dbus/dbus-threads.c - manifest_repos/dbus - Git at Google

 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
 /* dbus-threads.h  D-Bus threads handling
  *
  * Copyright (C) 2002, 2003, 2006 Red Hat Inc.
  *
  * Licensed under the Academic Free License version 2.1
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program 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 General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  *
  */
 #include <config.h>
 #include "dbus-threads.h"
 #include "dbus-internals.h"
 #include "dbus-threads-internal.h"
 #include "dbus-list.h"

 static int thread_init_generation = 0;

 /**
  * @defgroup DBusThreadsInternals Thread functions
  * @ingroup  DBusInternals
  * @brief _dbus_rmutex_lock(), etc.
  *
  * Functions and macros related to threads and thread locks.
  *
  * @{
  */

 /**
  * Creates a new mutex
  * or creates a no-op mutex if threads are not initialized.
  * May return #NULL even if threads are initialized, indicating
  * out-of-memory.
  *
  * If possible, the mutex returned by this function is recursive, to
  * avoid deadlocks. However, that cannot be relied on.
  *
  * @param location_p the location of the new mutex, can return #NULL on OOM
  */
 void
 _dbus_rmutex_new_at_location (DBusRMutex **location_p)
 {
   _dbus_assert (location_p != NULL);

   if (!dbus_threads_init_default ())
     {
       *location_p = NULL;
       return;
     }

   *location_p = _dbus_platform_rmutex_new ();
 }

 /**
  * Creates a new mutex
  * or creates a no-op mutex if threads are not initialized.
  * May return #NULL even if threads are initialized, indicating
  * out-of-memory.
  *
  * The returned mutex is suitable for use with condition variables.
  *
  * @param location_p the location of the new mutex, can return #NULL on OOM
  */
 void
 _dbus_cmutex_new_at_location (DBusCMutex **location_p)
 {
   _dbus_assert (location_p != NULL);

   if (!dbus_threads_init_default ())
     {
       *location_p = NULL;
       return;
     }

   *location_p = _dbus_platform_cmutex_new ();
 }

 /**
  * Frees a DBusRMutex; does nothing if passed a #NULL pointer.
  */
 void
 _dbus_rmutex_free_at_location (DBusRMutex **location_p)
 {
   if (location_p == NULL)
     return;

   if (*location_p != NULL)
     _dbus_platform_rmutex_free (*location_p);
 }

 /**
  * Frees a DBusCMutex; does nothing if passed a #NULL pointer.
  */
 void
 _dbus_cmutex_free_at_location (DBusCMutex **location_p)
 {
   if (location_p == NULL)
     return;

   if (*location_p != NULL)
     _dbus_platform_cmutex_free (*location_p);
 }

 /**
  * Locks a mutex. Does nothing if passed a #NULL pointer.
  * Locks may be recursive if threading implementation initialized
  * recursive locks.
  */
 void
 _dbus_rmutex_lock (DBusRMutex *mutex)
 {
   if (mutex == NULL)
     return;

   _dbus_platform_rmutex_lock (mutex);
 }

 /**
  * Locks a mutex. Does nothing if passed a #NULL pointer.
  * Locks may be recursive if threading implementation initialized
  * recursive locks.
  */
 void
 _dbus_cmutex_lock (DBusCMutex *mutex)
 {
   if (mutex == NULL)
     return;

   _dbus_platform_cmutex_lock (mutex);
 }

 /**
  * Unlocks a mutex. Does nothing if passed a #NULL pointer.
  *
  * @returns #TRUE on success
  */
 void
 _dbus_rmutex_unlock (DBusRMutex *mutex)
 {
   if (mutex == NULL)
     return;

   _dbus_platform_rmutex_unlock (mutex);
 }

 /**
  * Unlocks a mutex. Does nothing if passed a #NULL pointer.
  *
  * @returns #TRUE on success
  */
 void
 _dbus_cmutex_unlock (DBusCMutex *mutex)
 {
   if (mutex == NULL)
     return;

