--- /dev/null
+/* Locking in multithreaded situations.
+ Copyright (C) 2005-2012 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 <http://www.gnu.org/licenses/>. */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2005.
+ Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
+ gthr-win32.h. */
+
+#include <config.h>
+
+#include "glthread/lock.h"
+
+/* ========================================================================= */
+
+#if USE_POSIX_THREADS
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+# if HAVE_PTHREAD_RWLOCK
+
+# if !defined PTHREAD_RWLOCK_INITIALIZER
+
+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. */
+ /* POSIX says: "It is implementation-defined whether the calling thread
+ acquires the lock when a writer does not hold the lock and there are
+ writers blocked on the lock." Let's say, no: give the writers a higher
+ priority. */
+ 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;
+}
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_PTH_THREADS
+
+/* Use the GNU Pth threads library. */
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+static void
+glthread_once_call (void *arg)
+{
+ void (**gl_once_temp_addr) (void) = (void (**) (void)) arg;
+ void (*initfunction) (void) = *gl_once_temp_addr;
+ initfunction ();
+}
+
+int
+glthread_once_multithreaded (pth_once_t *once_control, void (*initfunction) (void))
+{
+ void (*temp) (void) = initfunction;
+ return (!pth_once (once_control, glthread_once_call, &temp) ? errno : 0);
+}
+
+int
+glthread_once_singlethreaded (pth_once_t *once_control)
+{
+ /* We know that pth_once_t is an integer type. */
+ if (*once_control == PTH_ONCE_INIT)
+ {
+ /* First time use of once_control. Invert the marker. */
+ *once_control = ~ PTH_ONCE_INIT;
+ return 1;
+ }
+ else
+ return 0;
+}
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_SOLARIS_THREADS
+
+/* Use the old Solaris threads library. */
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+int
+glthread_recursive_lock_init_multithreaded (gl_recursive_lock_t *lock)
+{
+ int err;
+
+ err = mutex_init (&lock->mutex, USYNC_THREAD, NULL);
+ if (err != 0)
+ return err;
+ lock->owner = (thread_t) 0;
+ lock->depth = 0;
+ return 0;
+}
+
+int
+glthread_recursive_lock_lock_multithreaded (gl_recursive_lock_t *lock)
+{
+ thread_t self = thr_self ();
+ if (lock->owner != self)
+ {
+ int err;
+
+ err = 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 != thr_self ())
+ return EPERM;
+ if (lock->depth == 0)
+ return EINVAL;
+ if (--(lock->depth) == 0)
+ {
+ lock->owner = (thread_t) 0;
+ return mutex_unlock (&lock->mutex);
+ }
+ else
+ return 0;
+}
+
+int
+glthread_recursive_lock_destroy_multithreaded (gl_recursive_lock_t *lock)
+{
+ if (lock->owner != (thread_t) 0)
+ return EBUSY;
+ return mutex_destroy (&lock->mutex);
+}
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+int
+glthread_once_multithreaded (gl_once_t *once_control, void (*initfunction) (void))
+{
+ if (!once_control->inited)
+ {
+ int err;
+
+ /* Use the mutex to guarantee that if another thread is already calling
+ the initfunction, this thread waits until it's finished. */
+ err = mutex_lock (&once_control->mutex);
+ if (err != 0)
+ return err;
+ if (!once_control->inited)
+ {
+ once_control->inited = 1;
+ initfunction ();
+ }
+ return mutex_unlock (&once_control->mutex);
+ }
+ else
+ return 0;
+}
+
+int
+glthread_once_singlethreaded (gl_once_t *once_control)
+{
+ /* We know that gl_once_t contains an integer type. */
+ if (!once_control->inited)
+ {
+ /* First time use of once_control. Invert the marker. */
