* 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.
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
/*
#include "config.h"
#include "gthread.h"
+
#include "gthreadprivate.h"
#include "gslice.h"
+#include "gmessages.h"
+#include "gstrfuncs.h"
+#include "gmain.h"
-#include <pthread.h>
#include <stdlib.h>
+#include <stdio.h>
#include <string.h>
#include <errno.h>
-#include <stdio.h>
+#include <pthread.h>
+
+#include <sys/time.h>
+#include <unistd.h>
+
+#ifdef HAVE_SCHED_H
+#include <sched.h>
+#endif
+#ifdef HAVE_SYS_PRCTL_H
+#include <sys/prctl.h>
+#endif
+#ifdef G_OS_WIN32
+#include <windows.h>
+#endif
+
+/* clang defines __ATOMIC_SEQ_CST but doesn't support the GCC extension */
+#if defined(HAVE_FUTEX) && defined(__ATOMIC_SEQ_CST) && !defined(__clang__)
+#define USE_NATIVE_MUTEX
+#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",
- strerror (status), function);
+ function, strerror (status));
abort ();
}
/* {{{1 GMutex */
-/**
- * G_MUTEX_INIT:
- *
- * Initializer for statically allocated #GMutexes.
- * Alternatively, g_mutex_init() can be used.
- *
- * |[
- * GMutex mutex = G_MUTEX_INIT;
- * ]|
- *
- * Since: 2.32
- */
+#if !defined(USE_NATIVE_MUTEX)
+
+static pthread_mutex_t *
+g_mutex_impl_new (void)
+{
+ pthread_mutexattr_t *pattr = NULL;
+ pthread_mutex_t *mutex;
+ gint status;
+#ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
+ pthread_mutexattr_t attr;
+#endif
+
+ mutex = malloc (sizeof (pthread_mutex_t));
+ if G_UNLIKELY (mutex == NULL)
+ g_thread_abort (errno, "malloc");
+
+#ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
+ 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 inline pthread_mutex_t *
+g_mutex_get_impl (GMutex *mutex)
+{
+ pthread_mutex_t *impl = g_atomic_pointer_get (&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:
* 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 with g_mutex_new(). Also see #G_MUTEX_INIT for an
- * alternative way to initialize statically allocated mutexes.
+ * statically allocated.
*
- * |[
+ * |[<!-- language="C" -->
* typedef struct {
* GMutex m;
* ...
void
g_mutex_init (GMutex *mutex)
{
- gint status;
- pthread_mutexattr_t *pattr = NULL;
-#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->impl, pattr)) != 0)
- g_thread_abort (status, "pthread_mutex_init");
-
-#ifdef PTHREAD_ADAPTIVE_MUTEX_NP
- pthread_mutexattr_destroy (&attr);
-#endif
+ mutex->p = g_mutex_impl_new ();
}
/**
*
* Frees the resources allocated to a mutex with g_mutex_init().
*
- * #GMutexes that have have been created with g_mutex_new() should
- * be freed with g_mutex_free() instead.
+ * 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.
void
g_mutex_clear (GMutex *mutex)
{
- gint status;
-
- if G_UNLIKELY ((status = pthread_mutex_destroy (&mutex->impl)) != 0)
- g_thread_abort (status, "pthread_mutex_destroy");
+ g_mutex_impl_free (mutex->p);
}
/**
* current thread will block until @mutex is unlocked by the other
* thread.
*
- * This function can be used even if g_thread_init() has not yet been
- * called, and, in that case, will do nothing.
- *
- * <note>#GMutex is neither guaranteed to be recursive nor to be
- * non-recursive, i.e. a thread could deadlock while calling
- * g_mutex_lock(), if it already has locked @mutex. Use
- * #GRecMutex if you need recursive mutexes.</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).
*/
void
g_mutex_lock (GMutex *mutex)
{
gint status;
- if G_UNLIKELY ((status = pthread_mutex_lock (&mutex->impl)) != 0)
+ if G_UNLIKELY ((status = pthread_mutex_lock (g_mutex_get_impl (mutex))) != 0)
g_thread_abort (status, "pthread_mutex_lock");
}
*
* Calling g_mutex_unlock() on a mutex that is not locked by the
* current thread leads to undefined behaviour.
- *
- * This function can be used even if g_thread_init() has not yet been
- * called, and, in that case, will do nothing.
*/
void
g_mutex_unlock (GMutex *mutex)
{
gint status;
- if G_UNLIKELY ((status = pthread_mutex_unlock (&mutex->impl)) != 0)
- g_thread_abort (status, "pthread_mutex_lock");
+ if G_UNLIKELY ((status = pthread_mutex_unlock (g_mutex_get_impl (mutex))) != 0)
+ g_thread_abort (status, "pthread_mutex_unlock");
}
/**
* it immediately returns %FALSE. Otherwise it locks @mutex and returns
* %TRUE.
