X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=glib%2Fgthread.c;h=ea8e5f9656f55945bb365f645e25dee26b61ed6b;hb=0a4ee12c7a9dfc82443133dfb2b18fb411d79f48;hp=7e0bb9b186a31094b40642f3c4da1efc5b1e27f7;hpb=3237eaf5d527ecccae51b490d9cfbbf7e6b8538c;p=platform%2Fupstream%2Fglib.git diff --git a/glib/gthread.c b/glib/gthread.c index 7e0bb9b..ea8e5f9 100644 --- a/glib/gthread.c +++ b/glib/gthread.c @@ -16,9 +16,7 @@ * 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 . */ /* Prelude {{{1 ----------------------------------------------------------- */ @@ -45,7 +43,7 @@ #include -#ifdef HAVE_UNISTD_H +#ifdef G_OS_UNIX #include #endif @@ -57,6 +55,7 @@ #endif /* G_OS_WIN32 */ #include "gslice.h" +#include "gstrfuncs.h" #include "gtestutils.h" /** @@ -82,28 +81,65 @@ * (#GMutex, #GRecMutex and #GRWLock). There is a facility to use * individual bits for locks (g_bit_lock()). There are primitives * for condition variables to allow synchronization of threads (#GCond). - * There are primitives for thread-private data - data that every thread - * has a private instance of (#GPrivate). There are - * facilities for one-time initialization (#GOnce, g_once_init_enter()). - * Finally there are primitives to create and manage threads (#GThread). + * There are primitives for thread-private data - data that every + * thread has a private instance of (#GPrivate). There are facilities + * for one-time initialization (#GOnce, g_once_init_enter()). Finally, + * there are primitives to create and manage threads (#GThread). * * The GLib threading system used to be initialized with g_thread_init(). * This is no longer necessary. Since version 2.32, the GLib threading * system is automatically initialized at the start of your program, * and all thread-creation functions and synchronization primitives - * are available right away. It is still possible to do thread-unsafe - * initialization and setup at the beginning of your program, before - * creating the first threads. - * - * GLib is internally completely thread-safe (all global data is + * are available right away. + * + * Note that it is not safe to assume that your program has no threads + * even if you don't call g_thread_new() yourself. GLib and GIO can + * and will create threads for their own purposes in some cases, such + * as when using g_unix_signal_source_new() or when using GDBus. + * + * Originally, UNIX did not have threads, and therefore some traditional + * UNIX APIs are problematic in threaded programs. Some notable examples + * are + * + * - C library functions that return data in statically allocated + * buffers, such as strtok() or strerror(). For many of these, + * there are thread-safe variants with a _r suffix, or you can + * look at corresponding GLib APIs (like g_strsplit() or g_strerror()). + * + * - The functions setenv() and unsetenv() manipulate the process + * environment in a not thread-safe way, and may interfere with getenv() + * calls in other threads. Note that getenv() calls may be hidden behind + * other APIs. For example, GNU gettext() calls getenv() under the + * covers. In general, it is best to treat the environment as readonly. + * If you absolutely have to modify the environment, do it early in + * main(), when no other threads are around yet. + * + * - The setlocale() function changes the locale for the entire process, + * affecting all threads. Temporary changes to the locale are often made + * to change the behavior of string scanning or formatting functions + * like scanf() or printf(). GLib offers a number of string APIs + * (like g_ascii_formatd() or g_ascii_strtod()) that can often be + * used as an alternative. Or you can use the uselocale() function + * to change the locale only for the current thread. + * + * - The fork() function only takes the calling thread into the child's + * copy of the process image. If other threads were executing in critical + * sections they could have left mutexes locked which could easily + * cause deadlocks in the new child. For this reason, you should + * call exit() or exec() as soon as possible in the child and only + * make signal-safe library calls before that. + * + * - The daemon() function uses fork() in a way contrary to what is + * described above. It should not be used with GLib programs. + * + * GLib itself is internally completely thread-safe (all global data is * automatically locked), but individual data structure instances are * not automatically locked for