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Sentinel: turn old master into a slave when it comes back.

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This commit is contained in:
antirez 2013-04-19 16:34:07 +02:00
parent 9d823fc222
commit 8e222c888f
1 changed files with 40 additions and 2 deletions
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42
src/sentinel.c
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@ -74,6 +74,8 @@ typedef struct sentinelAddr {
#define SRI_RECONF_DONE (1<<13) /* Slave synchronized with new master. */
#define SRI_FORCE_FAILOVER (1<<14) /* Force failover with master up. */
#define SRI_SCRIPT_KILL_SENT (1<<15) /* SCRIPT KILL already sent on -BUSY */
#define SRI_DEMOTE (1<<16) /* If the instance claims to be a master, demote
it into a slave sending SLAVEOF. */
#define SENTINEL_INFO_PERIOD 10000
#define SENTINEL_PING_PERIOD 1000
@ -1401,7 +1403,7 @@ void sentinelRefreshInstanceInfo(sentinelRedisInstance *ri, const char *info) {
* otherwise add it. */
if (sentinelRedisInstanceLookupSlave(ri,ip,atoi(port)) == NULL) {
if ((slave = createSentinelRedisInstance(NULL,SRI_SLAVE,ip,
atoi(port), ri->quorum,ri)) != NULL)
atoi(port), ri->quorum, ri)) != NULL)
{
sentinelEvent(REDIS_NOTICE,"+slave",slave,"%@");
}
@ -1467,7 +1469,19 @@ void sentinelRefreshInstanceInfo(sentinelRedisInstance *ri, const char *info) {
/* Act if a slave turned into a master. */
if ((ri->flags & SRI_SLAVE) && role == SRI_MASTER) {
if (!(ri->master->flags & SRI_FAILOVER_IN_PROGRESS) &&
if (ri->flags & SRI_DEMOTE) {
int retval;
/* Old master returned back? Turn it into a slave ASAP.
* We'll clear this flag only when we have the acknowledge
* that it's a slave again. */
retval = redisAsyncCommand(ri->cc,
sentinelDiscardReplyCallback, NULL, "SLAVEOF %s %d",
ri->master->addr->ip,
ri->master->addr->port);
if (retval == REDIS_OK)
sentinelEvent(REDIS_NOTICE,"+demote-old-slave",ri,"%@");
} else if (!(ri->master->flags & SRI_FAILOVER_IN_PROGRESS) &&
(runid_changed || first_runid))
{
/* If a slave turned into master but:
@ -1564,6 +1578,12 @@ void sentinelRefreshInstanceInfo(sentinelRedisInstance *ri, const char *info) {
ri->failover_state_change_time = mstime();
}
}
/* Detect if the old master was demoted as slave. */
if (role == SRI_SLAVE && ri->flags & SRI_DEMOTE) {
sentinelEvent(REDIS_NOTICE,"+slave",ri,"%@");
ri->flags &= ~SRI_DEMOTE;
}
}
void sentinelInfoReplyCallback(redisAsyncContext *c, void *reply, void *privdata) {
@ -1835,6 +1855,7 @@ void addReplySentinelRedisInstance(redisClient *c, sentinelRedisInstance *ri) {
if (ri->flags & SRI_RECONF_SENT) flags = sdscat(flags,"reconf_sent,");
if (ri->flags & SRI_RECONF_INPROG) flags = sdscat(flags,"reconf_inprog,");
if (ri->flags & SRI_RECONF_DONE) flags = sdscat(flags,"reconf_done,");
if (ri->flags & SRI_DEMOTE) flags = sdscat(flags,"demote,");
if (sdslen(flags) != 0) flags = sdsrange(flags,0,-2); /* remove last "," */
addReplyBulkCString(c,flags);
@ -2592,6 +2613,7 @@ sentinelRedisInstance *sentinelSelectSlave(sentinelRedisInstance *master) {
mstime_t info_validity_time = mstime()-SENTINEL_INFO_VALIDITY_TIME;
if (slave->flags & (SRI_S_DOWN|SRI_O_DOWN|SRI_DISCONNECTED)) continue;
if (slave->flags & SRI_DEMOTE) continue; /* Old master not yet ready. */
if (slave->last_avail_time < info_validity_time) continue;
if (slave->slave_priority == 0) continue;
@ -2837,12 +2859,28 @@ void sentinelFailoverReconfNextSlave(sentinelRedisInstance *master) {
void sentinelFailoverSwitchToPromotedSlave(sentinelRedisInstance *master) {
sentinelRedisInstance *ref = master->promoted_slave ?
master->promoted_slave : master;
sds old_master_ip;
int old_master_port;
sentinelEvent(REDIS_WARNING,"+switch-master",master,"%s %s %d %s %d",
master->name, master->addr->ip, master->addr->port,
ref->addr->ip, ref->addr->port);
old_master_ip = sdsdup(master->addr->ip);
old_master_port = master->addr->port;
sentinelResetMasterAndChangeAddress(master,ref->addr->ip,ref->addr->port);
/* If this is a real switch, that is, we have master->promoted_slave not
* NULL, then we want to add the old master as a slave of the new master,
* but flagging it with SRI_DEMOTE so that we know we'll need to send
* SLAVEOF once the old master is reachable again. */
if (master != ref) {
/* Add the new slave, but don't generate a Sentinel event as it will
* happen later when finally the instance will claim to be a slave
* in the INFO output. */
createSentinelRedisInstance(NULL,SRI_SLAVE|SRI_DEMOTE,
old_master_ip, old_master_port, master->quorum, master);
}
sdsfree(old_master_ip);
}
void sentinelFailoverStateMachine(sentinelRedisInstance *ri) {