ubik: update epoch as soon as sync-site is elected

[openafs.git] / src / ubik / beacon.c

diff --git a/src/ubik/beacon.c b/src/ubik/beacon.c
index bf32432..1e37e63 100644 (file)
--- a/src/ubik/beacon.c
+++ b/src/ubik/beacon.c
@@ -399,6 +399,11 @@ ubeacon_InitServerListCommon(afs_uint32 ame, struct afsconf_cell *info,
            beacon_globals.ubik_amSyncSite = 1; /* let's start as sync site */
            beacon_globals.syncSiteUntil = 0x7fffffff;  /* and be it quite a while */
            beacon_globals.ubik_syncSiteAdvertised = 1;
+           DBHOLD(ubik_dbase);
+           UBIK_VERSION_LOCK;
+           version_globals.ubik_epochTime = FT_ApproxTime();
+           UBIK_VERSION_UNLOCK;
+           DBRELE(ubik_dbase);
        }
     } else {
        if (nServers == 1)      /* special case 1 server */
@@ -406,8 +411,14 @@ ubeacon_InitServerListCommon(afs_uint32 ame, struct afsconf_cell *info,
     }
 
     if (ubik_singleServer) {
-       if (!beacon_globals.ubik_amSyncSite)
+       if (!beacon_globals.ubik_amSyncSite) {
            ubik_dprint("Ubik: I am the sync site - 1 server\n");
+           DBHOLD(ubik_dbase);
+           UBIK_VERSION_LOCK;
+           version_globals.ubik_epochTime = FT_ApproxTime();
+           UBIK_VERSION_UNLOCK;
+           DBRELE(ubik_dbase);
+       }
        beacon_globals.ubik_amSyncSite = 1;
        beacon_globals.syncSiteUntil = 0x7fffffff;      /* quite a while */
        beacon_globals.ubik_syncSiteAdvertised = 1;
@@ -431,6 +442,7 @@ ubeacon_Interact(void *dummy)
     afs_int32 i;
     struct ubik_server *ts;
     afs_int32 temp, yesVotes, lastWakeupTime, oldestYesVote, syncsite;
+    int becameSyncSite;
     struct ubik_tid ttid;
     struct ubik_version tversion;
     afs_int32 startTime;
@@ -604,17 +616,20 @@ ubeacon_Interact(void *dummy)
 
        /* now decide if we have enough votes to become sync site.
         * Note that we can still get enough votes even if we didn't for ourself. */
+       becameSyncSite = 0;
        if (yesVotes > nServers) {      /* yesVotes is bumped by 2 or 3 for each site */
            UBIK_BEACON_LOCK;
-           if (!beacon_globals.ubik_amSyncSite)
+           if (!beacon_globals.ubik_amSyncSite) {
                ubik_dprint("Ubik: I am the sync site\n");
-           else {
+               /* Defer actually changing any variables until we can take the
+                * DB lock (which is before the beacon lock in the lock order). */
+               becameSyncSite = 1;
+           } else {
+               beacon_globals.syncSiteUntil = oldestYesVote + SMALLTIME;
                /* at this point, we have the guarantee that at least quorum
                 * received a beacon packet informing we have a sync-site. */
                beacon_globals.ubik_syncSiteAdvertised = 1;
            }
-           beacon_globals.ubik_amSyncSite = 1;
-           beacon_globals.syncSiteUntil = oldestYesVote + SMALLTIME;
 #ifndef AFS_PTHREAD_ENV
                /* I did not find a corresponding LWP_WaitProcess(&ubik_amSyncSite) --
                   this may be a spurious signal call -- sjenkins */
@@ -632,6 +647,25 @@ ubeacon_Interact(void *dummy)
            urecovery_ResetState();     /* tell recovery we're no longer the sync site */
            DBRELE(ubik_dbase);
        }
+       /* We cannot take the DB lock around the entire preceding conditional,
+        * because if we are currently the sync site and this election serves
+        * to confirm that status, the DB lock may already be held for a long-running
+        * write transaction.  In such a case, attempting to acquire the DB lock
+        * would cause the beacon thread to block and disrupt election processing.
+        * However, if we are transitioning from not-sync-site to sync-site, there
+        * can be no outstanding transactions and acquiring the DB lock should be
+        * safe without extended blocking. */
+       if (becameSyncSite) {
+           DBHOLD(ubik_dbase);
+           UBIK_BEACON_LOCK;
+           UBIK_VERSION_LOCK;
+           version_globals.ubik_epochTime = FT_ApproxTime();
+           beacon_globals.ubik_amSyncSite = 1;
+           beacon_globals.syncSiteUntil = oldestYesVote + SMALLTIME;
+           UBIK_VERSION_UNLOCK;
+           UBIK_BEACON_UNLOCK;
+           DBRELE(ubik_dbase);
+       }
 
     }                          /* while loop */
     return NULL;