*
- * This function can be used even if g_thread_init() has not yet been
- * called, and, in that case, will immediately return %TRUE.
- *
- * <note>#GMutex is neither guaranteed to be recursive nor to be
- * non-recursive, i.e. the return value of g_mutex_trylock() could be
- * both %FALSE or %TRUE, if the current thread already has locked
- * @mutex. Use #GRecMutex if you need recursive mutexes.</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).
* Returns: %TRUE if @mutex could be locked
*/
{
gint status;
- if G_LIKELY ((status = pthread_mutex_trylock (&mutex->impl)) == 0)
+ if G_LIKELY ((status = pthread_mutex_trylock (g_mutex_get_impl (mutex))) == 0)
return TRUE;
if G_UNLIKELY (status != EBUSY)
return FALSE;
}
-/* {{{1 GRecMutex */
+#endif /* !defined(USE_NATIVE_MUTEX) */
-/**
- * GRecMutex:
- *
- * The GRecMutex struct is an opaque data structure to represent a
- * recursive mutex. It is similar to a #GMutex with the difference
- * that it is possible to lock a GRecMutex multiple times in the same
- * thread without deadlock. When doing so, care has to be taken to
- * unlock the recursive mutex as often as it has been locked.
- *
- * A GRecMutex should only be accessed with the
- * <function>g_rec_mutex_</function> functions. Before a GRecMutex
- * can be used, it has to be initialized with #G_REC_MUTEX_INIT or
- * g_rec_mutex_init().
- *
- * Since: 2.32
- */
+/* {{{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);
+ mutex = malloc (sizeof (pthread_mutex_t));
+ if G_UNLIKELY (mutex == NULL)
+ g_thread_abort (errno, "malloc");
+
pthread_mutexattr_init (&attr);
pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE);
pthread_mutex_init (mutex, &attr);
g_rec_mutex_impl_free (pthread_mutex_t *mutex)
{
pthread_mutex_destroy (mutex);
- g_slice_free (pthread_mutex_t, mutex);
+ free (mutex);
}
-static pthread_mutex_t *
-g_rec_mutex_get_impl (GRecMutex *mutex)
+static inline pthread_mutex_t *
+g_rec_mutex_get_impl (GRecMutex *rec_mutex)
{
- pthread_mutex_t *impl = mutex->impl;
+ pthread_mutex_t *impl = g_atomic_pointer_get (&rec_mutex->p);
- if G_UNLIKELY (mutex->impl == NULL)
+ if G_UNLIKELY (impl == NULL)
{
impl = g_rec_mutex_impl_new ();
- if (!g_atomic_pointer_compare_and_exchange (&mutex->impl, NULL, impl))
+ if (!g_atomic_pointer_compare_and_exchange (&rec_mutex->p, NULL, impl))
g_rec_mutex_impl_free (impl);
- impl = mutex->impl;
+ impl = rec_mutex->p;
}
return impl;
}
/**
- * G_REC_MUTEX_INIT:
- *
- * Initializer for statically allocated #GRecMutexes.
- * Alternatively, g_rec_mutex_init() can be used.
- *
- * |[
- * GRecMutex mutex = G_REC_MUTEX_INIT;
- * ]|
- *
- * Since: 2.32
- */
-
-/**
* g_rec_mutex_init:
* @rec_mutex: an uninitialized #GRecMutex
*
* 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 initialize a recursive mutex that has
- * been created with g_rec_mutex_new(). Also see #G_REC_MUTEX_INIT
- * for an alternative way to initialize statically allocated
- * recursive mutexes.
*
- * |[
+ * It is not necessary to initialise a recursive mutex that has been
+ * statically allocated.
+ *
+ * |[<!-- language="C" -->
* typedef struct {
* GRecMutex m;
* ...
void
g_rec_mutex_init (GRecMutex *rec_mutex)
{
- rec_mutex->impl = g_rec_mutex_impl_new ();
+ rec_mutex->p = g_rec_mutex_impl_new ();
}
/**
* Frees the resources allocated to a recursive mutex with
* g_rec_mutex_init().
*
- * #GRecMutexes that have have been created with g_rec_mutex_new()
- * should be freed with g_rec_mutex_free() instead.
+ * 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.
void
g_rec_mutex_clear (GRecMutex *rec_mutex)
{
- if (rec_mutex->impl)
- g_rec_mutex_impl_free (rec_mutex->impl);
+ g_rec_mutex_impl_free (rec_mutex->p);
}
/**
/**
* g_rec_mutex_unlock:
- * @rec_mutex: a #RecGMutex
+ * @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
void
g_rec_mutex_unlock (GRecMutex *rec_mutex)
{
- pthread_mutex_unlock (rec_mutex->impl);
+ pthread_mutex_unlock (rec_mutex->p);
}
/**
/* {{{1 GRWLock */
-/**
- * GRWLock:
- *
- * The GRWLock struct is an opaque data structure to represent a
- * reader-writer lock. It is similar to a #GMutex in that it allows
- * multiple threads to coordinate access to a shared resource.
