Changeset 729 for pjproject/trunk/pjsip/src/pjsip/sip_dialog.c

Timestamp:

Sep 19, 2006 1:37:53 PM (18 years ago)

Author:

bennylp

Message:

Fixed race-condition/deadlock problems in the dialog/user agent layer
all the way up to PJSUA-API:

• standardized locking order: dialog then user agent, and dialog then PJSUA
• any threads that attempt to acquire mutexes in different order than above MUST employ retry mechanism (for an example, see acquire_call() in pjsua_call.c). This retry mechanism has also been used in the UA layer (sip_ua_layer.c) since it needs to lock user agent layer first before the dialog.
• introduced pjsip_dlg_try_inc_lock() and PJSUA_TRY_LOCK() to accomodate above.
• pjsua tested on Quad Xeon with 4 threads and 200 cps, so far so good.

File:

• pjproject/trunk/pjsip/src/pjsip/sip_dialog.c (modified) (3 diffs)

pjproject/trunk/pjsip/src/pjsip/sip_dialog.c

@@ -693 +693 @@
               dlg->sess_count));
 
-    pjsip_ua_lock_dlg_table();
-
     pj_mutex_lock(dlg->mutex_);
     dlg->sess_count++;
 
-    //pjsip_ua_unlock_dlg_table();
-
     PJ_LOG(6,(dlg->obj_name, "Leaving pjsip_dlg_inc_lock(), sess_count=%d", 
               dlg->sess_count));
 }
 
+/* Try to acquire dialog's mutex, but bail out if mutex can not be
+ * acquired immediately.
+ */
+PJ_DEF(pj_status_t) pjsip_dlg_try_inc_lock(pjsip_dialog *dlg)
+{
+    pj_status_t status;
+
+    PJ_LOG(6,(dlg->obj_name,"Entering pjsip_dlg_try_inc_lock(), sess_count=%d", 
+              dlg->sess_count));
+
+    status = pj_mutex_trylock(dlg->mutex_);
+    if (status != PJ_SUCCESS) {
+        PJ_LOG(6,(dlg->obj_name, "pjsip_dlg_try_inc_lock() failed"));
+        return status;
+    }
+
+    dlg->sess_count++;
+
+    PJ_LOG(6,(dlg->obj_name, "Leaving pjsip_dlg_try_inc_lock(), sess_count=%d", 
+              dlg->sess_count));
+
+    return PJ_SUCCESS;
+}
+
 
 /*
@@ -713 +733 @@
     PJ_LOG(6,(dlg->obj_name, "Entering pjsip_dlg_dec_lock(), sess_count=%d", 
               dlg->sess_count));
-
-    //pjsip_ua_lock_dlg_table();
 
     pj_assert(dlg->sess_count > 0);
@@ -726 +744 @@
         pj_mutex_unlock(dlg->mutex_);
     }
-
-    pjsip_ua_unlock_dlg_table();
 
     PJ_LOG(6,(THIS_FILE, "Leaving pjsip_dlg_dec_lock() (dlg=%p)", dlg));