dbus-1.4.10/dbus/dbus-pending-call.c - nest-learning-thermostat/5.1.5/dbus - Git at Google

 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
 /* dbus-pending-call.c Object representing a call in progress.
  *
  * Copyright (C) 2002, 2003 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-internals.h"
 #include "dbus-connection-internal.h"
 #include "dbus-pending-call-internal.h"
 #include "dbus-pending-call.h"
 #include "dbus-list.h"
 #include "dbus-threads.h"
 #include "dbus-test.h"

 /**
  * @defgroup DBusPendingCallInternals DBusPendingCall implementation details
  * @ingroup DBusInternals
  * @brief DBusPendingCall private implementation details.
  *
  * The guts of DBusPendingCall and its methods.
  *
  * @{
  */

 /**
  * @brief Internals of DBusPendingCall
  *
  * Opaque object representing a reply message that we're waiting for.
  */

 /**
  * shorter and more visible way to write _dbus_connection_lock()
  */
 #define CONNECTION_LOCK(connection)   _dbus_connection_lock(connection)
 /**
  * shorter and more visible way to write _dbus_connection_unlock()
  */
 #define CONNECTION_UNLOCK(connection) _dbus_connection_unlock(connection)

 /**
  * Implementation details of #DBusPendingCall - all fields are private.
  */
 struct DBusPendingCall
 {
   DBusAtomic refcount;                            /**< reference count */

   DBusDataSlotList slot_list;                     /**< Data stored by allocated integer ID */

   DBusPendingCallNotifyFunction function;         /**< Notifier when reply arrives. */

   DBusConnection *connection;                     /**< Connections we're associated with */
   DBusMessage *reply;                             /**< Reply (after we've received it) */
   DBusTimeout *timeout;                           /**< Timeout */

   DBusList *timeout_link;                         /**< Preallocated timeout response */

   dbus_uint32_t reply_serial;                     /**< Expected serial of reply */

   unsigned int completed : 1;                     /**< TRUE if completed */
   unsigned int timeout_added : 1;                 /**< Have added the timeout */
 };

 static dbus_int32_t notify_user_data_slot = -1;

 /**
  * Creates a new pending reply object.
  *
  * @param connection connection where reply will arrive
  * @param timeout_milliseconds length of timeout, -1 for default, INT_MAX for no timeout
  * @param timeout_handler timeout handler, takes pending call as data
  * @returns a new #DBusPendingCall or #NULL if no memory.
  */
 DBusPendingCall*
 _dbus_pending_call_new_unlocked (DBusConnection    *connection,
                                  int                timeout_milliseconds,
                                  DBusTimeoutHandler timeout_handler)
 {
   DBusPendingCall *pending;
   DBusTimeout *timeout;

   _dbus_assert (timeout_milliseconds >= 0 || timeout_milliseconds == -1);

   if (timeout_milliseconds == -1)
     timeout_milliseconds = _DBUS_DEFAULT_TIMEOUT_VALUE;

   if (!dbus_pending_call_allocate_data_slot (&notify_user_data_slot))
     return NULL;

   pending = dbus_new0 (DBusPendingCall, 1);

   if (pending == NULL)
     {
       dbus_pending_call_free_data_slot (&notify_user_data_slot);
       return NULL;
     }

   if (timeout_milliseconds != _DBUS_INT_MAX)
     {
       timeout = _dbus_timeout_new (timeout_milliseconds,
                                    timeout_handler,
                                    pending, NULL);

       if (timeout == NULL)
         {
           dbus_pending_call_free_data_slot (&notify_user_data_slot);
           dbus_free (pending);
           return NULL;
         }

       pending->timeout = timeout;
     }
   else
     {
       pending->timeout = NULL;
     }

   pending->refcount.value = 1;
   pending->connection = connection;
   _dbus_connection_ref_unlocked (pending->connection);

   _dbus_data_slot_list_init (&pending->slot_list);

   return pending;
 }

 /**
  * Sets the reply of a pending call with the given message,
  * or if the message is #NULL, by timing out the pending call.
  *
  * @param pending the pending call
  * @param message the message to complete the call with, or #NULL
  *  to time out the call
  */
 void
 _dbus_pending_call_set_reply_unlocked (DBusPendingCall *pending,
                                        DBusMessage     *message)
 {
   if (message == NULL)
     {
       message = pending->timeout_link->data;
       _dbus_list_clear (&pending->timeout_link);
     }
   else
     dbus_message_ref (message);

   _dbus_verbose ("  handing message %p (%s) to pending call serial %u\n",
                  message,
                  dbus_message_get_type (message) == DBUS_MESSAGE_TYPE_METHOD_RETURN ?
                  "method return" :
                  dbus_message_get_type (message) == DBUS_MESSAGE_TYPE_ERROR ?
                  "error" : "other type",
                  pending->reply_serial);

   _dbus_assert (pending->reply == NULL);
   _dbus_assert (pending->reply_serial == dbus_message_get_reply_serial (message));
   pending->reply = message;
 }

 /**
  * Calls notifier function for the pending call
  * and sets the call to completed.
  *
  * @param pending the pending call
  *
  */
 void
 _dbus_pending_call_complete (DBusPendingCall *pending)
 {
   _dbus_assert (!pending->completed);

   pending->completed = TRUE;

   if (pending->function)
     {
       void *user_data;
       user_data = dbus_pending_call_get_data (pending,
                                               notify_user_data_slot);

       (* pending->function) (pending, user_data);
     }
 }

 /**
  * If the pending call hasn't been timed out, add its timeout
  * error reply to the connection's incoming message queue.
  *
  * @param pending the pending call
  * @param connection the connection the call was sent to
  */
 void
 _dbus_pending_call_queue_timeout_error_unlocked (DBusPendingCall *pending,
                                                  DBusConnection  *connection)
 {
   _dbus_assert (connection == pending->connection);

   if (pending->timeout_link)
     {
       _dbus_connection_queue_synthesized_message_link (connection,
 						       pending->timeout_link);
       pending->timeout_link = NULL;
     }
 }

