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+/* GLIB - Library of useful routines for C programming
+ * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
+ *
+ * gthread.c: posix thread system implementation
+ * Copyright 1998 Sebastian Wilhelmi; University of Karlsruhe
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/*
+ * Modified by the GLib Team and others 1997-2000. See the AUTHORS
+ * file for a list of people on the GLib Team. See the ChangeLog
+ * files for a list of changes. These files are distributed with
+ * GLib at ftp://ftp.gtk.org/pub/gtk/.
+ */
+
+/* The GMutex, GCond and GPrivate implementations in this file are some
+ * of the lowest-level code in GLib. All other parts of GLib (messages,
+ * memory, slices, etc) assume that they can freely use these facilities
+ * without risking recursion.
+ *
+ * As such, these functions are NOT permitted to call any other part of
+ * GLib.
+ *
+ * The thread manipulation functions (create, exit, join, etc.) have
+ * more freedom -- they can do as they please.
+ */
+
+#include "config.h"
+
+#include "gthread.h"
+
+#include "gthreadprivate.h"
+#include "gslice.h"
+#include "gmessages.h"
+#include "gstrfuncs.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <pthread.h>
+
+#ifdef HAVE_SYS_TIME_H
+# include <sys/time.h>
+#endif
+#ifdef HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+#ifdef HAVE_SCHED_H
+#include <sched.h>
+#endif
+#ifdef HAVE_SYS_PRCTL_H
+#include <sys/prctl.h>
+#endif
+
+static void
+g_thread_abort (gint status,
+ const gchar *function)
+{
+ fprintf (stderr, "GLib (gthread-posix.c): Unexpected error from C library during '%s': %s. Aborting.\n",
+ function, strerror (status));
+ abort ();
+}
+
+/* {{{1 GMutex */
+
+static pthread_mutex_t *
+g_mutex_impl_new (void)
+{
+ pthread_mutexattr_t *pattr = NULL;
+ pthread_mutex_t *mutex;
+ gint status;
+
+ mutex = malloc (sizeof (pthread_mutex_t));
+ if G_UNLIKELY (mutex == NULL)
+ g_thread_abort (errno, "malloc");
+
+#ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
+ pthread_mutexattr_t attr;
+ pthread_mutexattr_init (&attr);
+ pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_ADAPTIVE_NP);
+ pattr = &attr;
+#endif
+
+ if G_UNLIKELY ((status = pthread_mutex_init (mutex, pattr)) != 0)
+ g_thread_abort (status, "pthread_mutex_init");
+
+#ifdef PTHREAD_ADAPTIVE_MUTEX_NP
+ pthread_mutexattr_destroy (&attr);
+#endif
+
+ return mutex;
+}
+
+static void
+g_mutex_impl_free (pthread_mutex_t *mutex)
+{
+ pthread_mutex_destroy (mutex);
+ free (mutex);
+}
+
+static pthread_mutex_t *
+g_mutex_get_impl (GMutex *mutex)
+{
+ pthread_mutex_t *impl = mutex->p;
+
+ if G_UNLIKELY (impl == NULL)
+ {
+ impl = g_mutex_impl_new ();
+ if (!g_atomic_pointer_compare_and_exchange (&mutex->p, NULL, impl))
+ g_mutex_impl_free (impl);
+ impl = mutex->p;
+ }
+
+ return impl;
+}
+
+
+/**
+ * g_mutex_init:
+ * @mutex: an uninitialized #GMutex
+ *
+ * Initializes a #GMutex so that it can be used.
+ *
+ * This function is useful to initialize a mutex that has been
+ * allocated on the stack, or as part of a larger structure.
+ * It is not necessary to initialize a mutex that has been
+ * created that has been statically allocated.
+ *
+ * |[
+ * typedef struct {
+ * GMutex m;
+ * ...
+ * } Blob;
+ *
+ * Blob *b;
+ *
+ * b = g_new (Blob, 1);
+ * g_mutex_init (&b->m);
+ * ]|
+ *
+ * To undo the effect of g_mutex_init() when a mutex is no longer
+ * needed, use g_mutex_clear().
+ *
+ * Calling g_mutex_init() on an already initialized #GMutex leads
+ * to undefined behaviour.
+ *
+ * Since: 2.32
+ */
+void
+g_mutex_init (GMutex *mutex)
+{
+ mutex->p = g_mutex_impl_new ();
+}
+
+/**
+ * g_mutex_clear:
+ * @mutex: an initialized #GMutex
+ *
+ * Frees the resources allocated to a mutex with g_mutex_init().