performance reasons. For example, * you must coordinate accesses to the same #GHashTable from multiple * threads. The two notable exceptions from this rule are #GMainLoop - * and #GAsyncQueue, which are thread-safe and - * need no further application-level locking to be accessed from - * multiple threads. Most refcounting functions such as g_object_ref() - * are also thread-safe. + * and #GAsyncQueue, which are thread-safe and need no further + * application-level locking to be accessed from multiple threads. + * Most refcounting functions such as g_object_ref() are also thread-safe. */ /* G_LOCK Documentation {{{1 ---------------------------------------------- */ @@ -112,19 +148,17 @@ * G_LOCK_DEFINE: * @name: the name of the lock * - * The %G_LOCK_* macros provide a convenient interface to #GMutex. + * The #G_LOCK_ macros provide a convenient interface to #GMutex. * #G_LOCK_DEFINE defines a lock. It can appear in any place where * variable definitions may appear in programs, i.e. in the first block * of a function or outside of functions. The @name parameter will be * mangled to get the name of the #GMutex. This means that you * can use names of existing variables as the parameter - e.g. the name * of the variable you intend to protect with the lock. Look at our - * give_me_next_number() example using the - * %G_LOCK_* macros: + * give_me_next_number() example using the #G_LOCK macros: * - * - * Using the %G_LOCK_* convenience macros - * + * Here is an example for using the #G_LOCK convenience macros: + * |[ * G_LOCK_DEFINE (current_number); * * int @@ -139,8 +173,7 @@ * * return ret_val; * } - * - * + * ]| */ /** @@ -169,10 +202,11 @@ /** * G_TRYLOCK: * @name: the name of the lock - * @Returns: %TRUE, if the lock could be locked. * * Works like g_mutex_trylock(), but for a lock defined with * #G_LOCK_DEFINE. + * + * Returns: %TRUE, if the lock could be locked. */ /** @@ -190,33 +224,26 @@ * * The #GMutex struct is an opaque data structure to represent a mutex * (mutual exclusion). It can be used to protect data against shared - * access. Take for example the following function: + * access. * - * - * A function which will not work in a threaded environment - * + * Take for example the following function: + * |[ * int * give_me_next_number (void) * { * static int current_number = 0; * - * /* now do a very complicated calculation to calculate the new - * * number, this might for example be a random number generator - * */ + * // now do a very complicated calculation to calculate the new + * // number, this might for example be a random number generator * current_number = calc_next_number (current_number); * * return current_number; * } - * - * - * + * ]| * It is easy to see that this won't work in a multi-threaded * application. There current_number must be protected against shared * access. A #GMutex can be used as a solution to this problem: - * - * - * Using GMutex to protected a shared variable - * + * |[ * int * give_me_next_number (void) * { @@ -224,15 +251,13 @@ * static int current_number = 0; * int ret_val; * - * g_mutex_lock (&mutex); + * g_mutex_lock (&mutex); * ret_val = current_number = calc_next_number (current_number); - * g_mutex_unlock (&mutex); + * g_mutex_unlock (&mutex); * * return ret_val; * } - * - * - * + * ]| * Notice that the #GMutex is not initialised to any particular value. * Its placement in static storage ensures that it will be initialised * to all-zeros, which is appropriate. @@ -240,8 +265,7 @@ * If a #GMutex is placed in other contexts (eg: embedded in a struct) * then it must be explicitly initialised using g_mutex_init(). * - * A #GMutex should only be accessed via g_mutex_ - * functions. + * A #GMutex should only be accessed via g_mutex_ functions. */ /* GRecMutex Documentation {{{1 -------------------------------------- */ @@ -260,7 +284,7 @@ * g_rec_mutex_init() on it and g_rec_mutex_clear() when done. * * A GRecMutex should only be accessed with the - * g_rec_mutex_ functions. + * g_rec_mutex_ functions. * * Since: 2.32 */ @@ -281,9 +305,8 @@ * simultaneous read-only access (by holding the 'reader' lock via * g_rw_lock_reader_lock()). * - * - * An array with access functions - * + * Here is an example for an array with access functions: + * |[ * GRWLock lock; * GPtrArray *array; * @@ -295,10 +318,10 @@ * if (!array) * return NULL; * - * g_rw_lock_reader_lock (&lock); - * if (index < array->len) + * g_rw_lock_reader_lock (&lock); + * if (index < array->len) * retval = g_ptr_array_index (array, index); - * g_rw_lock_reader_unlock (&lock); + * g_rw_lock_reader_unlock (&lock); * * return retval; * } @@ -306,35 +329,30 @@ * void * my_array_set (guint index, gpointer data) * { - * g_rw_lock_writer_lock (&lock); + * g_rw_lock_writer_lock (&lock); * * if (!array) - * array = g_ptr_array_new (); + * 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); + * g_rw_lock_writer_unlock (&lock); * } - * - * - * This example shows an array which can be accessed by many readers - * (the my_array_get() function) simultaneously, - * whereas the writers (the my_array_set() - * 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. - * - * + * ]| + * This example shows an array which can be accessed by many readers + * (the my_array_get() function) simultaneously, whereas the writers + * (the my_array_set() function) will only be allowed one 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. * * If a #GRWLock is allocated in static storage then it can be used * without initialisation. Otherwise, you should call * g_rw_lock_init() on it and g_rw_lock_clear() when done. * - * A GRWLock should only be accessed with the - * g_rw_lock_ functions. + * A GRWLock should only be accessed with the g_rw_lock_ functions. * * Since: 2.32 */ @@ -350,22 +368,25 @@ * condition they signal the #GCond, and that causes the waiting * threads to be woken up. * - * - * - * Using GCond to block a thread until a condition is satisfied - * - * - * GCond* data_cond = NULL; /* Must be initialized somewhere */ - * GMutex* data_mutex = NULL; /* Must be initialized somewhere */ + * Consider the following example of a shared variable. One or more + * threads can wait for data to be published to the variable and when + * another thread publishes the data, it can signal one of the waiting + * threads to wake up to collect the data. + * + * Here is an example for using GCond to block a thread until a condition + * is satisfied: + * |[ * gpointer current_data = NULL; + * GMutex data_mutex; + * GCond data_cond; * * void * push_data (gpointer data) * { - * g_mutex_lock (data_mutex); + * g_mutex_lock (&data_mutex); * current_data = data; - * g_cond_signal (data_cond); - * g_mutex_unlock (data_mutex); + * g_cond_signal (&data_cond); + * g_mutex_unlock (&data_mutex); * } * * gpointer @@ -373,37 +394,39 @@ * { * gpointer data; * - * g_mutex_lock (data_mutex); + * g_mutex_lock (&data_mutex); * while (!current_data) - * g_cond_wait (data_cond, data_mutex); + * g_cond_wait (&data_cond, &data_mutex); * data = current_data; * current_data = NULL; - * g_mutex_unlock (data_mutex); + * g_mutex_unlock (&data_mutex); * * return data; * } - * - * - * + * ]| * Whenever a thread calls pop_data() now, it will wait until * current_data is non-%NULL, i.e. until some other thread * has called push_data(). * - * It is important to use the g_cond_wait() and - * g_cond_timed_wait() functions only inside a loop which checks for the - * condition to be true. It is not guaranteed that the waiting thread - * will find the condition fulfilled after it wakes up, even if the - * signaling thread left the condition in that state: another thread may - * have altered the condition before the waiting thread got the chance - * to be woken up, even if the condition itself is protected by a - * #GMutex, like above. + * The example shows that use of a condition variable must always be + * paired with a mutex. Without the use of a mutex, there would be a + * race between the check of @current_data by the while loop in + * pop_data() and waiting. Specifically, another thread could set + * @current_data after the check, and signal the cond (with nobody + * waiting on it) before the first thread goes to sleep. #GCond is + * specifically useful for its ability to release the mutex and go + * to sleep atomically. + * + * It is also important to use the g_cond_wait() and g_cond_wait_until() + * functions only inside a loop which checks for the condition to be + * true. See g_cond_wait() for an explanation of why the condition may + * not be true even after it returns. * * If a #GCond is allocated in static storage then it can be used - * without initialisation. Otherwise, you should call g_cond_init() on - * it and g_cond_clear() when done. + * without initialisation. Otherwise, you should call g_cond_init() + * on it and g_cond_clear() when done. * - * A #GCond should only be accessed via the g_cond_ - * functions. + * A #GCond