Fix a vicious bug: TCP socket use a buffer and read operation get as much data as...

[simgrid.git] / src / gras / Transport / rl_transport.c

diff --git a/src/gras/Transport/rl_transport.c b/src/gras/Transport/rl_transport.c
index 6d65d78..b10be51 100644 (file)
--- a/src/gras/Transport/rl_transport.c
+++ b/src/gras/Transport/rl_transport.c
@@ -42,7 +42,12 @@ gras_socket_t gras_trp_select(double timeout) {
   gras_socket_t sock_iter; /* iterating over all sockets */
   int cursor;              /* iterating over all sockets */
 
-   
+  /* Check whether there is more data to read from the socket we selected last time.
+     This can happen with tcp buffered sockets since we try to get as much data as we can for them */
+  static gras_socket_t _lastly_selected_socket = NULL;
+  if (_lastly_selected_socket && _lastly_selected_socket->moredata) 
+     return _lastly_selected_socket;
+  
   /* Compute FD_SETSIZE */
 #ifdef HAVE_SYSCONF
    fd_setsize = sysconf( _SC_OPEN_MAX );
@@ -59,7 +64,7 @@ gras_socket_t gras_trp_select(double timeout) {
       now = gras_os_time();
       DEBUG2("wakeup=%f now=%f",wakeup, now);
       if (now == -1 || now >= wakeup) {
-       /* didn't find anything */
+       /* didn't find anything; no need to update _lastly_selected_socket since its moredata is 0 (or we would have returned it directly) */
        THROW1(timeout_error,0,
               "Timeout (%f) elapsed with selecting for incomming connexions",
               timeout);
@@ -182,12 +187,14 @@ gras_socket_t gras_trp_select(double timeout) {
         } else { 
           /* Got a suited socket ! */
           XBT_OUT;
+          _lastly_selected_socket = sock_iter;
           return sock_iter;
         }
 
        } else {
         /* This is a file socket. Cannot recv() on it, but it must be alive */
           XBT_OUT;
+          _lastly_selected_socket = sock_iter;
           return sock_iter;
        }