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Diffstat (limited to 'glib/glib/gthread-posix.c')
-rw-r--r-- | glib/glib/gthread-posix.c | 1180 |
1 files changed, 1180 insertions, 0 deletions
diff --git a/glib/glib/gthread-posix.c b/glib/glib/gthread-posix.c new file mode 100644 index 0000000..3f74aa4 --- /dev/null +++ b/glib/glib/gthread-posix.c @@ -0,0 +1,1180 @@ +/* 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_unlock"); +} + +/** + * 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: */ |