- *
- * The difference to a mutex is that a reader-writer lock discriminates
- * between read-only ('reader') and full ('writer') access. While only
- * one thread at a time is allowed write access (by holding the 'writer'
- * lock via g_rw_lock_writer_lock()), multiple threads can gain
- * simultaneous read-only access (by holding the 'reader' lock via
- * g_rw_lock_reader_lock()).
- *
- * <example>
- * <title>An array with access functions</title>
- * <programlisting>
- * GRWLock lock = G_RW_LOCK_INIT;
- * GPtrArray *array;
- *
- * gpointer
- * my_array_get (guint index)
- * {
- * gpointer retval = NULL;
- *
- * if (!array)
- * return NULL;
- *
- * g_rw_lock_reader_lock (&lock);
- * if (index < array->len)
- * retval = g_ptr_array_index (array, index);
- * g_rw_lock_reader_unlock (&lock);
- *
- * return retval;
- * }
- *
- * void
- * my_array_set (guint index, gpointer data)
- * {
- * g_rw_lock_writer_lock (&lock);
- *
- * if (!array)
- * array = g_ptr_array_new (<!-- -->);
- *
- * if (index >= array->len)
- * g_ptr_array_set_size (array, index+1);
- * g_ptr_array_index (array, index) = data;
- *
- * g_rw_lock_writer_unlock (&lock);
- * }
- * </programlisting>
- * <para>
- * This example shows an array which can be accessed by many readers
- * (the <function>my_array_get()</function> function) simultaneously,
- * whereas the writers (the <function>my_array_set()</function>
- * function) will only be allowed once at a time and only if no readers
- * currently access the array. This is because of the potentially
- * dangerous resizing of the array. Using these functions is fully
- * multi-thread safe now.
- * </para>
- * </example>
- *
- * A GRWLock should only be accessed with the
- * <function>g_rw_lock_</function> functions. Before it can be used,
- * it has to be initialized with #G_RW_LOCK_INIT or g_rw_lock_init().
- *
- * Since: 2.32
- */
+static pthread_rwlock_t *
+g_rw_lock_impl_new (void)
+{
+ pthread_rwlock_t *rwlock;
+ gint status;
-/**
- * G_RW_LOCK_INIT:
- *
- * Initializer for statically allocated #GRWLocks.
- * Alternatively, g_rw_lock_init_init() can be used.
- *
- * |[
- * GRWLock lock = G_RW_LOCK_INIT;
- * ]|
- *
- * Since: 2.32
- */
+ 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 inline pthread_rwlock_t *
+g_rw_lock_get_impl (GRWLock *lock)
+{
+ pthread_rwlock_t *impl = g_atomic_pointer_get (&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:
- * @lock: an uninitialized #GRWLock
+ * @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.
- * Also see #G_RW_LOCK_INIT for an alternative way to initialize
- * statically allocated locks.
+ * 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.
*
- * |[
+ * |[<!-- language="C" -->
* typedef struct {
* GRWLock l;
* ...
* Since: 2.32
*/
void
-g_rw_lock_init (GRWLock *lock)
+g_rw_lock_init (GRWLock *rw_lock)
{
- pthread_rwlock_init (&lock->impl, NULL);
+ rw_lock->p = g_rw_lock_impl_new ();
}
/**
* g_rw_lock_clear:
- * @lock: an initialized #GRWLock
+ * @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 *lock)
+g_rw_lock_clear (GRWLock *rw_lock)
{
- pthread_rwlock_destroy (&lock->impl);
+ g_rw_lock_impl_free (rw_lock->p);
}
/**
* g_rw_lock_writer_lock:
- * @lock: a #GRWLock
+ * @rw_lock: a #GRWLock
*
- * Obtain a write lock on @lock. If any thread already holds
- * a read or write lock on @lock, the current thread will block
- * until all other threads have dropped their locks on @lock.
+ * 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 *lock)
+g_rw_lock_writer_lock (GRWLock *rw_lock)
{
- pthread_rwlock_wrlock (&lock->impl);
+ pthread_rwlock_wrlock (g_rw_lock_get_impl (rw_lock));
}
/**
* g_rw_lock_writer_trylock:
- * @lock: a #GRWLock
+ * @rw_lock: a #GRWLock
*
- * Tries to obtain a write lock on @lock. If any other thread holds
- * a read or write lock on @lock, it immediately returns %FALSE.
