luc14n0/glib
1
0
Fork 0
mirror of https://gitlab.gnome.org/GNOME/glib.git synced 2024-11-05 00:46:16 +01:00
Code Issues Packages Projects Releases Wiki Activity
62a133f55d
glib/glib/gthread.c
Christian Dywan 75b3bd99e1 Fix typo in introduction to threads in Glib
2010-02-01 12:37:23 +01:00

2539 lines
76 KiB
C
Raw Blame History

/* GLIB - Library of useful routines for C programming
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* gthread.c: MT safety related functions
* Copyright 1998 Sebastian Wilhelmi; University of Karlsruhe
* Owen Taylor
*
* 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.
*/
/* Prelude {{{1 ----------------------------------------------------------- */
/*
* 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/.
*/
/*
* MT safe
*/
/* implement gthread.h's inline functions */
#define G_IMPLEMENT_INLINES 1
#define __G_THREAD_C__
#include "config.h"
#include "glib.h"
#include "gthreadprivate.h"
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifndef G_OS_WIN32
#include <sys/time.h>
#include <time.h>
#else
#include <windows.h>
#endif /* G_OS_WIN32 */
#include <string.h>
#include "galias.h"
/**
* SECTION: threads
* @title: Threads
* @short_description: thread abstraction; including threads, different
* mutexes, conditions and thread private data
* @see_also: #GThreadPool, #GAsyncQueue
*
* Threads act almost like processes, but unlike processes all threads
* of one process share the same memory. This is good, as it provides
* easy communication between the involved threads via this shared
* memory, and it is bad, because strange things (so called
* "Heisenbugs") might happen if the program is not carefully designed.
* In particular, due to the concurrent nature of threads, no
* assumptions on the order of execution of code running in different
* threads can be made, unless order is explicitly forced by the
* programmer through synchronization primitives.
*
* The aim of the thread related functions in GLib is to provide a
* portable means for writing multi-threaded software. There are
* primitives for mutexes to protect the access to portions of memory
* (#GMutex, #GStaticMutex, #G_LOCK_DEFINE, #GStaticRecMutex and
* #GStaticRWLock). 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, #GStaticPrivate). Last but definitely not least there
* are primitives to portably create and manage threads (#GThread).
*
* The threading system is initialized with g_thread_init(), which
* takes an optional custom thread implementation or %NULL for the
* default implementation. If you want to call g_thread_init() with a
* non-%NULL argument this must be done before executing any other GLib
* functions (except g_mem_set_vtable()). This is a requirement even if
* no threads are in fact ever created by the process.
*
* Calling g_thread_init() with a %NULL argument is somewhat more
* relaxed. You may call any other glib functions in the main thread
* before g_thread_init() as long as g_thread_init() is not called from
* a glib callback, or with any locks held. However, many libraries
* above glib does not support late initialization of threads, so doing
* this should be avoided if possible.
*
* Please note that since version 2.24 the GObject initialization
* function g_type_init() initializes threads (with a %NULL argument),
* so most applications, including those using Gtk+ will run with
* threads enabled. If you want a special thread implementation, make
* sure you call g_thread_init() before g_type_init() is called.
*
* After calling g_thread_init(), GLib is completely thread safe (all
* global data is automatically locked), but individual data structure
* instances are not automatically locked for performance reasons. So,
* 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 <emphasis>are</emphasis>
* threadsafe and need no further application-level locking to be
* accessed from multiple threads.
*
* To help debugging problems in multithreaded applications, GLib
* supports error-checking mutexes that will give you helpful error
* messages on common problems. To use error-checking mutexes, define
* the symbol #G_ERRORCHECK_MUTEXES when compiling the application.
**/
/**
* G_THREADS_IMPL_POSIX:
*
* This macro is defined if POSIX style threads are used.
**/
/**
* G_THREADS_ENABLED:
*
* This macro is defined if GLib was compiled with thread support. This
* does not necessarily mean that there is a thread implementation
* available, but it does mean that the infrastructure is in place and
* that once you provide a thread implementation to g_thread_init(),
* GLib will be multi-thread safe. If #G_THREADS_ENABLED is not
* defined, then Glib is not, and cannot be, multi-thread safe.
**/
/**
* G_THREADS_IMPL_NONE:
*
* This macro is defined if no thread implementation is used. You can,
* however, provide one to g_thread_init() to make GLib multi-thread
* safe.
**/
/* G_LOCK Documentation {{{1 ---------------------------------------------- */
/* IMPLEMENTATION NOTE:
*
* G_LOCK_DEFINE and friends are convenience macros defined in
* gthread.h. Their documentation lives here.
*/
/**
* G_LOCK_DEFINE:
* @name: the name of the lock.
*
* The %G_LOCK_* macros provide a convenient interface to #GStaticMutex
* with the advantage that they will expand to nothing in programs
* compiled against a thread-disabled GLib, saving code and memory
* there. #G_LOCK_DEFINE defines a lock. It can appear anywhere
* 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 #GStaticMutex. This means that you
* can use names of existing variables as the parameter - e.g. the name
* of the variable you intent to protect with the lock. Look at our
* <function>give_me_next_number()</function> example using the
* %G_LOCK_* macros:
*
* <example>
* <title>Using the %G_LOCK_* convenience macros</title>
* <programlisting>
* G_LOCK_DEFINE (current_number);
*
* int
* give_me_next_number (void)
* {
* static int current_number = 0;
* int ret_val;
*
* G_LOCK (current_number);
* ret_val = current_number = calc_next_number (current_number);
* G_UNLOCK (current_number);
*
* return ret_val;
* }
* </programlisting>
* </example>
**/
/**
* G_LOCK_DEFINE_STATIC:
* @name: the name of the lock.
*
* This works like #G_LOCK_DEFINE, but it creates a static object.
**/
/**
* G_LOCK_EXTERN:
* @name: the name of the lock.
*
* This declares a lock, that is defined with #G_LOCK_DEFINE in another
* module.
**/
/**
* G_LOCK:
* @name: the name of the lock.
*
* Works like g_mutex_lock(), but for a lock defined with
* #G_LOCK_DEFINE.
**/
/**
* 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.
**/
/**
* G_UNLOCK:
* @name: the name of the lock.
*
* Works like g_mutex_unlock(), but for a lock defined with
* #G_LOCK_DEFINE.
**/
/* GThreadError {{{1 ------------------------------------------------------- */
/**
* GThreadError:
* @G_THREAD_ERROR_AGAIN: a thread couldn't be created due to resource
* shortage. Try again later.
*
* Possible errors of thread related functions.
**/
/**
* G_THREAD_ERROR:
*
* The error domain of the GLib thread subsystem.
**/
GQuark
g_thread_error_quark (void)
{
return g_quark_from_static_string ("g_thread_error");
}
/* Miscellaneous Structures {{{1 ------------------------------------------ */
/* Keep this in sync with GRealThread in gmain.c! */
typedef struct _GRealThread GRealThread;
struct _GRealThread
{
GThread thread;
gpointer private_data;
GRealThread *next;
gpointer retval;
GSystemThread system_thread;
};
typedef struct _GStaticPrivateNode GStaticPrivateNode;
struct _GStaticPrivateNode
{
gpointer data;
GDestroyNotify destroy;
};
static void g_thread_cleanup (gpointer data);
static void g_thread_fail (void);
static guint64 gettime (void);
guint64 (*g_thread_gettime) (void) = gettime;
/* Global Variables {{{1 -------------------------------------------------- */
static GSystemThread zero_thread; /* This is initialized to all zero */
gboolean g_thread_use_default_impl = TRUE;
/**
* g_thread_supported:
* @Returns: %TRUE, if the thread system is initialized.
*
* This function returns %TRUE if the thread system is initialized, and
* %FALSE if it is not.