 /**
  * Checks to see if a timeout has been added
  *
  * @param pending the pending_call
  * @returns #TRUE if there is a timeout or #FALSE if not
  */
 dbus_bool_t
 _dbus_pending_call_is_timeout_added_unlocked (DBusPendingCall  *pending)
 {
   _dbus_assert (pending != NULL);

   return pending->timeout_added;
 }


 /**
  * Sets wether the timeout has been added
  *
  * @param pending the pending_call
  * @param is_added whether or not a timeout is added
  */
 void
 _dbus_pending_call_set_timeout_added_unlocked (DBusPendingCall  *pending,
                                                dbus_bool_t       is_added)
 {
   _dbus_assert (pending != NULL);

   pending->timeout_added = is_added;
 }


 /**
  * Retrives the timeout
  *
  * @param pending the pending_call
  * @returns a timeout object or NULL if call has no timeout
  */
 DBusTimeout *
 _dbus_pending_call_get_timeout_unlocked (DBusPendingCall  *pending)
 {
   _dbus_assert (pending != NULL);

   return pending->timeout;
 }

 /**
  * Gets the reply's serial number
  *
  * @param pending the pending_call
  * @returns a serial number for the reply or 0
  */
 dbus_uint32_t
 _dbus_pending_call_get_reply_serial_unlocked (DBusPendingCall  *pending)
 {
   _dbus_assert (pending != NULL);

   return pending->reply_serial;
 }

 /**
  * Sets the reply's serial number
  *
  * @param pending the pending_call
  * @param serial the serial number
  */
 void
 _dbus_pending_call_set_reply_serial_unlocked  (DBusPendingCall *pending,
                                                dbus_uint32_t serial)
 {
   _dbus_assert (pending != NULL);
   _dbus_assert (pending->reply_serial == 0);

   pending->reply_serial = serial;
 }

 /**
  * Gets the connection associated with this pending call.
  *
  * @param pending the pending_call
  * @returns the connection associated with the pending call
  */
 DBusConnection *
 _dbus_pending_call_get_connection_and_lock (DBusPendingCall *pending)
 {
   _dbus_assert (pending != NULL);

   CONNECTION_LOCK (pending->connection);
   return pending->connection;
 }

 /**
  * Gets the connection associated with this pending call.
  *
  * @param pending the pending_call
  * @returns the connection associated with the pending call
  */
 DBusConnection *
 _dbus_pending_call_get_connection_unlocked (DBusPendingCall *pending)
 {
   _dbus_assert (pending != NULL);

   return pending->connection;
 }

 /**
  * Sets the reply message associated with the pending call to a timeout error
  *
  * @param pending the pending_call
  * @param message the message we are sending the error reply to
  * @param serial serial number for the reply
  * @return #FALSE on OOM
  */
 dbus_bool_t
 _dbus_pending_call_set_timeout_error_unlocked (DBusPendingCall *pending,
                                                DBusMessage     *message,
                                                dbus_uint32_t    serial)
 {
   DBusList *reply_link;
   DBusMessage *reply;

   reply = dbus_message_new_error (message, DBUS_ERROR_NO_REPLY,
                                   "Did not receive a reply. Possible causes include: "
                                   "the remote application did not send a reply, "
                                   "the message bus security policy blocked the reply, "
                                   "the reply timeout expired, or "
                                   "the network connection was broken.");
   if (reply == NULL)
     return FALSE;

   reply_link = _dbus_list_alloc_link (reply);
   if (reply_link == NULL)
     {
       dbus_message_unref (reply);
       return FALSE;
     }

   pending->timeout_link = reply_link;

   _dbus_pending_call_set_reply_serial_unlocked (pending, serial);

   return TRUE;
 }

 /**
  * Increments the reference count on a pending call,
  * while the lock on its connection is already held.
  *
  * @param pending the pending call object
  * @returns the pending call object
  */
 DBusPendingCall *
 _dbus_pending_call_ref_unlocked (DBusPendingCall *pending)
 {
   pending->refcount.value += 1;

   return pending;
 }


 static void
 _dbus_pending_call_last_unref (DBusPendingCall *pending)
 {
   DBusConnection *connection;

   /* If we get here, we should be already detached
    * from the connection, or never attached.
    */
   _dbus_assert (!pending->timeout_added);

   connection = pending->connection;

   /* this assumes we aren't holding connection lock... */
   _dbus_data_slot_list_free (&pending->slot_list);

   if (pending->timeout != NULL)
     _dbus_timeout_unref (pending->timeout);

   if (pending->timeout_link)
     {
       dbus_message_unref ((DBusMessage *)pending->timeout_link->data);
       _dbus_list_free_link (pending->timeout_link);
       pending->timeout_link = NULL;
     }

   if (pending->reply)
     {
       dbus_message_unref (pending->reply);
       pending->reply = NULL;
     }

   dbus_free (pending);

   dbus_pending_call_free_data_slot (&notify_user_data_slot);

   /* connection lock should not be held. */
   /* Free the connection last to avoid a weird state while
    * calling out to application code where the pending exists
    * but not the connection.
    */
   dbus_connection_unref (connection);
 }

 /**
  * Decrements the reference count on a pending call,
  * freeing it if the count reaches 0. Assumes
  * connection lock is already held.
  *
  * @param pending the pending call object
  */
 void
 _dbus_pending_call_unref_and_unlock (DBusPendingCall *pending)
 {
   dbus_bool_t last_unref;

