dbus daemon emulation exteneded

[platform/upstream/dbus.git] / dbus / dbus-threads.h

diff --git a/dbus/dbus-threads.h b/dbus/dbus-threads.h
index 344b0ff..6d28a0b 100644 (file)
--- a/dbus/dbus-threads.h
+++ b/dbus/dbus-threads.h
@@ -1,4 +1,4 @@
-/* -*- mode: C; c-file-style: "gnu" -*- */
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
 /* dbus-threads.h  D-Bus threads handling
  *
  * Copyright (C) 2002  Red Hat Inc.
@@ -17,7 +17,7 @@
  * 
  * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  *
  */
 #if !defined (DBUS_INSIDE_DBUS_H) && !defined (DBUS_COMPILATION)
@@ -46,44 +46,70 @@ typedef struct DBusCondVar DBusCondVar;
 typedef DBusMutex*  (* DBusMutexNewFunction)    (void);
 /** Deprecated, provide DBusRecursiveMutexFreeFunction instead. */
 typedef void        (* DBusMutexFreeFunction)   (DBusMutex *mutex);
-/** Deprecated, provide DBusRecursiveMutexLockFunction instead. */
+/** Deprecated, provide DBusRecursiveMutexLockFunction instead. Return value is lock success, but gets ignored in practice. */
 typedef dbus_bool_t (* DBusMutexLockFunction)   (DBusMutex *mutex);
-/** Deprecated, provide DBusRecursiveMutexUnlockFunction instead. */
+/** Deprecated, provide DBusRecursiveMutexUnlockFunction instead. Return value is unlock success, but gets ignored in practice. */
 typedef dbus_bool_t (* DBusMutexUnlockFunction) (DBusMutex *mutex);
 
-/** Creates a new recursively-lockable mutex, or returns #NULL if not enough memory.
- * Found in #DBusThreadFunctions
+/** Creates a new recursively-lockable mutex, or returns #NULL if not
+ * enough memory.  Can only fail due to lack of memory.  Found in
+ * #DBusThreadFunctions. Do not just use PTHREAD_MUTEX_RECURSIVE for
+ * this, because it does not save/restore the recursion count when
+ * waiting on a condition. libdbus requires the Java-style behavior
+ * where the mutex is fully unlocked to wait on a condition.
  */
 typedef DBusMutex*  (* DBusRecursiveMutexNewFunction)    (void);
 /** Frees a recursively-lockable mutex.  Found in #DBusThreadFunctions.
  */
 typedef void        (* DBusRecursiveMutexFreeFunction)   (DBusMutex *mutex);
 /** Locks a recursively-lockable mutex.  Found in #DBusThreadFunctions.
+ * Can only fail due to lack of memory.
  */
 typedef void        (* DBusRecursiveMutexLockFunction)   (DBusMutex *mutex);
 /** Unlocks a recursively-lockable mutex.  Found in #DBusThreadFunctions.
+ * Can only fail due to lack of memory.
  */
 typedef void        (* DBusRecursiveMutexUnlockFunction) (DBusMutex *mutex);
 
 /** Creates a new condition variable.  Found in #DBusThreadFunctions.
+ * Can only fail (returning #NULL) due to lack of memory.
  */
 typedef DBusCondVar*  (* DBusCondVarNewFunction)         (void);
 /** Frees a condition variable.  Found in #DBusThreadFunctions.
  */
 typedef void          (* DBusCondVarFreeFunction)        (DBusCondVar *cond);
-/** Waits on a condition variable.  Found in #DBusThreadFunctions.
+
+/** Waits on a condition variable.  Found in
+ * #DBusThreadFunctions. Must work with either a recursive or
+ * nonrecursive mutex, whichever the thread implementation
+ * provides. Note that PTHREAD_MUTEX_RECURSIVE does not work with
+ * condition variables (does not save/restore the recursion count) so
+ * don't try using simply pthread_cond_wait() and a
+ * PTHREAD_MUTEX_RECURSIVE to implement this, it won't work right.
+ *
+ * Has no error conditions. Must succeed if it returns.
  */
 typedef void          (* DBusCondVarWaitFunction)        (DBusCondVar *cond,
                                                          DBusMutex   *mutex);
-/** Waits on a condition variable with a timeout.  Found in #DBusThreadFunctions.
+
+/** Waits on a condition variable with a timeout.  Found in
+ *  #DBusThreadFunctions. Returns #TRUE if the wait did not
+ *  time out, and #FALSE if it did.
+ *
+ * Has no error conditions. Must succeed if it returns. 
  */
 typedef dbus_bool_t   (* DBusCondVarWaitTimeoutFunction) (DBusCondVar *cond,
                                                          DBusMutex   *mutex,
                                                          int          timeout_milliseconds);
 /** Wakes one waiting thread on a condition variable.  Found in #DBusThreadFunctions.
+ *
+ * Has no error conditions. Must succeed if it returns.
  */
 typedef void          (* DBusCondVarWakeOneFunction) (DBusCondVar *cond);
+
 /** Wakes all waiting threads on a condition variable.  Found in #DBusThreadFunctions.
+ *
+ * Has no error conditions. Must succeed if it returns.
  */
 typedef void          (* DBusCondVarWakeAllFunction) (DBusCondVar *cond);
 
@@ -108,13 +134,20 @@ typedef enum
   DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_FREE_MASK   = 1 << 11,
   DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_LOCK_MASK   = 1 << 12,
   DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_UNLOCK_MASK = 1 << 13,
-  DBUS_THREAD_FUNCTIONS_ALL_MASK     = (1 << 13) - 1
+  DBUS_THREAD_FUNCTIONS_ALL_MASK     = (1 << 14) - 1
 } DBusThreadFunctionsMask;
 
 /**
  * Functions that must be implemented to make the D-Bus library
- * thread-aware. The recursive mutex functions should be specified
- * rather than the old, deprecated nonrecursive ones.
+ * thread-aware.
+ *
+ * If you supply both recursive and non-recursive mutexes,
+ * libdbus will use the non-recursive version for condition variables,
+ * and the recursive version in other contexts.
+ *
+ * The condition variable functions have to work with nonrecursive
+ * mutexes if you provide those, or with recursive mutexes if you
+ * don't.
  */
 typedef struct
 {
@@ -144,7 +177,9 @@ typedef struct
   
 } DBusThreadFunctions;
 
+DBUS_EXPORT
 dbus_bool_t  dbus_threads_init         (const DBusThreadFunctions *functions);
+DBUS_EXPORT
 dbus_bool_t  dbus_threads_init_default (void);
 
 /** @} */