+ once_control->inited = ~ 0;
+ return 1;
+ }
+ else
+ return 0;
+}
+
+#endif
+
+/* ========================================================================= */
+
+#if USE_WINDOWS_THREADS
+
+/* -------------------------- gl_lock_t datatype -------------------------- */
+
+void
+glthread_lock_init_func (gl_lock_t *lock)
+{
+ InitializeCriticalSection (&lock->lock);
+ lock->guard.done = 1;
+}
+
+int
+glthread_lock_lock_func (gl_lock_t *lock)
+{
+ if (!lock->guard.done)
+ {
+ if (InterlockedIncrement (&lock->guard.started) == 0)
+ /* This thread is the first one to need this lock. Initialize it. */
+ glthread_lock_init (lock);
+ else
+ /* Yield the CPU while waiting for another thread to finish
+ initializing this lock. */
+ while (!lock->guard.done)
+ Sleep (0);
+ }
+ EnterCriticalSection (&lock->lock);
+ return 0;
+}
+
+int
+glthread_lock_unlock_func (gl_lock_t *lock)
+{
+ if (!lock->guard.done)
+ return EINVAL;
+ LeaveCriticalSection (&lock->lock);
+ return 0;
+}
+
+int
+glthread_lock_destroy_func (gl_lock_t *lock)
+{
+ if (!lock->guard.done)
+ return EINVAL;
+ DeleteCriticalSection (&lock->lock);
+ lock->guard.done = 0;
+ return 0;
+}
+
+/* ------------------------- gl_rwlock_t datatype ------------------------- */
+
+/* In this file, the waitqueues are implemented as circular arrays. */
+#define gl_waitqueue_t gl_carray_waitqueue_t
+
+static inline void
+gl_waitqueue_init (gl_waitqueue_t *wq)
+{
+ wq->array = NULL;
+ wq->count = 0;
+ wq->alloc = 0;
+ wq->offset = 0;
+}
+
+/* Enqueues the current thread, represented by an event, in a wait queue.
+ Returns INVALID_HANDLE_VALUE if an allocation failure occurs. */
+static HANDLE
+gl_waitqueue_add (gl_waitqueue_t *wq)
+{
+ HANDLE event;
+ unsigned int index;
+
+ if (wq->count == wq->alloc)
+ {
+ unsigned int new_alloc = 2 * wq->alloc + 1;
+ HANDLE *new_array =
+ (HANDLE *) realloc (wq->array, new_alloc * sizeof (HANDLE));
+ if (new_array == NULL)
+ /* No more memory. */
+ return INVALID_HANDLE_VALUE;
+ /* Now is a good opportunity to rotate the array so that its contents
+ starts at offset 0. */
+ if (wq->offset > 0)
+ {
+ unsigned int old_count = wq->count;
+ unsigned int old_alloc = wq->alloc;
+ unsigned int old_offset = wq->offset;
+ unsigned int i;
+ if (old_offset + old_count > old_alloc)
+ {
+ unsigned int limit = old_offset + old_count - old_alloc;
+ for (i = 0; i < limit; i++)
+ new_array[old_alloc + i] = new_array[i];
+ }
+ for (i = 0; i < old_count; i++)
+ new_array[i] = new_array[old_offset + i];
+ wq->offset = 0;
+ }
+ wq->array = new_array;
+ wq->alloc = new_alloc;
+ }
+ /* Whether the created event is a manual-reset one or an auto-reset one,
+ does not matter, since we will wait on it only once. */
+ event = CreateEvent (NULL, TRUE, FALSE, NULL);
+ if (event == INVALID_HANDLE_VALUE)
+ /* No way to allocate an event. */
+ return INVALID_HANDLE_VALUE;
+ index = wq->offset + wq->count;
+ if (index >= wq->alloc)
+ index -= wq->alloc;
+ wq->array[index] = event;
+ wq->count++;
+ return event;
+}
+
+/* Notifies the first thread from a wait queue and dequeues it. */
+static inline void
+gl_waitqueue_notify_first (gl_waitqueue_t *wq)
+{
+ SetEvent (wq->array[wq->offset + 0]);
+ wq->offset++;
+ wq->count--;
+ if (wq->count == 0 || wq->offset == wq->alloc)
+ wq->offset = 0;
+}
+
+/* Notifies all threads from a wait queue and dequeues them all. */
+static inline void
+gl_waitqueue_notify_all (gl_waitqueue_t *wq)
+{
+ unsigned int i;
+
+ for (i = 0; i < wq->count; i++)
+ {
+ unsigned int index = wq->offset + i;
