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Sentinel: SENTINEL CKQUORUM command

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A way for monitoring systems to check that Sentinel is technically able
to reach the quorum and failover, using the currently visible Sentinels.
This commit is contained in:
antirez 2015-05-18 12:52:03 +02:00
parent b43431ac25
commit abc65e8987
1 changed files with 51 additions and 0 deletions
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51
src/sentinel.c
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@ -2811,6 +2811,31 @@ sentinelRedisInstance *sentinelGetMasterByNameOrReplyError(redisClient *c,
return ri;
}
#define SENTINEL_ISQR_OK 0
#define SENTINEL_ISQR_NOQUORUM (1<<0)
#define SENTINEL_ISQR_NOAUTH (1<<1)
int sentinelIsQuorumReachable(sentinelRedisInstance *master, int *usableptr) {
dictIterator *di;
dictEntry *de;
int usable = 1; /* Number of usable Sentinels. Init to 1 to count myself. */
int result = SENTINEL_ISQR_OK;
int voters = dictSize(master->sentinels)+1; /* Known Sentinels + myself. */
di = dictGetIterator(master->sentinels);
while((de = dictNext(di)) != NULL) {
sentinelRedisInstance *ri = dictGetVal(de);
if (ri->flags & (SRI_S_DOWN|SRI_O_DOWN)) continue;
usable++;
}
dictReleaseIterator(di);
if (usable < (int)master->quorum) result |= SENTINEL_ISQR_NOQUORUM;
if (usable < voters/2+1) result |= SENTINEL_ISQR_NOAUTH;
if (usableptr) *usableptr = usable;
return result;
}
void sentinelCommand(redisClient *c) {
if (!strcasecmp(c->argv[1]->ptr,"masters")) {
/* SENTINEL MASTERS */
@ -2993,6 +3018,32 @@ void sentinelCommand(redisClient *c) {
dictDelete(sentinel.masters,c->argv[2]->ptr);
sentinelFlushConfig();
addReply(c,shared.ok);
} else if (!strcasecmp(c->argv[1]->ptr,"ckquorum")) {
/* SENTINEL CKQUORUM <name> */
sentinelRedisInstance *ri;
int usable;
if ((ri = sentinelGetMasterByNameOrReplyError(c,c->argv[2]))
== NULL) return;
int result = sentinelIsQuorumReachable(ri,&usable);
if (result == SENTINEL_ISQR_OK) {
addReplySds(c, sdscatfmt(sdsempty(),
"+OK %i usable Sentinels. Quorum and failover authorization "
"can be reached\r\n",usable));
} else {
sds e = sdscatfmt(sdsempty(),
"-NOQUORUM %i usable Sentinels. ",usable);
if (result & SENTINEL_ISQR_NOQUORUM)
e = sdscat(e,"Not enough available Sentinels to reach the"
" specified quorum for this master");
if (result & SENTINEL_ISQR_NOAUTH) {
if (result & SENTINEL_ISQR_NOQUORUM) e = sdscat(e,". ");
e = sdscat(e, "Not enough available Sentinels to reach the"
" majority and authorize a failover");
}
e = sdscat(e,"\r\n");
addReplySds(c,e);
}
} else if (!strcasecmp(c->argv[1]->ptr,"set")) {
if (c->argc < 3 || c->argc % 2 == 0) goto numargserr;
sentinelSetCommand(c);