   _dbus_platform_cmutex_unlock (mutex);
 }

 /**
  * Creates a new condition variable using the function supplied
  * to dbus_threads_init(), or creates a no-op condition variable
  * if threads are not initialized. May return #NULL even if
  * threads are initialized, indicating out-of-memory.
  *
  * @returns new mutex or #NULL
  */
 DBusCondVar *
 _dbus_condvar_new (void)
 {
   if (!dbus_threads_init_default ())
     return NULL;

   return _dbus_platform_condvar_new ();
 }


 /**
  * This does the same thing as _dbus_condvar_new.  It however
  * gives another level of indirection by allocating a pointer
  * to point to the condvar location; this used to be useful.
  *
  * @returns the location of a new condvar or #NULL on OOM
  */

 void
 _dbus_condvar_new_at_location (DBusCondVar **location_p)
 {
   _dbus_assert (location_p != NULL);

   *location_p = _dbus_condvar_new();
 }


 /**
  * Frees a conditional variable created with dbus_condvar_new(); does
  * nothing if passed a #NULL pointer.
  */
 void
 _dbus_condvar_free (DBusCondVar *cond)
 {
   if (cond == NULL)
     return;

   _dbus_platform_condvar_free (cond);
 }

 /**
  * Frees a condition variable; does nothing if passed a #NULL pointer.
  */
 void
 _dbus_condvar_free_at_location (DBusCondVar **location_p)
 {
   if (location_p == NULL)
     return;

   if (*location_p != NULL)
     _dbus_platform_condvar_free (*location_p);
 }

 /**
  * Atomically unlocks the mutex and waits for the conditions
  * variable to be signalled. Locks the mutex again before
  * returning.
  * Does nothing if passed a #NULL pointer.
  */
 void
 _dbus_condvar_wait (DBusCondVar *cond,
                     DBusCMutex  *mutex)
 {
   if (cond == NULL || mutex == NULL)
     return;

   _dbus_platform_condvar_wait (cond, mutex);
 }

 /**
  * Atomically unlocks the mutex and waits for the conditions variable
  * to be signalled, or for a timeout. Locks the mutex again before
  * returning.  Does nothing if passed a #NULL pointer.  Return value
  * is #FALSE if we timed out, #TRUE otherwise.
  *
  * @param cond the condition variable
  * @param mutex the mutex
  * @param timeout_milliseconds the maximum time to wait
  * @returns #FALSE if the timeout occurred, #TRUE if not
  */
 dbus_bool_t
 _dbus_condvar_wait_timeout (DBusCondVar               *cond,
                             DBusCMutex                *mutex,
                             int                        timeout_milliseconds)
 {
   if (cond == NULL || mutex == NULL)
     return TRUE;

   return _dbus_platform_condvar_wait_timeout (cond, mutex,
       timeout_milliseconds);
 }

 /**
  * If there are threads waiting on the condition variable, wake
  * up exactly one.
  * Does nothing if passed a #NULL pointer.
  */
 void
 _dbus_condvar_wake_one (DBusCondVar *cond)
 {
   if (cond == NULL)
     return;

   _dbus_platform_condvar_wake_one (cond);
 }

 static DBusRMutex *global_locks[_DBUS_N_GLOBAL_LOCKS] = { NULL };

 static void
 shutdown_global_locks (void *nil)
 {
   int i;

   for (i = 0; i < _DBUS_N_GLOBAL_LOCKS; i++)
     {
       _dbus_assert (global_locks[i] != NULL);
       _dbus_platform_rmutex_free (global_locks[i]);
       global_locks[i] = NULL;
     }
 }

 static dbus_bool_t
 init_global_locks (void)
 {
   int i;
   dbus_bool_t ok;

   for (i = 0; i < _DBUS_N_GLOBAL_LOCKS; i++)
     {
       _dbus_assert (global_locks[i] == NULL);

       global_locks[i] = _dbus_platform_rmutex_new ();