+ *
+ * This function should not be used with a #GMutex that has been
+ * statically allocated.
+ *
+ * Calling g_mutex_clear() on a locked mutex leads to undefined
+ * behaviour.
+ *
+ * Sine: 2.32
+ */
+void
+g_mutex_clear (GMutex *mutex)
+{
+ g_mutex_impl_free (mutex->p);
+}
+
+/**
+ * g_mutex_lock:
+ * @mutex: a #GMutex
+ *
+ * Locks @mutex. If @mutex is already locked by another thread, the
+ * current thread will block until @mutex is unlocked by the other
+ * thread.
+ *
+ * <note>#GMutex is neither guaranteed to be recursive nor to be
+ * non-recursive. As such, calling g_mutex_lock() on a #GMutex that has
+ * already been locked by the same thread results in undefined behaviour
+ * (including but not limited to deadlocks).</note>
+ */
+void
+g_mutex_lock (GMutex *mutex)
+{
+ gint status;
+
+ if G_UNLIKELY ((status = pthread_mutex_lock (g_mutex_get_impl (mutex))) != 0)
+ g_thread_abort (status, "pthread_mutex_lock");
+}
+
+/**
+ * g_mutex_unlock:
+ * @mutex: a #GMutex
+ *
+ * Unlocks @mutex. If another thread is blocked in a g_mutex_lock()
+ * call for @mutex, it will become unblocked and can lock @mutex itself.
+ *
+ * Calling g_mutex_unlock() on a mutex that is not locked by the
+ * current thread leads to undefined behaviour.
+ */
+void
+g_mutex_unlock (GMutex *mutex)
+{
+ gint status;
+
+ if G_UNLIKELY ((status = pthread_mutex_unlock (g_mutex_get_impl (mutex))) != 0)
+ g_thread_abort (status, "pthread_mutex_lock");
+}
+
+/**
+ * g_mutex_trylock:
+ * @mutex: a #GMutex
+ *
+ * Tries to lock @mutex. If @mutex is already locked by another thread,
+ * it immediately returns %FALSE. Otherwise it locks @mutex and returns
+ * %TRUE.
+ *
+ * <note>#GMutex is neither guaranteed to be recursive nor to be
+ * non-recursive. As such, calling g_mutex_lock() on a #GMutex that has
+ * already been locked by the same thread results in undefined behaviour
+ * (including but not limited to deadlocks or arbitrary return values).
+ * </note>
+
+ * Returns: %TRUE if @mutex could be locked
+ */
+gboolean
+g_mutex_trylock (GMutex *mutex)
+{
+ gint status;
+
+ if G_LIKELY ((status = pthread_mutex_trylock (g_mutex_get_impl (mutex))) == 0)
+ return TRUE;
+
+ if G_UNLIKELY (status != EBUSY)
+ g_thread_abort (status, "pthread_mutex_trylock");
+
+ return FALSE;
+}
+
+/* {{{1 GRecMutex */
+
+static pthread_mutex_t *
+g_rec_mutex_impl_new (void)
+{
+ pthread_mutexattr_t attr;
+ pthread_mutex_t *mutex;
+
+ mutex = g_slice_new (pthread_mutex_t);
+ pthread_mutexattr_init (&attr);
+ pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE);
+ pthread_mutex_init (mutex, &attr);
+ pthread_mutexattr_destroy (&attr);
+
+ return mutex;
+}
+
+static void
+g_rec_mutex_impl_free (pthread_mutex_t *mutex)
+{
+ pthread_mutex_destroy (mutex);
+ g_slice_free (pthread_mutex_t, mutex);
+}
+
+static pthread_mutex_t *
+g_rec_mutex_get_impl (GRecMutex *rec_mutex)
+{
+ pthread_mutex_t *impl = rec_mutex->p;
+
+ if G_UNLIKELY (impl == NULL)
+ {
+ impl = g_rec_mutex_impl_new ();
+ if (!g_atomic_pointer_compare_and_exchange (&rec_mutex->p, NULL, impl))
+ g_rec_mutex_impl_free (impl);
+ impl = rec_mutex->p;
+ }
+
+ return impl;
+}
+
+/**
+ * g_rec_mutex_init:
+ * @rec_mutex: an uninitialized #GRecMutex
+ *
+ * Initializes a #GRecMutex so that it can be used.
+ *
+ * This function is useful to initialize a recursive mutex
+ * that has been allocated on the stack, or as part of a larger
+ * structure.
+ *
+ * It is not necessary to initialise a recursive mutex that has been
+ * statically allocated.
