small modification to make the solver interface not block the GUI when the
solver runs without printing messages

Fltk/Solvers.cpp

-// $Id: Solvers.cpp,v 1.32 2005-01-13 23:39:10 geuzaine Exp $
+// $Id: Solvers.cpp,v 1.33 2005-01-14 01:40:49 geuzaine Exp $
 //
 // Copyright (C) 1997-2005 C. Geuzaine, J.-F. Remacle
 //
@@ -40,6 +40,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
+#include <sys/poll.h>
 #include <sys/un.h>
 #include <unistd.h>
 
@@ -118,10 +119,39 @@ int Solver(int num, char *args)
     SINFO[num].nbval[i] = 0;
   SINFO[num].pid = 0;
 
+  struct pollfd pfd;
+  pfd.fd = sock;
+  pfd.events = POLLIN|POLLPRI;
+  
+  while(1) {
+    // poll the socket file descriptor every 10 milliseconds until
+    // data is avalable; when nothing is available, just tend to
+    // pending GUI events. (This is much easier to manage than
+    // non-blocking IO. The real solution is of course to use threads,
+    // but that's still a bit of a nightmare to maintain in a portable
+    // way on all the platforms.)
     while(1){
-    if(SINFO[num].pid < 0)
+      if(SINFO[num].pid < 0){ // process has been killed
+	stop = 1;
+	break;
+      }
+      int ret = poll(&pfd, 1, 10);
+      if(ret == 0){ // nothing available
+	WID->check();
+      }
+      else if(ret > 0){ // data is there
+        break;
+      }
+      else{ // error
+        stop = 1;
         break;
-    Gmsh_ReceiveString(sock, &type, str);
+      }
+    }
+  
+    if(stop)
+      break;
+
+    if(Gmsh_ReceiveString(sock, &type, str)){
       switch (type) {
       case GMSH_CLIENT_START:
 	SINFO[num].pid = atoi(str);
@@ -163,7 +193,9 @@ int Solver(int num, char *args)
 	Msg(SOLVER, "%-8.8s: %s", SINFO[num].name, str);
 	break;
       }
-    WID->check(); // update the GUI
+      WID->check();
+    }
+
     if(stop)
       break;
   }

doc/VERSIONS

-$Id: VERSIONS,v 1.301 2005-01-13 05:45:45 geuzaine Exp $
+$Id: VERSIONS,v 1.302 2005-01-14 01:40:49 geuzaine Exp $
 
 New since 1.58: added support for discrete (triangulated) surfaces,
 either in STL format or with the new "Discrete Surface" command; added
@@ -9,7 +9,9 @@ view data (based on the same or on a different mesh); generalized
 Plugin(CutGrid); new plugins (Eigenvalues, Gradient, Curl,
 Divergence); changed default colormap to match Matlab's "Jet"
 colormap; new transformation matrix option for views (for
-non-destructive rotations, symmetries, etc.); fixed small bugs.
+non-destructive rotations, symmetries, etc.); improved solver
+interface to keep the GUI responsive during solver calls; the fixed
+small bugs.
 
 New in 1.58: fixed UNIX socket interface on Windows (broken by the TCP
 solver patch in 1.57); bumped version number of default