/* 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 2.1 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, see <http://www.gnu.org/licenses/>.

 */

/* 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 "gthread.h"

#include "gthreadprivate.h"

#include <string.h>

#ifdef G_OS_UNIX

#include <unistd.h>

#endif

#ifndef G_OS_WIN32

#include <sys/time.h>

#include <time.h>

#else

#include <windows.h>

#endif /* G_OS_WIN32 */

#include "gslice.h"

#include "gstrfuncs.h"

#include "gtestutils.h"

#include "glib_trace.h"

#include "gtrace-private.h"

/**

 * SECTION:threads

 * @title: Threads

 * @short_description: portable support for threads, mutexes, locks,

 *     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, #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).

 *

 * 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.

 *

 * 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.

 *

 * A common use for #GThreads is to move a long-running blocking operation out

 * of the main thread and into a worker thread. For GLib functions, such as

 * single GIO operations, this is not necessary, and complicates the code.

 * Instead, the `…_async()` version of the function should be used from the main

 * thread, eliminating the need for locking and synchronisation between multiple

 * threads. If an operation does need to be moved to a worker thread, consider

 * using g_task_run_in_thread(), or a #GThreadPool. #GThreadPool is often a

 * better choice than #GThread, as it handles thread reuse and task queueing;

 * #GTask uses this internally.

 *

 * However, if multiple blocking operations need to be performed in sequence,

 * and it is not possible to use #GTask for them, moving them to a worker thread

 * can clarify the code.

 */

/* G_LOCK Documentation {{{1 ---------------------------------------------- */

/**

 * G_LOCK_DEFINE:

 * @name: the name of the lock

 *

 * 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:

 *

 * Here is an example for using the #G_LOCK convenience macros:

 * |[<!-- language="C" --> 

 *   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;

 *   }

 * ]|

 */

/**

 * 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

 *

 * Works like g_mutex_trylock(), but for a lock defined with

 * #G_LOCK_DEFINE.

 *

 * Returns: %TRUE, if the lock could be locked.

 */

/**

 * G_UNLOCK:

 * @name: the name of the lock

 *

 * Works like g_mutex_unlock(), but for a lock defined with

 * #G_LOCK_DEFINE.

 */

/* GMutex Documentation {{{1 ------------------------------------------ */

/**

 * 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:

 * |[<!-- language="C" --> 

 *   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;

 *   }

 * ]|

 * 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:

 * |[<!-- language="C" --> 

 *   int

 *   give_me_next_number (void)

 *   {

 *     static GMutex mutex;

 *     static int current_number = 0;

 *     int ret_val;

 *

 *     g_mutex_lock (&mutex);

 *     ret_val = current_number = calc_next_number (current_number);

 *     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.

 *

 * 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.

 */

/* GRecMutex Documentation {{{1 -------------------------------------- */

/**

 * GRecMutex:

 *

 * The GRecMutex struct is an opaque data structure to represent a

 * recursive mutex. It is similar to a #GMutex with the difference

 * that it is possible to lock a GRecMutex multiple times in the same

 * thread without deadlock. When doing so, care has to be taken to

 * unlock the recursive mutex as often as it has been locked.

 *

 * If a #GRecMutex is allocated in static storage then it can be used

 * without initialisation.  Otherwise, you should call

 * 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.

 *

 * Since: 2.32

 */

/* GRWLock Documentation {{{1 ---------------------------------------- */

/**

 * GRWLock:

 *

 * The GRWLock struct is an opaque data structure to represent a

 * reader-writer lock. It is similar to a #GMutex in that it allows

 * multiple threads to coordinate access to a shared resource.

 *

 * The difference to a mutex is that a reader-writer lock discriminates

 * between read-only ('reader') and full ('writer') access. While only

 * one thread at a time is allowed write access (by holding the 'writer'

 * lock via g_rw_lock_writer_lock()), multiple threads can gain

 * simultaneous read-only access (by holding the 'reader' lock via

 * g_rw_lock_reader_lock()).

 *

 * It is unspecified whether readers or writers have priority in acquiring the

 * lock when a reader already holds the lock and a writer is queued to acquire

 * it.