       if (global_locks[i] == NULL)
         goto failed;
     }

   _dbus_platform_rmutex_lock (global_locks[_DBUS_LOCK_shutdown_funcs]);
   ok = _dbus_register_shutdown_func_unlocked (shutdown_global_locks, NULL);
   _dbus_platform_rmutex_unlock (global_locks[_DBUS_LOCK_shutdown_funcs]);

   if (!ok)
     goto failed;

   return TRUE;

  failed:
   for (i = i - 1; i >= 0; i--)
     {
       _dbus_platform_rmutex_free (global_locks[i]);
       global_locks[i] = NULL;
     }

   return FALSE;
 }

 dbus_bool_t
 _dbus_lock (DBusGlobalLock lock)
 {
   _dbus_assert (lock >= 0);
   _dbus_assert (lock < _DBUS_N_GLOBAL_LOCKS);

   if (thread_init_generation != _dbus_current_generation &&
       !dbus_threads_init_default ())
     return FALSE;

   _dbus_platform_rmutex_lock (global_locks[lock]);
   return TRUE;
 }

 void
 _dbus_unlock (DBusGlobalLock lock)
 {
   _dbus_assert (lock >= 0);
   _dbus_assert (lock < _DBUS_N_GLOBAL_LOCKS);

   _dbus_platform_rmutex_unlock (global_locks[lock]);
 }

 /** @} */ /* end of internals */

 /**
  * @defgroup DBusThreads Thread functions
  * @ingroup  DBus
  * @brief dbus_threads_init() and dbus_threads_init_default()
  *
  * Functions and macros related to threads and thread locks.
  *
  * If threads are initialized, the D-Bus library has locks on all
  * global data structures.  In addition, each #DBusConnection has a
  * lock, so only one thread at a time can touch the connection.  (See
  * @ref DBusConnection for more on connection locking.)
  *
  * Most other objects, however, do not have locks - they can only be
  * used from a single thread at a time, unless you lock them yourself.
  * For example, a #DBusMessage can't be modified from two threads
  * at once.
  *
  * @{
  */

 /**
  * Initializes threads, like dbus_threads_init_default().
  * This version previously allowed user-specified threading
  * primitives, but since D-Bus 1.6 it ignores them and behaves
  * exactly like dbus_threads_init_default().
  *
  * @param functions ignored, formerly functions for using threads
  * @returns #TRUE on success, #FALSE if no memory
  */
 dbus_bool_t
 dbus_threads_init (const DBusThreadFunctions *functions)
 {
   _dbus_threads_lock_platform_specific ();

   if (thread_init_generation == _dbus_current_generation)
     {
       _dbus_threads_unlock_platform_specific ();
       return TRUE;
     }

   if (!_dbus_threads_init_platform_specific() ||
       !init_global_locks ())
     {
       _dbus_threads_unlock_platform_specific ();
       return FALSE;
     }

   thread_init_generation = _dbus_current_generation;

   _dbus_threads_unlock_platform_specific ();
   return TRUE;
 }


 /* Default thread implemenation */

 /**
  * Initializes threads. If this function is not called, the D-Bus
  * library will not lock any data structures.  If it is called, D-Bus
  * will do locking, at some cost in efficiency.
  *
  * Since D-Bus 1.7 it is safe to call this function from any thread,
  * any number of times (but it must be called before any other
  * libdbus API is used).
  *
  * In D-Bus 1.6 or older, this function must be called in the main thread
  * before any other thread starts. As a result, it is not sufficient to
  * call this function in a library or plugin, unless the library or plugin
  * imposes a similar requirement on its callers.
  *
  * dbus_shutdown() reverses the effects of this function when it
  * resets all global state in libdbus.
  *
  * @returns #TRUE on success, #FALSE if not enough memory
  */
 dbus_bool_t
 dbus_threads_init_default (void)
 {
   return dbus_threads_init (NULL);
 }


 /** @} */

 #ifdef DBUS_ENABLE_EMBEDDED_TESTS

 dbus_bool_t
 _dbus_threads_init_debug (void)
 {
   return dbus_threads_init (NULL);
 }