   _dbus_assert (pending->refcount.value > 0);

   pending->refcount.value -= 1;
   last_unref = pending->refcount.value == 0;

   CONNECTION_UNLOCK (pending->connection);
   if (last_unref)
     _dbus_pending_call_last_unref (pending);
 }

 /**
  * Checks whether the pending call has received a reply
  * yet, or not. Assumes connection lock is held.
  *
  * @param pending the pending call
  * @returns #TRUE if a reply has been received
  */
 dbus_bool_t
 _dbus_pending_call_get_completed_unlocked (DBusPendingCall    *pending)
 {
   return pending->completed;
 }

 static DBusDataSlotAllocator slot_allocator;
 _DBUS_DEFINE_GLOBAL_LOCK (pending_call_slots);

 /**
  * Stores a pointer on a #DBusPendingCall, along
  * with an optional function to be used for freeing
  * the data when the data is set again, or when
  * the pending call is finalized. The slot number
  * must have been allocated with dbus_pending_call_allocate_data_slot().
  *
  * @param pending the pending_call
  * @param slot the slot number
  * @param data the data to store
  * @param free_data_func finalizer function for the data
  * @returns #TRUE if there was enough memory to store the data
  */
 dbus_bool_t
 _dbus_pending_call_set_data_unlocked (DBusPendingCall  *pending,
                                      dbus_int32_t      slot,
                                      void             *data,
                                      DBusFreeFunction  free_data_func)
 {
   DBusFreeFunction old_free_func;
   void *old_data;
   dbus_bool_t retval;

   retval = _dbus_data_slot_list_set (&slot_allocator,
                                      &pending->slot_list,
                                      slot, data, free_data_func,
                                      &old_free_func, &old_data);

   /* Drop locks to call out to app code */
   CONNECTION_UNLOCK (pending->connection);

   if (retval)
     {
       if (old_free_func)
         (* old_free_func) (old_data);
     }

   CONNECTION_LOCK (pending->connection);

   return retval;
 }

 /** @} */

 /**
  * @defgroup DBusPendingCall DBusPendingCall
  * @ingroup  DBus
  * @brief Pending reply to a method call message
  *
  * A DBusPendingCall is an object representing an
  * expected reply. A #DBusPendingCall can be created
  * when you send a message that should have a reply.
  *
  * @{
  */

 /**
  * @typedef DBusPendingCall
  *
  * Opaque data type representing a message pending.
  */

 /**
  * Increments the reference count on a pending call.
  *
  * @param pending the pending call object
  * @returns the pending call object
  */
 DBusPendingCall *
 dbus_pending_call_ref (DBusPendingCall *pending)
 {
   _dbus_return_val_if_fail (pending != NULL, NULL);

   /* The connection lock is better than the global
    * lock in the atomic increment fallback
    */
 #ifdef DBUS_HAVE_ATOMIC_INT
   _dbus_atomic_inc (&pending->refcount);
 #else
   CONNECTION_LOCK (pending->connection);
   _dbus_assert (pending->refcount.value > 0);

   pending->refcount.value += 1;
   CONNECTION_UNLOCK (pending->connection);
 #endif

   return pending;
 }

 /**
  * Decrements the reference count on a pending call,
  * freeing it if the count reaches 0.
  *
  * @param pending the pending call object
  */
 void
 dbus_pending_call_unref (DBusPendingCall *pending)
 {
   dbus_bool_t last_unref;

   _dbus_return_if_fail (pending != NULL);

   /* More efficient to use the connection lock instead of atomic
    * int fallback if we lack atomic int decrement
    */
 #ifdef DBUS_HAVE_ATOMIC_INT
   last_unref = (_dbus_atomic_dec (&pending->refcount) == 1);
 #else
   CONNECTION_LOCK (pending->connection);
   _dbus_assert (pending->refcount.value > 0);
   pending->refcount.value -= 1;
   last_unref = pending->refcount.value == 0;
   CONNECTION_UNLOCK (pending->connection);
 #endif

   if (last_unref)
     _dbus_pending_call_last_unref(pending);
 }

 /**
  * Sets a notification function to be called when the reply is
  * received or the pending call times out.
  *
  * @param pending the pending call
  * @param function notifier function
  * @param user_data data to pass to notifier function
  * @param free_user_data function to free the user data
  * @returns #FALSE if not enough memory
  */
 dbus_bool_t
 dbus_pending_call_set_notify (DBusPendingCall              *pending,
                               DBusPendingCallNotifyFunction function,
                               void                         *user_data,
                               DBusFreeFunction              free_user_data)
 {
   _dbus_return_val_if_fail (pending != NULL, FALSE);

   CONNECTION_LOCK (pending->connection);

   /* could invoke application code! */
   if (!_dbus_pending_call_set_data_unlocked (pending, notify_user_data_slot,
                                              user_data, free_user_data))
     return FALSE;

   pending->function = function;

   CONNECTION_UNLOCK (pending->connection);

   return TRUE;
 }

 /**
  * Cancels the pending call, such that any reply or error received
  * will just be ignored.  Drops the dbus library's internal reference
  * to the #DBusPendingCall so will free the call if nobody else is
  * holding a reference. However you usually get a reference from
  * dbus_connection_send_with_reply() so probably your app owns a ref
  * also.
  *
  * Note that canceling a pending call will <em>not</em> simulate a
  * timed-out call; if a call times out, then a timeout error reply is
  * received. If you cancel the call, no reply is received unless the
  * the reply was already received before you canceled.
  *
  * @param pending the pending call
  */
 void
 dbus_pending_call_cancel (DBusPendingCall *pending)
 {
   _dbus_return_if_fail (pending != NULL);

   _dbus_connection_remove_pending_call (pending->connection,
                                         pending);
 }