*
* <note><para>This function is actually a macro. Apart from taking the
* address of it you can however use it as if it was a
* function.</para></note>
**/
/* IMPLEMENTATION NOTE:
*
* g_thread_supported() is just returns g_threads_got_initialized
*/
gboolean g_threads_got_initialized = FALSE;
/* Thread Implementation Virtual Function Table {{{1 ---------------------- */
/* Virtual Function Table Documentation {{{2 ------------------------------ */
/**
* GThreadFunctions:
* @mutex_new: virtual function pointer for g_mutex_new()
* @mutex_lock: virtual function pointer for g_mutex_lock()
* @mutex_trylock: virtual function pointer for g_mutex_trylock()
* @mutex_unlock: virtual function pointer for g_mutex_unlock()
* @mutex_free: virtual function pointer for g_mutex_free()
* @cond_new: virtual function pointer for g_cond_new()
* @cond_signal: virtual function pointer for g_cond_signal()
* @cond_broadcast: virtual function pointer for g_cond_broadcast()
* @cond_wait: virtual function pointer for g_cond_wait()
* @cond_timed_wait: virtual function pointer for g_cond_timed_wait()
* @cond_free: virtual function pointer for g_cond_free()
* @private_new: virtual function pointer for g_private_new()
* @private_get: virtual function pointer for g_private_get()
* @private_set: virtual function pointer for g_private_set()
* @thread_create: virtual function pointer for g_thread_create()
* @thread_yield: virtual function pointer for g_thread_yield()
* @thread_join: virtual function pointer for g_thread_join()
* @thread_exit: virtual function pointer for g_thread_exit()
* @thread_set_priority: virtual function pointer for
* g_thread_set_priority()
* @thread_self: virtual function pointer for g_thread_self()
* @thread_equal: used internally by recursive mutex locks and by some
* assertion checks
*
* This function table is used by g_thread_init() to initialize the
* thread system. The functions in the table are directly used by their
* g_* prepended counterparts (described in this document). For
* example, if you call g_mutex_new() then mutex_new() from the table
* provided to g_thread_init() will be called.
*
* <note><para>Do not use this struct unless you know what you are
* doing.</para></note>
**/
/* IMPLEMENTATION NOTE:
*
* g_thread_functions_for_glib_use is a global symbol that gets used by
* most of the "primative" threading calls. g_mutex_lock(), for
* example, is just a macro that calls the appropriate virtual function
* out of this table.
*
* For that reason, all of those macros are documented here.
*/
GThreadFunctions g_thread_functions_for_glib_use = {
/* GMutex Virtual Functions {{{2 ------------------------------------------ */
/**
* GMutex:
*
* 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:
*
* <example>
* <title>A function which will not work in a threaded environment</title>
* <programlisting>
* 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
* *<!-- -->/
* current_number = calc_next_number (current_number);
*
* return current_number;
* }
* </programlisting>
* </example>
*
* 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 first naive implementation would be:
*
* <example>
* <title>The wrong way to write a thread-safe function</title>
* <programlisting>
* int
* give_me_next_number (void)
* {
* static int current_number = 0;
* int ret_val;
* static GMutex * mutex = NULL;
*
* if (!mutex) mutex = g_mutex_new (<!-- -->);
*
* g_mutex_lock (mutex);
* ret_val = current_number = calc_next_number (current_number);
* g_mutex_unlock (mutex);
*
* return ret_val;
* }
* </programlisting>
* </example>
*
* This looks like it would work, but there is a race condition while
* constructing the mutex and this code cannot work reliable. Please do
* not use such constructs in your own programs! One working solution
* is:
*
* <example>
* <title>A correct thread-safe function</title>
* <programlisting>
* static GMutex *give_me_next_number_mutex = NULL;
*
* /<!-- -->* this function must be called before any call to
* * give_me_next_number(<!-- -->)
* *
* * it must be called exactly once.
* *<!-- -->/
* void
* init_give_me_next_number (void)
* {
* g_assert (give_me_next_number_mutex == NULL);
* give_me_next_number_mutex = g_mutex_new (<!-- -->);
* }
*
* int
* give_me_next_number (void)
* {
* static int current_number = 0;
* int ret_val;
*
* g_mutex_lock (give_me_next_number_mutex);
* ret_val = current_number = calc_next_number (current_number);
* g_mutex_unlock (give_me_next_number_mutex);
*
* return ret_val;
* }
* </programlisting>
* </example>
*
* #GStaticMutex provides a simpler and safer way of doing this.
*
* If you want to use a mutex, and your code should also work without
* calling g_thread_init() first, then you can not use a #GMutex, as
* g_mutex_new() requires that the thread system be initialized. Use a
* #GStaticMutex instead.
*
* A #GMutex should only be accessed via the following functions.
*
* <note><para>All of the <function>g_mutex_*</function> functions are
* actually macros. Apart from taking their addresses, you can however
* use them as if they were functions.</para></note>
**/
/**
* g_mutex_new:
* @Returns: a new #GMutex.
*
* Creates a new #GMutex.
*
* <note><para>This function will abort if g_thread_init() has not been
* called yet.</para></note>
**/
(GMutex*(*)())g_thread_fail,
/**
* 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.
*
* This function can be used even if g_thread_init() has not yet been
* called, and, in that case, will do nothing.
*
* <note><para>#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
* #GStaticRecMutex, if you need recursive mutexes.</para></note>
**/
NULL,
/**
* g_mutex_trylock:
* @mutex: a #GMutex.
* @Returns: %TRUE, if @mutex could be locked.
*
* Tries to lock @mutex. If @mutex is already locked by another thread,
* 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><para>#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 #GStaticRecMutex, if you need recursive
* mutexes.</para></note>
**/
NULL,
/**
* g_mutex_unlock:
* @mutex: a #GMutex.
*
* Unlocks @mutex. If another thread is blocked in a g_mutex_lock()
* call for @mutex, it will be woken and can lock @mutex itself.
*
* This function can be used even if g_thread_init() has not yet been
* called, and, in that case, will do nothing.
**/
NULL,
/**
* g_mutex_free:
* @mutex: a #GMutex.
*
* Destroys @mutex.
*
* <note><para>Calling g_mutex_free() on a locked mutex may result in
* undefined behaviour.</para></note>
**/
NULL,
/* GCond Virtual Functions {{{2 ------------------------------------------ */
/**
* GCond:
*
* The #GCond struct is an opaque data structure that represents a
* condition. Threads can block on a #GCond if they find a certain
* condition to be false. If other threads change the state of this
* condition they signal the #GCond, and that causes the waiting
* threads to be woken up.
*
* <example>
* <title>
* Using GCond to block a thread until a condition is satisfied
* </title>
* <programlisting>
* GCond* data_cond = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
* GMutex* data_mutex = NULL; /<!-- -->* Must be initialized somewhere *<!-- -->/
* gpointer current_data = NULL;
*
* void
* push_data (gpointer data)
* {
* g_mutex_lock (data_mutex);
* current_data = data;
* g_cond_signal (data_cond);
* g_mutex_unlock (data_mutex);
* }
*
* gpointer
* pop_data (void)
* {
* gpointer data;
*
* g_mutex_lock (data_mutex);
* while (!current_data)
* g_cond_wait (data_cond, data_mutex);
* data = current_data;
* current_data = NULL;
* g_mutex_unlock (data_mutex);
*
* return data;
* }
* </programlisting>
* </example>
*
* Whenever a thread calls <function>pop_data()</function> now, it will
* wait until current_data is non-%NULL, i.e. until some other thread
* has called <function>push_data()</function>.
*
* <note><para>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.</para></note>
*
* A #GCond should only be accessed via the following functions.
*
* <note><para>All of the <function>g_cond_*</function> functions are
* actually macros. Apart from taking their addresses, you can however
* use them as if they were functions.</para></note>
**/
/**
* g_cond_new:
* @Returns: a new #GCond.
*
* Creates a new #GCond. This function will abort, if g_thread_init()
* has not been called yet.
**/
(GCond*(*)())g_thread_fail,
/**
* g_cond_signal:
* @cond: a #GCond.
*
* If threads are waiting for @cond, exactly one of them is woken up.
* 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.
**/
NULL,
/**
* g_cond_broadcast:
* @cond: a #GCond.
*
* If threads are waiting for @cond, all of them are woken up. 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.
**/
NULL,
/**
* g_cond_wait:
* @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.
**/
NULL,
/**
* g_cond_timed_wait:
* @cond: a #GCond.
* @mutex: a #GMutex that is currently locked.
* @abs_time: a #GTimeVal, determining the final time.
* @Returns: %TRUE if @cond was signalled, or %FALSE on timeout.
*
* 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.
*
* If @abs_time is %NULL, g_cond_timed_wait() acts like g_cond_wait().
*
* This function can be used even if g_thread_init() has not yet been
* called, and, in that case, will immediately return %TRUE.
*
* To easily calculate @abs_time a combination of g_get_current_time()
* and g_time_val_add() can be used.
**/
NULL,
/**
* g_cond_free:
* @cond: a #GCond.
*
* Destroys the #GCond.
**/
NULL,
/* GPrivate Virtual Functions {{{2 --------------------------------------- */
/**
* GPrivate:
*
* The #GPrivate struct is an opaque data structure to represent a
* thread private data key. Threads can thereby obtain and set a
* pointer which is private to the current thread. Take our
* <function>give_me_next_number(<!-- -->)</function> example from
* above. Suppose we don't want <literal>current_number</literal> to be
* shared between the threads, but instead to be private to each thread.
