When various nodes in the configuration are unreachable while trying
to send a command, we should attempt to contact a reachable node to
fetch an updated slots map up to $retryLimit times or until there are
no more servers in the pool before giving up.
It is possible that the slots map fetched from Redis contains stale
data and points to a dead server, this happens when the nodes still
have to agree that a master server is down before promoting a slave
to the role of master. In this case no further attempts to execute
the command are performed and an exception is thrown.
This still needs some more testing and will delay v1.0.4 a few days
past its scheduled release.
When the connection to a node in the cluster fails in the attempt to
execute a command, Predis now removes the failed connection from the
cluster pool and contacts a random node to ask for a fresh slots map
and tries to execute the command once again.
When the cluster is configured to have each master replicated to one
or more slaves, one the slaves is automatically promoted to the role
of master by redis-cluster with this change being reflected in the
output of CLUSTER SLOTS, so the next execution should run just fine.
Our current approach is relatively naive as CLUSTER SLOTS is executed
against a random master node, meaning that the client must open a new
connection and execute one more roundtrip only to fetch the new slots
map. For now it is enough, it is still better than having the client
fail when you actually have somes slaves in your redis-cluster setup,
but one improvement could consist in caching the list of slaves for
each master returned in the response of CLUSTER SLOTS so that when a
connection fails the client can try to guess which connection should
use for the next attempt.
This commit closes#173, closes#215, and closes#314.
When using redis-cluster it is now also possible to pass one slot or
non-contiguous ranges of slots via connection parameters in order to
improve the ability to pre-configure the slots map on the client.
Here is an example:
$parameters = [
'tcp://10.0.0.1:6379?slots=0-5460,5500-5600,11000',
'tcp://10.0.0.2:6379?slots=5461-5499,5600-10921',
'tcp://10.0.0.3:6379?slots=10922-10999,11001-16383',
];
This commit fixes#312 (props to @kenotr0n for the original PR).
This could be triggered when passing an array with "holes" to variadic commands.
Connection classes based on the protocol serialized exposed by phpiredis were
not affected by this bug.
Fixes#316.
When iterating a hash containing integer fields our iterator abstraction
based on HSCAN was always returning "0" as a field name after the first
$field => $value pair due to a wrong assumption on how the PHP function
array_shift() (which is used internally to advance to the next pair in
our buffered response to HSCAN) works.
The ZSCAN-based iterator had this very same bug which was already fixed
in 24e19a9 so I am not sure how this one went unnoticed until now.
Using IPv6 with Predis was basically impossible due to various inconsistencies
and bugs through the library, now it is supported by all the connection classes.
Following the standard for IPv6 literal addresses in URI strings, the IP literal
must be enclosed within square brackets when passing the parameters as a string:
$parameters = 'tcp://[2001:db8:0:f101::1]:6379';
See https://tools.ietf.org/html/rfc3986#section-3.2.2 for further details.
This commit also fixes#239 making redis-cluster usable with nodes using IPv6.
Daniele Alessandri
Remi Collet