plucky (3) AnyEvent::RipeRedis.3pm.gz
NAME
AnyEvent::RipeRedis - Flexible non-blocking Redis client
SYNOPSIS
use AnyEvent;
use AnyEvent::RipeRedis;
my $redis = AnyEvent::RipeRedis->new(
host => 'localhost',
port => 6379,
password => 'yourpass',
);
my $cv = AE::cv;
$redis->set( 'foo', 'bar',
sub {
my $err = $_[1];
if ( defined $err ) {
warn $err->message . "\n";
$cv->send;
return;
}
$redis->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 is flexible non-blocking Redis client. Supports subscriptions, transactions and can
automaticaly restore connection after failure.
Requires Redis 1.2 or higher, and any supported event loop.
CONSTRUCTOR
new( %params )
my $redis = AnyEvent::RipeRedis->new(
host => 'localhost',
port => 6379,
password => 'yourpass',
database => 7,
connection_timeout => 5,
read_timeout => 5,
lazy => 1,
reconnect_interval => 5,
on_connect => sub {
# handling...
},
on_disconnect => sub {
# handling...
},
on_error => sub {
my $err = shift;
# error handling...
},
);
host => $host
Server hostname (default: 127.0.0.1)
port => $port
Server port (default: 6379)
password => $password
If the password is specified, the "AUTH" command is sent to the server after connection.
database => $index
Database index. If the index is specified, the client switches to the specified database after
connection. You can also switch to another database after connection by using "SELECT" command. The
client remembers last selected database after reconnection and switches to it automaticaly.
The default database index is 0.
utf8 => $boolean
If enabled, all strings will be converted to UTF-8 before sending to the server, 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 server after specified timeout,
the "on_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 server after specified
timeout, the client close connection and call the "on_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 connection establishes at time when you will send the first command to the server. By
default the connection establishes after calling of the "new" method.
Disabled by default.
reconnect => $boolean
If the connection to the server 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.
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_connect => $cb->()
The "on_connect" callback is called when the connection is successfully established.
Not set by default.
on_disconnect => $cb->()
The "on_disconnect" callback is called when the connection is closed by any reason.
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.
connection error or authentication 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 ) ] )
To execute the command you must call specific 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. Error object is the instance of the class
AnyEvent::RipeRedis::Error.
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>.
$redis->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";
}
);
$redis->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";
}
}
);
$redis->incr( 'counter' );
You can execute multi-word commands like this:
$redis->client_getname(
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";
}
);
execute( $command, [ @args ] [, $cb->( $reply, $err ) ] )
An alternative method to execute commands. In some cases it can be more convenient.
$redis->execute( 'get', 'foo',
sub {
my $reply = shift;
my $err = shift;
if ( defined $err ) {
my $err_msg = $err->message;
my $err_code = $err->code;
return;
}
print "$reply\n";
}
);
TRANSACTIONS
The detailed information about the Redis transactions can be found here:
<http://redis.io/topics/transactions>.
multi( [ $cb->( $reply, $err ) ] )
Marks the start of a transaction block. Subsequent commands will be queued for atomic execution using
"EXEC".
exec( [ $cb->( $reply, $err ) ] )
Executes all previously queued commands in a transaction and restores the connection state to normal.
When using "WATCH", "EXEC" will execute commands only if the watched keys were not modified.
If during a transaction at least one command fails, to the callback will be passed error object, and the
reply will be contain nested error objects for every failed command.
$redis->multi();
$redis->set( 'foo', 'string' );
$redis->incr('foo'); # causes an error
$redis->exec(
sub {
my $reply = shift;
my $err = shift;
if ( defined $err ) {
my $err_msg = $err->message();
my $err_code = $err->code();
if ( defined $reply ) {
foreach my $nested_reply ( @{$reply} ) {
if ( ref($nested_reply) eq 'AnyEvent::RipeRedis::Error' ) {
my $nested_err_msg = $nested_reply->message();
my $nested_err_code = $nested_reply->code();
# error handling...
}
}
return;
}
# error handling...
return;
}
# reply handling...
},
);
discard( [ $cb->( $reply, $err ) ] )
Flushes all previously queued commands in a transaction and restores the connection state to normal.
If "WATCH" was used, "DISCARD" unwatches all keys.
watch( @keys [, $cb->( $reply, $err ) ] )
Marks the given keys to be watched for conditional execution of a transaction.
unwatch( [ $cb->( $reply, $err ) ] )
Forget about all watched keys.