* This can be done as follows:
*
* <example>
* <title>Using GPrivate for per-thread data</title>
* <programlisting>
* GPrivate* current_number_key = NULL; /<!-- -->* Must be initialized somewhere
* with g_private_new (g_free); *<!-- -->/
*
* int
* give_me_next_number (void)
* {
* int *current_number = g_private_get (current_number_key);
*
* if (!current_number)
* {
* current_number = g_new (int, 1);
* *current_number = 0;
* g_private_set (current_number_key, current_number);
* }
*
* *current_number = calc_next_number (*current_number);
*
* return *current_number;
* }
* </programlisting>
* </example>
*
* Here the pointer belonging to the key
* <literal>current_number_key</literal> is read. If it is %NULL, it has
* not been set yet. Then get memory for an integer value, assign this
* memory to the pointer and write the pointer back. Now we have an
* integer value that is private to the current thread.
*
* The #GPrivate struct should only be accessed via the following
* functions.
*
* <note><para>All of the <function>g_private_*</function> functions are
* actually macros. Apart from taking their addresses, you can however
* use them as if they were functions.</para></note>
**/
/**
* g_private_new:
* @destructor: a function to destroy the data keyed to #GPrivate when
* a thread ends.
* @Returns: a new #GPrivate.
*
* Creates a new #GPrivate. If @destructor is non-%NULL, it is a
* pointer to a destructor function. Whenever a thread ends and the
* corresponding pointer keyed to this instance of #GPrivate is
* non-%NULL, the destructor is called with this pointer as the
* argument.
*
* <note><para>@destructor is used quite differently from @notify in
* g_static_private_set().</para></note>
*
* <note><para>A #GPrivate can not be freed. Reuse it instead, if you
* can, to avoid shortage, or use #GStaticPrivate.</para></note>
*
* <note><para>This function will abort if g_thread_init() has not been
* called yet.</para></note>
**/
(GPrivate*(*)(GDestroyNotify))g_thread_fail,
/**
* g_private_get:
* @private_key: a #GPrivate.
* @Returns: the corresponding pointer.
*
* 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 intialization.
**/
NULL,
/**
* g_private_set:
* @private_key: a #GPrivate.
* @data: the new pointer.
*
* Sets the pointer keyed to @private_key for 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.
**/
NULL,
/* GThread Virtual Functions {{{2 ---------------------------------------- */
/**
* GThread:
*
* The #GThread struct represents a running thread. It has three public
* read-only members, but the underlying struct is bigger, so you must
* not copy this struct.
*
* <note><para>Resources for a joinable thread are not fully released
* until g_thread_join() is called for that thread.</para></note>
**/
/**
* GThreadFunc:
* @data: data passed to the thread.
* @Returns: the return value of the thread, which will be returned by
* g_thread_join().
*
* Specifies the type of the @func functions passed to
* g_thread_create() or g_thread_create_full().
**/
/**
* GThreadPriority:
* @G_THREAD_PRIORITY_LOW: a priority lower than normal
* @G_THREAD_PRIORITY_NORMAL: the default priority
* @G_THREAD_PRIORITY_HIGH: a priority higher than normal
* @G_THREAD_PRIORITY_URGENT: the highest priority
*
* Specifies the priority of a thread.
*
* <note><para>It is not guaranteed that threads with different priorities
* really behave accordingly. On some systems (e.g. Linux) there are no
* thread priorities. On other systems (e.g. Solaris) there doesn't
* seem to be different scheduling for different priorities. All in all
* try to avoid being dependent on priorities.</para></note>
**/
/**
* g_thread_create:
* @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.
* @Returns: the new #GThread on success.
*
* This function creates a new thread with the default priority.
*
* If @joinable is %TRUE, you can wait for this threads termination
* calling g_thread_join(). Otherwise the thread will just disappear
* when it terminates.
*
* The new thread executes the function @func with the argument @data.
* If the thread was created successfully, it is returned.
*
* @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.
**/
(void(*)(GThreadFunc, gpointer, gulong,
gboolean, gboolean, GThreadPriority,
gpointer, GError**))g_thread_fail,
/**
* g_thread_yield:
*
* Gives way to other threads waiting to be scheduled.
*
* 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.
**/
NULL,
NULL, /* thread_join */
NULL, /* thread_exit */
NULL, /* thread_set_priority */
NULL, /* thread_self */
NULL /* thread_equal */
};
/* Local Data {{{1 -------------------------------------------------------- */
static GMutex *g_once_mutex = NULL;
static GCond *g_once_cond = NULL;
static GPrivate *g_thread_specific_private = NULL;
static GRealThread *g_thread_all_threads = NULL;
static GSList *g_thread_free_indeces = NULL;
static GSList* g_once_init_list = NULL;
G_LOCK_DEFINE_STATIC (g_thread);
/* Initialisation {{{1 ---------------------------------------------------- */
#ifdef G_THREADS_ENABLED
/**
* g_thread_init:
* @vtable: a function table of type #GThreadFunctions, that provides
* the entry points to the thread system to be used.
*
* If you use GLib from more than one thread, you must initialize the
* thread system by calling g_thread_init(). Most of the time you will
* only have to call <literal>g_thread_init (NULL)</literal>.
*
* <note><para>Do not call g_thread_init() with a non-%NULL parameter unless
* you really know what you are doing.</para></note>
*
* <note><para>g_thread_init() must not be called directly or indirectly as a
* callback from GLib. Also no mutexes may be currently locked while
* calling g_thread_init().</para></note>
*
* <note><para>g_thread_init() changes the way in which #GTimer measures
* elapsed time. As a consequence, timers that are running while
* g_thread_init() is called may report unreliable times.</para></note>
*
* Calling g_thread_init() multiple times is allowed (since version
* 2.24), but nothing happens except for the first call. If the
* argument is non-%NULL on such a call a warning will be printed, but
* otherwise the argument is ignored.
*
* If no thread system is available and @vtable is %NULL or if not all
* elements of @vtable are non-%NULL, then g_thread_init() will abort.
*
* <note><para>To use g_thread_init() in your program, you have to link with
* the libraries that the command <command>pkg-config --libs
* gthread-2.0</command> outputs. This is not the case for all the
* other thread related functions of GLib. Those can be used without
* having to link with the thread libraries.</para></note>
**/
/* This must be called only once, before any threads are created.
* It will only be called from g_thread_init() in -lgthread.
*/
void
g_thread_init_glib (void)
{
/* We let the main thread (the one that calls g_thread_init) inherit
* the static_private data set before calling g_thread_init
*/
GRealThread* main_thread = (GRealThread*) g_thread_self ();
/* mutex and cond creation works without g_threads_got_initialized */
g_once_mutex = g_mutex_new ();
g_once_cond = g_cond_new ();
/* we may only create mutex and cond in here */
_g_mem_thread_init_noprivate_nomessage ();
/* setup the basic threading system */
g_threads_got_initialized = TRUE;
g_thread_specific_private = g_private_new (g_thread_cleanup);
g_private_set (g_thread_specific_private, main_thread);
G_THREAD_UF (thread_self, (&main_thread->system_thread));
/* complete memory system initialization, g_private_*() works now */
_g_slice_thread_init_nomessage ();
/* accomplish log system initialization to enable messaging */
_g_messages_thread_init_nomessage ();
/* we may run full-fledged initializers from here */
_g_atomic_thread_init ();
_g_convert_thread_init ();
_g_rand_thread_init ();
_g_main_thread_init ();
_g_utils_thread_init ();
_g_futex_thread_init ();
#ifdef G_OS_WIN32
_g_win32_thread_init ();
#endif
}
#endif /* G_THREADS_ENABLED */
/* The following sections implement: GOnce, GStaticMutex, GStaticRecMutex,
* GStaticPrivate,
**/
/* GOnce {{{1 ------------------------------------------------------------- */
/**
* GOnce:
* @status: the status of the #GOnce
* @retval: the value returned by the call to the function, if @status
* is %G_ONCE_STATUS_READY
*
* A #GOnce struct controls a one-time initialization function. Any
* one-time initialization function must have its own unique #GOnce
* struct.
*
* Since: 2.4
**/
/**
* G_ONCE_INIT:
*
* A #GOnce must be initialized with this macro before it can be used.
*
* <informalexample>
* <programlisting>
* GOnce my_once = G_ONCE_INIT;
* </programlisting>
* </informalexample>
*
* Since: 2.4
**/
/**
* GOnceStatus:
* @G_ONCE_STATUS_NOTCALLED: the function has not been called yet.