- * Otherwise it locks @lock and returns %TRUE.
+ * 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 @lock could be locked
+ * Returns: %TRUE if @rw_lock could be locked
*
* Since: 2.32
*/
gboolean
-g_rw_lock_writer_trylock (GRWLock *lock)
+g_rw_lock_writer_trylock (GRWLock *rw_lock)
{
- if (pthread_rwlock_trywrlock (&lock->impl) != 0)
+ if (pthread_rwlock_trywrlock (g_rw_lock_get_impl (rw_lock)) != 0)
return FALSE;
return TRUE;
/**
* g_rw_lock_writer_unlock:
- * @lock: a #GRWLock
+ * @rw_lock: a #GRWLock
*
- * Release a write lock on @lock.
+ * 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 *lock)
+g_rw_lock_writer_unlock (GRWLock *rw_lock)
{
- pthread_rwlock_unlock (&lock->impl);
+ pthread_rwlock_unlock (g_rw_lock_get_impl (rw_lock));
}
/**
* g_rw_lock_reader_lock:
- * @lock: a #GRWLock
+ * @rw_lock: a #GRWLock
*
- * Obtain a read lock on @lock. If another thread currently holds
- * the write lock on @lock or blocks waiting for it, the current
+ * 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
* Since: 2.32
*/
void
-g_rw_lock_reader_lock (GRWLock *lock)
+g_rw_lock_reader_lock (GRWLock *rw_lock)
{
- pthread_rwlock_rdlock (&lock->impl);
+ pthread_rwlock_rdlock (g_rw_lock_get_impl (rw_lock));
}
/**
* g_rw_lock_reader_trylock:
- * @lock: a #GRWLock
+ * @rw_lock: a #GRWLock
*
- * Tries to obtain a read lock on @lock and returns %TRUE if
+ * 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 @lock could be locked
+ * Returns: %TRUE if @rw_lock could be locked
*
* Since: 2.32
*/
gboolean
-g_rw_lock_reader_trylock (GRWLock *lock)
+g_rw_lock_reader_trylock (GRWLock *rw_lock)
{
- if (pthread_rwlock_tryrdlock (&lock->impl) != 0)
+ if (pthread_rwlock_tryrdlock (g_rw_lock_get_impl (rw_lock)) != 0)
return FALSE;
return TRUE;
/**
* g_rw_lock_reader_unlock:
- * @lock: a #GRWLock
+ * @rw_lock: a #GRWLock
*
- * Release a read lock on @lock.
+ * 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 *lock)
+g_rw_lock_reader_unlock (GRWLock *rw_lock)
{
- pthread_rwlock_unlock (&lock->impl);
+ pthread_rwlock_unlock (g_rw_lock_get_impl (rw_lock));
}
/* {{{1 GCond */
-/**
- * G_COND_INIT:
- *
- * Initializer for statically allocated #GConds.
- * Alternatively, g_cond_init() can be used.
- *
- * |[
- * GCond cond = G_COND_INIT;
- * ]|
- *
- * Since: 2.32
- */
+#if !defined(USE_NATIVE_MUTEX)
+
+static pthread_cond_t *
+g_cond_impl_new (void)
+{
+ pthread_condattr_t attr;
+ pthread_cond_t *cond;
+ gint status;
+
+ pthread_condattr_init (&attr);
+
+#ifdef HAVE_PTHREAD_COND_TIMEDWAIT_RELATIVE_NP
+#elif defined (HAVE_PTHREAD_CONDATTR_SETCLOCK) && defined (CLOCK_MONOTONIC)
+ if G_UNLIKELY ((status = pthread_condattr_setclock (&attr, CLOCK_MONOTONIC)) != 0)
+ g_thread_abort (status, "pthread_condattr_setclock");
+#else
+#error Cannot support GCond on your platform.
+#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 inline pthread_cond_t *
+g_cond_get_impl (GCond *cond)
+{
+ pthread_cond_t *impl = g_atomic_pointer_get (&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
*
- * Initialized a #GCond so that it can be used.
+ * Initialises a #GCond so that it can be used.
*
- * This function is useful to initialize a #GCond that has been
- * allocated on the stack, or as part of a larger structure.
- * It is not necessary to initialize a #GCond that has been
- * created with g_cond_new(). Also see #G_COND_INIT for an
- * alternative way to initialize statically allocated #GConds.
+ * 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 initialized #GCond leads
+ * Calling g_cond_init() on an already-initialised #GCond leads
* to undefined behaviour.
*
* Since: 2.32
void
g_cond_init (GCond *cond)
{
- gint status;
-
- if G_UNLIKELY ((status = pthread_cond_init (&cond->impl, NULL)) != 0)
- g_thread_abort (status, "pthread_cond_init");
+ cond->p = g_cond_impl_new ();
}
/**
* g_cond_clear:
- * @cond: an initialized #GCond
+ * @cond: an initialised #GCond
*
* Frees the resources allocated to a #GCond with g_cond_init().
