Overload the event_base_t struct to include a (hopefully) temporary change to deal with cross-event-base synchronization. This is done transparently so no code changes are required within the rest of the code base. Comments explain what was changed and why.

This commit was SVN r24105.

opal/mca/event/libevent207/libevent207.h

@@ -58,7 +58,19 @@
 #include "opal/mca/event/event.h"
 
 typedef struct event opal_event_t;
-typedef struct event_base opal_event_base_t;
+/*** Overload the event_base_t struct ***/
+/* This may (hopefully) be a temporary change
+ * to deal with cross-base sync. Specifically,
+ * when an event in one base needs to release
+ * a condition_wait in another base, we need
+ * to "wakeup" the event base in the second base
+ * so the condition_wait can be checked
+ */
+typedef struct {
+    struct event_base *base;
+    opal_event_t wakeup_event;
+    int wakeup_pipe[2];
+} opal_event_base_t;
 
 BEGIN_C_DECLS
 
@@ -75,8 +87,9 @@ OPAL_DECLSPEC extern opal_event_base_t *opal_event_base;
 #define OPAL_EVLOOP_ONCE     EVLOOP_ONCE        /**< Block at most once. */
 #define OPAL_EVLOOP_NONBLOCK EVLOOP_NONBLOCK    /**< Do not block. */
 
-/* Global function to create an event base */
+/* Global function to create and release an event base */
 OPAL_DECLSPEC opal_event_base_t* opal_event_base_create(void);
+OPAL_DECLSPEC void opal_event_base_finalize(opal_event_base_t *base);
 
 OPAL_DECLSPEC int opal_event_init(void);
 
@@ -92,11 +105,9 @@ OPAL_DECLSPEC int opal_event_init(void);
 #endif
 
 /* Basic event APIs */
-#define opal_event_base_finalize(x) event_base_free((x))
-
 #define opal_event_set_debug_output(x) event_set_debug_output((x))
 
-#define opal_event_set(b, ev, fd, fg, cb, arg) event_assign((ev), (b), (fd), (fg), (event_callback_fn) (cb), (arg))
+#define opal_event_set(b, ev, fd, fg, cb, arg) event_assign((ev), (b)->base, (fd), (fg), (event_callback_fn) (cb), (arg))
 
 #define opal_event_add(ev, tv) event_add((ev), (tv))
 
@@ -105,11 +116,11 @@ OPAL_DECLSPEC int opal_event_init(void);
 #define opal_event_active(x, y, z) event_active((x), (y), (z))
 
 /* Timer APIs */
-#define opal_event_evtimer_new(b, cb, arg) event_new((b), -1, 0, (event_callback_fn) (cb), (arg)) 
+#define opal_event_evtimer_new(b, cb, arg) event_new((b)->base, -1, 0, (event_callback_fn) (cb), (arg)) 
 
 #define opal_event_evtimer_add(ev, tv) event_add((ev), (tv))
 
-#define opal_event_evtimer_set(b, ev, cb, arg) event_assign((ev), (b), -1, 0, (event_callback_fn) (cb), (arg))
+#define opal_event_evtimer_set(b, ev, cb, arg) event_assign((ev), (b)->base, -1, 0, (event_callback_fn) (cb), (arg))
 
 #define opal_event_evtimer_del(ev) event_del((ev))
 
@@ -120,7 +131,7 @@ OPAL_DECLSPEC int opal_event_init(void);
 /* Signal APIs */
 #define opal_event_signal_add(ev, tv) event_add((ev), (tv))
 
-#define opal_event_signal_set(b, ev, fd, cb, arg) event_assign((ev), (b), (fd), EV_SIGNAL|EV_PERSIST, (event_callback_fn) (cb), (arg))
+#define opal_event_signal_set(b, ev, fd, cb, arg) event_assign((ev), (b)->base, (fd), EV_SIGNAL|EV_PERSIST, (event_callback_fn) (cb), (arg))
 
 #define opal_event_signal_del(ev) event_del((ev))
 
@@ -130,9 +141,9 @@ OPAL_DECLSPEC int opal_event_init(void);
 
 #define opal_event_get_signal(ev) event_get_signal((ev))
 
-#define opal_event_loop(b, fg) event_base_loop((b), (fg))
+#define opal_event_loop(b, fg) event_base_loop((b->base), (fg))
 
-#define opal_event_dispatch(b) event_base_loop((b), 0)
+#define opal_event_dispatch(b) event_base_loop((b)->base, 0)
 
 END_C_DECLS
 

opal/mca/event/libevent207/libevent207_module.c

@@ -3,6 +3,7 @@
  * Copyright (c) 2010      Oracle and/or its affiliates.  All rights reserved.
  */
 #include "opal_config.h"
+#include "opal/constants.h"
 #include "config.h"
 
 #ifdef HAVE_SYS_TYPES_H
@@ -36,9 +37,10 @@
 #include "opal/threads/mutex.h"
 #include "opal/threads/threads.h"
 #include "opal/util/output.h"
-#include "opal/constants.h"
 #include "opal/util/argv.h"
+#include "opal/util/fd.h"
 #include "opal/mca/base/mca_base_param.h"
+
 #include "libevent207.h"
 #include "opal/mca/event/base/base.h"
 
@@ -98,17 +100,60 @@ static const struct eventop *eventops[] = {
 
 static struct event_config *config=NULL;
 
+static void wakeup_event(int fd, short flags, void* arg)
+{
+    char byte;
+
+    /* clear the event */
+    opal_fd_read(fd, 1, &byte);
+    return;
+}
+
 /* Public function -- not part of the module */
+/* This includes (hopefully) a temporary change
+ * to deal with cross-base sync. Specifically,
+ * when an event in one base needs to release
+ * a condition_wait in another base, we need
+ * to "wakeup" the event base in the second base
+ * so the condition_wait can be checked
+ */
 opal_event_base_t* opal_event_base_create(void)
 {
     struct event_base *base;
+    opal_event_base_t *evbase;
 
     base = event_base_new_with_config(config);
     if (NULL == base) {
         /* there is no backend method that does what we want */
         opal_output(0, "No event method available");
+        return NULL;
     }
-    return base;
+    evbase = (opal_event_base_t*)malloc(sizeof(opal_event_base_t));
+    evbase->base = base;
+    if (pipe(evbase->wakeup_pipe) < 0) {
+        opal_output(0, "Unable to open wakeup pipe");
+        free(evbase);
+        event_base_free(base);
+        return NULL;
+    }
+    event_assign(&evbase->wakeup_event, base,
+                 evbase->wakeup_pipe[0], EV_READ | EV_PERSIST,
+                 wakeup_event, NULL);
+    event_add(&evbase->wakeup_event, 0);
+    return evbase;
+}
+
+void opal_event_base_finalize(opal_event_base_t *evbase)
+{
+    /* delete the wakeup event */
+    event_del(&evbase->wakeup_event);
+    /* close the pipe */
+    close(evbase->wakeup_pipe[0]);
+    close(evbase->wakeup_pipe[1]);
+    /* release the base */
+    event_base_free(evbase->base);
+    /* free the storage */
+    free(evbase);
 }
 
 int opal_event_init(void)