* @G_ONCE_STATUS_PROGRESS: the function call is currently in progress.
* @G_ONCE_STATUS_READY: the function has been called.
*
* The possible statuses of a one-time initialization function
* controlled by a #GOnce struct.
*
* Since: 2.4
**/
/**
* g_once:
* @once: a #GOnce structure
* @func: the #GThreadFunc function associated to @once. This function
* is called only once, regardless of the number of times it and
* its associated #GOnce struct are passed to g_once().
* @arg: data to be passed to @func
*
* The first call to this routine by a process with a given #GOnce
* struct calls @func with the given argument. Thereafter, subsequent
* calls to g_once() with the same #GOnce struct do not call @func
* again, but return the stored result of the first call. On return
* from g_once(), the status of @once will be %G_ONCE_STATUS_READY.
*
* For example, a mutex or a thread-specific data key must be created
* exactly once. In a threaded environment, calling g_once() ensures
* that the initialization is serialized across multiple threads.
*
* <note><para>Calling g_once() recursively on the same #GOnce struct in
* @func will lead to a deadlock.</para></note>
*
* <informalexample>
* <programlisting>
* gpointer
* get_debug_flags (void)
* {
* static GOnce my_once = G_ONCE_INIT;
*
* g_once (&my_once, parse_debug_flags, NULL);
*
* return my_once.retval;
* }
* </programlisting>
* </informalexample>
*
* Since: 2.4
**/
gpointer
g_once_impl (GOnce *once,
GThreadFunc func,
gpointer arg)
{
g_mutex_lock (g_once_mutex);
while (once->status == G_ONCE_STATUS_PROGRESS)
g_cond_wait (g_once_cond, g_once_mutex);
if (once->status != G_ONCE_STATUS_READY)
{
once->status = G_ONCE_STATUS_PROGRESS;
g_mutex_unlock (g_once_mutex);
once->retval = func (arg);
g_mutex_lock (g_once_mutex);
once->status = G_ONCE_STATUS_READY;
g_cond_broadcast (g_once_cond);
}
g_mutex_unlock (g_once_mutex);
return once->retval;
}
/**
* g_once_init_enter:
* @value_location: location of a static initializable variable
* containing 0.
* @Returns: %TRUE if the initialization section should be entered,
* %FALSE and blocks otherwise
*
* Function to be called when starting a critical initialization
* section. The argument @value_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
* be ensured that an initialization section will be executed only once
* during a program's life time, and that concurrent threads are
* blocked until initialization completed. To be used in constructs
* like this:
*
* <informalexample>
* <programlisting>
* static gsize initialization_value = 0;
*
* if (g_once_init_enter (&amp;initialization_value))
* {
* gsize setup_value = 42; /<!-- -->* initialization code here *<!-- -->/
*
* g_once_init_leave (&amp;initialization_value, setup_value);
* }
*
* /<!-- -->* use initialization_value here *<!-- -->/
* </programlisting>
* </informalexample>
*
* Since: 2.14
**/
gboolean
g_once_init_enter_impl (volatile gsize *value_location)
{
gboolean need_init = FALSE;
g_mutex_lock (g_once_mutex);
if (g_atomic_pointer_get (value_location) == NULL)
{
if (!g_slist_find (g_once_init_list, (void*) value_location))
{
need_init = TRUE;
g_once_init_list = g_slist_prepend (g_once_init_list, (void*) value_location);
}
else
do
g_cond_wait (g_once_cond, g_once_mutex);
while (g_slist_find (g_once_init_list, (void*) value_location));
}
g_mutex_unlock (g_once_mutex);
return need_init;
}
/**
* g_once_init_leave:
* @value_location: location of a static initializable variable
* containing 0.
* @initialization_value: new non-0 value for *@value_location.
*
* Counterpart to g_once_init_enter(). Expects a location of a static
* 0-initialized initialization variable, and an initialization value
* other than 0. Sets the variable to the initialization value, and
* releases concurrent threads blocking in g_once_init_enter() on this
* initialization variable.
*
* Since: 2.14
**/
void
g_once_init_leave (volatile gsize *value_location,
gsize initialization_value)
{
g_return_if_fail (g_atomic_pointer_get (value_location) == NULL);
g_return_if_fail (initialization_value != 0);
g_return_if_fail (g_once_init_list != NULL);
g_atomic_pointer_set ((void**)value_location, (void*) initialization_value);
g_mutex_lock (g_once_mutex);
g_once_init_list = g_slist_remove (g_once_init_list, (void*) value_location);
g_cond_broadcast (g_once_cond);
g_mutex_unlock (g_once_mutex);
}
/* GStaticMutex {{{1 ------------------------------------------------------ */
/**
* GStaticMutex:
*
* A #GStaticMutex works like a #GMutex, but it has one significant
* advantage. It doesn't need to be created at run-time like a #GMutex,
* but can be defined at compile-time. Here is a shorter, easier and
* safer version of our <function>give_me_next_number()</function>
* example:
*
* <example>
* <title>
* Using <structname>GStaticMutex</structname>
* to simplify thread-safe programming
* </title>
* <programlisting>
* int
* give_me_next_number (void)
* {
* static int current_number = 0;
* int ret_val;
* static GStaticMutex mutex = G_STATIC_MUTEX_INIT;
*
* g_static_mutex_lock (&amp;mutex);
* ret_val = current_number = calc_next_number (current_number);
* g_static_mutex_unlock (&amp;mutex);
*
* return ret_val;
* }
* </programlisting>
* </example>
*
* Sometimes you would like to dynamically create a mutex. If you don't
* want to require prior calling to g_thread_init(), because your code
* should also be usable in non-threaded programs, you are not able to
* use g_mutex_new() and thus #GMutex, as that requires a prior call to
* g_thread_init(). In theses cases you can also use a #GStaticMutex.
* It must be initialized with g_static_mutex_init() before using it
* and freed with with g_static_mutex_free() when not needed anymore to
* free up any allocated resources.
*
* Even though #GStaticMutex is not opaque, it should only be used with
* the following functions, as it is defined differently on different
* platforms.
*
* All of the <function>g_static_mutex_*</function> functions apart
* from <function>g_static_mutex_get_mutex</function> can also be used
* even if g_thread_init() has not yet been called. Then they do
* nothing, apart from <function>g_static_mutex_trylock</function>,
* which does nothing but returning %TRUE.
*
* <note><para>All of the <function>g_static_mutex_*</function>
* functions are actually macros. Apart from taking their addresses, you
* can however use them as if they were functions.</para></note>
**/
/**
* G_STATIC_MUTEX_INIT:
*
* A #GStaticMutex must be initialized with this macro, before it can
* be used. This macro can used be to initialize a variable, but it
* cannot be assigned to a variable. In that case you have to use
* g_static_mutex_init().
*
* <informalexample>
* <programlisting>
* GStaticMutex my_mutex = G_STATIC_MUTEX_INIT;
* </programlisting>
* </informalexample>
**/
/**
* g_static_mutex_init:
* @mutex: a #GStaticMutex to be initialized.
*
* Initializes @mutex. Alternatively you can initialize it with
* #G_STATIC_MUTEX_INIT.
**/
void
g_static_mutex_init (GStaticMutex *mutex)
{
static const GStaticMutex init_mutex = G_STATIC_MUTEX_INIT;
g_return_if_fail (mutex);
*mutex = init_mutex;
}
/* IMPLEMENTATION NOTE:
*
* On some platforms a GStaticMutex is actually a normal GMutex stored
* inside of a structure instead of being allocated dynamically. We can
* only do this for platforms on which we know, in advance, how to
* allocate (size) and initialise (value) that memory.
*
* On other platforms, a GStaticMutex is nothing more than a pointer to
* a GMutex. In that case, the first access we make to the static mutex
* must first allocate the normal GMutex and store it into the pointer.
*
* configure.in writes macros into glibconfig.h to determine if
* g_static_mutex_get_mutex() accesses the sturcture in memory directly
* (on platforms where we are able to do that) or if it ends up here,
* where we may have to allocate the GMutex before returning it.
*/
/**
* g_static_mutex_get_mutex:
* @mutex: a #GStaticMutex.
* @Returns: the #GMutex corresponding to @mutex.
*
* For some operations (like g_cond_wait()) you must have a #GMutex
* instead of a #GStaticMutex. This function will return the
* corresponding #GMutex for @mutex.