*
- * #GConds that have been created with g_cond_new() should
- * be freed with g_cond_free() instead.
+ * 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.
void
g_cond_clear (GCond *cond)
{
- gint status;
-
- if G_UNLIKELY ((status = pthread_cond_destroy (&cond->impl)) != 0)
- g_thread_abort (status, "pthread_cond_destroy");
+ g_cond_impl_free (cond->p);
}
/**
* @cond: a #GCond
* @mutex: a #GMutex that is currently locked
*
- * Waits until this thread is woken up on @cond. The @mutex is unlocked
- * before falling asleep and locked again before resuming.
- *
- * This function can be used even if g_thread_init() has not yet been
- * called, and, in that case, will immediately return.
- */
+ * Atomically releases @mutex and waits until @cond is signalled.
+ * When this function returns, @mutex is locked again and owned by the
+ * calling thread.
+ *
+ * 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 (&cond->impl, &mutex->impl)) != 0)
+ 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");
}
* 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.
- *
- * This function can be used even if g_thread_init() has not yet been
- * called, and, in that case, will do nothing.
*/
void
g_cond_signal (GCond *cond)
{
gint status;
- if G_UNLIKELY ((status = pthread_cond_signal (&cond->impl)) != 0)
+ if G_UNLIKELY ((status = pthread_cond_signal (g_cond_get_impl (cond))) != 0)
g_thread_abort (status, "pthread_cond_signal");
}
* 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.
- *
- * This function can be used even if g_thread_init() has not yet been
- * called, and, in that case, will do nothing.
*/
void
g_cond_broadcast (GCond *cond)
{
gint status;
- if G_UNLIKELY ((status = pthread_cond_broadcast (&cond->impl)) != 0)
+ if G_UNLIKELY ((status = pthread_cond_broadcast (g_cond_get_impl (cond))) != 0)
g_thread_abort (status, "pthread_cond_broadcast");
}
/**
- * g_cond_timed_wait:
+ * g_cond_wait_until:
* @cond: a #GCond
* @mutex: a #GMutex that is currently locked
- * @abs_time: a #GTimeVal, determining the final time
+ * @end_time: the monotonic time to wait until
*
- * Waits until this thread is woken up on @cond, but not longer than
- * until the time specified by @abs_time. The @mutex is unlocked before
- * falling asleep and locked again before resuming.
+ * Waits until either @cond is signalled or @end_time has passed.
*
- * If @abs_time is %NULL, g_cond_timed_wait() acts like g_cond_wait().
+ * 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.
*
- * This function can be used even if g_thread_init() has not yet been
- * called, and, in that case, will immediately return %TRUE.
+ * %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.
*
- * To easily calculate @abs_time a combination of g_get_current_time()
- * and g_time_val_add() can be used.
+ * The following code shows how to correctly perform a timed wait on a
+ * condition variable (extending the example presented in the
+ * documentation for #GCond):
*
- * Returns: %TRUE if @cond was signalled, or %FALSE on timeout
- */
+ * |[<!-- language="C" -->
+ * 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_timed_wait (GCond *cond,
- GMutex *mutex,
- GTimeVal *abs_time)
+g_cond_wait_until (GCond *cond,
+ GMutex *mutex,
+ gint64 end_time)
{
- struct timespec end_time;
+ struct timespec ts;
gint status;
- if (abs_time == NULL)
- {
- g_cond_wait (cond, mutex);
- return TRUE;
- }
+#ifdef HAVE_PTHREAD_COND_TIMEDWAIT_RELATIVE_NP
+ /* end_time is given relative to the monotonic clock as returned by
+ * g_get_monotonic_time().
+ *
+ * Since this pthreads wants the relative time, convert it back again.
+ */
+ {
+ gint64 now = g_get_monotonic_time ();
+ gint64 relative;
- end_time.tv_sec = abs_time->tv_sec;
- end_time.tv_nsec = abs_time->tv_usec * 1000;
+ if (end_time <= now)
+ return FALSE;
- if ((status = pthread_cond_timedwait (&cond->impl, &mutex->impl, &end_time)) == 0)
- return TRUE;
+ relative = end_time - now;
+
+ ts.tv_sec = relative / 1000000;
+ ts.tv_nsec = (relative % 1000000) * 1000;
+
+ if ((status = pthread_cond_timedwait_relative_np (g_cond_get_impl (cond), g_mutex_get_impl (mutex), &ts)) == 0)
+ return TRUE;
+ }
+#elif defined (HAVE_PTHREAD_CONDATTR_SETCLOCK) && defined (CLOCK_MONOTONIC)
+ /* This is the exact check we used during init to set the clock to
+ * monotonic, so if we're in this branch, timedwait() will already be
+ * expecting a monotonic clock.