 #endif /* DBUS_ENABLE_EMBEDDED_TESTS */
	/* -- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -- */
	/* dbus-threads.h D-Bus threads handling
	*
	* Copyright (C) 2002, 2003, 2006 Red Hat Inc.
	*
	* Licensed under the Academic Free License version 2.1
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program 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 General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	*
	*/
	#include <config.h>
	#include "dbus-threads.h"
	#include "dbus-internals.h"
	#include "dbus-threads-internal.h"
	#include "dbus-list.h"

	static int thread_init_generation = 0;

	/**
	* @defgroup DBusThreadsInternals Thread functions
	* @ingroup DBusInternals
	* @brief _dbus_rmutex_lock(), etc.
	*
	* Functions and macros related to threads and thread locks.
	*
	* @{
	*/

	/**
	* Creates a new mutex
	* or creates a no-op mutex if threads are not initialized.
	* May return #NULL even if threads are initialized, indicating
	* out-of-memory.
	*
	* If possible, the mutex returned by this function is recursive, to
	* avoid deadlocks. However, that cannot be relied on.
	*
	* @param location_p the location of the new mutex, can return #NULL on OOM
	*/
	void
	_dbus_rmutex_new_at_location (DBusRMutex **location_p)
	{
	_dbus_assert (location_p != NULL);

	if (!dbus_threads_init_default ())
	{
	*location_p = NULL;
	return;
	}

	*location_p = _dbus_platform_rmutex_new ();
	}

	/**
	* Creates a new mutex
	* or creates a no-op mutex if threads are not initialized.
	* May return #NULL even if threads are initialized, indicating
	* out-of-memory.
	*
	* The returned mutex is suitable for use with condition variables.
	*
	* @param location_p the location of the new mutex, can return #NULL on OOM
	*/
	void
	_dbus_cmutex_new_at_location (DBusCMutex **location_p)
	{
	_dbus_assert (location_p != NULL);

	if (!dbus_threads_init_default ())
	{
	*location_p = NULL;
	return;
	}

	*location_p = _dbus_platform_cmutex_new ();
	}

	/**
	* Frees a DBusRMutex; does nothing if passed a #NULL pointer.
	*/
	void
	_dbus_rmutex_free_at_location (DBusRMutex **location_p)
	{
	if (location_p == NULL)
	return;

	if (*location_p != NULL)
	_dbus_platform_rmutex_free (*location_p);
	}

	/**
	* Frees a DBusCMutex; does nothing if passed a #NULL pointer.
	*/
	void
	_dbus_cmutex_free_at_location (DBusCMutex **location_p)
	{
	if (location_p == NULL)
	return;

	if (*location_p != NULL)
	_dbus_platform_cmutex_free (*location_p);
	}

	/**
	* Locks a mutex. Does nothing if passed a #NULL pointer.
	* Locks may be recursive if threading implementation initialized
	* recursive locks.
	*/
	void
	_dbus_rmutex_lock (DBusRMutex *mutex)
	{
	if (mutex == NULL)
	return;

	_dbus_platform_rmutex_lock (mutex);
	}

	/**
	* Locks a mutex. Does nothing if passed a #NULL pointer.
	* Locks may be recursive if threading implementation initialized
	* recursive locks.
	*/
	void
	_dbus_cmutex_lock (DBusCMutex *mutex)
	{
	if (mutex == NULL)
	return;

	_dbus_platform_cmutex_lock (mutex);
	}

	/**
	* Unlocks a mutex. Does nothing if passed a #NULL pointer.
	*
	* @returns #TRUE on success
	*/
	void
	_dbus_rmutex_unlock (DBusRMutex *mutex)
	{
	if (mutex == NULL)
	return;

	_dbus_platform_rmutex_unlock (mutex);
	}

	/**
	* Unlocks a mutex. Does nothing if passed a #NULL pointer.
	*
	* @returns #TRUE on success
	*/
	void
	_dbus_cmutex_unlock (DBusCMutex *mutex)
	{
	if (mutex == NULL)
	return;