**/
GMutex *
g_static_mutex_get_mutex_impl (GMutex** mutex)
{
if (!g_thread_supported ())
return NULL;
g_assert (g_once_mutex);
g_mutex_lock (g_once_mutex);
if (!(*mutex))
g_atomic_pointer_set (mutex, g_mutex_new());
g_mutex_unlock (g_once_mutex);
return *mutex;
}
/* IMPLEMENTATION NOTE:
*
* g_static_mutex_lock(), g_static_mutex_trylock() and
* g_static_mutex_unlock() are all preprocessor macros that wrap the
* corresponding g_mutex_*() function around a call to
* g_static_mutex_get_mutex().
*/
/**
* g_static_mutex_lock:
* @mutex: a #GStaticMutex.
*
* Works like g_mutex_lock(), but for a #GStaticMutex.
**/
/**
* g_static_mutex_trylock:
* @mutex: a #GStaticMutex.
* @Returns: %TRUE, if the #GStaticMutex could be locked.
*
* Works like g_mutex_trylock(), but for a #GStaticMutex.
**/
/**
* g_static_mutex_unlock:
* @mutex: a #GStaticMutex.
*
* Works like g_mutex_unlock(), but for a #GStaticMutex.
**/
/**
* g_static_mutex_free:
* @mutex: a #GStaticMutex to be freed.
*
* Releases all resources allocated to @mutex.
*
* You don't have to call this functions for a #GStaticMutex with an
* unbounded lifetime, i.e. objects declared 'static', but if you have
* a #GStaticMutex as a member of a structure and the structure is
* freed, you should also free the #GStaticMutex.
*
* <note><para>Calling g_static_mutex_free() on a locked mutex may
* result in undefined behaviour.</para></note>
**/
void
g_static_mutex_free (GStaticMutex* mutex)
{
GMutex **runtime_mutex;
g_return_if_fail (mutex);
/* The runtime_mutex is the first (or only) member of GStaticMutex,
* see both versions (of glibconfig.h) in configure.in. Note, that
* this variable is NULL, if g_thread_init() hasn't been called or
* if we're using the default thread implementation and it provides
* static mutexes. */
runtime_mutex = ((GMutex**)mutex);
if (*runtime_mutex)
g_mutex_free (*runtime_mutex);
*runtime_mutex = NULL;
}
/* ------------------------------------------------------------------------ */
/**
* GStaticRecMutex:
*
* A #GStaticRecMutex works like a #GStaticMutex, but it can be locked
* multiple times by one thread. If you enter it n times, you have to
* unlock it n times again to let other threads lock it. An exception
* is the function g_static_rec_mutex_unlock_full(): that allows you to
* unlock a #GStaticRecMutex completely returning the depth, (i.e. the
* number of times this mutex was locked). The depth can later be used
* to restore the state of the #GStaticRecMutex by calling
* g_static_rec_mutex_lock_full().
*
* Even though #GStaticRecMutex is not opaque, it should only be used
* with the following functions.
*
* All of the <function>g_static_rec_mutex_*</function> functions can
* be used even if g_thread_init() has not been called. Then they do
* nothing, apart from <function>g_static_rec_mutex_trylock</function>,
* which does nothing but returning %TRUE.
**/
/**
* G_STATIC_REC_MUTEX_INIT:
*
* A #GStaticRecMutex must be initialized with this macro before it can
* be used. This macro can used be to initialize a variable, but it
* cannot be assigned to a variable. In that case you have to use
* g_static_rec_mutex_init().
*
* <informalexample>
* <programlisting>
* GStaticRecMutex my_mutex = G_STATIC_REC_MUTEX_INIT;
* </programlisting>
</informalexample>
**/
/**
* g_static_rec_mutex_init:
* @mutex: a #GStaticRecMutex to be initialized.
*
* A #GStaticRecMutex must be initialized with this function before it
* can be used. Alternatively you can initialize it with
* #G_STATIC_REC_MUTEX_INIT.
**/
void
g_static_rec_mutex_init (GStaticRecMutex *mutex)
{
static const GStaticRecMutex init_mutex = G_STATIC_REC_MUTEX_INIT;
g_return_if_fail (mutex);
*mutex = init_mutex;
}
/**
* g_static_rec_mutex_lock:
* @mutex: a #GStaticRecMutex to lock.
*
* Locks @mutex. If @mutex is already locked by another thread, the
* current thread will block until @mutex is unlocked by the other
* thread. If @mutex is already locked by the calling thread, this
* functions increases the depth of @mutex and returns immediately.
**/
void
g_static_rec_mutex_lock (GStaticRecMutex* mutex)
{
GSystemThread self;
g_return_if_fail (mutex);
if (!g_thread_supported ())
return;
G_THREAD_UF (thread_self, (&self));
if (g_system_thread_equal (self, mutex->owner))
{
mutex->depth++;
return;
}
g_static_mutex_lock (&mutex->mutex);
g_system_thread_assign (mutex->owner, self);
mutex->depth = 1;
}
/**
* g_static_rec_mutex_trylock:
* @mutex: a #GStaticRecMutex to lock.
* @Returns: %TRUE, if @mutex could be locked.
*
* Tries to lock @mutex. If @mutex is already locked by another thread,
* it immediately returns %FALSE. Otherwise it locks @mutex and returns
* %TRUE. If @mutex is already locked by the calling thread, this
* functions increases the depth of @mutex and immediately returns
* %TRUE.
**/
gboolean
g_static_rec_mutex_trylock (GStaticRecMutex* mutex)
{
GSystemThread self;
g_return_val_if_fail (mutex, FALSE);
if (!g_thread_supported ())
return TRUE;
G_THREAD_UF (thread_self, (&self));
if (g_system_thread_equal (self, mutex->owner))
{
mutex->depth++;
return TRUE;
}
if (!g_static_mutex_trylock (&mutex->mutex))
return FALSE;
g_system_thread_assign (mutex->owner, self);
mutex->depth = 1;
return TRUE;
}
/**
* g_static_rec_mutex_unlock:
* @mutex: a #GStaticRecMutex to unlock.
*
* Unlocks @mutex. Another thread will be allowed to lock @mutex only
* when it has been unlocked as many times as it had been locked
* before. If @mutex is completely unlocked and another thread is
* blocked in a g_static_rec_mutex_lock() call for @mutex, it will be
* woken and can lock @mutex itself.
**/
void
g_static_rec_mutex_unlock (GStaticRecMutex* mutex)
{
g_return_if_fail (mutex);
if (!g_thread_supported ())
return;
if (mutex->depth > 1)
{
mutex->depth--;
return;
}
g_system_thread_assign (mutex->owner, zero_thread);
g_static_mutex_unlock (&mutex->mutex);
}
/**
* g_static_rec_mutex_lock_full:
* @mutex: a #GStaticRecMutex to lock.
* @depth: number of times this mutex has to be unlocked to be
* completely unlocked.
*
* Works like calling g_static_rec_mutex_lock() for @mutex @depth times.
**/
void
g_static_rec_mutex_lock_full (GStaticRecMutex *mutex,
guint depth)
{
GSystemThread self;
g_return_if_fail (mutex);
if (!g_thread_supported ())
return;
if (depth == 0)
return;
G_THREAD_UF (thread_self, (&self));
if (g_system_thread_equal (self, mutex->owner))
{
mutex->depth += depth;
return;
}
g_static_mutex_lock (&mutex->mutex);
g_system_thread_assign (mutex->owner, self);
mutex->depth = depth;
}
/**
* g_static_rec_mutex_unlock_full:
* @mutex: a #GStaticRecMutex to completely unlock.
* @Returns: number of times @mutex has been locked by the current
* thread.
*
* Completely unlocks @mutex. If another thread is blocked in a
* g_static_rec_mutex_lock() call for @mutex, it will be woken and can
* lock @mutex itself. This function returns the number of times that
* @mutex has been locked by the current thread. To restore the state
* before the call to g_static_rec_mutex_unlock_full() you can call
* g_static_rec_mutex_lock_full() with the depth returned by this
* function.
**/
guint
g_static_rec_mutex_unlock_full (GStaticRecMutex *mutex)
{
guint depth;
g_return_val_if_fail (mutex, 0);
if (!g_thread_supported ())
return 1;
depth = mutex->depth;
g_system_thread_assign (mutex->owner, zero_thread);
mutex->depth = 0;
g_static_mutex_unlock (&mutex->mutex);
return depth;
}
/**
* g_static_rec_mutex_free:
* @mutex: a #GStaticRecMutex to be freed.
*
* Releases all resources allocated to a #GStaticRecMutex.
*
* You don't have to call this functions for a #GStaticRecMutex with an
* unbounded lifetime, i.e. objects declared 'static', but if you have
* a #GStaticRecMutex as a member of a structure and the structure is
* freed, you should also free the #GStaticRecMutex.