+ */
+ {
+ 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;
+ }
+#else
+#error Cannot support GCond on your platform.
+#endif
if G_UNLIKELY (status != ETIMEDOUT)
g_thread_abort (status, "pthread_cond_timedwait");
return FALSE;
}
+#endif /* defined(USE_NATIVE_MUTEX) */
+
+/* {{{1 GPrivate */
+
/**
- * g_cond_timedwait:
- * @cond: a #GCond
- * @mutex: a #GMutex that is currently locked
- * @abs_time: the final time, in microseconds
+ * GPrivate:
*
- * A variant of g_cond_timed_wait() that takes @abs_time
- * as a #gint64 instead of a #GTimeVal.
- * See g_cond_timed_wait() for details.
+ * 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.
*
- * Returns: %TRUE if @cond was signalled, or %FALSE on timeout
+ * If you don't already know why you might want this functionality,
+ * then you probably don't need it.
*
- * Since: 2.32
+ * #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 g_private_ functions.
*/
-gboolean
-g_cond_timedwait (GCond *cond,
- GMutex *mutex,
- gint64 abs_time)
+
+/**
+ * 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.
+ *
+ * |[<!-- language="C" -->
+ * 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)
{
- struct timespec end_time;
+ pthread_key_t *key;
gint status;
- end_time.tv_sec = abs_time / 1000000;
- end_time.tv_nsec = (abs_time % 1000000) * 1000;
+ 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");
- if ((status = pthread_cond_timedwait (&cond->impl, &mutex->impl, &end_time)) == 0)
- return TRUE;
+ return key;
+}
- if G_UNLIKELY (status != ETIMEDOUT)
- g_thread_abort (status, "pthread_cond_timedwait");
+static void
+g_private_impl_free (pthread_key_t *key)
+{
+ gint status;
- return FALSE;
+ status = pthread_key_delete (*key);
+ if G_UNLIKELY (status != 0)
+ g_thread_abort (status, "pthread_key_delete");
+ free (key);
}
-/* {{{1 GPrivate */
-
-void
-g_private_init (GPrivate *key,
- GDestroyNotify notify)
+static inline pthread_key_t *
+g_private_get_impl (GPrivate *key)
{
- pthread_key_create (&key->key, notify);
- key->ready = TRUE;
+ pthread_key_t *impl = g_atomic_pointer_get (&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:
- * @private_key: a #GPrivate
- *
- * Returns the pointer keyed to @private_key for the current thread. If
- * g_private_set() hasn't been called for the current @private_key and
- * thread yet, this pointer will be %NULL.
- *
- * This function can be used even if g_thread_init() has not yet been
- * called, and, in that case, will return the value of @private_key
- * casted to #gpointer. Note however, that private data set
- * <emphasis>before</emphasis> g_thread_init() will
- * <emphasis>not</emphasis> be retained <emphasis>after</emphasis> the
- * call. Instead, %NULL will be returned in all threads directly after
- * g_thread_init(), regardless of any g_private_set() calls issued
- * before threading system initialization.
- *
- * Returns: the corresponding pointer
+ * @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)
{
- if (!key->ready)
- return key->single_value;
-
/* quote POSIX: No errors are returned from pthread_getspecific(). */
- return pthread_getspecific (key->key);
+ return pthread_getspecific (*g_private_get_impl (key));
}
/**
* g_private_set:
- * @private_key: a #GPrivate
- * @data: the new pointer
+ * @key: a #GPrivate
+ * @value: the new value
*
- * Sets the pointer keyed to @private_key for the current thread.
+ * Sets the thread local variable @key to have the value @value in the
+ * current thread.
*
- * This function can be used even if g_thread_init() has not yet been
- * called, and, in that case, will set @private_key to @data casted to
- * #GPrivate*. See g_private_get() for resulting caveats.
