xenserverd: Give XAPI a grace period before refreshing network UUIDs.

XAPI updates the pool.conf file before it actually refreshes its database
from the new pool, so we need to wait for that to happen.  Hard-coded
delays aren't a good idea, but in the long term XAPI will probably be
adding a hook script for us to use, so this may be an OK stopgap measure.

Bug #2756.

diff --git a/xenserver/ovs-xenserverd.c b/xenserver/ovs-xenserverd.c
index 72617ae..a69ca8a 100644 (file)
--- a/xenserver/ovs-xenserverd.c
+++ b/xenserver/ovs-xenserverd.c
@@ -162,6 +162,9 @@ static struct timespec pool_conf_mtime;
 /* The executing instance of refresh-network-uuids, or NULL if none. */
 static struct process *refresh_script;
 
+/* Time at which to start the refresh script. */
+static long long int next_refresh = LLONG_MAX;
+
 static void
 network_uuid_refresh_run(void)
 {
@@ -183,7 +186,9 @@ network_uuid_refresh_run(void)
         refresh_script = NULL;
     }
 
-    /* Otherwise, check for a change in timestamp.
+    /* Otherwise, schedule a refresh in a few seconds if the timestamp has
+     * changed.  Refreshing immediately doesn't work because XAPI takes a while
+     * to switch over to new UUIDs.
      *
      * (We will always detect a change in timestamp when we start up.  That's
      * good, since it means that the refresh-network-uuids script gets
@@ -192,9 +197,17 @@ network_uuid_refresh_run(void)
     get_mtime("/etc/xensource/pool.conf", &new_mtime);
     if (new_mtime.tv_sec != pool_conf_mtime.tv_sec
         || new_mtime.tv_nsec != pool_conf_mtime.tv_nsec) {
+        next_refresh = time_msec() + 10 * 1000;
+        return;
+    }
+
+    /* Otherwise, if our timer expired then start the refresh. */
+    if (time_msec() >= next_refresh) {
         struct stat s;
         char *argv[2];
 
+        next_refresh = LLONG_MAX;
+
         argv[0] = xasprintf("%s/scripts/refresh-network-uuids",
                             ovs_pkgdatadir);
         argv[1] = NULL;
@@ -222,7 +235,12 @@ network_uuid_refresh_wait(void)
 {
     if (refresh_script) {
         process_wait(refresh_script);
-    } else if (pool_conf_mtime.tv_sec) {
-        poll_timer_wait(1000);
+    } else {
+        if (pool_conf_mtime.tv_sec) {
+            poll_timer_wait(1000);
+        }
+        if (next_refresh != LLONG_MAX) {
+            poll_timer_wait(next_refresh - time_msec());
+        }
     }
 }