 /**
  * Checks whether the pending call has received a reply
  * yet, or not.
  *
  * @param pending the pending call
  * @returns #TRUE if a reply has been received
  */
 dbus_bool_t
 dbus_pending_call_get_completed (DBusPendingCall *pending)
 {
   dbus_bool_t completed;

   _dbus_return_val_if_fail (pending != NULL, FALSE);

   CONNECTION_LOCK (pending->connection);
   completed = pending->completed;
   CONNECTION_UNLOCK (pending->connection);

   return completed;
 }

 /**
  * Gets the reply, or returns #NULL if none has been received
  * yet. Ownership of the reply message passes to the caller. This
  * function can only be called once per pending call, since the reply
  * message is tranferred to the caller.
  *
  * @param pending the pending call
  * @returns the reply message or #NULL.
  */
 DBusMessage*
 dbus_pending_call_steal_reply (DBusPendingCall *pending)
 {
   DBusMessage *message;

   _dbus_return_val_if_fail (pending != NULL, NULL);
   _dbus_return_val_if_fail (pending->completed, NULL);
   _dbus_return_val_if_fail (pending->reply != NULL, NULL);

   CONNECTION_LOCK (pending->connection);

   message = pending->reply;
   pending->reply = NULL;

   CONNECTION_UNLOCK (pending->connection);

   return message;
 }

 /**
  * Block until the pending call is completed.  The blocking is as with
  * dbus_connection_send_with_reply_and_block(); it does not enter the
  * main loop or process other messages, it simply waits for the reply
  * in question.
  *
  * If the pending call is already completed, this function returns
  * immediately.
  *
  * @todo when you start blocking, the timeout is reset, but it should
  * really only use time remaining since the pending call was created.
  * This requires storing timestamps instead of intervals in the timeout
  *
  * @param pending the pending call
  */
 void
 dbus_pending_call_block (DBusPendingCall *pending)
 {
   _dbus_return_if_fail (pending != NULL);

   _dbus_connection_block_pending_call (pending);
 }

 /**
  * Allocates an integer ID to be used for storing application-specific
  * data on any DBusPendingCall. The allocated ID may then be used
  * with dbus_pending_call_set_data() and dbus_pending_call_get_data().
  * The passed-in slot must be initialized to -1, and is filled in
  * with the slot ID. If the passed-in slot is not -1, it's assumed
  * to be already allocated, and its refcount is incremented.
  *
  * The allocated slot is global, i.e. all DBusPendingCall objects will
  * have a slot with the given integer ID reserved.
  *
  * @param slot_p address of a global variable storing the slot
  * @returns #FALSE on failure (no memory)
  */
 dbus_bool_t
 dbus_pending_call_allocate_data_slot (dbus_int32_t *slot_p)
 {
   _dbus_return_val_if_fail (slot_p != NULL, FALSE);

   return _dbus_data_slot_allocator_alloc (&slot_allocator,
                                           &_DBUS_LOCK_NAME (pending_call_slots),
                                           slot_p);
 }

 /**
  * Deallocates a global ID for #DBusPendingCall data slots.
  * dbus_pending_call_get_data() and dbus_pending_call_set_data() may
  * no longer be used with this slot.  Existing data stored on existing
  * DBusPendingCall objects will be freed when the #DBusPendingCall is
  * finalized, but may not be retrieved (and may only be replaced if
  * someone else reallocates the slot).  When the refcount on the
  * passed-in slot reaches 0, it is set to -1.
  *
  * @param slot_p address storing the slot to deallocate
  */
 void
 dbus_pending_call_free_data_slot (dbus_int32_t *slot_p)
 {
   _dbus_return_if_fail (slot_p != NULL);
   _dbus_return_if_fail (*slot_p >= 0);

   _dbus_data_slot_allocator_free (&slot_allocator, slot_p);
 }

 /**
  * Stores a pointer on a #DBusPendingCall, along
  * with an optional function to be used for freeing
  * the data when the data is set again, or when
  * the pending call is finalized. The slot number
  * must have been allocated with dbus_pending_call_allocate_data_slot().
  *
  * @param pending the pending_call
  * @param slot the slot number
  * @param data the data to store
  * @param free_data_func finalizer function for the data
  * @returns #TRUE if there was enough memory to store the data
  */
 dbus_bool_t
 dbus_pending_call_set_data (DBusPendingCall  *pending,
                             dbus_int32_t      slot,
                             void             *data,
                             DBusFreeFunction  free_data_func)
 {
   dbus_bool_t retval;

   _dbus_return_val_if_fail (pending != NULL, FALSE);
   _dbus_return_val_if_fail (slot >= 0, FALSE);


   CONNECTION_LOCK (pending->connection);
   retval = _dbus_pending_call_set_data_unlocked (pending, slot, data, free_data_func);
   CONNECTION_UNLOCK (pending->connection);
   return retval;
 }

 /**
  * Retrieves data previously set with dbus_pending_call_set_data().
  * The slot must still be allocated (must not have been freed).
  *
  * @param pending the pending_call
  * @param slot the slot to get data from
  * @returns the data, or #NULL if not found
  */
 void*
 dbus_pending_call_get_data (DBusPendingCall   *pending,
                             dbus_int32_t       slot)
 {
   void *res;

   _dbus_return_val_if_fail (pending != NULL, NULL);