+ *
+ * |[
+ * typedef struct {
+ * GRecMutex m;
+ * ...
+ * } Blob;
+ *
+ * Blob *b;
+ *
+ * b = g_new (Blob, 1);
+ * g_rec_mutex_init (&b->m);
+ * ]|
+ *
+ * Calling g_rec_mutex_init() on an already initialized #GRecMutex
+ * leads to undefined behaviour.
+ *
+ * To undo the effect of g_rec_mutex_init() when a recursive mutex
+ * is no longer needed, use g_rec_mutex_clear().
+ *
+ * Since: 2.32
+ */
+void
+g_rec_mutex_init (GRecMutex *rec_mutex)
+{
+ rec_mutex->p = g_rec_mutex_impl_new ();
+}
+
+/**
+ * g_rec_mutex_clear:
+ * @rec_mutex: an initialized #GRecMutex
+ *
+ * Frees the resources allocated to a recursive mutex with
+ * g_rec_mutex_init().
+ *
+ * This function should not be used with a #GRecMutex that has been
+ * statically allocated.
+ *
+ * Calling g_rec_mutex_clear() on a locked recursive mutex leads
+ * to undefined behaviour.
+ *
+ * Sine: 2.32
+ */
+void
+g_rec_mutex_clear (GRecMutex *rec_mutex)
+{
+ g_rec_mutex_impl_free (rec_mutex->p);
+}
+
+/**
+ * g_rec_mutex_lock:
+ * @rec_mutex: a #GRecMutex
+ *
+ * Locks @rec_mutex. If @rec_mutex is already locked by another
+ * thread, the current thread will block until @rec_mutex is
+ * unlocked by the other thread. If @rec_mutex is already locked
+ * by the current thread, the 'lock count' of @rec_mutex is increased.
+ * The mutex will only become available again when it is unlocked
+ * as many times as it has been locked.
+ *
+ * Since: 2.32
+ */
+void
+g_rec_mutex_lock (GRecMutex *mutex)
+{
+ pthread_mutex_lock (g_rec_mutex_get_impl (mutex));
+}
+
+/**
+ * g_rec_mutex_unlock:
+ * @rec_mutex: a #GRecMutex
+ *
+ * Unlocks @rec_mutex. If another thread is blocked in a
+ * g_rec_mutex_lock() call for @rec_mutex, it will become unblocked
+ * and can lock @rec_mutex itself.
+ *
+ * Calling g_rec_mutex_unlock() on a recursive mutex that is not
+ * locked by the current thread leads to undefined behaviour.
+ *
+ * Since: 2.32
+ */
+void
+g_rec_mutex_unlock (GRecMutex *rec_mutex)
+{
+ pthread_mutex_unlock (rec_mutex->p);
+}
+
+/**
+ * g_rec_mutex_trylock:
+ * @rec_mutex: a #GRecMutex
+ *
+ * Tries to lock @rec_mutex. If @rec_mutex is already locked
+ * by another thread, it immediately returns %FALSE. Otherwise
+ * it locks @rec_mutex and returns %TRUE.
+ *
+ * Returns: %TRUE if @rec_mutex could be locked
+ *
+ * Since: 2.32
+ */
+gboolean
+g_rec_mutex_trylock (GRecMutex *rec_mutex)
+{
+ if (pthread_mutex_trylock (g_rec_mutex_get_impl (rec_mutex)) != 0)
+ return FALSE;
+
+ return TRUE;
+}
+
+/* {{{1 GRWLock */
+
+static pthread_rwlock_t *
+g_rw_lock_impl_new (void)
+{
+ pthread_rwlock_t *rwlock;
+ gint status;
+
+ rwlock = malloc (sizeof (pthread_rwlock_t));
+ if G_UNLIKELY (rwlock == NULL)
+ g_thread_abort (errno, "malloc");
+
+ if G_UNLIKELY ((status = pthread_rwlock_init (rwlock, NULL)) != 0)
+ g_thread_abort (status, "pthread_rwlock_init");
+
+ return rwlock;
+}
+
+static void
+g_rw_lock_impl_free (pthread_rwlock_t *rwlock)
+{
+ pthread_rwlock_destroy (rwlock);
+ free (rwlock);
+}
+
+static pthread_rwlock_t *
+g_rw_lock_get_impl (GRWLock *lock)
+{
+ pthread_rwlock_t *impl = lock->p;
+
+ if G_UNLIKELY (impl == NULL)
+ {
+ impl = g_rw_lock_impl_new ();
+ if (!g_atomic_pointer_compare_and_exchange (&lock->p, NULL, impl))
+ g_rw_lock_impl_free (impl);
+ impl = lock->p;
+ }
+
+ return impl;
+}
+
+/**
+ * g_rw_lock_init:
+ * @rw_lock: an uninitialized #GRWLock
+ *
+ * Initializes a #GRWLock so that it can be used.
