The new system detects a failure only when there is quorum from masters.

This commit allows Redis to set a process name that includes the binding
address and the port number in order to make operations simpler.

Redis children processes doing AOF rewrites or RDB saving change the
name into redis-aof-rewrite and redis-rdb-bgsave respectively.

This in general makes harder to kill the wrong process because of an
error and makes simpler to identify saving children.

This feature was suggested by Arnaud GRANAL in the Redis Google Group,
Arnaud also pointed me to the setproctitle.c implementation includeed in
this commit.

This feature should work on all the Linux, OSX, and all the three major
BSD systems.

This is not very important as anyway when the function counting the
number of reports is called the cleanup is performed. However with this
change if only part of the nodes that reported the failure will report
the node is back ok, we'll cleanup the older entries ASAP. In complex
split net split scenarios, and when we are dealing with clusters having
nodes in the order of ~ 1000, this can save some CPU.

This is the missing part of the API that will be used to reimplement
failure detection of Cluster nodes.

Fix error "repl-backlog-size must be 1 or greater"

The parameter repl-backlog-size is not parsed correctly in the configuration file. argv[0] is parsed instead of argv[1].

Not sure why I set a limit to 1 million keys, there is no reason for
this artificial limit, and anyway this is s a stupid limit because it is
already high enough to create latency issues. So let's the users shoot
on their feet because maybe they just actually know what they are doing.

The new sub-command uses the new countKeysInSlot() API and allows a
cluster client to get the number of keys for a given hashslot.

Redis functions start in low case. A few functions about cluster were
capitalized the wrong way.

See the top-comment for the function in this commit for details about
what the function is supposed to do.

This is similar to getKeysInSlot() but just returns the number of keys
found in a given hash slot, without returning the keys.

The definition of cluster size is: the number of known nodes in the
cluster that are masters and serving at least an hash slot.

A §Redis Cluster node used to mark a node as failing when itself
detected a failure for that node, and a single acknowledge was received
about the possible failure state.

The new API will be used in order to possible to require that N other
nodes have a PFAIL or FAIL state for a given node for a node to set it
as failing.