From 671c1dfb5629e32f3addfe865e5e5a04f35b007d Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Tue, 5 Nov 2013 17:23:11 +0100
Subject: [PATCH] Sentinel: always send CONFIG REWRITE when changing instance
role.
This change makes Sentinel less fragile about a number of failure modes.
This commit also fixes a different bug as a side effect, SLAVEOF command
was sent multiple times without incrementing the pending commands count.
---
src/db.c | 2 +-
src/sentinel.c | 64 +++++++++++++++++++++++++++++++-------------------
2 files changed, 41 insertions(+), 25 deletions(-)
diff --git a/src/db.c b/src/db.c
index 8d538662..1bdcf9e8 100644
--- a/src/db.c
+++ b/src/db.c
@@ -350,7 +350,7 @@ void scanCallback(void *privdata, const dictEntry *de) {
if (val) listAddNodeTail(keys, val);
}
-/* Try to parse a SCAN cursor stored ad object 'o':
+/* Try to parse a SCAN cursor stored at object 'o':
* if the cursor is valid, store it as unsigned integer into *cursor and
* returns REDIS_OK. Otherwise return REDIS_ERR and send an error to the
* client. */
diff --git a/src/sentinel.c b/src/sentinel.c
index 4bea156d..307a6071 100644
--- a/src/sentinel.c
+++ b/src/sentinel.c
@@ -1518,8 +1518,7 @@ void sentinelRefreshInstanceInfo(sentinelRedisInstance *ri, const char *info) {
(mstime() - ri->master->info_refresh) < SENTINEL_INFO_PERIOD*2)
{
int retval;
- retval = redisAsyncCommand(ri->cc,
- sentinelDiscardReplyCallback, NULL, "SLAVEOF %s %d",
+ retval = sentinelSendSlaveOf(ri,
ri->master->addr->ip,
ri->master->addr->port);
if (retval == REDIS_OK)
@@ -2521,6 +2520,39 @@ char *sentinelGetObjectiveLeader(sentinelRedisInstance *master) {
return winner;
}
+/* Send SLAVEOF to the specified instance, always followed by a
+ * CONFIG REWRITE command in order to store the new configuration on disk
+ * when possible (that is, if the Redis instance is recent enough to support
+ * config rewriting, and if the server was started with a configuration file).
+ *
+ * If Host is NULL the function sends "SLAVEOF NO ONE".
+ *
+ * The command returns REDIS_OK if the SLAVEOF command was accepted for
+ * (later) delivery otherwise REDIS_ERR. The command replies are just
+ * discarded. */
+int sentinelSendSlaveOf(sentinelRedisInstance *ri, char *host, int port) {
+ char portstr[32];
+
+ ll2string(portstr,sizeof(portstr),port);
+
+ if (host == NULL) {
+ host = "NO";
+ memcpy(portstr,"ONE",4);
+ }
+
+ retval = redisAsyncCommand(ri->cc,
+ sentinelDiscardReplyCallback, NULL, "SLAVEOF %s %s", host, portstr);
+ if (retval == REDIS_ERR) return retval;
+
+ ri->pending_commands++;
+ if (redisAsyncCommand(ri->cc,
+ sentinelDiscardReplyCallback, NULL, "CONFIG REWRITE") == REDIS_OK)
+ {
+ ri->pending_commands++;
+ }
+ return REDIS_OK;
+}
+
/* Setup the master state to start a failover as a leader.
*
* State can be either:
@@ -2750,10 +2782,8 @@ void sentinelFailoverSendSlaveOfNoOne(sentinelRedisInstance *ri) {
* We actually register a generic callback for this command as we don't
* really care about the reply. We check if it worked indirectly observing
* if INFO returns a different role (master instead of slave). */
- retval = redisAsyncCommand(ri->promoted_slave->cc,
- sentinelDiscardReplyCallback, NULL, "SLAVEOF NO ONE");
+ retval = sentinelSendSlaveOf(ri->promoted_slave,NULL,0);
if (retval != REDIS_OK) return;
- ri->promoted_slave->pending_commands++;
sentinelEvent(REDIS_NOTICE, "+failover-state-wait-promotion",
ri->promoted_slave,"%@");
ri->failover_state = SENTINEL_FAILOVER_STATE_WAIT_PROMOTION;
@@ -2823,10 +2853,6 @@ void sentinelFailoverDetectEnd(sentinelRedisInstance *master) {
if (timeout && (master->flags & SRI_I_AM_THE_LEADER)) {
dictIterator *di;
dictEntry *de;
- char master_port[32];
-
- ll2string(master_port,sizeof(master_port),
- master->promoted_slave->addr->port);
di = dictGetIterator(master->slaves);
while((de = dictNext(di)) != NULL) {
@@ -2836,10 +2862,9 @@ void sentinelFailoverDetectEnd(sentinelRedisInstance *master) {
if (slave->flags &
(SRI_RECONF_DONE|SRI_RECONF_SENT|SRI_DISCONNECTED)) continue;
- retval = redisAsyncCommand(slave->cc,
- sentinelDiscardReplyCallback, NULL, "SLAVEOF %s %s",
+ retval = sentinelSendSlaveOf(slave,
master->promoted_slave->addr->ip,
- master_port);
+ master->promoted_slave->addr->port);
if (retval == REDIS_OK) {
sentinelEvent(REDIS_NOTICE,"+slave-reconf-sent-be",slave,"%@");
slave->flags |= SRI_RECONF_SENT;
@@ -2892,15 +2917,11 @@ void sentinelFailoverReconfNextSlave(sentinelRedisInstance *master) {
continue;
/* Send SLAVEOF <new master>. */
- ll2string(master_port,sizeof(master_port),
- master->promoted_slave->addr->port);
- retval = redisAsyncCommand(slave->cc,
- sentinelDiscardReplyCallback, NULL, "SLAVEOF %s %s",
+ retval = sentinelSendSlaveOf(slave,
master->promoted_slave->addr->ip,
- master_port);
+ master->promoted_slave->addr->port);
if (retval == REDIS_OK) {
slave->flags |= SRI_RECONF_SENT;
- slave->pending_commands++;
slave->slave_reconf_sent_time = mstime();
sentinelEvent(REDIS_NOTICE,"+slave-reconf-sent",slave,"%@");
in_progress++;
@@ -2982,13 +3003,11 @@ void sentinelFailoverStateMachine(sentinelRedisInstance *ri) {
* back to the master as well, sending a best effort SLAVEOF command.
*/
void sentinelAbortFailover(sentinelRedisInstance *ri) {
- char master_port[32];
dictIterator *di;
dictEntry *de;
int sentinel_role;
redisAssert(ri->flags & SRI_FAILOVER_IN_PROGRESS);
- ll2string(master_port,sizeof(master_port),ri->addr->port);
/* Clear failover related flags from slaves.
* Also if we are the leader make sure to send SLAVEOF commands to all the
@@ -3004,10 +3023,7 @@ void sentinelAbortFailover(sentinelRedisInstance *ri) {
{
int retval;
- retval = redisAsyncCommand(slave->cc,
- sentinelDiscardReplyCallback, NULL, "SLAVEOF %s %s",
- ri->addr->ip,
- master_port);
+ retval = sentinelSendSlaveOf(slave,ri->addr->ip,ri->addr->port);
if (retval == REDIS_OK)
sentinelEvent(REDIS_NOTICE,"-slave-reconf-undo",slave,"%@");
}