+ *
+ * This function is useful to initialize a lock that has been
+ * allocated on the stack, or as part of a larger structure. It is not
+ * necessary to initialise a reader-writer lock that has been statically
+ * allocated.
+ *
+ * |[
+ * typedef struct {
+ * GRWLock l;
+ * ...
+ * } Blob;
+ *
+ * Blob *b;
+ *
+ * b = g_new (Blob, 1);
+ * g_rw_lock_init (&b->l);
+ * ]|
+ *
+ * To undo the effect of g_rw_lock_init() when a lock is no longer
+ * needed, use g_rw_lock_clear().
+ *
+ * Calling g_rw_lock_init() on an already initialized #GRWLock leads
+ * to undefined behaviour.
+ *
+ * Since: 2.32
+ */
+void
+g_rw_lock_init (GRWLock *rw_lock)
+{
+ rw_lock->p = g_rw_lock_impl_new ();
+}
+
+/**
+ * g_rw_lock_clear:
+ * @rw_lock: an initialized #GRWLock
+ *
+ * Frees the resources allocated to a lock with g_rw_lock_init().
+ *
+ * This function should not be used with a #GRWLock that has been
+ * statically allocated.
+ *
+ * Calling g_rw_lock_clear() when any thread holds the lock
+ * leads to undefined behaviour.
+ *
+ * Sine: 2.32
+ */
+void
+g_rw_lock_clear (GRWLock *rw_lock)
+{
+ g_rw_lock_impl_free (rw_lock->p);
+}
+
+/**
+ * g_rw_lock_writer_lock:
+ * @rw_lock: a #GRWLock
+ *
+ * Obtain a write lock on @rw_lock. If any thread already holds
+ * a read or write lock on @rw_lock, the current thread will block
+ * until all other threads have dropped their locks on @rw_lock.
+ *
+ * Since: 2.32
+ */
+void
+g_rw_lock_writer_lock (GRWLock *rw_lock)
+{
+ pthread_rwlock_wrlock (g_rw_lock_get_impl (rw_lock));
+}
+
+/**
+ * g_rw_lock_writer_trylock:
+ * @rw_lock: a #GRWLock
+ *
+ * Tries to obtain a write lock on @rw_lock. If any other thread holds
+ * a read or write lock on @rw_lock, it immediately returns %FALSE.
+ * Otherwise it locks @rw_lock and returns %TRUE.
+ *
+ * Returns: %TRUE if @rw_lock could be locked
+ *
+ * Since: 2.32
+ */
+gboolean
+g_rw_lock_writer_trylock (GRWLock *rw_lock)
+{
+ if (pthread_rwlock_trywrlock (g_rw_lock_get_impl (rw_lock)) != 0)
+ return FALSE;
+
+ return TRUE;
+}
+
+/**
+ * g_rw_lock_writer_unlock:
+ * @rw_lock: a #GRWLock
+ *
+ * Release a write lock on @rw_lock.
+ *
+ * Calling g_rw_lock_writer_unlock() on a lock that is not held
+ * by the current thread leads to undefined behaviour.
+ *
+ * Since: 2.32
+ */
+void
+g_rw_lock_writer_unlock (GRWLock *rw_lock)
+{
+ pthread_rwlock_unlock (g_rw_lock_get_impl (rw_lock));
+}
+
+/**
+ * g_rw_lock_reader_lock:
+ * @rw_lock: a #GRWLock
+ *
+ * Obtain a read lock on @rw_lock. If another thread currently holds
+ * the write lock on @rw_lock or blocks waiting for it, the current
+ * thread will block. Read locks can be taken recursively.
+ *
+ * It is implementation-defined how many threads are allowed to
+ * hold read locks on the same lock simultaneously.
+ *
+ * Since: 2.32
+ */
+void
+g_rw_lock_reader_lock (GRWLock *rw_lock)
+{
+ pthread_rwlock_rdlock (g_rw_lock_get_impl (rw_lock));
+}
+
+/**
+ * g_rw_lock_reader_trylock:
+ * @rw_lock: a #GRWLock
+ *
+ * Tries to obtain a read lock on @rw_lock and returns %TRUE if
+ * the read lock was successfully obtained. Otherwise it
+ * returns %FALSE.
