NAME

Redis::ClusterRider - Daring Redis Cluster client

SYNOPSIS

use Redis::ClusterRider;

my $cluster = Redis::ClusterRider->new(
  startup_nodes => [
    'localhost:7000',
    'localhost:7001',
    'localhost:7002',
  ],
);

$cluster->set( 'foo', 'bar' );
my $value = $cluster->get('foo');

print "$value\n";

DESCRIPTION

Redis::ClusterRider is the Redis Cluster client built on top of the Redis.

Requires Redis 3.0 or higher.

For more information about Redis Cluster see here:

• http://redis.io/topics/cluster-tutorial
• http://redis.io/topics/cluster-spec

CONSTRUCTOR

new( %params )

my $cluster = Redis::ClusterRider->new(
  startup_nodes => [
    'localhost:7000',
    'localhost:7001',
    'localhost:7002',
  ],
  username         => 'yourname',
  password         => 'yourpass',
  cnx_timeout      => 5,
  read_timeout     => 5,
  refresh_interval => 5,
  lazy             => 1,

  on_node_connect => sub {
    my $hostport = shift;

    # handling...
  },

  on_node_error => sub {
    my $err = shift;
    my $hostport = shift;

    # error handling...
  },
);

• startup_nodes => \@nodes

  Specifies the list of startup nodes. Parameter should contain the array of addresses of some nodes in the cluster. The client will try to connect to random node from the list to retrieve information about all cluster nodes and slots mapping. If the client could not connect to first selected node, it will try to connect to another random node from the list.

• password => $password

  If the password is specified, the AUTH command is sent to all nodes of the cluster after connection.

• username => $username

  Authenticate to the server using Redis 6.0+ ACL System (see https://redis.io/commands/auth)

• allow_slaves => $boolean

  If enabled, the client will try to send read-only commands to slave nodes.

• cnx_timeout => $fractional_seconds

  The cnx_timeout option enables connection timeout. The client will wait at most that number of seconds (can be fractional) before giving up connecting to a server.

    cnx_timeout => 10.5,
  

  By default the client use kernel's connection timeout.

• read_timeout => $fractional_seconds

  The read_timeout option enables read timeout. The client will wait at most that number of seconds (can be fractional) before giving up when reading from the server.

  Not set by default.

• lazy => $boolean

  If enabled, the initial connection to the startup node establishes at time when you will send the first command to the cluster. By default the initial connection establishes after calling of the new method.

  Disabled by default.

• refresh_interval => $fractional_seconds

  Cluster state refresh interval. If set to zero, cluster state will be updated only on MOVED redirect.

  By default is 15 seconds.

• on_node_connect => $cb->($hostport)

  The on_node_connect callback is called when the connection to particular node is successfully established. To callback is passed address of the node to which the client was connected.

  Not set by default.

• on_node_error => $cb->( $err, $hostport )

  The on_node_error callback is called when occurred an error on particular node. To callback are passed two arguments: error message, and address of the node on which an error occurred.

  Not set by default.

See documentation on Redis for more options.

Attention, Redis options reconnect and every are redefined inside the Redis::ClusterRider for own purproses. User defined values for this options will be ignored.

COMMAND EXECUTION

<command>( [ @args ] )

To execute the command you must call particular method with corresponding name. If any error occurred during the command execution, the client throw an exception.

Before the command execution, the client determines the pool of nodes, on which the command can be executed. The pool can contain the one or more nodes depending on the cluster and the client configurations, and the command type. The client will try to execute the command on random node from the pool and, if the command failed on selected node, the client will try to execute it on another random node.

If the connection to the some node was lost, the client will try to restore the connection when you execute next command. The client will try to reconnect only once and, if attempt fails, the client throw an exception. If you need several attempts of the reconnection, you must catch the exception and retry a command as many times, as you need. Such behavior allows to control reconnection procedure.

The full list of the Redis commands can be found here: http://redis.io/commands.

my $value   = $cluster->get('foo');
my $list    = $cluster->lrange( 'list', 0, -1 );
my $counter = $cluster->incr('counter');

run_command( $command [, @args ] )

The alternative way of command execution is explicit "run_command()" call. This approach is the only way if Redis commands contain punctuation, such as "GRAPH.QUERY" command of RedisGraph module.

my $list = $cluster->run_command( 'GRAPH.QUERY', $graph, $cypher_query );

TRANSACTIONS

To perform the transaction you must get the master node by the key using nodes method. Then you need to execute ECHO command or any other command before MULTI command to avoid the error "reconnect disabled inside transaction or watch" because all connection in the cluster client are lazy.

my $node = $cluster->nodes('foo');
$node->echo('ping');

$node->multi;
$node->set( '{foo}bar', "some\r\nstring" );
$node->set( '{foo}car', 42 );
my $reply = $node->exec;

The detailed information about the Redis transactions can be found here: http://redis.io/topics/transactions.

OTHER METHODS

nodes( [ $key ] [, $allow_slaves ] )

Gets particular nodes of the cluster. In scalar context method returns the first node from the list.

Getting all master nodes of the cluster:

my @master_nodes = $cluster->nodes;

Getting all nodes of the cluster, including slave nodes:

my @nodes = $cluster->nodes( undef, 1 );

Getting master node by the key:

my $master_node = $cluster->nodes('foo');

Getting nodes by the key, including slave nodes:

my @nodes = $cluster->nodes( 'foo', 1 );

refresh_interval( [ $fractional_seconds ] )

Gets or sets the refresh_interval of the client. The undef value resets the refresh_interval to default value.

SERVICE FUNCTIONS

Service functions provided by Redis::ClusterRider can be imported.

use Redis::ClusterRider qw( crc16 hash_slot );

crc16( $data )

Compute CRC16 for the specified data as defined in Redis Cluster specification.

hash_slot( $key );

Returns slot number by the key.

SEE ALSO

Redis, AnyEvent::RipeRedis, AnyEvent::RipeRedis::Cluster

AUTHOR

Eugene Ponizovsky, ponizovsky@gmail.com

Sponsored by SMS Online, dev.opensource@sms-online.com

COPYRIGHT AND LICENSE

Copyright (c) 2017-2018, Eugene Ponizovsky, SMS Online. All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.