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Sentinel: do not crash against slaves not publishing the runid.

Older versions of Redis (before 2.4.17) don't publish the runid field in
INFO. This commit makes Sentinel able to handle that without crashing.
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1 parent 58186b9 commit 6276434ad22ded9f5bf9997137c311e447154908 @antirez committed Aug 30, 2012
Showing with 13 additions and 1 deletion.
  1. +13 −1 src/sentinel.c
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@@ -2521,9 +2521,21 @@ void sentinelStartFailoverIfNeeded(sentinelRedisInstance *master) {
int compareSlavesForPromotion(const void *a, const void *b) {
sentinelRedisInstance **sa = (sentinelRedisInstance **)a,
**sb = (sentinelRedisInstance **)b;
+ char *sa_runid, *sb_runid;
+
if ((*sa)->slave_priority != (*sb)->slave_priority)
return (*sa)->slave_priority - (*sb)->slave_priority;
- return strcasecmp((*sa)->runid,(*sb)->runid);
+
+ /* If priority is the same, select the slave with that has the
+ * lexicographically smaller runid. Note that we try to handle runid
+ * == NULL as there are old Redis versions that don't publish runid in
+ * INFO. A NULL runid is considered bigger than any other runid. */
+ sa_runid = (*sa)->runid;
+ sb_runid = (*sb)->runid;
+ if (sa_runid == NULL && sb_runid == NULL) return 0;
+ else if (sa_runid == NULL) return 1; /* a > b */
+ else if (sb_runid == NULL) return -1; /* a < b */
+ return strcasecmp(sa_runid, sb_runid);
}
sentinelRedisInstance *sentinelSelectSlave(sentinelRedisInstance *master) {

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