+ * 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,
{
gint status;
- if (!key->ready)
- {
- key->single_value = value;
- return;
- }
-
- if G_UNLIKELY ((status = pthread_setspecific (key->key, value)) != 0)
+ if G_UNLIKELY ((status = pthread_setspecific (*g_private_get_impl (key), value)) != 0)
g_thread_abort (status, "pthread_setspecific");
}
-/* {{{1 GThread */
+/**
+ * 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;
-#include "glib.h"
-#include "gthreadprivate.h"
+ old = pthread_getspecific (*impl);
+ if (old && key->notify)
+ key->notify (old);
-#include <pthread.h>
-#include <errno.h>
-#include <stdlib.h>
-#ifdef HAVE_SYS_TIME_H
-# include <sys/time.h>
-#endif
-#ifdef HAVE_UNISTD_H
-# include <unistd.h>
-#endif
+ if G_UNLIKELY ((status = pthread_setspecific (*impl, value)) != 0)
+ g_thread_abort (status, "pthread_setspecific");
+}
-#ifdef HAVE_SCHED_H
-#include <sched.h>
-#endif
+/* {{{1 GThread */
#define posix_check_err(err, name) G_STMT_START{ \
int error = (err); \
#define posix_check_cmd(cmd) posix_check_err (cmd, #cmd)
-#define G_MUTEX_SIZE (sizeof (pthread_mutex_t))
+typedef struct
+{
+ GRealThread thread;
+
+ pthread_t system_thread;
+ gboolean joined;
+ GMutex lock;
+} GThreadPosix;
void
-g_system_thread_create (GThreadFunc thread_func,
- gpointer arg,
- gulong stack_size,
- gboolean joinable,
- gpointer thread,
- GError **error)
+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;
- g_return_if_fail (thread_func);
+ thread = g_slice_new0 (GThreadPosix);
posix_check_cmd (pthread_attr_init (&attr));
}
#endif /* HAVE_PTHREAD_ATTR_SETSTACKSIZE */
- posix_check_cmd (pthread_attr_setdetachstate (&attr,
- joinable ? PTHREAD_CREATE_JOINABLE : PTHREAD_CREATE_DETACHED));
-
- ret = pthread_create (thread, &attr, (void* (*)(void*))thread_func, arg);
+ 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));
- return;
+ "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:
*
- * Gives way to other threads waiting to be scheduled.
+ * 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.
- * But in most cases you will encounter, there are better methods to do
- * that. So in general you shouldn't use this function.
*/
void
g_thread_yield (void)
}
void
-g_system_thread_join (gpointer thread)
+g_system_thread_wait (GRealThread *thread)
{
- gpointer ignore;
- posix_check_cmd (pthread_join (*(pthread_t*)thread, &ignore));
+ 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
}
void
-g_system_thread_self (gpointer thread)
+g_system_thread_set_name (const gchar *name)
+{
+#ifdef HAVE_SYS_PRCTL_H
+#ifdef PR_SET_NAME
+ prctl (PR_SET_NAME, name, 0, 0, 0, 0);
+#endif
+#endif
+}
+
+/* {{{1 GMutex and GCond futex implementation */
+
+#if defined(USE_NATIVE_MUTEX)
+
+#include <linux/futex.h>
+#include <sys/syscall.h>
+
+/* We should expand the set of operations available in gatomic once we
+ * have better C11 support in GCC in common distributions (ie: 4.9).
+ *
+ * Before then, let's define a couple of useful things for our own
+ * purposes...
+ */
+
+#define exchange_acquire(ptr, new) \
+ __atomic_exchange_4((ptr), (new), __ATOMIC_ACQUIRE)
+#define compare_exchange_acquire(ptr, old, new) \
+ __atomic_compare_exchange_4((ptr), (old), (new), 0, __ATOMIC_ACQUIRE, __ATOMIC_RELAXED)
+
+#define exchange_release(ptr, new) \
+ __atomic_exchange_4((ptr), (new), __ATOMIC_RELEASE)
+#define store_release(ptr, new) \
+ __atomic_store_4((ptr), (new), __ATOMIC_RELEASE)
+
+/* Our strategy for the mutex is pretty simple:
+ *
+ * 0: not in use
+ *
+ * 1: acquired by one thread only, no contention
+ *
+ * > 1: contended
+ *
+ *
+ * As such, attempting to acquire the lock should involve an increment.
+ * If we find that the previous value was 0 then we can return
+ * immediately.
+ *
+ * On unlock, we always store 0 to indicate that the lock is available.
+ * If the value there was 1 before then we didn't have contention and
+ * can return immediately. If the value was something other than 1 then
+ * we have the contended case and need to wake a waiter.
+ *
+ * If it was not 0 then there is another thread holding it and we must
+ * wait. We must always ensure that we mark a value >1 while we are
+ * waiting in order to instruct the holder to do a wake operation on
+ * unlock.
+ */
+
+void
+g_mutex_init (GMutex *mutex)
+{
+ mutex->i[0] = 0;
+}
+
+void
+g_mutex_clear (GMutex *mutex)
+{
+ if G_UNLIKELY (mutex->i[0] != 0)
+ {
+ fprintf (stderr, "g_mutex_clear() called on uninitialised or locked mutex\n");
+ abort ();
+ }
+}
+
+static void __attribute__((noinline))
+g_mutex_lock_slowpath (GMutex *mutex)
+{
+ /* Set to 2 to indicate contention. If it was zero before then we
+ * just acquired the lock.
+ *
+ * Otherwise, sleep for as long as the 2 remains...
