Cluster: clarify node->slave may be NULL.

Cluster: replica migration with delay.

We wait a fixed amount of time (5 seconds currently) much greater than
the usual Cluster node to node communication latency, before migrating.
This way when a

Cluster: replica migration with delay.

We wait a fixed amount of time (5 seconds currently) much greater than
the usual Cluster node to node communication latency, before migrating.
This way when a failover occurs, before detecting the new master as a
target for migration, we give the time to its natural slaves (the slaves
of the failed over master) to announce they switched to the new master,
preventing an useless migration operation.

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Fix replicas migration by adding a new flag.

Some time ago I broken replicas migration (reported in #2924).
The idea was to prevent masters without replicas from getting replicas
because of replica

Fix replicas migration by adding a new flag.

Some time ago I broken replicas migration (reported in #2924).
The idea was to prevent masters without replicas from getting replicas
because of replica migration, I remember it to create issues with tests,
but there is no clue in the commit message about why it was so
undesirable.

However my patch as a side effect totally ruined the concept of replicas
migration since we want it to work also for instances that, technically,
never had slaves in the past: promoted slaves.

So now instead the ability to be targeted by replicas migration, is a
new flag "migrate-to". It only applies to masters, and is set in the
following two cases:

1. When a master gets a slave, it is set.
2. When a slave turns into a master because of fail over, it is set.

This way replicas migration targets are only masters that used to have
slaves, and slaves of masters (that used to have slaves... obviously)
and are promoted.

The new flag is only internal, and is never exposed in the output nor
persisted in the nodes configuration, since all the information to
handle it are implicit in the cluster configuration we already have.

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RDMF: more names updated.

RDMF: More consistent define names.

RDMF: use client instead of redisClient, like Disque.

Cluster: redirection refactoring + handling of blocked clients.

There was a bug in Redis Cluster caused by clients blocked in a blocking
list pop operation, for keys no longer handled by the instanc

Cluster: redirection refactoring + handling of blocked clients.

There was a bug in Redis Cluster caused by clients blocked in a blocking
list pop operation, for keys no longer handled by the instance, or
in a condition where the cluster became down after the client blocked.

A typical situation is:

1) BLPOP <somekey> 0
2) <somekey> hash slot is resharded to another master.

The client will block forever int this case.

A symmentrical non-cluster-specific bug happens when an instance is
turned from master to slave. In that case it is more serious since this
will desynchronize data between slaves and masters. This other bug was
discovered as a side effect of thinking about the bug explained and
fixed in this commit, but will be fixed in a separated commit.

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Cluster: better cluster state transiction handling.

Before we relied on the global cluster state to make sure all the hash
slots are linked to some node, when getNodeByQuery() is called. So
finding

Cluster: better cluster state transiction handling.

Before we relied on the global cluster state to make sure all the hash
slots are linked to some node, when getNodeByQuery() is called. So
finding the hash slot unbound was checked with an assertion. However
this is fragile. The cluster state is often updated in the
clusterBeforeSleep() function, and not ASAP on state change, so it may
happen to process clients with a cluster state that is 'ok' but yet
certain hash slots set to NULL.

With this commit the condition is also checked in getNodeByQuery() and
reported with a identical error code of -CLUSTERDOWN but slightly
different error message so that we have more debugging clue in the
future.

Root cause of issue #2288.

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Cluster: clusterMsgDataGossip structure, explict padding + minor stuff.

Also explicitly set version to 0, add a protocol version define, improve
comments in the gossip structure.

Note that the stru

Cluster: clusterMsgDataGossip structure, explict padding + minor stuff.

Also explicitly set version to 0, add a protocol version define, improve
comments in the gossip structure.

Note that the structure layout is the same after the change, we are just
making the padding explicit with an additional not used 16 bits field.
So this commit is still able to talk with the previous versions of
cluster nodes.

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Cluster PUBLISH message: fix totlen count.

bulk_data field size was not removed from the count. It is not possible
to declare it simply as 'char bulk_data[]' since the structure is nested
into anoth

Cluster PUBLISH message: fix totlen count.

bulk_data field size was not removed from the count. It is not possible
to declare it simply as 'char bulk_data[]' since the structure is nested
into another structure.

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Cluster: more chatty slaves when failover is stalled.

Clean up text throughout project

- Remove trailing newlines from redis.conf
- Fix comment misspelling
- Clarifies zipEncodeLength usage and a C API mention (#1243, #1242)
- Fix cluster typos

Clean up text throughout project

- Remove trailing newlines from redis.conf
- Fix comment misspelling
- Clarifies zipEncodeLength usage and a C API mention (#1243, #1242)
- Fix cluster typos (inspired by @papanikge #1507)
- Fix rewite -> rewrite in a few places (inspired by #682)

Closes #1243, #1242, #1507

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Cluster: new option to work with partial slots coverage.

Use modern typedef form in cluster.h.

Cluster: slave validity factor is now user configurable.

Check the commit changes in the example redis.conf for more information.

Cluster: last_vote_epoch -> lastVoteEpoch.

Use cammel case for epochs that are persisted on disk.

Cluster: better timeout and retry time for failover.

When node-timeout is too small, in the order of a few milliseconds,
there is no way the voting process can terminate during that time, so we
set

Cluster: better timeout and retry time for failover.

When node-timeout is too small, in the order of a few milliseconds,
there is no way the voting process can terminate during that time, so we
set a lower limit for the failover timeout of two seconds.

The retry time is set to two times the failover timeout time, so it is
at least 4 seconds.

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Redis Cluster: support for multi-key operations.

Remove redundant IP length definition

REDIS_CLUSTER_IPLEN had the same value as
REDIS_IP_STR_LEN. They were both #define'd
to the same INET6_ADDRSTRLEN.

Fix IP representation in clusterMsgDataGossip

Cluster: clusterReadHandler() fixed to work with new message header.

Cluster: signature changed to "RCmb" (Redis Cluster message bus).

Sounds better after all.

Cluster: added signature + version in bus packets.

Cluster: force AUTH ACK on manual failover.

When a slave requests masters vote for a manual failover, the
REQUEST_AUTH message is flagged in a special way in order to force the
masters to give the a

Cluster: force AUTH ACK on manual failover.

When a slave requests masters vote for a manual failover, the
REQUEST_AUTH message is flagged in a special way in order to force the
masters to give the authorization even if the master is not marked as
failing.

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Cluster: manual failover initial implementation.