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock)
+{
+ if (!lock->initialized)
+ return EINVAL;
+ return pthread_mutex_unlock (&lock->recmutex);
+}
+
+int
+glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock)
+{
+ int err;
+
+ if (!lock->initialized)
+ return EINVAL;
+ err = pthread_mutex_destroy (&lock->recmutex);
+ if (err != 0)
+ return err;
+ lock->initialized = 0;
+ return 0;
+}
+
+# endif
+
+# else
+
+int
+glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock)
+{
+ int err;
+
+ err = pthread_mutex_init (&lock->mutex, NULL);
+ if (err != 0)
+ return err;
+ lock->owner = (pthread_t) 0;
+ lock->depth = 0;
+ return 0;
+}
+
+int
+glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock)
+{
+ pthread_t self = pthread_self ();
+ if (lock->owner != self)
+ {
+ int err;
+
+ err = pthread_mutex_lock (&lock->mutex);
+ if (err != 0)
+ return err;
+ lock->owner = self;
+ }
+ if (++(lock->depth) == 0) /* wraparound? */
+ {
+ lock->depth--;
+ return EAGAIN;
+ }
+ return 0;
+}
+
+int
+glthread_recursive_lock_unlock_multithreaded (gl_recursive_lock_t *lock)
+{
+ if (lock->owner != pthread_self ())
+ return EPERM;
+ if (lock->depth == 0)
+ return EINVAL;
+ if (--(lock->depth) == 0)
+ {
+ lock->owner = (pthread_t) 0;
+ return pthread_mutex_unlock (&lock->mutex);
+ }
+ else
+ return 0;
+}
+
+int
+glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock)
+{
+ if (lock->owner != (pthread_t) 0)
+ return EBUSY;
+ return pthread_mutex_destroy (&lock->mutex);
+}
+
+# endif
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+static const pthread_once_t fresh_once = PTHREAD_ONCE_INIT;
+
+int
+glthread_once_singlethreaded (pthread_once_t *once_control)
+{
+ /* We don't know whether pthread_once_t is an integer type, a floating-point
+ type, a pointer type, or a structure type. */
+ char *firstbyte = (char *)once_control;
+ if (*firstbyte == *(const char *)&fresh_once)
+ {
+ /* First time use of once_control. Invert the first byte. */
+ *firstbyte = ~ *(const char *)&fresh_once;
+ return 1;
+ }
+ else
+ return 0;
+}
+
+# if !(PTHREAD_IN_USE_DETECTION_HARD || USE_POSIX_THREADS_WEAK)
+
+int
+glthread_once_multithreaded (pthread_once_t *once_control,
+ void (*init_function) (void))
+{
+ int err = pthread_once (once_control, init_function);
+ if (err == ENOSYS)
+ {
+ /* This happens on FreeBSD 11: The pthread_once function in libc returns
+ ENOSYS. */
+ if (glthread_once_singlethreaded (once_control))
+ init_function ();
+ return 0;
+ }
+ return err;
+}
+
+# endif
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_WINDOWS_THREADS
+
+#endif
+
+/* ========================================================================= */