This addresses two problems, one where infinite (negative) repeat count is broken for all types for Redis,
and another specific to cluster mode where redirection is needed.
Now allows and works correctly for negative (i.e. -1) repeat values passed with `-r` argument to redis-cli
as documented here https://redis.io/topics/rediscli#continuously-run-the-same-command which seems to have
regressed as a feature in 95b988 (though that commit removed bad integer wrap-around to `0` behaviour).
This broken behaviour exists currently (e50458), and redis-cli will just exit immediately with repeat `-r <= 0`
as opposed to send commands indefinitely as it should with `-r < 0`
Additionally prevents a repeat * interval seconds hang/time spent doing nothing at the start before issuing
commands in cluster mode (`-c`), where the command needed to redirect to a slot on another node, as commands
where failing and waiting to be reissued but this was fully repeated before being reissued. For example,
redis-cli -c -r 10 -i 0.5 INCR test_key_not_on_6379
Would hang and show nothing for 5 seconds (10 * 0.5) before showing
(integer) 1
(integer) 2
(integer) 3
(integer) 4
(integer) 5
(integer) 6
(integer) 7
(integer) 8
(integer) 9
(integer) 10
at half second intervals as intended.
If a key exists in the target node during a migration (BUSYKEY),
the value of the key on both nodes (source and target) will be compared.
If the key has the same value on both keys, the migration will be
automatically retried with the REPLACE argument in order to override
the target's key.
If the key has different values, the behaviour will depend on such
cases:
- In case of 'fix' command, the migration will stop and the user
will be warned to manually check the key(s).
- In other cases (ie. reshard), if the user launched the command
with the --cluster-replace option, the migration will be
retried with the REPLACE argument, elsewhere the migration will
stop and the user will be warned.
When loading data, we call processEventsWhileBlocked
to process events and execute commands.
But if we are loading AOF it's dangerous, because
processCommand would call freeMemoryIfNeeded to evict,
and that will break data consistency, see issue #5686.
Thanks to @soloestoy for discovering this issue in #5667.
This is an alternative fix in order to avoid both cycling the clients
and also disconnecting clients just having valid read-only transactions
pending.