 *

 * Here is an example for an array with access functions:

 * |[<!-- language="C" --> 

 *   GRWLock lock;

 *   GPtrArray *array;

 *

 *   gpointer

 *   my_array_get (guint index)

 *   {

 *     gpointer retval = NULL;

 *

 *     if (!array)

 *       return NULL;

 *

 *     g_rw_lock_reader_lock (&lock);

 *     if (index < array->len)

 *       retval = g_ptr_array_index (array, index);

 *     g_rw_lock_reader_unlock (&lock);

 *

 *     return retval;

 *   }

 *

 *   void

 *   my_array_set (guint index, gpointer data)

 *   {

 *     g_rw_lock_writer_lock (&lock);

 *

 *     if (!array)

 *       array = g_ptr_array_new ();

 *

 *     if (index >= array->len)

 *       g_ptr_array_set_size (array, index+1);

 *     g_ptr_array_index (array, index) = data;

 *

 *     g_rw_lock_writer_unlock (&lock);

 *   }

 *  ]|

 * 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.

 *

 * Since: 2.32

 */

/* GCond Documentation {{{1 ------------------------------------------ */

/**

 * 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.

 *

 * 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:

 * |[<!-- language="C" --> 

 *   gpointer current_data = NULL;

 *   GMutex data_mutex;

 *   GCond data_cond;

 *

 *   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;

 *   }

 * ]|

 * 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().

 *

 * 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.

 *

 * A #GCond should only be accessed via the g_cond_ functions.

 */

/* GThread Documentation {{{1 ---------------------------------------- */

/**

 * GThread:

 *

 * The #GThread struct represents a running thread. This struct

 * 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.

 */

/**

 * GThreadFunc:

 * @data: data passed to the thread

 *

 * Specifies the type of the @func functions passed to g_thread_new()

 * or g_thread_try_new().

 *

 * Returns: the return value of the thread

 */

/**

 * g_thread_supported:

 *

 * This macro returns %TRUE if the thread system is initialized,

 * and %FALSE if it is not.

 *

 * For language bindings, g_thread_get_initialized() provides

 * the same functionality as a function.

 *

 * Returns: %TRUE, if the thread system is initialized

 */

/* 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.

 **/

G_DEFINE_QUARK (g_thread_error, g_thread_error)

/* Local Data {{{1 -------------------------------------------------------- */

static GMutex    g_once_mutex;

static GCond     g_once_cond;

static GSList   *g_once_init_list = NULL;

static guint g_thread_n_created_counter = 0;  /* (atomic) */

static void g_thread_cleanup (gpointer data);

static GPrivate     g_thread_specific_private = G_PRIVATE_INIT (g_thread_cleanup);

/*

 * g_private_set_alloc0:

 * @key: a #GPrivate

 * @size: size of the allocation, in bytes

 *

 * Sets the thread local variable @key to have a newly-allocated and zero-filled

 * value of given @size, and returns a pointer to that memory. Allocations made

 * using this API will be suppressed in valgrind: it is intended to be used for

 * one-time allocations which are known to be leaked, such as those for

 * per-thread initialisation data. Otherwise, this function behaves the same as

 * g_private_set().

 *

 * Returns: (transfer full): new thread-local heap allocation of size @size

 * Since: 2.60

 */

/*< private >*/

gpointer

g_private_set_alloc0 (GPrivate *key,

                      gsize     size)

{

  gpointer allocated = g_malloc0 (size);

  g_private_set (key, allocated);

  return g_steal_pointer (&allocated);

}

/* 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.

 *

 * |[<!-- language="C" --> 

 *   GOnce my_once = G_ONCE_INIT;

 * ]|

 *

 * 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.

 *

 * Calling g_once() recursively on the same #GOnce struct in

 * @func will lead to a deadlock.