should only be accessed via the g_cond_ functions. */ /* GThread Documentation {{{1 ---------------------------------------- */ @@ -412,10 +435,16 @@ * GThread: * * The #GThread struct represents a running thread. This struct - * is returned by g_thread_new() or g_thread_new_full(). You can - * obtain the #GThread struct representing the current thead by + * is returned by g_thread_new() or g_thread_try_new(). You can + * obtain the #GThread struct representing the current thread by * calling g_thread_self(). * + * GThread is refcounted, see g_thread_ref() and g_thread_unref(). + * The thread represented by it holds a reference while it is running, + * and g_thread_join() consumes the reference that it is given, so + * it is normally not necessary to manage GThread references + * explicitly. + * * The structure is opaque -- none of its fields may be directly * accessed. */ @@ -424,12 +453,8 @@ * GThreadFunc: * @data: data passed to the thread * - * Specifies the type of the @func functions passed to - * g_thread_new() or g_thread_new_full(). - * - * If the thread is joinable, the return value of this function - * is returned by a g_thread_join() call waiting for the thread. - * If the thread is not joinable, the return value is ignored. + * Specifies the type of the @func functions passed to g_thread_new() + * or g_thread_try_new(). * * Returns: the return value of the thread */ @@ -460,11 +485,7 @@ * * The error domain of the GLib thread subsystem. **/ -GQuark -g_thread_error_quark (void) -{ - return g_quark_from_static_string ("g_thread_error"); -} +G_DEFINE_QUARK (g_thread_error, g_thread_error) /* Local Data {{{1 -------------------------------------------------------- */ @@ -497,7 +518,7 @@ G_LOCK_DEFINE_STATIC (g_thread_new); * * A #GOnce must be initialized with this macro before it can be used. * - * |[ + * |[ * GOnce my_once = G_ONCE_INIT; * ]| * @@ -537,7 +558,7 @@ G_LOCK_DEFINE_STATIC (g_thread_new); * Calling g_once() recursively on the same #GOnce struct in * @func will lead to a deadlock. * - * |[ + * |[ * gpointer * get_debug_flags (void) * { @@ -580,11 +601,10 @@ g_once_impl (GOnce *once, /** * g_once_init_enter: - * @value_location: location of a static initializable variable - * containing 0 + * @location: location of a static initializable variable containing 0 * * Function to be called when starting a critical initialization - * section. The argument @value_location must point to a static + * section. The argument @location must point to a static * 0-initialized variable that will be set to a value other than 0 at * the end of the initialization section. In combination with * g_once_init_leave() and the unique address @value_location, it can @@ -593,17 +613,17 @@ g_once_impl (GOnce *once, * blocked until initialization completed. To be used in constructs * like this: * - * |[ + * |[ * static gsize initialization_value = 0; * - * if (g_once_init_enter (&initialization_value)) + * if (g_once_init_enter (&initialization_value)) * { - * gsize setup_value = 42; /** initialization code here **/ + * gsize setup_value = 42; // initialization code here * - * g_once_init_leave (&initialization_value, setup_value); + * g_once_init_leave (&initialization_value, setup_value); * } * - * /** use initialization_value here **/ + * // use initialization_value here * ]| * * Returns: %TRUE if the initialization section should be entered, @@ -612,9 +632,9 @@ g_once_impl (GOnce *once, * Since: 2.14 */ gboolean -(g_once_init_enter) (volatile void *pointer) +(g_once_init_enter) (volatile void *location) { - volatile gsize *value_location = pointer; + volatile gsize *value_location = location; gboolean need_init = FALSE; g_mutex_lock (&g_once_mutex); if (g_atomic_pointer_get (value_location) == NULL) @@ -635,8 +655,7 @@ gboolean /** * g_once_init_leave: - * @value_location: location of a static initializable variable - * containing 0 + * @location: location of a static initializable variable containing 0 * @result: new non-0 value for *@value_location * * Counterpart to g_once_init_enter(). Expects a location of a static @@ -648,10 +667,10 @@ gboolean * Since: 2.14 */ void -(g_once_init_leave) (volatile void *pointer, +(g_once_init_leave) (volatile void *location, gsize result) { - volatile gsize *value_location = pointer; + volatile gsize *value_location = location; g_return_if_fail (g_atomic_pointer_get (value_location) == NULL); g_return_if_fail (result != 0); @@ -666,21 +685,59 @@ void /* GThread {{{1 -------------------------------------------------------- */ -static void -g_thread_cleanup (gpointer data) +/** + * g_thread_ref: + * @thread: a #GThread + * + * Increase the reference count on @thread. + * + * Returns: a new reference to @thread + * + * Since: 2.32 + */ +GThread * +g_thread_ref (GThread *thread) { - if (data) - { - GRealThread* thread = data; + GRealThread *real = (GRealThread *) thread; - /* We only free the thread structure if it isn't joinable. - * If it is, the structure is freed in g_thread_join() - */ - if (!thread->thread.joinable) - g_system_thread_free (thread); + g_atomic_int_inc (&real->ref_count); + + return thread; +} + +/** + * g_thread_unref: + * @thread: a #GThread + * + * Decrease the reference count on @thread, possibly freeing all + * resources associated with it. + * + * Note that each thread holds a reference to its #GThread while + * it is running, so it is safe to drop your own reference to it + * if you don't need it anymore. + * + * Since: 2.32 + */ +void +g_thread_unref (GThread *thread) +{ + GRealThread *real = (GRealThread *) thread; + + if (g_atomic_int_dec_and_test (&real->ref_count)) + { + if (real->ours) + g_system_thread_free (real); + else + g_slice_free (GRealThread, real); } } +static void +g_thread_cleanup (gpointer data) +{ + g_thread_unref (data); +} + gpointer g_thread_proxy (gpointer data) { @@ -688,18 +745,22 @@ g_thread_proxy (gpointer data) g_assert (data); - if (thread->name) - g_system_thread_set_name (thread->name); - /* This has to happen before G_LOCK, as that might call g_thread_self */ g_private_set (&g_thread_specific_private, data); - /* The lock makes sure that thread->system_thread is written, - * before thread->thread.func is called. See g_thread_new_internal(). + /* The lock makes sure that g_thread_new_internal() has a chance to + * setup 'func' and 'data' before we make the call. */ G_LOCK (g_thread_new); G_UNLOCK (g_thread_new); + if (thread->name) + { + g_system_thread_set_name (thread->name); + g_free (thread->name); + thread->name = NULL; + } + thread->retval = thread->thread.func (thread->thread.data); return NULL; @@ -707,87 +768,70 @@ g_thread_proxy (gpointer data) /** * g_thread_new: - * @name: a name for the new thread + * @name: (allow-none): an (optional) name for the new thread * @func: a function to execute in the new thread * @data: an argument to supply to the new thread - * @joinable: should this thread be joinable? - * @error: return location for error * * This function creates a new thread. The new thread starts by invoking * @func with the argument data. The thread will run until @func returns - * or until g_thread_exit() is called from the new thread. + * or until g_thread_exit() is called from the new thread. The return value + * of @func becomes the return value of the thread, which can be obtained + * with g_thread_join(). * - * The @name can be useful for discriminating threads in - * a debugger. Some systems restrict the length of @name to - * 16 bytes. + * The @name can be useful for discriminating threads in a debugger. + * It is not used for other purposes and does not have to be unique. + * Some systems restrict the length of @name to 16 bytes. * - * If @joinable is %TRUE, you can wait for this thread's termination - * calling g_thread_join(). Resources for a joinable thread are not - * fully released until g_thread_join() is called for that thread. - * Otherwise the thread will just disappear when it terminates. + * If the thread can not be created the program aborts. See + * g_thread_try_new() if you want to attempt to deal with failures. * - * @error can be %NULL to ignore errors, or non-%NULL to report errors. - * The error is set, if and only if the function returns %NULL. + * To free the struct returned by this function, use g_thread_unref(). + * Note that g_thread_join() implicitly unrefs the #GThread as well. * - * Returns: the new #GThread, or %NULL if an error occurred + * Returns: the new #GThread * * Since: 2.32 */ GThread * -g_thread_new (const gchar *name, - GThreadFunc func, - gpointer data, - gboolean joinable, - GError **error) +g_thread_new (const gchar *name, + GThreadFunc func, + gpointer data) { - return g_thread_new_internal (name, g_thread_proxy, func, data, joinable, 0, error); + GError *error = NULL; + GThread *thread; + + thread = g_thread_new_internal (name, g_thread_proxy, func, data, 0, &error); + + if G_UNLIKELY (thread == NULL) + g_error ("creating thread '%s': %s", name ? name : "", error->message); + + return thread; } /** - * g_thread_new_full: - * @name: a name for the new thread + * g_thread_try_new: + * @name: (allow-none): an (optional) name for the new thread * @func: a function to execute in the new thread * @data: an argument to supply to the new thread - * @joinable: should this thread be joinable? - * @stack_size: a stack size for the new thread - * @error: return location for error - * - * This function creates a new thread. The new thread starts by - * invoking @func with the argument data. The thread will run - * until @func returns or until g_thread_exit() is called. + * @error: return location for error, or %NULL * - * The @name can be useful for discriminating threads in - * a debugger. Some systems restrict the length of @name to - * 16 bytes. + * This function is the same as g_thread_new() except that + * it allows for the possibility of failure. * - * If the underlying thread implementation supports it, the thread - * gets a stack size of @stack_size or the default value for the - * current platform, if @stack_size is 0. Note that you should only - * use a non-zero @stack_size if you really can't use the default. - * In most cases, using g_thread_new() (which doesn't take a - * @stack_size) is better. - * - * If @joinable is %TRUE, you can wait for this thread's termination - * calling g_thread_join(). Resources for a joinable thread are not - * fully released until g_thread_join() is called for that thread. - * Otherwise the thread will just disappear when it terminates. - * - * @error can be %NULL to ignore errors, or non-%NULL to report errors. - * The error is set, if and only if the function returns %NULL. + * If a thread can not be created (due to resource limits), + * @error is set and %NULL is returned. * * Returns: the new #GThread, or %NULL if an error occurred * * Since: 2.32 */ GThread * -g_thread_new_full (const gchar *name, - GThreadFunc func, - gpointer data, - gboolean joinable, - gsize stack_size, - GError **error) +g_thread_try_new (const gchar *name, + GThreadFunc func, + gpointer data, + GError **error) { - return g_thread_new_internal (name, g_thread_proxy, func, data, joinable, stack_size, error); + return g_thread_new_internal (name, g_thread_proxy, func, data, 0, error); } GThread * @@ -795,34 +839,27 @@ g_thread_new_internal (const gchar *name, GThreadFunc proxy, GThreadFunc func, gpointer data, - gboolean joinable, gsize stack_size, GError **error) { - GRealThread *result; - GError *local_error = NULL; + GRealThread *thread; g_return_val_if_fail (func != NULL, NULL); - result = g_system_thread_new (); - - result->thread.joinable = joinable; - result->thread.func = func; - result->thread.data = data; - result->name = name; G_LOCK (g_thread_new); - g_system_thread_create (proxy, result, stack_size, joinable, - result, &local_error); - G_UNLOCK (g_thread_new); - - if (local_error) + thread = g_system_thread_new (proxy, stack_size, error); + if (thread) { - g_propagate_error (error, local_error); - g_system_thread_free (result); - return NULL; + thread->ref_count = 2; + thread->ours = TRUE; + thread->thread.joinable = TRUE; + thread->thread.func = func; + thread->thread.data = data; + thread->name = g_strdup (name); } + G_UNLOCK (g_thread_new); - return (GThread*) result; + return (GThread*) thread; } /** @@ -831,22 +868,26 @@ g_thread_new_internal (const gchar *name, * * Terminates the current thread. * - * If another thread is waiting for that thread using g_thread_join() - * and the current thread is joinable, the waiting thread will be woken - * up and get @retval as the return value of g_thread_join(). If the - * current thread is not joinable, @retval is ignored. + * If another thread is waiting for us using g_thread_join() then the + * waiting thread will be woken up and get @retval as the return value + * of g_thread_join(). * - * Calling g_thread_exit (retval) is equivalent to + * Calling g_thread_exit() with a parameter @retval is equivalent to * returning @retval from the function @func, as given to g_thread_new(). * - * Never call g_thread_exit() from within a thread of a - * #GThreadPool, as that will mess up the bookkeeping and lead to funny - * and unwanted results. + * You must only call g_thread_exit() from a thread that you created + * yourself with g_thread_new() or related APIs. You must not call + * this function from a thread created with another threading