   CONNECTION_LOCK (pending->connection);
   res = _dbus_data_slot_list_get (&slot_allocator,
                                   &pending->slot_list,
                                   slot);
   CONNECTION_UNLOCK (pending->connection);

   return res;
 }

 /** @} */

 #ifdef DBUS_BUILD_TESTS

 /**
  * @ingroup DBusPendingCallInternals
  * Unit test for DBusPendingCall.
  *
  * @returns #TRUE on success.
  */
 dbus_bool_t
 _dbus_pending_call_test (const char *test_data_dir)
 {

   return TRUE;
 }
 #endif /* DBUS_BUILD_TESTS */
	/* -- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -- */
	/* dbus-pending-call.c Object representing a call in progress.
	*
	* Copyright (C) 2002, 2003 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-internals.h"
	#include "dbus-connection-internal.h"
	#include "dbus-pending-call-internal.h"
	#include "dbus-pending-call.h"
	#include "dbus-list.h"
	#include "dbus-threads.h"
	#include "dbus-test.h"

	/**
	* @defgroup DBusPendingCallInternals DBusPendingCall implementation details
	* @ingroup DBusInternals
	* @brief DBusPendingCall private implementation details.
	*
	* The guts of DBusPendingCall and its methods.
	*
	* @{
	*/

	/**
	* @brief Internals of DBusPendingCall
	*
	* Opaque object representing a reply message that we're waiting for.
	*/

	/**
	* shorter and more visible way to write _dbus_connection_lock()
	*/
	#define CONNECTION_LOCK(connection) _dbus_connection_lock(connection)
	/**
	* shorter and more visible way to write _dbus_connection_unlock()
	*/
	#define CONNECTION_UNLOCK(connection) _dbus_connection_unlock(connection)

	/**
	* Implementation details of #DBusPendingCall - all fields are private.
	*/
	struct DBusPendingCall
	{
	DBusAtomic refcount; /*< reference count /

	DBusDataSlotList slot_list; /*< Data stored by allocated integer ID /

	DBusPendingCallNotifyFunction function; /*< Notifier when reply arrives. /

	DBusConnection connection; /< Connections we're associated with /
	DBusMessage reply; /< Reply (after we've received it) /
	DBusTimeout timeout; /< Timeout /

	DBusList timeout_link; /< Preallocated timeout response /

	dbus_uint32_t reply_serial; /*< Expected serial of reply /

	unsigned int completed : 1; /*< TRUE if completed /
	unsigned int timeout_added : 1; /*< Have added the timeout /
	};

	static dbus_int32_t notify_user_data_slot = -1;

	/**
	* Creates a new pending reply object.
	*
	* @param connection connection where reply will arrive
	* @param timeout_milliseconds length of timeout, -1 for default, INT_MAX for no timeout
	* @param timeout_handler timeout handler, takes pending call as data
	* @returns a new #DBusPendingCall or #NULL if no memory.
	*/
	DBusPendingCall*
	_dbus_pending_call_new_unlocked (DBusConnection *connection,
	int timeout_milliseconds,
	DBusTimeoutHandler timeout_handler)
	{
	DBusPendingCall *pending;
	DBusTimeout *timeout;

	_dbus_assert (timeout_milliseconds >= 0 \|\| timeout_milliseconds == -1);

	if (timeout_milliseconds == -1)
	timeout_milliseconds = _DBUS_DEFAULT_TIMEOUT_VALUE;

	if (!dbus_pending_call_allocate_data_slot (&notify_user_data_slot))
	return NULL;

	pending = dbus_new0 (DBusPendingCall, 1);

	if (pending == NULL)
	{
	dbus_pending_call_free_data_slot (&notify_user_data_slot);
	return NULL;
	}

	if (timeout_milliseconds != _DBUS_INT_MAX)
	{
	timeout = _dbus_timeout_new (timeout_milliseconds,
	timeout_handler,
	pending, NULL);

	if (timeout == NULL)
	{
	dbus_pending_call_free_data_slot (&notify_user_data_slot);
	dbus_free (pending);
	return NULL;
	}

	pending->timeout = timeout;
	}
	else
	{
	pending->timeout = NULL;
	}

	pending->refcount.value = 1;
	pending->connection = connection;
	_dbus_connection_ref_unlocked (pending->connection);

	_dbus_data_slot_list_init (&pending->slot_list);

	return pending;
	}

	/**
	* Sets the reply of a pending call with the given message,
	* or if the message is #NULL, by timing out the pending call.
	*
	* @param pending the pending call
	* @param message the message to complete the call with, or #NULL
	* to time out the call
	*/
	void
	_dbus_pending_call_set_reply_unlocked (DBusPendingCall *pending,
	DBusMessage *message)
	{
	if (message == NULL)
	{
	message = pending->timeout_link->data;
	_dbus_list_clear (&pending->timeout_link);
	}
	else
	dbus_message_ref (message);

	_dbus_verbose (" handing message %p (%s) to pending call serial %u\n",
	message,
	dbus_message_get_type (message) == DBUS_MESSAGE_TYPE_METHOD_RETURN ?
	"method return" :
	dbus_message_get_type (message) == DBUS_MESSAGE_TYPE_ERROR ?
	"error" : "other type",
	pending->reply_serial);

	_dbus_assert (pending->reply == NULL);
	_dbus_assert (pending->reply_serial == dbus_message_get_reply_serial (message));
	pending->reply = message;
	}

	/**
	* Calls notifier function for the pending call
	* and sets the call to completed.
	*
	* @param pending the pending call
	*
	*/
	void
	_dbus_pending_call_complete (DBusPendingCall *pending)
	{
	_dbus_assert (!pending->completed);

	pending->completed = TRUE;

	if (pending->function)
	{
	void *user_data;
	user_data = dbus_pending_call_get_data (pending,
	notify_user_data_slot);

	(* pending->function) (pending, user_data);
	}
	}

	/**
	* If the pending call hasn't been timed out, add its timeout
	* error reply to the connection's incoming message queue.
	*
	* @param pending the pending call
	* @param connection the connection the call was sent to
	*/
	void
	_dbus_pending_call_queue_timeout_error_unlocked (DBusPendingCall *pending,
	DBusConnection *connection)
	{
	_dbus_assert (connection == pending->connection);

	if (pending->timeout_link)
	{
	_dbus_connection_queue_synthesized_message_link (connection,
	pending->timeout_link);
	pending->timeout_link = NULL;
	}
	}