SUBSCRIPTIONS
Once the client enters the subscribed state it is not supposed to issue any other commands, except for
additional "SUBSCRIBE", "PSUBSCRIBE", "UNSUBSCRIBE", "PUNSUBSCRIBE" and "QUIT" commands.
The detailed information about Redis Pub/Sub can be found here: <http://redis.io/topics/pubsub>
subscribe( @channels, ( $cb->( $msg, $channel ) | \%cbs ) )
Subscribes the client to the specified channels.
Method can accept two callbacks: "on_reply" and "on_message". The "on_reply" callback is called when
subscription to all specified channels will be activated. In first argument to the callback is passed the
number of channels we are currently subscribed. If subscription to specified channels was lost, the
"on_reply" callback is called with the error object in the second argument.
The "on_message" callback is called on every published message. If the "subscribe" method is called with
one callback, this callback will be act as "on_message" callback.
$redis->subscribe( qw( foo bar ),
{ on_reply => sub {
my $channels_num = shift;
my $err = shift;
if ( defined $err ) {
# error handling...
return;
}
# reply handling...
},
on_message => sub {
my $msg = shift;
my $channel = shift;
# message handling...
},
}
);
$redis->subscribe( qw( foo bar ),
sub {
my $msg = shift;
my $channel = shift;
# message handling...
}
);
psubscribe( @patterns, ( $cb->( $msg, $pattern, $channel ) | \%cbs ) )
Subscribes the client to the given patterns. See subscribe() method for details.
$redis->psubscribe( qw( foo_* bar_* ),
{ on_reply => sub {
my $channels_num = shift;
my $err = shift;
if ( defined $err ) {
# error handling...
return;
}
# reply handling...
},
on_message => sub {
my $msg = shift;
my $pattern = shift;
my $channel = shift;
# message handling...
},
}
);
$redis->psubscribe( qw( foo_* bar_* ),
sub {
my $msg = shift;
my $pattern = shift;
my $channel = shift;
# message handling...
}
);
publish( $channel, $message [, $cb->( $reply, $err ) ] )
Posts a message to the given channel.
unsubscribe( [ @channels ] [, $cb->( $reply, $err ) ] )
Unsubscribes the client from the given channels, or from all of them if none is given. In first argument
to the callback is passed the number of channels we are currently subscribed or zero if we were
unsubscribed from all channels.
$redis->unsubscribe( qw( foo bar ),
sub {
my $channels_num = shift;
my $err = shift;
if ( defined $err ) {
# error handling...
return;
}
# reply handling...
}
);
punsubscribe( [ @patterns ] [, $cb->( $reply, $err ) ] )
Unsubscribes the client from the given patterns, or from all of them if none is given. See unsubscribe()
method for details.
$redis->punsubscribe( qw( foo_* bar_* ),
sub {
my $channels_num = shift;
my $err = shift;
if ( defined $err ) {
# error handling...
return;
}
# reply handling...
}
);
CONNECTION VIA UNIX-SOCKET
Redis 2.2 and higher support connection via UNIX domain socket. To connect via a UNIX-socket in the
parameter "host" you have to specify "unix/", and in the parameter "port" you have to specify the path to
the socket.
my $redis = AnyEvent::RipeRedis->new(
host => 'unix/',
port => '/tmp/redis.sock',
);
LUA SCRIPTS EXECUTION
Redis 2.6 and higher support execution of Lua scripts on the server side. To execute a Lua script you
can send one of the commands "EVAL" or "EVALSHA", or use the special method eval_cached().
eval_cached( $script, $keys_num [, @keys ] [, @args ] [, $cb->( $reply, $err ) ] ] );
When you call the eval_cached() method, the client first generate a SHA1 hash for a Lua script and cache
it in memory. Then the client optimistically send the "EVALSHA" command under the hood. If the
"E_NO_SCRIPT" error will be returned, the client send the "EVAL" command.
If you call the eval_cached() method with the same Lua script, client don not generate a SHA1 hash for
this script repeatedly, it gets a hash from the cache instead.