**/
void
g_static_rec_mutex_free (GStaticRecMutex *mutex)
{
g_return_if_fail (mutex);
g_static_mutex_free (&mutex->mutex);
}
/* GStaticPrivate {{{1 ---------------------------------------------------- */
/**
* GStaticPrivate:
*
* A #GStaticPrivate works almost like a #GPrivate, but it has one
* significant advantage. It doesn't need to be created at run-time
* like a #GPrivate, but can be defined at compile-time. This is
* similar to the difference between #GMutex and #GStaticMutex. Now
* look at our <function>give_me_next_number()</function> example with
* #GStaticPrivate:
*
* <example>
* <title>Using GStaticPrivate for per-thread data</title>
* <programlisting>
* int
* give_me_next_number (<!-- -->)
* {
* static GStaticPrivate current_number_key = G_STATIC_PRIVATE_INIT;
* int *current_number = g_static_private_get (&amp;current_number_key);
*
* if (!current_number)
* {
* current_number = g_new (int,1);
* *current_number = 0;
* g_static_private_set (&amp;current_number_key, current_number, g_free);
* }
*
* *current_number = calc_next_number (*current_number);
*
* return *current_number;
* }
* </programlisting>
* </example>
**/
/**
* G_STATIC_PRIVATE_INIT:
*
* Every #GStaticPrivate must be initialized with this macro, before it
* can be used.
*
* <informalexample>
* <programlisting>
* GStaticPrivate my_private = G_STATIC_PRIVATE_INIT;
* </programlisting>
* </informalexample>
**/
/**
* g_static_private_init:
* @private_key: a #GStaticPrivate to be initialized.
*
* Initializes @private_key. Alternatively you can initialize it with
* #G_STATIC_PRIVATE_INIT.
**/
void
g_static_private_init (GStaticPrivate *private_key)
{
private_key->index = 0;
}
/**
* g_static_private_get:
* @private_key: a #GStaticPrivate.
* @Returns: the corresponding pointer.
*
* Works like g_private_get() only for a #GStaticPrivate.
*
* This function works even if g_thread_init() has not yet been called.
**/
gpointer
g_static_private_get (GStaticPrivate *private_key)
{
GRealThread *self = (GRealThread*) g_thread_self ();
GArray *array;
array = self->private_data;
if (!array)
return NULL;
if (!private_key->index)
return NULL;
else if (private_key->index <= array->len)
return g_array_index (array, GStaticPrivateNode,
private_key->index - 1).data;
else
return NULL;
}
/**
* g_static_private_set:
* @private_key: a #GStaticPrivate.
* @data: the new pointer.
* @notify: a function to be called with the pointer whenever the
* current thread ends or sets this pointer again.
*
* Sets the pointer keyed to @private_key for the current thread and
* the function @notify to be called with that pointer (%NULL or
* non-%NULL), whenever the pointer is set again or whenever the
* current thread ends.
*
* This function works even if g_thread_init() has not yet been called.
* If g_thread_init() is called later, the @data keyed to @private_key
* will be inherited only by the main thread, i.e. the one that called
* g_thread_init().
*
* <note><para>@notify is used quite differently from @destructor in
* g_private_new().</para></note>
**/
void
g_static_private_set (GStaticPrivate *private_key,
gpointer data,
GDestroyNotify notify)
{
GRealThread *self = (GRealThread*) g_thread_self ();
GArray *array;
static guint next_index = 0;
GStaticPrivateNode *node;
array = self->private_data;
if (!array)
{
array = g_array_new (FALSE, TRUE, sizeof (GStaticPrivateNode));
self->private_data = array;
}
if (!private_key->index)
{
G_LOCK (g_thread);
if (!private_key->index)
{
if (g_thread_free_indeces)
{
private_key->index =
GPOINTER_TO_UINT (g_thread_free_indeces->data);
g_thread_free_indeces =
g_slist_delete_link (g_thread_free_indeces,
g_thread_free_indeces);
}
else
private_key->index = ++next_index;
}
G_UNLOCK (g_thread);
}
if (private_key->index > array->len)
g_array_set_size (array, private_key->index);
node = &g_array_index (array, GStaticPrivateNode, private_key->index - 1);
if (node->destroy)
{
gpointer ddata = node->data;
GDestroyNotify ddestroy = node->destroy;
node->data = data;
node->destroy = notify;
ddestroy (ddata);
}
else
{
node->data = data;
node->destroy = notify;
}
}
/**
* g_static_private_free:
* @private_key: a #GStaticPrivate to be freed.
*
* Releases all resources allocated to @private_key.
*
* You don't have to call this functions for a #GStaticPrivate with an
* unbounded lifetime, i.e. objects declared 'static', but if you have
* a #GStaticPrivate as a member of a structure and the structure is
* freed, you should also free the #GStaticPrivate.
**/
void
g_static_private_free (GStaticPrivate *private_key)
{
guint idx = private_key->index;
GRealThread *thread;
if (!idx)
return;
private_key->index = 0;
G_LOCK (g_thread);
thread = g_thread_all_threads;
while (thread)
{
GArray *array = thread->private_data;
thread = thread->next;
if (array && idx <= array->len)
{
GStaticPrivateNode *node = &g_array_index (array,
GStaticPrivateNode,
idx - 1);
gpointer ddata = node->data;
GDestroyNotify ddestroy = node->destroy;
node->data = NULL;
node->destroy = NULL;
if (ddestroy)
{
G_UNLOCK (g_thread);
ddestroy (ddata);
G_LOCK (g_thread);
}
}
}
g_thread_free_indeces = g_slist_prepend (g_thread_free_indeces,
GUINT_TO_POINTER (idx));
G_UNLOCK (g_thread);
}
/* GThread Extra Functions {{{1 ------------------------------------------- */
static void
g_thread_cleanup (gpointer data)
{
if (data)
{
GRealThread* thread = data;
if (thread->private_data)
{
GArray* array = thread->private_data;
guint i;
for (i = 0; i < array->len; i++ )
{
GStaticPrivateNode *node =
&g_array_index (array, GStaticPrivateNode, i);
if (node->destroy)
node->destroy (node->data);
}
g_array_free (array, TRUE);
}
/* 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)
{
GRealThread *t, *p;
G_LOCK (g_thread);
for (t = g_thread_all_threads, p = NULL; t; p = t, t = t->next)
{
if (t == thread)
{
if (p)
p->next = t->next;
else
g_thread_all_threads = t->next;
break;
}
}
G_UNLOCK (g_thread);
/* Just to make sure, this isn't used any more */
g_system_thread_assign (thread->system_thread, zero_thread);
g_free (thread);
}
}
}
static void
g_thread_fail (void)
{
g_error ("The thread system is not yet initialized.");
}
#define G_NSEC_PER_SEC 1000000000
static guint64
gettime (void)
{
#ifdef G_OS_WIN32
guint64 v;
/* Returns 100s of nanoseconds since start of 1601 */
GetSystemTimeAsFileTime ((FILETIME *)&v);
/* Offset to Unix epoch */
v -= G_GINT64_CONSTANT (116444736000000000);
/* Convert to nanoseconds */
v *= 100;
return v;
#else
struct timeval tv;
gettimeofday (&tv, NULL);
return (guint64) tv.tv_sec * G_NSEC_PER_SEC + tv.tv_usec * (G_NSEC_PER_SEC / G_USEC_PER_SEC);
#endif
}
static gpointer
g_thread_create_proxy (gpointer data)
{
GRealThread* thread = data;
g_assert (data);
/* 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_create. */
G_LOCK (g_thread);
G_UNLOCK (g_thread);
thread->retval = thread->thread.func (thread->thread.data);
return NULL;
}
/**
* g_thread_create_full:
* @func: a function to execute in the new thread.
* @data: an argument to supply to the new thread.
* @stack_size: a stack size for the new thread.
* @joinable: should this thread be joinable?
* @bound: should this thread be bound to a system thread?
* @priority: a priority for the thread.
* @error: return location for error.
* @Returns: the new #GThread on success.
*
* This function creates a new thread with the priority @priority. 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.
*
* If @joinable is %TRUE, you can wait for this threads termination
* calling g_thread_join(). Otherwise the thread will just disappear
* when it terminates. If @bound is %TRUE, this thread will be
* scheduled in the system scope, otherwise the implementation is free
* to do scheduling in the process scope. The first variant is more
* expensive resource-wise, but generally faster. On some systems (e.g.
* Linux) all threads are bound.
*
* The new thread executes the function @func with the argument @data.
* If the thread was created successfully, it is returned.
*
* @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.
