merge from srs2

@@ -105,11 +105,12 @@ namespace internal
             return ret;
         }
         
+        disposed = false;
         // we set to loop to true for thread to run.
         loop = true;
         
         // wait for cid to ready, for parent thread to get the cid.
-        while (_cid < 0 && loop) {
+        while (_cid < 0) {
             st_usleep(10 * 1000);
         }
         
@@ -129,6 +130,8 @@ namespace internal
         
         dispose();
         
+        _cid = -1;
+        can_run = false;
         tid = NULL;
     }
     

@@ -105,7 +105,7 @@ bool SrsBuffer::empty()
 
 bool SrsBuffer::require(int required_size)
 {
-    srs_assert(required_size > 0);
+    srs_assert(required_size >= 0);
     
     return required_size <= nb_bytes - (p - bytes);
 }