+ *
+ * Returns: %TRUE if @rw_lock could be locked
+ *
+ * Since: 2.32
+ */
+gboolean
+g_rw_lock_reader_trylock (GRWLock *rw_lock)
+{
+ if (pthread_rwlock_tryrdlock (g_rw_lock_get_impl (rw_lock)) != 0)
+ return FALSE;
+
+ return TRUE;
+}
+
+/**
+ * g_rw_lock_reader_unlock:
+ * @rw_lock: a #GRWLock
+ *
+ * Release a read lock on @rw_lock.
+ *
+ * Calling g_rw_lock_reader_unlock() on a lock that is not held
+ * by the current thread leads to undefined behaviour.
+ *
+ * Since: 2.32
+ */
+void
+g_rw_lock_reader_unlock (GRWLock *rw_lock)
+{
+ pthread_rwlock_unlock (g_rw_lock_get_impl (rw_lock));
+}
+
+/* {{{1 GCond */
+
+static pthread_cond_t *
+g_cond_impl_new (void)
+{
+ pthread_condattr_t attr;
+ pthread_cond_t *cond;
+ gint status;
+
+ pthread_condattr_init (&attr);
+#if defined (HAVE_PTHREAD_CONDATTR_SETCLOCK) && defined (CLOCK_MONOTONIC)
+ pthread_condattr_setclock (&attr, CLOCK_MONOTONIC);
+#endif
+
+ cond = malloc (sizeof (pthread_cond_t));
+ if G_UNLIKELY (cond == NULL)
+ g_thread_abort (errno, "malloc");
+
+ if G_UNLIKELY ((status = pthread_cond_init (cond, &attr)) != 0)
+ g_thread_abort (status, "pthread_cond_init");
+
+ pthread_condattr_destroy (&attr);
+
+ return cond;
+}
+
+static void
+g_cond_impl_free (pthread_cond_t *cond)
+{
+ pthread_cond_destroy (cond);
+ free (cond);
+}
+
+static pthread_cond_t *
+g_cond_get_impl (GCond *cond)
+{
+ pthread_cond_t *impl = cond->p;
+
+ if G_UNLIKELY (impl == NULL)
+ {
+ impl = g_cond_impl_new ();
+ if (!g_atomic_pointer_compare_and_exchange (&cond->p, NULL, impl))
+ g_cond_impl_free (impl);
+ impl = cond->p;
+ }
+
+ return impl;
+}
+
+/**
+ * g_cond_init:
+ * @cond: an uninitialized #GCond
+ *
+ * Initialises a #GCond so that it can be used.
+ *
+ * This function is useful to initialise a #GCond that has been
+ * allocated as part of a larger structure. It is not necessary to
+ * initialise a #GCond that has been statically allocated.
+ *
+ * To undo the effect of g_cond_init() when a #GCond is no longer
+ * needed, use g_cond_clear().
+ *
+ * Calling g_cond_init() on an already-initialised #GCond leads
+ * to undefined behaviour.
+ *
+ * Since: 2.32
+ */
+void
+g_cond_init (GCond *cond)
+{
+ cond->p = g_cond_impl_new ();
+}
+
+/**
+ * g_cond_clear:
+ * @cond: an initialised #GCond
+ *
+ * Frees the resources allocated to a #GCond with g_cond_init().
+ *
+ * This function should not be used with a #GCond that has been
+ * statically allocated.
+ *
+ * Calling g_cond_clear() for a #GCond on which threads are
+ * blocking leads to undefined behaviour.
+ *
+ * Since: 2.32
+ */
+void
+g_cond_clear (GCond *cond)
+{
+ g_cond_impl_free (cond->p);
+}
+
+/**
+ * g_cond_wait:
+ * @cond: a #GCond
+ * @mutex: a #GMutex that is currently locked
+ *
+ * Atomically releases @mutex and waits until @cond is signalled.
+ *
+ * When using condition variables, it is possible that a spurious wakeup
+ * may occur (ie: g_cond_wait() returns even though g_cond_signal() was
+ * not called). It's also possible that a stolen wakeup may occur.
+ * This is when g_cond_signal() is called, but another thread acquires
+ * @mutex before this thread and modifies the state of the program in
+ * such a way that when g_cond_wait() is able to return, the expected
+ * condition is no longer met.
+ *
+ * For this reason, g_cond_wait() must always be used in a loop. See
+ * the documentation for #GCond for a complete example.
