From 16237d78c83ed7c7182b60b9e66d29db44465986 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Tue, 19 Nov 2013 10:55:43 +0100
Subject: [PATCH] Sentinel: call sentinelFlushConfig() to persist state when
 needed.

Also the sentinel configuration rewriting was modified in order to
account for failover in progress, where we need to provide the promoted
slave address as master address, and the old master address as one of
the slaves address.
---
 src/sentinel.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/sentinel.c b/src/sentinel.c
index bd951d8c..99a5bb50 100644
--- a/src/sentinel.c
+++ b/src/sentinel.c
@@ -334,6 +334,7 @@ void sentinelStartFailover(sentinelRedisInstance *master);
 void sentinelDiscardReplyCallback(redisAsyncContext *c, void *reply, void *privdata);
 int sentinelSendSlaveOf(sentinelRedisInstance *ri, char *host, int port);
 char *sentinelVoteLeader(sentinelRedisInstance *master, uint64_t req_epoch, char *req_runid, uint64_t *leader_epoch);
+void sentinelFlushConfig(void);
 
 /* ========================= Dictionary types =============================== */
 
@@ -1201,13 +1202,17 @@ int sentinelResetMasterAndChangeAddress(sentinelRedisInstance *master, char *ip,
         slave = createSentinelRedisInstance(NULL,SRI_SLAVE,slaves[j]->ip,
                     slaves[j]->port, master->quorum, master);
         releaseSentinelAddr(slaves[j]);
-        if (slave) sentinelEvent(REDIS_NOTICE,"+slave",slave,"%@");
+        if (slave) {
+            sentinelEvent(REDIS_NOTICE,"+slave",slave,"%@");
+            sentinelFlushConfig();
+        }
     }
     zfree(slaves);
 
     /* Release the old address at the end so we are safe even if the function
      * gets the master->addr->ip and master->addr->port as arguments. */
     releaseSentinelAddr(oldaddr);
+    sentinelFlushConfig();
     return REDIS_OK;
 }
 
@@ -1345,12 +1350,14 @@ void rewriteConfigSentinelOption(struct rewriteConfigState *state) {
     di = dictGetIterator(sentinel.masters);
     while((de = dictNext(di)) != NULL) {
         sentinelRedisInstance *master, *ri;
+        sentinelAddr *master_addr;
         sds line;
 
         /* sentinel monitor */
         master = dictGetVal(de);
+        master_addr = sentinelGetCurrentMasterAddress(master);
         line = sdscatprintf(sdsempty(),"sentinel monitor %s %s %d %d",
-            master->name, master->addr->ip, master->addr->port,
+            master->name, master_addr->ip, master_addr->port,
             master->quorum);
         rewriteConfigRewriteLine(state,"sentinel",line,1);
 
@@ -1411,7 +1418,18 @@ void rewriteConfigSentinelOption(struct rewriteConfigState *state) {
         /* sentinel known-slave */
         di2 = dictGetIterator(master->slaves);
         while((de = dictNext(di)) != NULL) {
+            sentinelAddr *slave_addr;
+
             ri = dictGetVal(de);
+            slave_addr = ri->addr;
+
+            /* If master_addr (obtained using sentinelGetCurrentMasterAddress()
+             * so it may be the address of the promoted slave) is equal to this
+             * slave's address, a failover is in progress and the slave was
+             * already successfully promoted. So as the address of this slave
+             * we use the old master address instead. */
+            if (sentinelAddrIsEqual(slave_addr,master_addr))
+                slave_addr = master->addr;
             line = sdscatprintf(sdsempty(),
                 "sentinel known-slave %s %s %d",
                 master->name, ri->addr->ip, ri->addr->port);
@@ -1754,6 +1772,7 @@ void sentinelRefreshInstanceInfo(sentinelRedisInstance *ri, const char *info) {
             ri->master->config_epoch = ri->master->failover_epoch;
             ri->master->failover_state = SENTINEL_FAILOVER_STATE_RECONF_SLAVES;
             ri->master->failover_state_change_time = mstime();
+            sentinelFlushConfig();
             sentinelEvent(REDIS_WARNING,"+promoted-slave",ri,"%@");
             sentinelEvent(REDIS_WARNING,"+failover-state-reconf-slaves",
                 ri->master,"%@");
@@ -1974,6 +1993,7 @@ void sentinelReceiveHelloMessages(redisAsyncContext *c, void *reply, void *privd
                      * for Sentinels we don't have a later chance to fill it,
                      * so do it now. */
                     si->runid = sdsnew(token[2]);
+                    sentinelFlushConfig();
                 }
             }