	_dbus_platform_cmutex_unlock (mutex);
	}

	/**
	* Creates a new condition variable using the function supplied
	* to dbus_threads_init(), or creates a no-op condition variable
	* if threads are not initialized. May return #NULL even if
	* threads are initialized, indicating out-of-memory.
	*
	* @returns new mutex or #NULL
	*/
	DBusCondVar *
	_dbus_condvar_new (void)
	{
	if (!dbus_threads_init_default ())
	return NULL;

	return _dbus_platform_condvar_new ();
	}


	/**
	* This does the same thing as _dbus_condvar_new. It however
	* gives another level of indirection by allocating a pointer
	* to point to the condvar location; this used to be useful.
	*
	* @returns the location of a new condvar or #NULL on OOM
	*/

	void
	_dbus_condvar_new_at_location (DBusCondVar **location_p)
	{
	_dbus_assert (location_p != NULL);

	*location_p = _dbus_condvar_new();
	}


	/**
	* Frees a conditional variable created with dbus_condvar_new(); does
	* nothing if passed a #NULL pointer.
	*/
	void
	_dbus_condvar_free (DBusCondVar *cond)
	{
	if (cond == NULL)
	return;

	_dbus_platform_condvar_free (cond);
	}

	/**
	* Frees a condition variable; does nothing if passed a #NULL pointer.
	*/
	void
	_dbus_condvar_free_at_location (DBusCondVar **location_p)
	{
	if (location_p == NULL)
	return;

	if (*location_p != NULL)
	_dbus_platform_condvar_free (*location_p);
	}

	/**
	* Atomically unlocks the mutex and waits for the conditions
	* variable to be signalled. Locks the mutex again before
	* returning.
	* Does nothing if passed a #NULL pointer.
	*/
	void
	_dbus_condvar_wait (DBusCondVar *cond,
	DBusCMutex *mutex)
	{
	if (cond == NULL \|\| mutex == NULL)
	return;

	_dbus_platform_condvar_wait (cond, mutex);
	}

	/**
	* Atomically unlocks the mutex and waits for the conditions variable
	* to be signalled, or for a timeout. Locks the mutex again before
	* returning. Does nothing if passed a #NULL pointer. Return value
	* is #FALSE if we timed out, #TRUE otherwise.
	*
	* @param cond the condition variable
	* @param mutex the mutex
	* @param timeout_milliseconds the maximum time to wait
	* @returns #FALSE if the timeout occurred, #TRUE if not
	*/
	dbus_bool_t
	_dbus_condvar_wait_timeout (DBusCondVar *cond,
	DBusCMutex *mutex,
	int timeout_milliseconds)
	{
	if (cond == NULL \|\| mutex == NULL)
	return TRUE;

	return _dbus_platform_condvar_wait_timeout (cond, mutex,
	timeout_milliseconds);
	}

	/**
	* If there are threads waiting on the condition variable, wake
	* up exactly one.
	* Does nothing if passed a #NULL pointer.
	*/
	void
	_dbus_condvar_wake_one (DBusCondVar *cond)
	{
	if (cond == NULL)
	return;

	_dbus_platform_condvar_wake_one (cond);
	}

	static DBusRMutex *global_locks[_DBUS_N_GLOBAL_LOCKS] = { NULL };

	static void
	shutdown_global_locks (void *nil)
	{
	int i;

	for (i = 0; i < _DBUS_N_GLOBAL_LOCKS; i++)
	{
	_dbus_assert (global_locks[i] != NULL);
	_dbus_platform_rmutex_free (global_locks[i]);
	global_locks[i] = NULL;
	}
	}

	static dbus_bool_t
	init_global_locks (void)
	{
	int i;
	dbus_bool_t ok;

	for (i = 0; i < _DBUS_N_GLOBAL_LOCKS; i++)
	{
	_dbus_assert (global_locks[i] == NULL);

	global_locks[i] = _dbus_platform_rmutex_new ();