*
* <note><para>It is not guaranteed that threads with different priorities
* really behave accordingly. On some systems (e.g. Linux) there are no
* thread priorities. On other systems (e.g. Solaris) there doesn't
* seem to be different scheduling for different priorities. All in all
* try to avoid being dependent on priorities. Use
* %G_THREAD_PRIORITY_NORMAL here as a default.</para></note>
*
* <note><para>Only use g_thread_create_full() if you really can't use
* g_thread_create() instead. g_thread_create() does not take
* @stack_size, @bound, and @priority as arguments, as they should only
* be used in cases in which it is unavoidable.</para></note>
**/
GThread*
g_thread_create_full (GThreadFunc func,
gpointer data,
gulong stack_size,
gboolean joinable,
gboolean bound,
GThreadPriority priority,
GError **error)
{
GRealThread* result;
GError *local_error = NULL;
g_return_val_if_fail (func, NULL);
g_return_val_if_fail (priority >= G_THREAD_PRIORITY_LOW, NULL);
g_return_val_if_fail (priority <= G_THREAD_PRIORITY_URGENT, NULL);
result = g_new0 (GRealThread, 1);
result->thread.joinable = joinable;
result->thread.priority = priority;
result->thread.func = func;
result->thread.data = data;
result->private_data = NULL;
G_LOCK (g_thread);
G_THREAD_UF (thread_create, (g_thread_create_proxy, result,
stack_size, joinable, bound, priority,
&result->system_thread, &local_error));
if (!local_error)
{
result->next = g_thread_all_threads;
g_thread_all_threads = result;
}
G_UNLOCK (g_thread);
if (local_error)
{
g_propagate_error (error, local_error);
g_free (result);
return NULL;
}
return (GThread*) result;
}
/**
* g_thread_exit:
* @retval: the return value of this thread.
*
* Exits 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. Calling
*
* <informalexample>
* <programlisting>
* g_thread_exit (retval);
* </programlisting>
* </informalexample>
*
* is equivalent to returning @retval from the function @func, as given
* to g_thread_create().
*
* <note><para>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.</para></note>
**/
void
g_thread_exit (gpointer retval)
{
GRealThread* real = (GRealThread*) g_thread_self ();
real->retval = retval;
G_THREAD_CF (thread_exit, (void)0, ());
}
/**
* g_thread_join:
* @thread: a #GThread to be waited for.
* @Returns: the return value of the thread.
*
* Waits until @thread finishes, i.e. the function @func, as given to
* g_thread_create(), returns or g_thread_exit() is called by @thread.
* All resources of @thread including the #GThread struct are released.
* @thread must have been created with @joinable=%TRUE in
* g_thread_create(). The value returned by @func or given to
* g_thread_exit() by @thread is returned by this function.
**/
gpointer
g_thread_join (GThread* thread)
{
GRealThread* real = (GRealThread*) thread;
GRealThread *p, *t;
gpointer retval;
g_return_val_if_fail (thread, NULL);
g_return_val_if_fail (thread->joinable, NULL);
g_return_val_if_fail (!g_system_thread_equal (real->system_thread,
zero_thread), NULL);
G_THREAD_UF (thread_join, (&real->system_thread));
retval = real->retval;
G_LOCK (g_thread);
for (t = g_thread_all_threads, p = NULL; t; p = t, t = t->next)
{
if (t == (GRealThread*) thread)
{
if (p)
p->next = t->next;
else
g_thread_all_threads = t->next;
break;
}
}
G_UNLOCK (g_thread);
/* Just to make sure, this isn't used any more */
thread->joinable = 0;
g_system_thread_assign (real->system_thread, zero_thread);
/* 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_free (thread);
return retval;
}
/**
* g_thread_set_priority:
* @thread: a #GThread.
* @priority: a new priority for @thread.
*
* Changes the priority of @thread to @priority.
*
* <note><para>It is not guaranteed that threads with different
* priorities really behave accordingly. On some systems (e.g. Linux)
* there are no thread priorities. On other systems (e.g. Solaris) there
* doesn't seem to be different scheduling for different priorities. All
* in all try to avoid being dependent on priorities.</para></note>
**/
void
g_thread_set_priority (GThread* thread,
GThreadPriority priority)
{
GRealThread* real = (GRealThread*) thread;
g_return_if_fail (thread);
g_return_if_fail (!g_system_thread_equal (real->system_thread, zero_thread));
g_return_if_fail (priority >= G_THREAD_PRIORITY_LOW);
g_return_if_fail (priority <= G_THREAD_PRIORITY_URGENT);
thread->priority = priority;
G_THREAD_CF (thread_set_priority, (void)0,
(&real->system_thread, priority));
}
/**
* g_thread_self:
* @Returns: the current thread.
*
* This functions returns the #GThread corresponding to the calling
* thread.
**/
GThread*
g_thread_self (void)
{
GRealThread* thread = g_private_get (g_thread_specific_private);
if (!thread)
{
/* If no thread data is available, provide and set one. 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 save guess */
thread->thread.priority = G_THREAD_PRIORITY_NORMAL; /* This is
just a guess */
thread->thread.func = NULL;
thread->thread.data = NULL;
thread->private_data = NULL;
if (g_thread_supported ())
G_THREAD_UF (thread_self, (&thread->system_thread));
g_private_set (g_thread_specific_private, thread);
G_LOCK (g_thread);
thread->next = g_thread_all_threads;
g_thread_all_threads = thread;
G_UNLOCK (g_thread);
}
return (GThread*)thread;
}
/* GStaticRWLock {{{1 ----------------------------------------------------- */
/**
* GStaticRWLock:
*
* The #GStaticRWLock struct represents a read-write lock. A read-write
* lock can be used for protecting data that some portions of code only
* read from, while others also write. In such situations it is
* desirable that several readers can read at once, whereas of course
* only one writer may write at a time. Take a look at the following
* example:
*
* <example>
* <title>An array with access functions</title>
* <programlisting>
* GStaticRWLock rwlock = G_STATIC_RW_LOCK_INIT;
* GPtrArray *array;
*
* gpointer
* my_array_get (guint index)
* {
* gpointer retval = NULL;
*
* if (!array)
* return NULL;
*
* g_static_rw_lock_reader_lock (&amp;rwlock);
* if (index &lt; array->len)
* retval = g_ptr_array_index (array, index);
* g_static_rw_lock_reader_unlock (&amp;rwlock);
*
* return retval;
* }
*
* void
* my_array_set (guint index, gpointer data)
* {
* g_static_rw_lock_writer_lock (&amp;rwlock);
*
* 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_static_rw_lock_writer_unlock (&amp;rwlock);
* }
* </programlisting>
* </example>
*
* 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.
*
* Most of the time, writers should have precedence over readers. That
* means, for this implementation, that as soon as a writer wants to
* lock the data, no other reader is allowed to lock the data, whereas,
* of course, the readers that already have locked the data are allowed
* to finish their operation. As soon as the last reader unlocks the
* data, the writer will lock it.
*
* Even though #GStaticRWLock is not opaque, it should only be used
* with the following functions.
*
* All of the <function>g_static_rw_lock_*</function> functions can be
* used even if g_thread_init() has not been called. Then they do
* nothing, apart from <function>g_static_rw_lock_*_trylock</function>,
* which does nothing but returning %TRUE.
*
* <note><para>A read-write lock has a higher overhead than a mutex. For
* example, both g_static_rw_lock_reader_lock() and
* g_static_rw_lock_reader_unlock() have to lock and unlock a
* #GStaticMutex, so it takes at least twice the time to lock and unlock
* a #GStaticRWLock that it does to lock and unlock a #GStaticMutex. So
* only data structures that are accessed by multiple readers, and which
* keep the lock for a considerable time justify a #GStaticRWLock. The
* above example most probably would fare better with a
* #GStaticMutex.</para></note>
**/
/**
* G_STATIC_RW_LOCK_INIT:
*
* A #GStaticRWLock must be initialized with this macro before it can
* be used. This macro can used be to initialize a variable, but it
* cannot be assigned to a variable. In that case you have to use
* g_static_rw_lock_init().
*
* <informalexample>
* <programlisting>
* GStaticRWLock my_lock = G_STATIC_RW_LOCK_INIT;
* </programlisting>
* </informalexample>
**/
/**
* g_static_rw_lock_init:
* @lock: a #GStaticRWLock to be initialized.
*
* A #GStaticRWLock must be initialized with this function before it
* can be used. Alternatively you can initialize it with
* #G_STATIC_RW_LOCK_INIT.