library + * or or from within a #GThreadPool. */ void g_thread_exit (gpointer retval) { GRealThread* real = (GRealThread*) g_thread_self (); + + if G_UNLIKELY (!real->ours) + g_error ("attempt to g_thread_exit() a thread not created by GLib"); + real->retval = retval; g_system_thread_exit (); @@ -854,23 +895,24 @@ g_thread_exit (gpointer retval) /** * g_thread_join: - * @thread: a joinable #GThread + * @thread: a #GThread * * Waits until @thread finishes, i.e. the function @func, as * given to g_thread_new(), returns or g_thread_exit() is called. * If @thread has already terminated, then g_thread_join() - * returns immediately. @thread must be joinable. + * returns immediately. * - * Any thread can wait for any other (joinable) thread by calling - * g_thread_join(), not just its 'creator'. Calling g_thread_join() - * from multiple threads for the same @thread leads to undefined - * behaviour. + * Any thread can wait for any other thread by calling g_thread_join(), + * not just its 'creator'. Calling g_thread_join() from multiple threads + * for the same @thread leads to undefined behaviour. * * The value returned by @func or given to g_thread_exit() is * returned by this function. * - * All resources of @thread including the #GThread struct are - * released before g_thread_join() returns. + * g_thread_join() consumes the reference to the passed-in @thread. + * This will usually cause the #GThread struct and associated resources + * to be freed. Use g_thread_ref() to obtain an extra reference if you + * want to keep the GThread alive beyond the g_thread_join() call. * * Returns: the return value of the thread */ @@ -881,7 +923,7 @@ g_thread_join (GThread *thread) gpointer retval; g_return_val_if_fail (thread, NULL); - g_return_val_if_fail (thread->joinable, NULL); + g_return_val_if_fail (real->ours, NULL); g_system_thread_wait (real); @@ -890,11 +932,7 @@ g_thread_join (GThread *thread) /* Just to make sure, this isn't used any more */ thread->joinable = 0; - /* the thread structure for non-joinable threads is freed upon - * thread end. We free the memory here. This will leave a loose end, - * if a joinable thread is not joined. - */ - g_system_thread_free (real); + g_thread_unref (thread); return retval; } @@ -903,7 +941,14 @@ g_thread_join (GThread *thread) * g_thread_self: * * This functions returns the #GThread corresponding to the - * current thread. + * current thread. Note that this function does not increase + * the reference count of the returned struct. + * + * This function will return a #GThread even for threads that + * were not created by GLib (i.e. those created by other threading + * APIs). This may be useful for thread identification purposes + * (i.e. comparisons) but you must not use GLib functions (such + * as g_thread_join()) on these threads. * * Returns: the #GThread representing the current thread */ @@ -918,15 +963,69 @@ g_thread_self (void) * This can happen for the main thread and for threads * that are not created by GLib. */ - thread = g_new0 (GRealThread, 1); - thread->thread.joinable = FALSE; /* This is a safe guess */ - thread->thread.func = NULL; - thread->thread.data = NULL; + thread = g_slice_new0 (GRealThread); + thread->ref_count = 1; g_private_set (&g_thread_specific_private, thread); } - return (GThread*)thread; + return (GThread*) thread; +} + +/** + * g_get_num_processors: + * + * Determine the approximate number of threads that the system will + * schedule simultaneously for this process. This is intended to be + * used as a parameter to g_thread_pool_new() for CPU bound tasks and + * similar cases. + * + * Returns: Number of schedulable threads, always greater than 0 + * + * Since: 2.36 + */ +guint +g_get_num_processors (void) +{ +#ifdef G_OS_WIN32 + DWORD_PTR process_cpus; + DWORD_PTR system_cpus; + + if (GetProcessAffinityMask (GetCurrentProcess (), + &process_cpus, &system_cpus)) + { + unsigned int count; + + for (count = 0; process_cpus != 0; process_cpus >>= 1) + if (process_cpus & 1) + count++; + + if (count > 0) + return count; + } +#elif defined(_SC_NPROCESSORS_ONLN) + { + int count; + + count = sysconf (_SC_NPROCESSORS_ONLN); + if (count > 0) + return count; + } +#elif defined HW_NCPU + { + int mib[2], count = 0; + size_t len; + + mib[0] = CTL_HW; + mib[1] = HW_NCPU; + len = sizeof(count); + + if (sysctl (mib, 2, &count, &len, NULL, 0) == 0 && count > 0) + return count; + } +#endif + + return 1; /* Fallback */ } /* Epilogue {{{1 */