+ */
+ while (exchange_acquire (&mutex->i[0], 2) != 0)
+ syscall (__NR_futex, &mutex->i[0], (gsize) FUTEX_WAIT, (gsize) 2, NULL);
+}
+
+static void __attribute__((noinline))
+g_mutex_unlock_slowpath (GMutex *mutex,
+ guint prev)
+{
+ /* We seem to get better code for the uncontended case by splitting
+ * this out...
+ */
+ if G_UNLIKELY (prev == 0)
+ {
+ fprintf (stderr, "Attempt to unlock mutex that was not locked\n");
+ abort ();
+ }
+
+ syscall (__NR_futex, &mutex->i[0], (gsize) FUTEX_WAKE, (gsize) 1, NULL);
+}
+
+void
+g_mutex_lock (GMutex *mutex)
+{
+ /* 0 -> 1 and we're done. Anything else, and we need to wait... */
+ if G_UNLIKELY (g_atomic_int_add (&mutex->i[0], 1) != 0)
+ g_mutex_lock_slowpath (mutex);
+}
+
+void
+g_mutex_unlock (GMutex *mutex)
+{
+ guint prev;
+
+ prev = exchange_release (&mutex->i[0], 0);
+
+ /* 1-> 0 and we're done. Anything else and we need to signal... */
+ if G_UNLIKELY (prev != 1)
+ g_mutex_unlock_slowpath (mutex, prev);
+}
+
+gboolean
+g_mutex_trylock (GMutex *mutex)
+{
+ guint zero = 0;
+
+ /* We don't want to touch the value at all unless we can move it from
+ * exactly 0 to 1.
+ */
+ return compare_exchange_acquire (&mutex->i[0], &zero, 1);
+}
+
+/* Condition variables are implemented in a rather simple way as well.
+ * In many ways, futex() as an abstraction is even more ideally suited
+ * to condition variables than it is to mutexes.
+ *
+ * We store a generation counter. We sample it with the lock held and
+ * unlock before sleeping on the futex.
+ *
+ * Signalling simply involves increasing the counter and making the
+ * appropriate futex call.
+ *
+ * The only thing that is the slightest bit complicated is timed waits
+ * because we must convert our absolute time to relative.
+ */
+
+void
+g_cond_init (GCond *cond)
+{
+ cond->i[0] = 0;
+}
+
+void
+g_cond_clear (GCond *cond)
+{
+}
+
+void
+g_cond_wait (GCond *cond,
+ GMutex *mutex)
+{
+ guint sampled = g_atomic_int_get (&cond->i[0]);
+
+ g_mutex_unlock (mutex);
+ syscall (__NR_futex, &cond->i[0], (gsize) FUTEX_WAIT, (gsize) sampled, NULL);
+ g_mutex_lock (mutex);
+}
+
+void
+g_cond_signal (GCond *cond)
+{
+ g_atomic_int_inc (&cond->i[0]);
+
+ syscall (__NR_futex, &cond->i[0], (gsize) FUTEX_WAKE, (gsize) 1, NULL);
+}
+
+void
+g_cond_broadcast (GCond *cond)
{
- *(pthread_t*)thread = pthread_self();
+ g_atomic_int_inc (&cond->i[0]);
+
+ syscall (__NR_futex, &cond->i[0], (gsize) FUTEX_WAKE, (gsize) INT_MAX, NULL);
}
gboolean
-g_system_thread_equal (gpointer thread1,
- gpointer thread2)
+g_cond_wait_until (GCond *cond,
+ GMutex *mutex,
+ gint64 end_time)
{
- return (pthread_equal (*(pthread_t*)thread1, *(pthread_t*)thread2) != 0);
+ struct timespec now;
+ struct timespec span;
+ guint sampled;
+ int res;
+
+ if (end_time < 0)
+ return FALSE;
+
+ clock_gettime (CLOCK_MONOTONIC, &now);
+ span.tv_sec = (end_time / 1000000) - now.tv_sec;
+ span.tv_nsec = ((end_time % 1000000) * 1000) - now.tv_nsec;
+ if (span.tv_nsec < 0)
+ {
+ span.tv_nsec += 1000000000;
+ span.tv_sec--;
+ }
+
+ if (span.tv_sec < 0)
+ return FALSE;
+
+ sampled = cond->i[0];
+ g_mutex_unlock (mutex);
+ res = syscall (__NR_futex, &cond->i[0], (gsize) FUTEX_WAIT, (gsize) sampled, &span);
+ g_mutex_lock (mutex);
+
+ return (res < 0 && errno == ETIMEDOUT) ? FALSE : TRUE;
}
-/* {{{1 Epilogue */
+#endif
+
+ /* {{{1 Epilogue */
/* vim:set foldmethod=marker: */
projects / platform / upstream / glib.git / blobdiff