unlock event queue when handling event.

and make lock scope smaller.

src/pc_pomelo.c

@@ -350,8 +350,6 @@ int pc_client_poll(pc_client_t* client)
         return PC_RC_ERROR;
     }
 
-    pc_mutex_lock(&client->event_mutex);
-
     /*
      * `is_in_poll` is used to avoid recursive invocation of pc_client_poll
      * by identical thread as `pc_mutex_t` is recursive.
@@ -362,21 +360,25 @@ int pc_client_poll(pc_client_t* client)
     if (!client->is_in_poll) {
         client->is_in_poll = 1;
 
+        pc_mutex_lock(&client->event_mutex);
         while(!QUEUE_EMPTY(&client->pending_ev_queue)) {
             q = QUEUE_HEAD(&client->pending_ev_queue);
             ev = (pc_event_t*) QUEUE_DATA(q, pc_event_t, queue);
 
             QUEUE_REMOVE(&ev->queue);
+            pc_mutex_unlock(&client->event_mutex);
+
             QUEUE_INIT(&ev->queue);
 
             assert((PC_IS_PRE_ALLOC(ev->type) && PC_PRE_ALLOC_IS_BUSY(ev->type)) || PC_IS_DYN_ALLOC(ev->type));
 
             pc__handle_event(client, ev);
+            pc_mutex_lock(&client->event_mutex);
         }
+        pc_mutex_unlock(&client->event_mutex);
         client->is_in_poll = 0;
     }
 
-    pc_mutex_unlock(&client->event_mutex);
 
     return PC_RC_OK;
 }