 *

 * |[<!-- language="C" --> 

 *   gpointer

 *   get_debug_flags (void)

 *   {

 *     static GOnce my_once = G_ONCE_INIT;

 *

 *     g_once (&my_once, parse_debug_flags, NULL);

 *

 *     return my_once.retval;

 *   }

 * ]|

 *

 * 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)

    {

      gpointer retval;

      once->status = G_ONCE_STATUS_PROGRESS;

      g_mutex_unlock (&g_once_mutex);

      retval = func (arg);

      g_mutex_lock (&g_once_mutex);

/* We prefer the new C11-style atomic extension of GCC if available. If not,

 * fall back to always locking. */

#if defined(G_ATOMIC_LOCK_FREE) && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4) && defined(__ATOMIC_SEQ_CST)

      /* Only the second store needs to be atomic, as the two writes are related

       * by a happens-before relationship here. */

      once->retval = retval;

      __atomic_store_n (&once->status, G_ONCE_STATUS_READY, __ATOMIC_RELEASE);

#else

      once->retval = retval;

      once->status = G_ONCE_STATUS_READY;

#endif

      g_cond_broadcast (&g_once_cond);

    }

  g_mutex_unlock (&g_once_mutex);

  return once->retval;

}

/**

 * g_once_init_enter:

 * @location: (not nullable): location of a static initializable variable

 *    containing 0

 *

 * Function to be called when starting a critical initialization

 * 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

 * 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:

 *

 * |[<!-- language="C" --> 

 *   static gsize initialization_value = 0;

 *

 *   if (g_once_init_enter (&initialization_value))

 *     {

 *       gsize setup_value = 42; // initialization code here

 *

 *       g_once_init_leave (&initialization_value, setup_value);

 *     }

 *

 *   // use initialization_value here

 * ]|

 *

 * While @location has a `volatile` qualifier, this is a historical artifact and

 * the pointer passed to it should not be `volatile`.

 *

 * Returns: %TRUE if the initialization section should be entered,

 *     %FALSE and blocks otherwise

 *

 * Since: 2.14

 */

gboolean

(g_once_init_enter) (volatile void *location)

{

  gsize *value_location = (gsize *) location;

  gboolean need_init = FALSE;

  g_mutex_lock (&g_once_mutex);

  if (g_atomic_pointer_get (value_location) == 0)

    {

      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:

 * @location: (not nullable): 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

 * 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.

 *

 * While @location has a `volatile` qualifier, this is a historical artifact and

 * the pointer passed to it should not be `volatile`.

 *

 * Since: 2.14

 */

void

(g_once_init_leave) (volatile void *location,

                     gsize          result)

{

  gsize *value_location = (gsize *) location;

  g_return_if_fail (g_atomic_pointer_get (value_location) == 0);

  g_return_if_fail (result != 0);

  g_atomic_pointer_set (value_location, result);

  g_mutex_lock (&g_once_mutex);

  g_return_if_fail (g_once_init_list != NULL);

  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);

}

/* GThread {{{1 -------------------------------------------------------- */

/**

 * g_thread_ref:

 * @thread: a #GThread

 *

 * Increase the reference count on @thread.

 *

 * Returns: (transfer full): a new reference to @thread

 *

 * Since: 2.32

 */

GThread *

g_thread_ref (GThread *thread)

{

  GRealThread *real = (GRealThread *) thread;

  g_atomic_int_inc (&real->ref_count);

  return thread;

}

/**

 * g_thread_unref:

 * @thread: (transfer full): 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)

{

  GRealThread* thread = data;

  g_assert (data);

  g_private_set (&g_thread_specific_private, data);

  TRACE (GLIB_THREAD_SPAWNED (thread->thread.func, thread->thread.data,

                              thread->name));

  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;

}

guint

g_thread_n_created (void)

{

  return g_atomic_int_get (&g_thread_n_created_counter);

}

/**

 * g_thread_new:

 * @name: (nullable): an (optional) name for the new thread

 * @func: (closure data) (scope async): a function to execute in the new thread

 * @data: (nullable): an argument to supply to the new thread

 *

 * 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. 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.

 * 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 the thread can not be created the program aborts. See

 * g_thread_try_new() if you want to attempt to deal with failures.

 *

 * If you are using threads to offload (potentially many) short-lived tasks,

 * #GThreadPool may be more appropriate than manually spawning and tracking

 * multiple #GThreads.

 *

 * To free the struct returned by this function, use g_thread_unref().

 * Note that g_thread_join() implicitly unrefs the #GThread as well.

 *

 * New threads by default inherit their scheduler policy (POSIX) or thread

 * priority (Windows) of the thread creating the new thread.

 *

 * This behaviour changed in GLib 2.64: before threads on Windows were not

 * inheriting the thread priority but were spawned with the default priority.

