Non-blocking Redis Cluster client
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MANIFEST
Makefile.PL
README.md

README.md

NAME

AnyEvent::RipeRedis::Cluster - Non-blocking Redis Cluster client

SYNOPSIS

use AnyEvent;
use AnyEvent::RipeRedis::Cluster;

my $cluster = AnyEvent::RipeRedis::Cluster->new(
  startup_nodes => [
    { host => 'localhost', port => 7000 },
    { host => 'localhost', port => 7001 },
    { host => 'localhost', port => 7002 },
  ],
);

my $cv = AE::cv;

$cluster->set( 'foo', 'bar',
  sub {
    my $err = $_[1];

    if ( defined $err ) {
      warn $err->message . "\n";
      $cv->send;

      return;
    }

    $cluster->get( 'foo',
      sub {
        my $reply = shift;
        my $err   = shift;

        if ( defined $err ) {
          warn $err->message . "\n";
          $cv->send;

          return;
        }

        print "$reply\n";
        $cv->send;
      }
    );
  }
);

$cv->recv;

DESCRIPTION

AnyEvent::RipeRedis::Cluster is non-blocking Redis Cluster client built on top of the AnyEvent::RipeRedis.

Requires Redis 3.0 or higher, and any supported event loop.

For more information about Redis Cluster see here:

CONSTRUCTOR

new( %params )

my $cluster = AnyEvent::RipeRedis::Cluster->new(
  startup_nodes => [
    { host => 'localhost', port => 7000 },
    { host => 'localhost', port => 7001 },
    { host => 'localhost', port => 7002 },
  ],
  password           => 'yourpass',
  connection_timeout => 5,
  read_timeout       => 5,
  refresh_interval   => 5,
  lazy               => 1,
  reconnect_interval => 5,

  on_node_connect => sub {
    my $host = shift;
    my $port = shift;

    # handling...
  },

  on_node_disconnect => sub {
    my $host = shift;
    my $port = shift;

    # handling...
  },

  on_node_error => sub {
    my $err = shift;
    my $host = shift;
    my $port = shift;

    # error handling...
  },

  on_error => sub {
    my $err = shift;

    # error handling...
  },
);
  • startup_nodes => \@nodes

    Specifies the list of startup nodes. Parameter should contain the array of hashes that contains addresses of some nodes in the cluster. Each hash should contain host and port elements. 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.

  • allow_slaves => $boolean

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

    Disabled by default.

  • utf8 => $boolean

    If enabled, all strings will be converted to UTF-8 before sending to nodes, and all results will be decoded from UTF-8.

    Enabled by default.

  • connection_timeout => $fractional_seconds

    Specifies connection timeout. If the client could not connect to the node after specified timeout, the on_node_error callback is called with the E_CANT_CONN error. The timeout specifies in seconds and can contain a fractional part.

      connection_timeout => 10.5,
    

    By default the client use kernel's connection timeout.

  • read_timeout => $fractional_seconds

    Specifies read timeout. If the client could not receive a reply from the node after specified timeout, the client close connection and call the on_node_error callback with the E_READ_TIMEDOUT error. The timeout is specifies in seconds and can contain a fractional part.

      read_timeout => 3.5,
    

    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.

  • reconnect => $boolean

    If the connection to the node was lost and the parameter reconnect is TRUE (default), 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 error object is passed to command callback. If you need several attempts of the reconnection, you must retry a command from the callback as many times, as you need. Such behavior allows to control reconnection procedure.

    Enabled by default.

  • reconnect_interval => $fractional_seconds

    If the parameter is specified, the client will try to reconnect only after this interval. Commands executed between reconnections will be queued.

      reconnect_interval => 5,
    

    Not set 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.

  • handle_params => \%params

    Specifies AnyEvent::Handle parameters.

      handle_params => {
        autocork => 1,
        linger   => 60,
      }
    

    Enabling of the autocork parameter can improve performance. See documentation on AnyEvent::Handle for more information.

  • on_node_connect => $cb->( $host, $port )

    The on_node_connect callback is called when the connection to particular node is successfully established. To callback are passed two arguments: host and port of the node to which the client was connected.

    Not set by default.

  • on_node_disconnect => $cb->( $host, $port )

    The on_node_disconnect callback is called when the connection to particular node is closed by any reason. To callback are passed two arguments: host and port of the node from which the client was disconnected.

