* interupt polling for an incoming signal right away by adding an event for

a pipe.  This eliminates the 2-3 second delay in signal delivery that
  was making using libevent for cntl-c in mpirun a bit evil.

This commit was SVN r3620.

src/event/signal.c

@@ -56,25 +56,61 @@
 
 #include "event.h"
 #include "evsignal.h"
+#include "util/output.h"
 
 extern struct ompi_event_list ompi_signalqueue;
 
 static short ompi_evsigcaught[NSIG];
 static int ompi_needrecalc;
+static int ompi_event_signal_pipe[2];
+static ompi_event_t ompi_event_signal_pipe_event;
+static int ompi_event_signal_count = 0;
+static bool initialized = false;
 volatile sig_atomic_t ompi_evsignal_caught = 0;
 
+static void ompi_event_signal_pipe_handler(int sd, short flags, void* user)
+{
+    unsigned char byte;
+    if(read(sd, &byte, 1) != 1) {
+        ompi_output(0, "ompi_event_signal_pipe: read failed with: errno=%d\n", errno);
+        ompi_event_del(&ompi_event_signal_pipe_event);
+    }
+    ompi_event_signal_count = 0;
+}
+
 void ompi_evsignal_handler(int sig);
 
 void
 ompi_evsignal_init(sigset_t *evsigmask)
 {
-	sigemptyset(evsigmask);
+    if (pipe(ompi_event_signal_pipe) != 0) {
+        ompi_output(0, "ompi_evsignal_init: pipe() failed with errno=%d\n", 
+                    errno);
+        return;
+    }
+    ompi_event_signal_count = 0;
+
+    sigemptyset(evsigmask);
 }
 
+
 int
 ompi_evsignal_add(sigset_t *evsigmask, struct ompi_event *ev)
 {
 	int evsignal;
+
+	if (!initialized) {
+	    /* Must delay the event add until after init() because
+	       it may trigger poll events that are not yet setup
+	       to be triggered. */
+    	    ompi_event_set(&ompi_event_signal_pipe_event,
+                           ompi_event_signal_pipe[0],
+	                   OMPI_EV_READ|OMPI_EV_PERSIST,
+	                   ompi_event_signal_pipe_handler,
+	                   0);
+	    ompi_event_add_i(&ompi_event_signal_pipe_event, 0);
+	    initialized = true;
+	}
 	
 	if (ev->ev_events & (OMPI_EV_READ|OMPI_EV_WRITE))
 		errx(1, "%s: OMPI_EV_SIGNAL incompatible use", __func__);
@@ -103,8 +139,17 @@ ompi_evsignal_del(sigset_t *evsigmask, struct ompi_event *ev)
 void
 ompi_evsignal_handler(int sig)
 {
+	const char errmsg[] = "ompi_evsignal_handler: error in write\n";
+
 	ompi_evsigcaught[sig]++;
 	ompi_evsignal_caught = 1;
+	if (ompi_event_signal_count == 0) {
+            unsigned char byte = 0;
+            if (write(ompi_event_signal_pipe[1], &byte, 1) != 1) {
+                write(2, errmsg, sizeof(errmsg));
+            }
+	    ompi_event_signal_count++;
+	}
 }
 
 int