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

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/simgrid/simgrid/trunk@2671 48e7efb5-ca39-0410-a469-dd3cf9ba447f

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 */
 
   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 );
   /* 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) {
       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);
        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;
         } 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;
           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;
        }
 
           return sock_iter;
        }
 

diff --git a/src/gras/Transport/transport.c b/src/gras/Transport/transport.c
index 476780f..aff786e 100644 (file)
--- a/src/gras/Transport/transport.c
+++ b/src/gras/Transport/transport.c
@@ -160,6 +160,7 @@ void gras_trp_socket_new(int incoming,
   sock->meas = 0;
   sock->recv_ok = 1;
   sock->valid = 1;
   sock->meas = 0;
   sock->recv_ok = 1;
   sock->valid = 1;

+  sock->moredata = 0;

 
   sock->sd     = -1;
   sock->port      = -1;
 
   sock->sd     = -1;
   sock->port      = -1;

diff --git a/src/gras/Transport/transport_plugin_tcp.c b/src/gras/Transport/transport_plugin_tcp.c
index a4db1b6..b92dccc 100644 (file)
--- a/src/gras/Transport/transport_plugin_tcp.c
+++ b/src/gras/Transport/transport_plugin_tcp.c
@@ -338,6 +338,8 @@ gras_trp_tcp_recv_withbuffer(gras_socket_t sock,
             got);
     }
   }
             got);
     }
   }

+  /* indicate to the gras_select function that there is more to read on this socket so that it does not actually select */
+  sock->moredata = (bufsize != 0);

   return got;
 }
 
   return got;
 }
 

diff --git a/src/gras/Transport/transport_private.h b/src/gras/Transport/transport_private.h
index a2d50dc..9b384ec 100644 (file)
--- a/src/gras/Transport/transport_private.h
+++ b/src/gras/Transport/transport_private.h
@@ -42,6 +42,9 @@ typedef struct s_gras_socket  {
   int meas :1; /* true if this is an experiment socket instead of messaging */
   int recv_ok :1; /* true if it is valid to recv() on the socket (false if it is a file) */
   int valid :1; /* false if a select returned that the peer quitted, forcing us to "close" the socket */
   int meas :1; /* true if this is an experiment socket instead of messaging */
   int recv_ok :1; /* true if it is valid to recv() on the socket (false if it is a file) */
   int valid :1; /* false if a select returned that the peer quitted, forcing us to "close" the socket */

+  int moredata :1; /* TCP socket use a buffer and read operation get as much data as possible. 
+                     It is possible that several messages are received in one shoot, and select won't catch them afterward again.
+                     This boolean indicates that this is the case, so that we don't call select in that case. */

 
   unsigned long int buf_size; /* what to say to the OS. field here to remember it when accepting */
    
 
   unsigned long int buf_size; /* what to say to the OS. field here to remember it when accepting */