    Not set by default.

  • on_node_error => $cb->( $err, $host, $port )

    The on_node_error callback is called when occurred an error, which was affected on entire node (e. g. connection error or authentication error). Also the on_node_error callback can be called on command errors if the command callback is not specified. To callback are passed three arguments: error object, and host and port of the node on which an error occurred.

    Not set by default.

  • on_error => $cb->( $err )

    The on_error callback is called when occurred an error, which was affected on entire client (e. g. nodes discovery error). Also the on_error callback is called on command errors if the command callback is not specified. If the on_error callback is not specified, the client just print an error messages to STDERR.

COMMAND EXECUTION

<command>( [ @args ] [, ( $cb->( $reply, $err ) | \%cbs ) ] )

To execute the command you must call particular method with corresponding name. The reply to the command is passed to the callback in first argument. If any error occurred during the command execution, the error object is passed to the callback in second argument. The error object is the instance of the class AnyEvent::RipeRedis::Error.

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.

The command callback is optional. If it is not specified and any error occurred, the on_error callback of the client is called.

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

$cluster->get( 'foo',
  sub {
    my $reply = shift;
    my $err   = shift;

    if ( defined $err ) {
      my $err_msg  = $err->message;
      my $err_code = $err->code;

      # error handling...

      return;
    }

    print "$reply\n";
  }
);

$cluster->lrange( 'list', 0, -1,
  sub {
    my $reply = shift;
    my $err   = shift;

    if ( defined $err ) {
      my $err_msg  = $err->message;
      my $err_code = $err->code;

      # error handling...

      return;
    }

    foreach my $value ( @{$reply}  ) {
      print "$value\n";
    }
  }
);

$cluster->incr( 'counter' );

If you want to track errors on particular nodes, you must specify on_node_error callback in command method.

$cluster->get( 'foo',
  { on_reply => sub {
      my $reply = shift;
      my $err   = shift;

      if ( defined $err ) {
        my $err_msg  = $err->message;
        my $err_code = $err->code;

        # error handling...

        return;
      }

      print "$reply\n";
    },

    on_node_error => sub {
      my $err  = shift;
      my $host = shift;
      my $port = shift;

      # error handling...
    }
  }
);

execute( $command [, @args ] [, ( $cb->( $reply, $err ) | \%cbs ) ] )

An alternative method to execute commands. In some cases it can be more convenient.

$cluster->execute( 'get', 'foo',
  sub {
    my $reply = shift;
    my $err   = shift;

    if ( defined $err ) {
      my $err_msg  = $err->message;
      my $err_code = $err->code;

      # error handling...

      return;
    }

    print "$reply\n";
  }
);

TRANSACTIONS

To perform the transaction you must get the master node by the key using nodes method and then execute all commands on this node. Nodes must be discovered first.

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

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

    if ( defined $err ) {
      # error handling...

      return;
    }

    # reply handling...
  }
);

The detailed information about the Redis transactions can be found in documentation on AnyEvent::RipeRedis and here: http://redis.io/topics/transactions.

ERROR CODES

Every error object, passed to callback, contain error code, which can be used for programmatic handling of errors. AnyEvent::RipeRedis::Cluster provides constants for error codes. They can be imported and used in expressions.

use AnyEvent::RipeRedis::Cluster qw( :err_codes );

Full list of error codes see in documentation on AnyEvent::RipeRedis.

DISCONNECTION

When the connection to the cluster is no longer needed you can close it in two ways: call the method disconnect() or just "forget" any references to an AnyEvent::RipeRedis::Cluster object, but in this case the client object is destroyed without calling any callbacks, including the on_disconnect callback, to avoid an unexpected behavior.

disconnect()

The method for disconnection. All uncompleted operations will be aborted.

OTHER METHODS

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

Gets particular nodes of the cluster. Nodes must be discovered first. 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.

on_error( [ $callback ] )

Gets or sets the on_error callback.

SERVICE FUNCTIONS

Service functions provided by AnyEvent::RipeRedis::Cluster can be imported.

use AnyEvent::RipeRedis::Cluster 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

AnyEvent::RipeRedis

AUTHOR

Eugene Ponizovsky, ponizovsky@gmail.com

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

COPYRIGHT AND LICENSE

Copyright (c) 2016-2017, 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.