	/**
	* Checks to see if a timeout has been added
	*
	* @param pending the pending_call
	* @returns #TRUE if there is a timeout or #FALSE if not
	*/
	dbus_bool_t
	_dbus_pending_call_is_timeout_added_unlocked (DBusPendingCall *pending)
	{
	_dbus_assert (pending != NULL);

	return pending->timeout_added;
	}


	/**
	* Sets wether the timeout has been added
	*
	* @param pending the pending_call
	* @param is_added whether or not a timeout is added
	*/
	void
	_dbus_pending_call_set_timeout_added_unlocked (DBusPendingCall *pending,
	dbus_bool_t is_added)
	{
	_dbus_assert (pending != NULL);

	pending->timeout_added = is_added;
	}


	/**
	* Retrives the timeout
	*
	* @param pending the pending_call
	* @returns a timeout object or NULL if call has no timeout
	*/
	DBusTimeout *
	_dbus_pending_call_get_timeout_unlocked (DBusPendingCall *pending)
	{
	_dbus_assert (pending != NULL);

	return pending->timeout;
	}

	/**
	* Gets the reply's serial number
	*
	* @param pending the pending_call
	* @returns a serial number for the reply or 0
	*/
	dbus_uint32_t
	_dbus_pending_call_get_reply_serial_unlocked (DBusPendingCall *pending)
	{
	_dbus_assert (pending != NULL);

	return pending->reply_serial;
	}

	/**
	* Sets the reply's serial number
	*
	* @param pending the pending_call
	* @param serial the serial number
	*/
	void
	_dbus_pending_call_set_reply_serial_unlocked (DBusPendingCall *pending,
	dbus_uint32_t serial)
	{
	_dbus_assert (pending != NULL);
	_dbus_assert (pending->reply_serial == 0);

	pending->reply_serial = serial;
	}

	/**
	* Gets the connection associated with this pending call.
	*
	* @param pending the pending_call
	* @returns the connection associated with the pending call
	*/
	DBusConnection *
	_dbus_pending_call_get_connection_and_lock (DBusPendingCall *pending)
	{
	_dbus_assert (pending != NULL);

	CONNECTION_LOCK (pending->connection);
	return pending->connection;
	}

	/**
	* Gets the connection associated with this pending call.
	*
	* @param pending the pending_call
	* @returns the connection associated with the pending call
	*/
	DBusConnection *
	_dbus_pending_call_get_connection_unlocked (DBusPendingCall *pending)
	{
	_dbus_assert (pending != NULL);

	return pending->connection;
	}

	/**
	* Sets the reply message associated with the pending call to a timeout error
	*
	* @param pending the pending_call
	* @param message the message we are sending the error reply to
	* @param serial serial number for the reply
	* @return #FALSE on OOM
	*/
	dbus_bool_t
	_dbus_pending_call_set_timeout_error_unlocked (DBusPendingCall *pending,
	DBusMessage *message,
	dbus_uint32_t serial)
	{
	DBusList *reply_link;
	DBusMessage *reply;

	reply = dbus_message_new_error (message, DBUS_ERROR_NO_REPLY,
	"Did not receive a reply. Possible causes include: "
	"the remote application did not send a reply, "
	"the message bus security policy blocked the reply, "
	"the reply timeout expired, or "
	"the network connection was broken.");
	if (reply == NULL)
	return FALSE;

	reply_link = _dbus_list_alloc_link (reply);
	if (reply_link == NULL)
	{
	dbus_message_unref (reply);
	return FALSE;
	}

	pending->timeout_link = reply_link;

	_dbus_pending_call_set_reply_serial_unlocked (pending, serial);

	return TRUE;
	}

	/**
	* Increments the reference count on a pending call,
	* while the lock on its connection is already held.
	*
	* @param pending the pending call object
	* @returns the pending call object
	*/
	DBusPendingCall *
	_dbus_pending_call_ref_unlocked (DBusPendingCall *pending)
	{
	pending->refcount.value += 1;

	return pending;
	}


	static void
	_dbus_pending_call_last_unref (DBusPendingCall *pending)
	{
	DBusConnection *connection;

	/* If we get here, we should be already detached
	* from the connection, or never attached.
	*/
	_dbus_assert (!pending->timeout_added);

	connection = pending->connection;

	/* this assumes we aren't holding connection lock... */
	_dbus_data_slot_list_free (&pending->slot_list);

	if (pending->timeout != NULL)
	_dbus_timeout_unref (pending->timeout);

	if (pending->timeout_link)
	{
	dbus_message_unref ((DBusMessage *)pending->timeout_link->data);
	_dbus_list_free_link (pending->timeout_link);
	pending->timeout_link = NULL;
	}

	if (pending->reply)
	{
	dbus_message_unref (pending->reply);
	pending->reply = NULL;
	}

	dbus_free (pending);

	dbus_pending_call_free_data_slot (&notify_user_data_slot);

	/* connection lock should not be held. */
	/* Free the connection last to avoid a weird state while
	* calling out to application code where the pending exists
	* but not the connection.
	*/
	dbus_connection_unref (connection);
	}

	/**
	* Decrements the reference count on a pending call,
	* freeing it if the count reaches 0. Assumes
	* connection lock is already held.
	*
	* @param pending the pending call object
	*/
	void
	_dbus_pending_call_unref_and_unlock (DBusPendingCall *pending)
	{
	dbus_bool_t last_unref;

	_dbus_assert (pending->refcount.value > 0);

	pending->refcount.value -= 1;
	last_unref = pending->refcount.value == 0;