+ **/
+void
+g_cond_wait (GCond *cond,
+ GMutex *mutex)
+{
+ gint status;
+
+ if G_UNLIKELY ((status = pthread_cond_wait (g_cond_get_impl (cond), g_mutex_get_impl (mutex))) != 0)
+ g_thread_abort (status, "pthread_cond_wait");
+}
+
+/**
+ * g_cond_signal:
+ * @cond: a #GCond
+ *
+ * If threads are waiting for @cond, at least one of them is unblocked.
+ * If no threads are waiting for @cond, this function has no effect.
+ * It is good practice to hold the same lock as the waiting thread
+ * while calling this function, though not required.
+ */
+void
+g_cond_signal (GCond *cond)
+{
+ gint status;
+
+ if G_UNLIKELY ((status = pthread_cond_signal (g_cond_get_impl (cond))) != 0)
+ g_thread_abort (status, "pthread_cond_signal");
+}
+
+/**
+ * g_cond_broadcast:
+ * @cond: a #GCond
+ *
+ * If threads are waiting for @cond, all of them are unblocked.
+ * If no threads are waiting for @cond, this function has no effect.
+ * It is good practice to lock the same mutex as the waiting threads
+ * while calling this function, though not required.
+ */
+void
+g_cond_broadcast (GCond *cond)
+{
+ gint status;
+
+ if G_UNLIKELY ((status = pthread_cond_broadcast (g_cond_get_impl (cond))) != 0)
+ g_thread_abort (status, "pthread_cond_broadcast");
+}
+
+/**
+ * g_cond_wait_until:
+ * @cond: a #GCond
+ * @mutex: a #GMutex that is currently locked
+ * @end_time: the monotonic time to wait until
+ *
+ * Waits until either @cond is signalled or @end_time has passed.
+ *
+ * As with g_cond_wait() it is possible that a spurious or stolen wakeup
+ * could occur. For that reason, waiting on a condition variable should
+ * always be in a loop, based on an explicitly-checked predicate.
+ *
+ * %TRUE is returned if the condition variable was signalled (or in the
+ * case of a spurious wakeup). %FALSE is returned if @end_time has
+ * passed.
+ *
+ * The following code shows how to correctly perform a timed wait on a
+ * condition variable (extended the example presented in the
+ * documentation for #GCond):
+ *
+ * |[
+ * gpointer
+ * pop_data_timed (void)
+ * {
+ * gint64 end_time;
+ * gpointer data;
+ *
+ * g_mutex_lock (&data_mutex);
+ *
+ * end_time = g_get_monotonic_time () + 5 * G_TIME_SPAN_SECOND;
+ * while (!current_data)
+ * if (!g_cond_wait_until (&data_cond, &data_mutex, end_time))
+ * {
+ * // timeout has passed.
+ * g_mutex_unlock (&data_mutex);
+ * return NULL;
+ * }
+ *
+ * // there is data for us
+ * data = current_data;
+ * current_data = NULL;
+ *
+ * g_mutex_unlock (&data_mutex);
+ *
+ * return data;
+ * }
+ * ]|
+ *
+ * Notice that the end time is calculated once, before entering the
+ * loop and reused. This is the motivation behind the use of absolute
+ * time on this API -- if a relative time of 5 seconds were passed
+ * directly to the call and a spurious wakeup occurred, the program would
+ * have to start over waiting again (which would lead to a total wait
+ * time of more than 5 seconds).
+ *
+ * Returns: %TRUE on a signal, %FALSE on a timeout
+ * Since: 2.32
+ **/
+gboolean
+g_cond_wait_until (GCond *cond,
+ GMutex *mutex,
+ gint64 end_time)
+{
+ struct timespec ts;
+ gint status;
+
+ ts.tv_sec = end_time / 1000000;
+ ts.tv_nsec = (end_time % 1000000) * 1000;
+
+ if ((status = pthread_cond_timedwait (g_cond_get_impl (cond), g_mutex_get_impl (mutex), &ts)) == 0)
+ return TRUE;
+
+ if G_UNLIKELY (status != ETIMEDOUT)
+ g_thread_abort (status, "pthread_cond_timedwait");
+
+ return FALSE;
+}
+
+/* {{{1 GPrivate */
+
+/**
+ * GPrivate:
+ *
+ * The #GPrivate struct is an opaque data structure to represent a
+ * thread-local data key. It is approximately equivalent to the
+ * pthread_setspecific()/pthread_getspecific() APIs on POSIX and to
+ * TlsSetValue()/TlsGetValue() on Windows.
