Compute fd_setsize only once, and not on each select

[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 b10be51..098a235 100644 (file)
--- a/src/gras/Transport/rl_transport.c
+++ b/src/gras/Transport/rl_transport.c
@@ -12,6 +12,9 @@
 #include "gras/Transport/transport_private.h"
 XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(gras_trp);
 
+/* check transport_private.h for an explanation of this variable */
+gras_socket_t _gras_lastly_selected_socket = NULL;
+
 /**
  * gras_trp_select:
  *
@@ -37,34 +40,37 @@ gras_socket_t gras_trp_select(double timeout) {
      with this tiny optimisation on BillWare */
   fd_set FDS;
   int ready; /* return of select: number of socket ready to be serviced */
-  int fd_setsize; /* FD_SETSIZE not always defined. Get this portably */
+  static int fd_setsize=-1; /* FD_SETSIZE not always defined. Get this portably */
 
   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;
+  if (_gras_lastly_selected_socket && _gras_lastly_selected_socket->moredata) {
+     VERB0("Returning _gras_lastly_selected_socket since there is more data on it");
+     return _gras_lastly_selected_socket;
+  }
   
-  /* Compute FD_SETSIZE */
+  /* Compute FD_SETSIZE on need */
+  if (fd_setsize < 0) {        
 #ifdef HAVE_SYSCONF
-   fd_setsize = sysconf( _SC_OPEN_MAX );
+     fd_setsize = sysconf( _SC_OPEN_MAX );
 #else
 #  ifdef HAVE_GETDTABLESIZE 
-   fd_setsize = getdtablesize();
+     fd_setsize = getdtablesize();
 #  else
-   fd_setsize = FD_SETSIZE;
+     fd_setsize = FD_SETSIZE;
 #  endif /* !USE_SYSCONF */
 #endif
+  }
 
   while (done == -1) {
     if (timeout > 0) { /* did we timeout already? */
       now = gras_os_time();
       DEBUG2("wakeup=%f now=%f",wakeup, now);
       if (now == -1 || now >= wakeup) {
-       /* didn't find anything; no need to update _lastly_selected_socket since its moredata is 0 (or we would have returned it directly) */
+       /* didn't find anything; no need to update _gras_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);
@@ -187,14 +193,14 @@ gras_socket_t gras_trp_select(double timeout) {
         } else { 
           /* Got a suited socket ! */
           XBT_OUT;
-          _lastly_selected_socket = sock_iter;
+          _gras_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;
+          _gras_lastly_selected_socket = sock_iter;
           return sock_iter;
        }