	CONNECTION_UNLOCK (pending->connection);
	if (last_unref)
	_dbus_pending_call_last_unref (pending);
	}

	/**
	* Checks whether the pending call has received a reply
	* yet, or not. Assumes connection lock is held.
	*
	* @param pending the pending call
	* @returns #TRUE if a reply has been received
	*/
	dbus_bool_t
	_dbus_pending_call_get_completed_unlocked (DBusPendingCall *pending)
	{
	return pending->completed;
	}

	static DBusDataSlotAllocator slot_allocator;
	_DBUS_DEFINE_GLOBAL_LOCK (pending_call_slots);

	/**
	* Stores a pointer on a #DBusPendingCall, along
	* with an optional function to be used for freeing
	* the data when the data is set again, or when
	* the pending call is finalized. The slot number
	* must have been allocated with dbus_pending_call_allocate_data_slot().
	*
	* @param pending the pending_call
	* @param slot the slot number
	* @param data the data to store
	* @param free_data_func finalizer function for the data
	* @returns #TRUE if there was enough memory to store the data
	*/
	dbus_bool_t
	_dbus_pending_call_set_data_unlocked (DBusPendingCall *pending,
	dbus_int32_t slot,
	void *data,
	DBusFreeFunction free_data_func)
	{
	DBusFreeFunction old_free_func;
	void *old_data;
	dbus_bool_t retval;

	retval = _dbus_data_slot_list_set (&slot_allocator,
	&pending->slot_list,
	slot, data, free_data_func,
	&old_free_func, &old_data);

	/* Drop locks to call out to app code */
	CONNECTION_UNLOCK (pending->connection);

	if (retval)
	{
	if (old_free_func)
	(* old_free_func) (old_data);
	}

	CONNECTION_LOCK (pending->connection);

	return retval;
	}

	/** @} */

	/**
	* @defgroup DBusPendingCall DBusPendingCall
	* @ingroup DBus
	* @brief Pending reply to a method call message
	*
	* A DBusPendingCall is an object representing an
	* expected reply. A #DBusPendingCall can be created
	* when you send a message that should have a reply.
	*
	* @{
	*/

	/**
	* @typedef DBusPendingCall
	*
	* Opaque data type representing a message pending.
	*/

	/**
	* Increments the reference count on a pending call.
	*
	* @param pending the pending call object
	* @returns the pending call object
	*/
	DBusPendingCall *
	dbus_pending_call_ref (DBusPendingCall *pending)
	{
	_dbus_return_val_if_fail (pending != NULL, NULL);

	/* The connection lock is better than the global
	* lock in the atomic increment fallback
	*/
	#ifdef DBUS_HAVE_ATOMIC_INT
	_dbus_atomic_inc (&pending->refcount);
	#else
	CONNECTION_LOCK (pending->connection);
	_dbus_assert (pending->refcount.value > 0);

	pending->refcount.value += 1;
	CONNECTION_UNLOCK (pending->connection);
	#endif

	return pending;
	}

	/**
	* Decrements the reference count on a pending call,
	* freeing it if the count reaches 0.
	*
	* @param pending the pending call object
	*/
	void
	dbus_pending_call_unref (DBusPendingCall *pending)
	{
	dbus_bool_t last_unref;

	_dbus_return_if_fail (pending != NULL);

	/* More efficient to use the connection lock instead of atomic
	* int fallback if we lack atomic int decrement
	*/
	#ifdef DBUS_HAVE_ATOMIC_INT
	last_unref = (_dbus_atomic_dec (&pending->refcount) == 1);
	#else
	CONNECTION_LOCK (pending->connection);
	_dbus_assert (pending->refcount.value > 0);
	pending->refcount.value -= 1;
	last_unref = pending->refcount.value == 0;
	CONNECTION_UNLOCK (pending->connection);
	#endif

	if (last_unref)
	_dbus_pending_call_last_unref(pending);
	}

	/**
	* Sets a notification function to be called when the reply is
	* received or the pending call times out.
	*
	* @param pending the pending call
	* @param function notifier function
	* @param user_data data to pass to notifier function
	* @param free_user_data function to free the user data
	* @returns #FALSE if not enough memory
	*/
	dbus_bool_t
	dbus_pending_call_set_notify (DBusPendingCall *pending,
	DBusPendingCallNotifyFunction function,
	void *user_data,
	DBusFreeFunction free_user_data)
	{
	_dbus_return_val_if_fail (pending != NULL, FALSE);

	CONNECTION_LOCK (pending->connection);

	/* could invoke application code! */
	if (!_dbus_pending_call_set_data_unlocked (pending, notify_user_data_slot,
	user_data, free_user_data))
	return FALSE;

	pending->function = function;

	CONNECTION_UNLOCK (pending->connection);

	return TRUE;
	}

	/**
	* Cancels the pending call, such that any reply or error received
	* will just be ignored. Drops the dbus library's internal reference
	* to the #DBusPendingCall so will free the call if nobody else is
	* holding a reference. However you usually get a reference from
	* dbus_connection_send_with_reply() so probably your app owns a ref
	* also.
	*
	* Note that canceling a pending call will <em>not</em> simulate a
	* timed-out call; if a call times out, then a timeout error reply is
	* received. If you cancel the call, no reply is received unless the
	* the reply was already received before you canceled.
	*
	* @param pending the pending call
	*/
	void
	dbus_pending_call_cancel (DBusPendingCall *pending)
	{
	_dbus_return_if_fail (pending != NULL);

	_dbus_connection_remove_pending_call (pending->connection,
	pending);
	}

	/**
	* Checks whether the pending call has received a reply
	* yet, or not.
	*
	* @param pending the pending call
	* @returns #TRUE if a reply has been received
	*/
	dbus_bool_t
	dbus_pending_call_get_completed (DBusPendingCall *pending)
	{
	dbus_bool_t completed;