+ *
+ * If you don't already know why you might want this functionality,
+ * then you probably don't need it.
+ *
+ * #GPrivate is a very limited resource (as far as 128 per program,
+ * shared between all libraries). It is also not possible to destroy a
+ * #GPrivate after it has been used. As such, it is only ever acceptable
+ * to use #GPrivate in static scope, and even then sparingly so.
+ *
+ * See G_PRIVATE_INIT() for a couple of examples.
+ *
+ * The #GPrivate structure should be considered opaque. It should only
+ * be accessed via the <function>g_private_</function> functions.
+ */
+
+/**
+ * G_PRIVATE_INIT:
+ * @notify: a #GDestroyNotify
+ *
+ * A macro to assist with the static initialisation of a #GPrivate.
+ *
+ * This macro is useful for the case that a #GDestroyNotify function
+ * should be associated the key. This is needed when the key will be
+ * used to point at memory that should be deallocated when the thread
+ * exits.
+ *
+ * Additionally, the #GDestroyNotify will also be called on the previous
+ * value stored in the key when g_private_replace() is used.
+ *
+ * If no #GDestroyNotify is needed, then use of this macro is not
+ * required -- if the #GPrivate is declared in static scope then it will
+ * be properly initialised by default (ie: to all zeros). See the
+ * examples below.
+ *
+ * |[
+ * static GPrivate name_key = G_PRIVATE_INIT (g_free);
+ *
+ * // return value should not be freed
+ * const gchar *
+ * get_local_name (void)
+ * {
+ * return g_private_get (&name_key);
+ * }
+ *
+ * void
+ * set_local_name (const gchar *name)
+ * {
+ * g_private_replace (&name_key, g_strdup (name));
+ * }
+ *
+ *
+ * static GPrivate count_key; // no free function
+ *
+ * gint
+ * get_local_count (void)
+ * {
+ * return GPOINTER_TO_INT (g_private_get (&count_key));
+ * }
+ *
+ * void
+ * set_local_count (gint count)
+ * {
+ * g_private_set (&count_key, GINT_TO_POINTER (count));
+ * }
+ * ]|
+ *
+ * Since: 2.32
+ **/
+
+static pthread_key_t *
+g_private_impl_new (GDestroyNotify notify)
+{
+ pthread_key_t *key;
+ gint status;
+
+ key = malloc (sizeof (pthread_key_t));
+ if G_UNLIKELY (key == NULL)
+ g_thread_abort (errno, "malloc");
+ status = pthread_key_create (key, notify);
+ if G_UNLIKELY (status != 0)
+ g_thread_abort (status, "pthread_key_create");
+
+ return key;
+}
+
+static void
+g_private_impl_free (pthread_key_t *key)
+{
+ gint status;
+
+ status = pthread_key_delete (*key);
+ if G_UNLIKELY (status != 0)
+ g_thread_abort (status, "pthread_key_delete");
+ free (key);
+}
+
+static pthread_key_t *
+g_private_get_impl (GPrivate *key)
+{
+ pthread_key_t *impl = key->p;
+
+ if G_UNLIKELY (impl == NULL)
+ {
+ impl = g_private_impl_new (key->notify);
+ if (!g_atomic_pointer_compare_and_exchange (&key->p, NULL, impl))
+ {
+ g_private_impl_free (impl);
+ impl = key->p;
+ }
+ }
+
+ return impl;
+}
+
+/**
+ * g_private_get:
+ * @key: a #GPrivate
+ *
+ * Returns the current value of the thread local variable @key.
+ *
+ * If the value has not yet been set in this thread, %NULL is returned.
+ * Values are never copied between threads (when a new thread is
+ * created, for example).
+ *
+ * Returns: the thread-local value
+ */
+gpointer
+g_private_get (GPrivate *key)
+{
+ /* quote POSIX: No errors are returned from pthread_getspecific(). */
+ return pthread_getspecific (*g_private_get_impl (key));
+}
+
+/**
+ * g_private_set:
+ * @key: a #GPrivate
+ * @value: the new value
+ *
+ * Sets the thread local variable @key to have the value @value in the
+ * current thread.
+ *
+ * This function differs from g_private_replace() in the following way:
+ * the #GDestroyNotify for @key is not called on the old value.
+ */
+void
+g_private_set (GPrivate *key,
+ gpointer value)
+{
+ gint status;
+
+ if G_UNLIKELY ((status = pthread_setspecific (*g_private_get_impl (key), value)) != 0)
+ g_thread_abort (status, "pthread_setspecific");
+}
+
+/**
+ * g_private_replace:
+ * @key: a #GPrivate
+ * @value: the new value
+ *
+ * Sets the thread local variable @key to have the value @value in the
+ * current thread.
