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Sentinel: different comments updated to new implementation.

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This commit is contained in:
antirez 2013-11-21 16:22:59 +01:00
parent 685e79998c
commit cc6053681f
1 changed files with 18 additions and 21 deletions
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39
src/sentinel.c
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@ -993,8 +993,8 @@ const char *sentinelRedisInstanceTypeStr(sentinelRedisInstance *ri) {
else return "unknown";
}
/* This function removes all the instances found in the dictionary of instances
* 'd', having either:
/* This function removes all the instances found in the dictionary of
* sentinels in the specified 'master', having either:
*
* 1) The same ip/port as specified.
* 2) The same runid.
@ -1005,13 +1005,9 @@ const char *sentinelRedisInstanceTypeStr(sentinelRedisInstance *ri) {
*
* This function is useful because every time we add a new Sentinel into
* a master's Sentinels dictionary, we want to be very sure about not
* having duplicated instances for any reason. This is so important because
* we use those other sentinels in order to run our quorum protocol to
* understand if it's time to proceed with the fail over.
*
* Making sure no duplication is possible we greatly improve the robustness
* of the quorum (otherwise we may end counting the same instance multiple
* times for some reason).
* having duplicated instances for any reason. This is important because
* other sentinels are needed to reach ODOWN quorum, and later to get
* voted for a given configuration epoch in order to perform the failover.
*
* The function returns the number of Sentinels removed. */
int removeMatchingSentinelsFromMaster(sentinelRedisInstance *master, char *ip, int port, char *runid) {
@ -1623,7 +1619,7 @@ void sentinelReconnectInstance(sentinelRedisInstance *ri) {
* 1) It is actually a master in the current configuration.
* 2) It reports itself as a master.
* 3) It is not SDOWN or ODOWN.
* 4) We obtained last INFO no more than two times the INFO period of time ago. */
* 4) We obtained last INFO no more than two times the INFO period time ago. */
int sentinelMasterLooksSane(sentinelRedisInstance *master) {
return
master->flags & SRI_MASTER &&
@ -2560,8 +2556,8 @@ void sentinelCheckSubjectivelyDown(sentinelRedisInstance *ri) {
sentinelKillLink(ri,ri->pc);
}
/* Update the subjectively down flag. We believe the instance is in SDOWN
* state if:
/* Update the SDOWN flag. We believe the instance is SDOWN if:
*
* 1) It is not replying.
* 2) We believe it is a master, it reports to be a slave for enough time
* to meet the down_after_period, plus enough time to get two times
@ -2587,7 +2583,12 @@ void sentinelCheckSubjectivelyDown(sentinelRedisInstance *ri) {
}
}
/* Is this instance down accordingly to the configured quorum? */
/* Is this instance down according to the configured quorum?
*
* Note that ODOWN is a weak quorum, it only means that enough Sentinels
* reported in a given time range that the instance was not reachable.
* However messages can be delayed so there are no strong guarantees about
* N instances agreeing at the same time about the down state. */
void sentinelCheckObjectivelyDown(sentinelRedisInstance *master) {
dictIterator *di;
dictEntry *de;
@ -2657,10 +2658,10 @@ void sentinelReceiveIsMasterDownReply(redisAsyncContext *c, void *reply, void *p
}
}
/* If we think (subjectively) the master is down, we start sending
/* If we think the master is down, we start sending
* SENTINEL IS-MASTER-DOWN-BY-ADDR requests to other sentinels
* in order to get the replies that allow to reach the quorum and
* possibly also mark the master as objectively down. */
* in order to get the replies that allow to reach the quorum
* needed to mark the master in ODOWN state and trigger a failover. */
#define SENTINEL_ASK_FORCED (1<<0)
void sentinelAskMasterStateToOtherSentinels(sentinelRedisInstance *master, int flags) {
dictIterator *di;
@ -3222,11 +3223,7 @@ void sentinelFailoverReconfNextSlave(sentinelRedisInstance *master) {
/* This function is called when the slave is in
* SENTINEL_FAILOVER_STATE_UPDATE_CONFIG state. In this state we need
* to remove it from the master table and add the promoted slave instead.
*
* If there are no promoted slaves as this instance is unique, we remove
* and re-add it with the same address to trigger a complete state
* refresh. */
* to remove it from the master table and add the promoted slave instead. */
void sentinelFailoverSwitchToPromotedSlave(sentinelRedisInstance *master) {
sentinelRedisInstance *ref = master->promoted_slave ?
master->promoted_slave : master;