**/
void
g_static_rw_lock_init (GStaticRWLock* lock)
{
static const GStaticRWLock init_lock = G_STATIC_RW_LOCK_INIT;
g_return_if_fail (lock);
*lock = init_lock;
}
inline static void
g_static_rw_lock_wait (GCond** cond, GStaticMutex* mutex)
{
if (!*cond)
*cond = g_cond_new ();
g_cond_wait (*cond, g_static_mutex_get_mutex (mutex));
}
inline static void
g_static_rw_lock_signal (GStaticRWLock* lock)
{
if (lock->want_to_write && lock->write_cond)
g_cond_signal (lock->write_cond);
else if (lock->want_to_read && lock->read_cond)
g_cond_broadcast (lock->read_cond);
}
/**
* g_static_rw_lock_reader_lock:
* @lock: a #GStaticRWLock to lock for reading.
*
* Locks @lock for reading. There may be unlimited concurrent locks for
* reading of a #GStaticRWLock at the same time. If @lock is already
* locked for writing by another thread or if another thread is already
* waiting to lock @lock for writing, this function will block until
* @lock is unlocked by the other writing thread and no other writing
* threads want to lock @lock. This lock has to be unlocked by
* g_static_rw_lock_reader_unlock().
*
* #GStaticRWLock is not recursive. It might seem to be possible to
* recursively lock for reading, but that can result in a deadlock, due
* to writer preference.
**/
void
g_static_rw_lock_reader_lock (GStaticRWLock* lock)
{
g_return_if_fail (lock);
if (!g_threads_got_initialized)
return;
g_static_mutex_lock (&lock->mutex);
lock->want_to_read++;
while (lock->have_writer || lock->want_to_write)
g_static_rw_lock_wait (&lock->read_cond, &lock->mutex);
lock->want_to_read--;
lock->read_counter++;
g_static_mutex_unlock (&lock->mutex);
}
/**
* g_static_rw_lock_reader_trylock:
* @lock: a #GStaticRWLock to lock for reading.
* @Returns: %TRUE, if @lock could be locked for reading.
*
* Tries to lock @lock for reading. If @lock is already locked for
* writing by another thread or if another thread is already waiting to
* lock @lock for writing, immediately returns %FALSE. Otherwise locks
* @lock for reading and returns %TRUE. This lock has to be unlocked by
* g_static_rw_lock_reader_unlock().
**/
gboolean
g_static_rw_lock_reader_trylock (GStaticRWLock* lock)
{
gboolean ret_val = FALSE;
g_return_val_if_fail (lock, FALSE);
if (!g_threads_got_initialized)
return TRUE;
g_static_mutex_lock (&lock->mutex);
if (!lock->have_writer && !lock->want_to_write)
{
lock->read_counter++;
ret_val = TRUE;
}
g_static_mutex_unlock (&lock->mutex);
return ret_val;
}
/**
* g_static_rw_lock_reader_unlock:
* @lock: a #GStaticRWLock to unlock after reading.
*
* Unlocks @lock. If a thread waits to lock @lock for writing and all
* locks for reading have been unlocked, the waiting thread is woken up
* and can lock @lock for writing.
**/
void
g_static_rw_lock_reader_unlock (GStaticRWLock* lock)
{
g_return_if_fail (lock);
if (!g_threads_got_initialized)
return;
g_static_mutex_lock (&lock->mutex);
lock->read_counter--;
if (lock->read_counter == 0)
g_static_rw_lock_signal (lock);
g_static_mutex_unlock (&lock->mutex);
}
/**
* g_static_rw_lock_writer_lock:
* @lock: a #GStaticRWLock to lock for writing.
*
* Locks @lock for writing. If @lock is already locked for writing or
* reading by other threads, this function will block until @lock is
* completely unlocked and then lock @lock for writing. While this
* functions waits to lock @lock, no other thread can lock @lock for
* reading. When @lock is locked for writing, no other thread can lock
* @lock (neither for reading nor writing). This lock has to be
* unlocked by g_static_rw_lock_writer_unlock().
**/
void
g_static_rw_lock_writer_lock (GStaticRWLock* lock)
{
g_return_if_fail (lock);
if (!g_threads_got_initialized)
return;
g_static_mutex_lock (&lock->mutex);
lock->want_to_write++;
while (lock->have_writer || lock->read_counter)
g_static_rw_lock_wait (&lock->write_cond, &lock->mutex);
lock->want_to_write--;
lock->have_writer = TRUE;
g_static_mutex_unlock (&lock->mutex);
}
/**
* g_static_rw_lock_writer_trylock:
* @lock: a #GStaticRWLock to lock for writing.
* @Returns: %TRUE, if @lock could be locked for writing.
*
* Tries to lock @lock for writing. If @lock is already locked (for
* either reading or writing) by another thread, it immediately returns
* %FALSE. Otherwise it locks @lock for writing and returns %TRUE. This
* lock has to be unlocked by g_static_rw_lock_writer_unlock().
**/
gboolean
g_static_rw_lock_writer_trylock (GStaticRWLock* lock)
{
gboolean ret_val = FALSE;
g_return_val_if_fail (lock, FALSE);
if (!g_threads_got_initialized)
return TRUE;
g_static_mutex_lock (&lock->mutex);
if (!lock->have_writer && !lock->read_counter)
{
lock->have_writer = TRUE;
ret_val = TRUE;
}
g_static_mutex_unlock (&lock->mutex);
return ret_val;
}
/**
* g_static_rw_lock_writer_unlock:
* @lock: a #GStaticRWLock to unlock after writing.
*
* Unlocks @lock. If a thread is waiting to lock @lock for writing and
* all locks for reading have been unlocked, the waiting thread is
* woken up and can lock @lock for writing. If no thread is waiting to
* lock @lock for writing, and some thread or threads are waiting to
* lock @lock for reading, the waiting threads are woken up and can
* lock @lock for reading.
**/
void
g_static_rw_lock_writer_unlock (GStaticRWLock* lock)
{
g_return_if_fail (lock);
if (!g_threads_got_initialized)
return;
g_static_mutex_lock (&lock->mutex);
lock->have_writer = FALSE;
g_static_rw_lock_signal (lock);
g_static_mutex_unlock (&lock->mutex);
}
/**
* g_static_rw_lock_free:
* @lock: a #GStaticRWLock to be freed.
*
* Releases all resources allocated to @lock.
*
* You don't have to call this functions for a #GStaticRWLock with an
* unbounded lifetime, i.e. objects declared 'static', but if you have
* a #GStaticRWLock as a member of a structure, and the structure is
* freed, you should also free the #GStaticRWLock.
**/
void
g_static_rw_lock_free (GStaticRWLock* lock)
{
g_return_if_fail (lock);
if (lock->read_cond)
{
g_cond_free (lock->read_cond);
lock->read_cond = NULL;
}
if (lock->write_cond)
{
g_cond_free (lock->write_cond);
lock->write_cond = NULL;
}
g_static_mutex_free (&lock->mutex);
}
/* Unsorted {{{1 ---------------------------------------------------------- */
/**
* g_thread_foreach
* @thread_func: function to call for all GThread structures
* @user_data: second argument to @thread_func
*
* Call @thread_func on all existing #GThread structures. Note that
* threads may decide to exit while @thread_func is running, so
* without intimate knowledge about the lifetime of foreign threads,
* @thread_func shouldn't access the GThread* pointer passed in as
* first argument. However, @thread_func will not be called for threads
* which are known to have exited already.
*
* Due to thread lifetime checks, this function has an execution complexity
* which is quadratic in the number of existing threads.
*
* Since: 2.10
*/
void
g_thread_foreach (GFunc thread_func,
gpointer user_data)
{
GSList *slist = NULL;
GRealThread *thread;
g_return_if_fail (thread_func != NULL);
/* snapshot the list of threads for iteration */
G_LOCK (g_thread);
for (thread = g_thread_all_threads; thread; thread = thread->next)
slist = g_slist_prepend (slist, thread);
G_UNLOCK (g_thread);
/* walk the list, skipping non-existant threads */
while (slist)
{
GSList *node = slist;
slist = node->next;
/* check whether the current thread still exists */
G_LOCK (g_thread);
for (thread = g_thread_all_threads; thread; thread = thread->next)
if (thread == node->data)
break;
G_UNLOCK (g_thread);
if (thread)
thread_func (thread, user_data);
g_slist_free_1 (node);
}
}
/**
* g_thread_get_initialized
*
* Indicates if g_thread_init() has been called.
*
* Returns: %TRUE if threads have been initialized.
*
* Since: 2.20
*/
gboolean
g_thread_get_initialized ()
{
return g_thread_supported ();
}
#define __G_THREAD_C__
#include "galiasdef.c"
Reference in New Issue View Git Blame Copy Permalink