+ *
+ * This function differs from g_private_set() in the following way: if
+ * the previous value was non-%NULL then the #GDestroyNotify handler for
+ * @key is run on it.
+ *
+ * Since: 2.32
+ **/
+void
+g_private_replace (GPrivate *key,
+ gpointer value)
+{
+ pthread_key_t *impl = g_private_get_impl (key);
+ gpointer old;
+ gint status;
+
+ old = pthread_getspecific (*impl);
+ if (old && key->notify)
+ key->notify (old);
+
+ if G_UNLIKELY ((status = pthread_setspecific (*impl, value)) != 0)
+ g_thread_abort (status, "pthread_setspecific");
+}
+
+/* {{{1 GThread */
+
+#define posix_check_err(err, name) G_STMT_START{ \
+ int error = (err); \
+ if (error) \
+ g_error ("file %s: line %d (%s): error '%s' during '%s'", \
+ __FILE__, __LINE__, G_STRFUNC, \
+ g_strerror (error), name); \
+ }G_STMT_END
+
+#define posix_check_cmd(cmd) posix_check_err (cmd, #cmd)
+
+typedef struct
+{
+ GRealThread thread;
+
+ pthread_t system_thread;
+ gboolean joined;
+ GMutex lock;
+} GThreadPosix;
+
+void
+g_system_thread_free (GRealThread *thread)
+{
+ GThreadPosix *pt = (GThreadPosix *) thread;
+
+ if (!pt->joined)
+ pthread_detach (pt->system_thread);
+
+ g_mutex_clear (&pt->lock);
+
+ g_slice_free (GThreadPosix, pt);
+}
+
+GRealThread *
+g_system_thread_new (GThreadFunc thread_func,
+ gulong stack_size,
+ GError **error)
+{
+ GThreadPosix *thread;
+ pthread_attr_t attr;
+ gint ret;
+
+ thread = g_slice_new0 (GThreadPosix);
+
+ posix_check_cmd (pthread_attr_init (&attr));
+
+#ifdef HAVE_PTHREAD_ATTR_SETSTACKSIZE
+ if (stack_size)
+ {
+#ifdef _SC_THREAD_STACK_MIN
+ stack_size = MAX (sysconf (_SC_THREAD_STACK_MIN), stack_size);
+#endif /* _SC_THREAD_STACK_MIN */
+ /* No error check here, because some systems can't do it and
+ * we simply don't want threads to fail because of that. */
+ pthread_attr_setstacksize (&attr, stack_size);
+ }
+#endif /* HAVE_PTHREAD_ATTR_SETSTACKSIZE */
+
+ ret = pthread_create (&thread->system_thread, &attr, (void* (*)(void*))thread_func, thread);
+
+ posix_check_cmd (pthread_attr_destroy (&attr));
+
+ if (ret == EAGAIN)
+ {
+ g_set_error (error, G_THREAD_ERROR, G_THREAD_ERROR_AGAIN,
+ "Error creating thread: %s", g_strerror (ret));
+ g_slice_free (GThreadPosix, thread);
+ return NULL;
+ }
+
+ posix_check_err (ret, "pthread_create");
+
+ g_mutex_init (&thread->lock);
+
+ return (GRealThread *) thread;
+}
+
+/**
+ * g_thread_yield:
+ *
+ * Causes the calling thread to voluntarily relinquish the CPU, so
+ * that other threads can run.
+ *
+ * This function is often used as a method to make busy wait less evil.
+ */
+void
+g_thread_yield (void)
+{
+ sched_yield ();
+}
+
+void
+g_system_thread_wait (GRealThread *thread)
+{
+ GThreadPosix *pt = (GThreadPosix *) thread;
+
+ g_mutex_lock (&pt->lock);
+
+ if (!pt->joined)
+ {
+ posix_check_cmd (pthread_join (pt->system_thread, NULL));
+ pt->joined = TRUE;
+ }
+
+ g_mutex_unlock (&pt->lock);
+}
+
+void
+g_system_thread_exit (void)
+{
+ pthread_exit (NULL);
+}
+
+void
+g_system_thread_set_name (const gchar *name)
+{
+#ifdef HAVE_SYS_PRCTL_H
+ prctl (PR_SET_NAME, name, 0, 0, 0, 0);
+#endif
+}
+
+/* {{{1 Epilogue */
+/* vim:set foldmethod=marker: */
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