	_dbus_return_val_if_fail (pending != NULL, FALSE);

	CONNECTION_LOCK (pending->connection);
	completed = pending->completed;
	CONNECTION_UNLOCK (pending->connection);

	return completed;
	}

	/**
	* Gets the reply, or returns #NULL if none has been received
	* yet. Ownership of the reply message passes to the caller. This
	* function can only be called once per pending call, since the reply
	* message is tranferred to the caller.
	*
	* @param pending the pending call
	* @returns the reply message or #NULL.
	*/
	DBusMessage*
	dbus_pending_call_steal_reply (DBusPendingCall *pending)
	{
	DBusMessage *message;

	_dbus_return_val_if_fail (pending != NULL, NULL);
	_dbus_return_val_if_fail (pending->completed, NULL);
	_dbus_return_val_if_fail (pending->reply != NULL, NULL);

	CONNECTION_LOCK (pending->connection);

	message = pending->reply;
	pending->reply = NULL;

	CONNECTION_UNLOCK (pending->connection);

	return message;
	}

	/**
	* Block until the pending call is completed. The blocking is as with
	* dbus_connection_send_with_reply_and_block(); it does not enter the
	* main loop or process other messages, it simply waits for the reply
	* in question.
	*
	* If the pending call is already completed, this function returns
	* immediately.
	*
	* @todo when you start blocking, the timeout is reset, but it should
	* really only use time remaining since the pending call was created.
	* This requires storing timestamps instead of intervals in the timeout
	*
	* @param pending the pending call
	*/
	void
	dbus_pending_call_block (DBusPendingCall *pending)
	{
	_dbus_return_if_fail (pending != NULL);

	_dbus_connection_block_pending_call (pending);
	}

	/**
	* Allocates an integer ID to be used for storing application-specific
	* data on any DBusPendingCall. The allocated ID may then be used
	* with dbus_pending_call_set_data() and dbus_pending_call_get_data().
	* The passed-in slot must be initialized to -1, and is filled in
	* with the slot ID. If the passed-in slot is not -1, it's assumed
	* to be already allocated, and its refcount is incremented.
	*
	* The allocated slot is global, i.e. all DBusPendingCall objects will
	* have a slot with the given integer ID reserved.
	*
	* @param slot_p address of a global variable storing the slot
	* @returns #FALSE on failure (no memory)
	*/
	dbus_bool_t
	dbus_pending_call_allocate_data_slot (dbus_int32_t *slot_p)
	{
	_dbus_return_val_if_fail (slot_p != NULL, FALSE);

	return _dbus_data_slot_allocator_alloc (&slot_allocator,
	&_DBUS_LOCK_NAME (pending_call_slots),
	slot_p);
	}

	/**
	* Deallocates a global ID for #DBusPendingCall data slots.
	* dbus_pending_call_get_data() and dbus_pending_call_set_data() may
	* no longer be used with this slot. Existing data stored on existing
	* DBusPendingCall objects will be freed when the #DBusPendingCall is
	* finalized, but may not be retrieved (and may only be replaced if
	* someone else reallocates the slot). When the refcount on the
	* passed-in slot reaches 0, it is set to -1.
	*
	* @param slot_p address storing the slot to deallocate
	*/
	void
	dbus_pending_call_free_data_slot (dbus_int32_t *slot_p)
	{
	_dbus_return_if_fail (slot_p != NULL);
	_dbus_return_if_fail (*slot_p >= 0);

	_dbus_data_slot_allocator_free (&slot_allocator, slot_p);
	}

	/**
	* Stores a pointer on a #DBusPendingCall, along
	* with an optional function to be used for freeing
	* the data when the data is set again, or when
	* the pending call is finalized. The slot number
	* must have been allocated with dbus_pending_call_allocate_data_slot().
	*
	* @param pending the pending_call
	* @param slot the slot number
	* @param data the data to store
	* @param free_data_func finalizer function for the data
	* @returns #TRUE if there was enough memory to store the data
	*/
	dbus_bool_t
	dbus_pending_call_set_data (DBusPendingCall *pending,
	dbus_int32_t slot,
	void *data,
	DBusFreeFunction free_data_func)
	{
	dbus_bool_t retval;

	_dbus_return_val_if_fail (pending != NULL, FALSE);
	_dbus_return_val_if_fail (slot >= 0, FALSE);


	CONNECTION_LOCK (pending->connection);
	retval = _dbus_pending_call_set_data_unlocked (pending, slot, data, free_data_func);
	CONNECTION_UNLOCK (pending->connection);
	return retval;
	}

	/**
	* Retrieves data previously set with dbus_pending_call_set_data().
	* The slot must still be allocated (must not have been freed).
	*
	* @param pending the pending_call
	* @param slot the slot to get data from
	* @returns the data, or #NULL if not found
	*/
	void*
	dbus_pending_call_get_data (DBusPendingCall *pending,
	dbus_int32_t slot)
	{
	void *res;

	_dbus_return_val_if_fail (pending != NULL, NULL);

	CONNECTION_LOCK (pending->connection);
	res = _dbus_data_slot_list_get (&slot_allocator,
	&pending->slot_list,
	slot);
	CONNECTION_UNLOCK (pending->connection);

	return res;
	}

	/** @} */

	#ifdef DBUS_BUILD_TESTS

	/**
	* @ingroup DBusPendingCallInternals
	* Unit test for DBusPendingCall.
	*
	* @returns #TRUE on success.
	*/
	dbus_bool_t
	_dbus_pending_call_test (const char *test_data_dir)
	{

	return TRUE;
	}
	#endif /* DBUS_BUILD_TESTS */