+ if (index >= wq->alloc)
+ index -= wq->alloc;
+ SetEvent (wq->array[index]);
+ }
+ wq->count = 0;
+ wq->offset = 0;
+}
+
+void
+glthread_rwlock_init_func (gl_rwlock_t *lock)
+{
+ InitializeCriticalSection (&lock->lock);
+ gl_waitqueue_init (&lock->waiting_readers);
+ gl_waitqueue_init (&lock->waiting_writers);
+ lock->runcount = 0;
+ lock->guard.done = 1;
+}
+
+int
+glthread_rwlock_rdlock_func (gl_rwlock_t *lock)
+{
+ if (!lock->guard.done)
+ {
+ if (InterlockedIncrement (&lock->guard.started) == 0)
+ /* This thread is the first one to need this lock. Initialize it. */
+ glthread_rwlock_init (lock);
+ else
+ /* Yield the CPU while waiting for another thread to finish
+ initializing this lock. */
+ while (!lock->guard.done)
+ Sleep (0);
+ }
+ EnterCriticalSection (&lock->lock);
+ /* Test whether only readers are currently running, and whether the runcount
+ field will not overflow. */
+ if (!(lock->runcount + 1 > 0))
+ {
+ /* This thread has to wait for a while. Enqueue it among the
+ waiting_readers. */
+ HANDLE event = gl_waitqueue_add (&lock->waiting_readers);
+ if (event != INVALID_HANDLE_VALUE)
+ {
+ DWORD result;
+ LeaveCriticalSection (&lock->lock);
+ /* Wait until another thread signals this event. */
+ result = WaitForSingleObject (event, INFINITE);
+ if (result == WAIT_FAILED || result == WAIT_TIMEOUT)
+ abort ();
+ CloseHandle (event);
+ /* The thread which signalled the event already did the bookkeeping:
+ removed us from the waiting_readers, incremented lock->runcount. */
+ if (!(lock->runcount > 0))
+ abort ();
+ return 0;
+ }
+ else
+ {
+ /* Allocation failure. Weird. */
+ do
+ {
+ LeaveCriticalSection (&lock->lock);
+ Sleep (1);
+ EnterCriticalSection (&lock->lock);
+ }
+ while (!(lock->runcount + 1 > 0));
+ }
+ }
+ lock->runcount++;
+ LeaveCriticalSection (&lock->lock);
+ return 0;
+}
+
+int
+glthread_rwlock_wrlock_func (gl_rwlock_t *lock)
+{
+ if (!lock->guard.done)
+ {
+ if (InterlockedIncrement (&lock->guard.started) == 0)
+ /* This thread is the first one to need this lock. Initialize it. */
+ glthread_rwlock_init (lock);
+ else
+ /* Yield the CPU while waiting for another thread to finish
+ initializing this lock. */
+ while (!lock->guard.done)
+ Sleep (0);
+ }
+ EnterCriticalSection (&lock->lock);
+ /* Test whether no readers or writers are currently running. */
+ if (!(lock->runcount == 0))
+ {
+ /* This thread has to wait for a while. Enqueue it among the
+ waiting_writers. */
+ HANDLE event = gl_waitqueue_add (&lock->waiting_writers);
+ if (event != INVALID_HANDLE_VALUE)
+ {
+ DWORD result;
+ LeaveCriticalSection (&lock->lock);
+ /* Wait until another thread signals this event. */
+ result = WaitForSingleObject (event, INFINITE);
+ if (result == WAIT_FAILED || result == WAIT_TIMEOUT)
+ abort ();
+ CloseHandle (event);
+ /* The thread which signalled the event already did the bookkeeping:
+ removed us from the waiting_writers, set lock->runcount = -1. */
+ if (!(lock->runcount == -1))
+ abort ();
+ return 0;
+ }
+ else
+ {
+ /* Allocation failure. Weird. */
+ do
+ {
+ LeaveCriticalSection (&lock->lock);
+ Sleep (1);
+ EnterCriticalSection (&lock->lock);
+ }
+ while (!(lock->runcount == 0));
+ }
+ }
+ lock->runcount--; /* runcount becomes -1 */
+ LeaveCriticalSection (&lock->lock);
+ return 0;
+}
+
+int
+glthread_rwlock_unlock_func (gl_rwlock_t *lock)
+{
+ if (!lock->guard.done)
+ return EINVAL;
+ EnterCriticalSection (&lock->lock);
+ if (lock->runcount < 0)
+ {
+ /* Drop a writer lock. */
+ if (!(lock->runcount == -1))
+ abort ();
+ lock->runcount = 0;
+ }
+ else
