- 18 Mar, 2014 4 commits
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Matt Stancliff authored
GCC-4.9 warned about this, but clang didn't. This commit fixes warning: sentinel.c: In function 'sentinelReceiveHelloMessages': sentinel.c:2156:43: warning: variable 'master' set but not used [-Wunused-but-set-variable] sentinelRedisInstance *ri = c->data, *master;
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antirez authored
Test sentinel.tilt condition on top and return if it is true. This allows to remove the check for the tilt condition in the remaining code paths of the function.
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antirez authored
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antirez authored
addReplySentinelRedisInstance() modified so that this field is displayed for all the kind of instances: Sentinels, Masters, Slaves.
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- 17 Mar, 2014 1 commit
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antirez authored
Failure detection in Sentinel is ping-pong based. It used to work by remembering the last time a valid PONG reply was received, and checking if the reception time was too old compared to the current current time. PINGs were sent at a fixed interval of 1 second. This works in a decent way, but does not scale well when we want to set very small values of "down-after-milliseconds" (this is the node timeout basically). This commit reiplements the failure detection making a number of changes. Some changes are inspired to Redis Cluster failure detection code: * A new last_ping_time field is added in representation of instances. If non zero, we have an active ping that was sent at the specified time. When a valid reply to ping is received, the field is zeroed again. * last_ping_time is not reset when we reconnect the link or send a new ping, so from our point of view it represents the time we started waiting for the instance to reply to our pings without receiving a reply. * last_ping_time is now used in order to check if the instance is timed out. This means that we can have a node timeout of 100 milliseconds and yet the system will work well since the new check is not bound to the period used to send pings. * Pings are now sent every second, or often if the value of down-after-milliseconds is less than one second. With a lower limit of 10 HZ ping frequency. * Link reconnection code was improved. This is used in order to try to reconnect the link when we are at 50% of the node timeout without a valid reply received yet. However the old code triggered unnecessary reconnections when the node timeout was very small. Now that should be ok. The new code passes the tests but more testing is needed and more unit tests stressing the failure detector, so currently this is merged only in the unstable branch.
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- 15 Mar, 2014 1 commit
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antirez authored
This makes debugging / monitoring of Sentinels simpler since you can identify sentinels in CLIENT LIST output of Redis instances.
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- 14 Mar, 2014 4 commits
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Matt Stancliff authored
argc == 2; argv[2] == crash
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antirez authored
Sentinel's main safety argument is that there are no two configurations for the same master with the same version (configuration epoch). For this to be true Sentinels require to be authorized by a majority. Additionally Sentinels require to do two important things: * Never vote again for the same epoch. * Never exchange an old vote for a fresh one. The first prerequisite, in a crash-recovery system model, requires to persist the master->leader_epoch on durable storage before to reply to messages. This was not the case. We also make sure to persist the current epoch in order to never reply to stale votes requests from other Sentinels, after a recovery. The configuration is persisted by making use of fsync(), this is considered in the context of this code a good enough guarantee that after a restart our durable state is restored, however this may not always be the case depending on the kind of hardware and operating system used.
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antirez authored
Now the way HELLO messages are received is unified. Now it is no longer needed for Sentinels to converge to the higher configuration for a master to be able to chat via some Redis instance, the are able to directly exchanges configurations. Note that this commit does not include the (trivial) change needed to send HELLO messages to Sentinel instances as well, since for an error I committed the change in the previous commit that refactored hello messages processing into a separated function.
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antirez authored
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- 04 Mar, 2014 2 commits
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Jan-Erik Rediger authored
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antirez authored
Sentinel needs to avoid split brain conditions due to multiple sentinels trying to get voted at the exact same time. So far some desynchronization was provided by fluctuating server.hz, that is the frequency of the timer function call. However the desynchonization provided in this way was not enough when using many Sentinel instances, especially when a large quorum value is used in order to force a greater degree of agreement (more than N/2+1). It was verified that it was likely to trigger a split brain condition, forcing the system to try again after a timeout. Usually the system will succeed after a few retries, but this is not optimal. This commit desynchronizes instances in a more effective way to make it likely that the first attempt will be successful.
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- 24 Feb, 2014 4 commits
- 22 Feb, 2014 1 commit
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antirez authored
This error was conceived for the older version of Sentinel that worked via master redirection and that was not able to get configuration updates from other Sentinels via the Pub/Sub channel of masters or slaves. This reply does not make sense today, every Sentinel should reply with the best information it has currently. The error will make even more sense in the future since the plan is to allow Sentinels to update the configuration of other Sentinels via gossip with a direct chat without the prerequisite that they have at least a monitored instance in common.
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- 20 Feb, 2014 1 commit
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antirez authored
This is useful mostly for debugging of issues.
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- 18 Feb, 2014 2 commits
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antirez authored
Rename define to match the new meaning.
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antirez authored
If we can't reconfigure a slave in time during failover, go forward as anyway the slave will be fixed by Sentinels in the future, once they detect it is misconfigured. Otherwise a failover in progress may never terminate if for some reason the slave is uncapable to sync with the master while at the same time it is not disconnected.
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- 17 Feb, 2014 1 commit
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antirez authored
Now it logs the file name if it is not accessible. Also there is a different error for the missing config file case, and for the non writable file case.
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- 07 Feb, 2014 1 commit
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antirez authored
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- 31 Jan, 2014 1 commit
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antirez authored
This fixes issue #1530.
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- 14 Jan, 2014 1 commit
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antirez authored
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- 13 Jan, 2014 3 commits
- 10 Jan, 2014 7 commits
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antirez authored
The command totally removes a monitored master.
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antirez authored
The claim about unlinking the instance from the connected hash tables was the opposite of the reality. Also the current actual behavior is safer in most cases, so it is better to manually unlink when needed.
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antirez authored
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antirez authored
It allows to add new masters to monitor at runtime.
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antirez authored
With SENTINEL MASTERS it was already possible to list all the configured masters, but not a specific one.
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antirez authored
Note: the auth password with the master is voluntarily not exposed.
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antirez authored
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- 13 Dec, 2013 1 commit
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antirez authored
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- 10 Dec, 2013 1 commit
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antirez authored
Redis hash table implementation has many non-blocking features like incremental rehashing, however while deleting a large hash table there was no way to have a callback called to do some incremental work. This commit adds this support, as an optiona callback argument to dictEmpty() that is currently called at a fixed interval (one time every 65k deletions).
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- 06 Dec, 2013 2 commits
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antirez authored
The way the role change was recoded was not sane and too much convoluted, causing the role information to be not always updated. This commit fixes issue #1445.
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antirez authored
When there is a master address switch, the reported role must be set to master so that we have a chance to re-sample the INFO output to check if the new address is reporting the right role. Otherwise if the role was wrong, it will be sensed as wrong even after the address switch, and for enough time according to the role change time, for Sentinel consider the master SDOWN. This fixes isue #1446, that describes the effects of this bug in practice.
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- 05 Dec, 2013 1 commit
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antirez authored
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- 02 Dec, 2013 1 commit
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antirez authored
See issue #1419.
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