 * Starting with GLib 2.64 the behaviour is now consistent between Windows and

 * POSIX and all threads inherit their parent thread's priority.

 *

 * Returns: (transfer full): the new #GThread

 *

 * Since: 2.32

 */

GThread *

g_thread_new (const gchar *name,

              GThreadFunc  func,

              gpointer     data)

{

  GError *error = NULL;

  GThread *thread;

  thread = g_thread_new_internal (name, g_thread_proxy, func, data, 0, NULL, &error);

  if G_UNLIKELY (thread == NULL)

    g_error ("creating thread '%s': %s", name ? name : "", error->message);

  return thread;

}

/**

 * g_thread_try_new:

 * @name: (nullable): an (optional) name for the new thread

 * @func: (closure data) (scope async): a function to execute in the new thread

 * @data: (nullable): an argument to supply to the new thread

 * @error: return location for error, or %NULL

 *

 * This function is the same as g_thread_new() except that

 * it allows for the possibility of failure.

 *

 * If a thread can not be created (due to resource limits),

 * @error is set and %NULL is returned.

 *

 * Returns: (transfer full): the new #GThread, or %NULL if an error occurred

 *

 * Since: 2.32

 */

GThread *

g_thread_try_new (const gchar  *name,

                  GThreadFunc   func,

                  gpointer      data,

                  GError      **error)

{

  return g_thread_new_internal (name, g_thread_proxy, func, data, 0, NULL, error);

}

GThread *

g_thread_new_internal (const gchar *name,

                       GThreadFunc proxy,

                       GThreadFunc func,

                       gpointer data,

                       gsize stack_size,

                       const GThreadSchedulerSettings *scheduler_settings,

                       GError **error)

{

  g_return_val_if_fail (func != NULL, NULL);

  g_atomic_int_inc (&g_thread_n_created_counter);

  g_trace_mark (G_TRACE_CURRENT_TIME, 0, "GLib", "GThread created", "%s", name ? name : "(unnamed)");

  return (GThread *) g_system_thread_new (proxy, stack_size, scheduler_settings,

                                          name, func, data, error);

}

gboolean

g_thread_get_scheduler_settings (GThreadSchedulerSettings *scheduler_settings)

{

  g_return_val_if_fail (scheduler_settings != NULL, FALSE);

  return g_system_thread_get_scheduler_settings (scheduler_settings);

}

/**

 * g_thread_exit:

 * @retval: the return value of this thread

 *

 * Terminates the current thread.

 *

 * 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() with a parameter @retval is equivalent to

 * returning @retval from the function @func, as given to g_thread_new().

 *

 * 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 ();

}

/**

 * g_thread_join:

 * @thread: (transfer full): 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.

 *

 * 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.

 *

 * 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: (transfer full): the return value of the thread

 */

gpointer

g_thread_join (GThread *thread)

{

  GRealThread *real = (GRealThread*) thread;

  gpointer retval;

  g_return_val_if_fail (thread, NULL);

  g_return_val_if_fail (real->ours, NULL);

  g_system_thread_wait (real);

  retval = real->retval;

  /* Just to make sure, this isn't used any more */

  thread->joinable = 0;

  g_thread_unref (thread);

  return retval;

}

/**

 * g_thread_self:

 *

 * This function returns the #GThread corresponding to the

 * 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: (transfer none): the #GThread representing the current 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_slice_new0 (GRealThread);

      thread->ref_count = 1;

      g_private_set (&g_thread_specific_private, 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

  unsigned int count;

  SYSTEM_INFO sysinfo;

  DWORD_PTR process_cpus;

  DWORD_PTR system_cpus;

  /* This *never* fails, use it as fallback */

  GetNativeSystemInfo (&sysinfo);

  count = (int) sysinfo.dwNumberOfProcessors;

  if (GetProcessAffinityMask (GetCurrentProcess (),

                              &process_cpus, &system_cpus))

    {

      unsigned int af_count;

      for (af_count = 0; process_cpus != 0; process_cpus >>= 1)

        if (process_cpus & 1)

          af_count++;

      /* Prefer affinity-based result, if available */

      if (af_count > 0)

        count = af_count;

    }

  if (count > 0)

    return count;