+ {
+ /* Drop a reader lock. */
+ if (!(lock->runcount > 0))
+ {
+ LeaveCriticalSection (&lock->lock);
+ return EPERM;
+ }
+ 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. */
+ lock->runcount--;
+ gl_waitqueue_notify_first (&lock->waiting_writers);
+ }
+ else
+ {
+ /* Wake up all waiting readers. */
+ lock->runcount += lock->waiting_readers.count;
+ gl_waitqueue_notify_all (&lock->waiting_readers);
+ }
+ }
+ LeaveCriticalSection (&lock->lock);
+ return 0;
+}
+
+int
+glthread_rwlock_destroy_func (gl_rwlock_t *lock)
+{
+ if (!lock->guard.done)
+ return EINVAL;
+ if (lock->runcount != 0)
+ return EBUSY;
+ DeleteCriticalSection (&lock->lock);
+ if (lock->waiting_readers.array != NULL)
+ free (lock->waiting_readers.array);
+ if (lock->waiting_writers.array != NULL)
+ free (lock->waiting_writers.array);
+ lock->guard.done = 0;
+ return 0;
+}
+
+/* --------------------- gl_recursive_lock_t datatype --------------------- */
+
+void
+glthread_recursive_lock_init_func (gl_recursive_lock_t *lock)
+{
+ lock->owner = 0;
+ lock->depth = 0;
+ InitializeCriticalSection (&lock->lock);
+ lock->guard.done = 1;
+}
+
+int
+glthread_recursive_lock_lock_func (gl_recursive_lock_t *lock)
+{
+ if (!lock->guard.done)
+ {
+ if (InterlockedIncrement (&lock->guard.started) == 0)
+ /* This thread is the first one to need this lock. Initialize it. */
+ glthread_recursive_lock_init (lock);
+ else
+ /* Yield the CPU while waiting for another thread to finish
+ initializing this lock. */
+ while (!lock->guard.done)
+ Sleep (0);
+ }
+ {
+ DWORD self = GetCurrentThreadId ();
+ if (lock->owner != self)
+ {
+ EnterCriticalSection (&lock->lock);
+ lock->owner = self;
+ }
+ if (++(lock->depth) == 0) /* wraparound? */
+ {
+ lock->depth--;
+ return EAGAIN;
+ }
+ }
+ return 0;
+}
+
+int
+glthread_recursive_lock_unlock_func (gl_recursive_lock_t *lock)
+{
+ if (lock->owner != GetCurrentThreadId ())
+ return EPERM;
+ if (lock->depth == 0)
+ return EINVAL;
+ if (--(lock->depth) == 0)
+ {
+ lock->owner = 0;
+ LeaveCriticalSection (&lock->lock);
+ }
+ return 0;
+}
+
+int
+glthread_recursive_lock_destroy_func (gl_recursive_lock_t *lock)
+{
+ if (lock->owner != 0)
+ return EBUSY;
+ DeleteCriticalSection (&lock->lock);
+ lock->guard.done = 0;
+ return 0;
+}
+
+/* -------------------------- gl_once_t datatype -------------------------- */
+
+void
+glthread_once_func (gl_once_t *once_control, void (*initfunction) (void))
+{
+ if (once_control->inited <= 0)
+ {
+ if (InterlockedIncrement (&once_control->started) == 0)
+ {
+ /* This thread is the first one to come to this once_control. */
+ InitializeCriticalSection (&once_control->lock);
+ EnterCriticalSection (&once_control->lock);
+ once_control->inited = 0;
+ initfunction ();
+ once_control->inited = 1;
+ LeaveCriticalSection (&once_control->lock);
+ }
+ else
+ {
+ /* Undo last operation. */
+ InterlockedDecrement (&once_control->started);
+ /* Some other thread has already started the initialization.
+ Yield the CPU while waiting for the other thread to finish
+ initializing and taking the lock. */
+ while (once_control->inited < 0)
+ Sleep (0);
+ if (once_control->inited <= 0)
+ {
+ /* Take the lock. This blocks until the other thread has
+ finished calling the initfunction. */
+ EnterCriticalSection (&once_control->lock);
+ LeaveCriticalSection (&once_control->lock);
+ if (!(once_control->inited > 0))
+ abort ();
+ }
+ }
+ }
+}
+
+#endif
+
+/* ========================================================================= */
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