Calling R_PolledEvents from R_CheckUserInterrupt

On 5/5/07, Luke Tierney <luke at stat.uiowa.edu> wrote:

[...]

However, R_PolledEvents is only called from a limited set of places
now (including the socket reading code to keep things responsive
during blocking reads).  But it is not called from the interupt
checking code, which means if a user does something equivalent to

    while (TRUE) {}

there is not point where events get looked at to see a user interrupt
action. The current definition of R_CheckUserInterrupt is

void R_CheckUserInterrupt(void)
{
     R_CheckStack();
     /* This is the point where GUI systems need to do enough event
        processing to determine whether there is a user interrupt event
        pending.  Need to be careful not to do too much event
        processing though: if event handlers written in R are allowed
        to run at this point then we end up with concurrent R
        evaluations and that can cause problems until we have proper
        concurrency support. LT */
#if  ( defined(HAVE_AQUA) || defined(Win32) )
     R_ProcessEvents();
#else
     if (R_interrupts_pending)
         onintr();
#endif /* Win32 */
}

So only on Windows or Mac do we do event processing.  We could add a
R_PolledEvents() call in the #else bit to support this, though the
cautions in the comment do need to be kept in mind.

I have been using the following patch to src/main/errors.c for a while
without any obvious ill effects. Could we add this to r-devel (with
necessary changes for Windows, if any)?

-Deepayan

Index: errors.c
===================================================================
--- errors.c    (revision 41764)
+++ errors.c    (working copy)
@@ -39,6 +39,8 @@
 #include <R_ext/GraphicsEngine.h> /* for GEonExit */
 #include <Rmath.h> /* for imax2 */

+#include <R_ext/eventloop.h>
+
 #ifndef min
 #define min(a, b) (a<b?a:b)
 #endif
@@ -117,6 +119,8 @@
 #if  ( defined(HAVE_AQUA) || defined(Win32) )
     R_ProcessEvents();
 #else
+    R_PolledEvents();
     if (R_interrupts_pending)
        onintr();
 #endif /* Win32 */