	if (global_locks[i] == NULL)
	goto failed;
	}

	_dbus_platform_rmutex_lock (global_locks[_DBUS_LOCK_shutdown_funcs]);
	ok = _dbus_register_shutdown_func_unlocked (shutdown_global_locks, NULL);
	_dbus_platform_rmutex_unlock (global_locks[_DBUS_LOCK_shutdown_funcs]);

	if (!ok)
	goto failed;

	return TRUE;

	failed:
	for (i = i - 1; i >= 0; i--)
	{
	_dbus_platform_rmutex_free (global_locks[i]);
	global_locks[i] = NULL;
	}

	return FALSE;
	}

	dbus_bool_t
	_dbus_lock (DBusGlobalLock lock)
	{
	_dbus_assert (lock >= 0);
	_dbus_assert (lock < _DBUS_N_GLOBAL_LOCKS);

	if (thread_init_generation != _dbus_current_generation &&
	!dbus_threads_init_default ())
	return FALSE;

	_dbus_platform_rmutex_lock (global_locks[lock]);
	return TRUE;
	}

	void
	_dbus_unlock (DBusGlobalLock lock)
	{
	_dbus_assert (lock >= 0);
	_dbus_assert (lock < _DBUS_N_GLOBAL_LOCKS);

	_dbus_platform_rmutex_unlock (global_locks[lock]);
	}

	/** @} / / end of internals */

	/**
	* @defgroup DBusThreads Thread functions
	* @ingroup DBus
	* @brief dbus_threads_init() and dbus_threads_init_default()
	*
	* Functions and macros related to threads and thread locks.
	*
	* If threads are initialized, the D-Bus library has locks on all
	* global data structures. In addition, each #DBusConnection has a
	* lock, so only one thread at a time can touch the connection. (See
	* @ref DBusConnection for more on connection locking.)
	*
	* Most other objects, however, do not have locks - they can only be
	* used from a single thread at a time, unless you lock them yourself.
	* For example, a #DBusMessage can't be modified from two threads
	* at once.
	*
	* @{
	*/

	/**
	* Initializes threads, like dbus_threads_init_default().
	* This version previously allowed user-specified threading
	* primitives, but since D-Bus 1.6 it ignores them and behaves
	* exactly like dbus_threads_init_default().
	*
	* @param functions ignored, formerly functions for using threads
	* @returns #TRUE on success, #FALSE if no memory
	*/
	dbus_bool_t
	dbus_threads_init (const DBusThreadFunctions *functions)
	{
	_dbus_threads_lock_platform_specific ();

	if (thread_init_generation == _dbus_current_generation)
	{
	_dbus_threads_unlock_platform_specific ();
	return TRUE;
	}

	if (!_dbus_threads_init_platform_specific() \|\|
	!init_global_locks ())
	{
	_dbus_threads_unlock_platform_specific ();
	return FALSE;
	}

	thread_init_generation = _dbus_current_generation;

	_dbus_threads_unlock_platform_specific ();
	return TRUE;
	}



	/* Default thread implemenation */

	/**
	* Initializes threads. If this function is not called, the D-Bus
	* library will not lock any data structures. If it is called, D-Bus
	* will do locking, at some cost in efficiency.
	*
	* Since D-Bus 1.7 it is safe to call this function from any thread,
	* any number of times (but it must be called before any other
	* libdbus API is used).
	*
	* In D-Bus 1.6 or older, this function must be called in the main thread
	* before any other thread starts. As a result, it is not sufficient to
	* call this function in a library or plugin, unless the library or plugin
	* imposes a similar requirement on its callers.
	*
	* dbus_shutdown() reverses the effects of this function when it
	* resets all global state in libdbus.
	*
	* @returns #TRUE on success, #FALSE if not enough memory
	*/
	dbus_bool_t
	dbus_threads_init_default (void)
	{
	return dbus_threads_init (NULL);
	}


	/** @} */

	#ifdef DBUS_ENABLE_EMBEDDED_TESTS

	dbus_bool_t
	_dbus_threads_init_debug (void)
	{
	return dbus_threads_init (NULL);
	}

	#endif /* DBUS_ENABLE_EMBEDDED_TESTS */