$redis->eval_cached( 'return { KEYS[1], KEYS[2], ARGV[1], ARGV[2] }',
2, 'key1', 'key2', 'first', 'second',
sub {
my $reply = shift;
my $err = shift;
if ( defined $err ) {
# error handling...
return;
}
foreach my $value ( @{$reply} ) {
print "$value\n";
}
}
);
Be care, passing a different Lua scripts to eval_cached() method every time cause memory leaks.
If Lua script returns multi-bulk reply with at least one error reply, to the callback will be passed
error object, and the reply will be contain nested error objects.
$redis->eval_cached( "return { 'foo', redis.error_reply( 'Error.' ) }", 0,
sub {
my $reply = shift;
my $err = shift;
if ( defined $err ) {
my $err_msg = $err->message;
my $err_code = $err->code;
if ( defined $reply ) {
foreach my $nested_reply ( @{$reply} ) {
if ( ref($nested_reply) eq 'AnyEvent::RipeRedis::Error' ) {
my $nested_err_msg = $nested_reply->message();
my $nested_err_code = $nested_reply->code();
# error handling...
}
}
}
# error handling...
return;
}
# reply handling...
}
);
ERROR CODES
Every error object, passed to callback, contain error code, which can be used for programmatic handling
of errors. AnyEvent::RipeRedis provides constants for error codes. They can be imported and used in
expressions.
use AnyEvent::RipeRedis qw( :err_codes );
E_CANT_CONN
Can't connect to the server. All operations were aborted.
E_LOADING_DATASET
Redis is loading the dataset in memory.
E_IO
Input/Output operation error. The connection to the Redis server was closed and all operations were
aborted.
E_CONN_CLOSED_BY_REMOTE_HOST
The connection closed by remote host. All operations were aborted.
E_CONN_CLOSED_BY_CLIENT
Connection closed by client prematurely. Uncompleted operations were aborted.
E_NO_CONN
No connection to the Redis server. Connection was lost by any reason on previous operation.
E_OPRN_ERROR
Operation error. For example, wrong number of arguments for a command.
E_UNEXPECTED_DATA
The client received unexpected reply from the server. The connection to the Redis server was closed
and all operations were aborted.
E_READ_TIMEDOUT
Read timed out. The connection to the Redis server was closed and all operations were aborted.
Error codes available since Redis 2.6.
E_NO_SCRIPT
No matching script. Use the "EVAL" command.
E_BUSY
Redis is busy running a script. You can only call "SCRIPT KILL" or "SHUTDOWN NOSAVE".
E_NOT_BUSY
No scripts in execution right now.
E_MASTER_DOWN
Link with MASTER is down and slave-serve-stale-data is set to 'no'.
E_MISCONF
Redis is configured to save RDB snapshots, but is currently not able to persist on disk. Commands
that may modify the data set are disabled. Please check Redis logs for details about the error.
E_READONLY
You can't write against a read only slave.
E_OOM
Command not allowed when used memory > 'maxmemory'.
E_EXEC_ABORT
Transaction discarded because of previous errors.
Error codes available since Redis 2.8.
E_NO_AUTH
Authentication required.
E_WRONG_TYPE
Operation against a key holding the wrong kind of value.
E_NO_REPLICAS
Not enough good slaves to write.
E_BUSY_KEY
Target key name already exists.
Error codes available since Redis 3.0.
E_CROSS_SLOT
Keys in request don't hash to the same slot.
E_TRY_AGAIN
Multiple keys request during rehashing of slot.
E_ASK
Redirection required. For more information see: <http://redis.io/topics/cluster-spec>
E_MOVED
Redirection required. For more information see: <http://redis.io/topics/cluster-spec>
E_CLUSTER_DOWN
The cluster is down or hash slot not served.
DISCONNECTION
When the connection to the server is no longer needed you can close it in three ways: call the method
disconnect(), send the "QUIT" command or you can just "forget" any references to an AnyEvent::RipeRedis
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 synchronous disconnection. All uncompleted operations will be aborted.
quit( [ $cb->( $reply, $err ) ] )
The method for asynchronous disconnection.
OTHER METHODS
info( [ $section ] [, $cb->( $reply, $err ) ] )
Gets and parses information and statistics about the server. The result is passed to callback as a hash
reference.
More information about "INFO" command can be found here: <http://redis.io/commands/info>
host()
Gets current host of the client.
port()
Gets current port of the client.
select( $index, [, $cb->( $reply, $err ) ] )
Selects the database by numeric index.
database()
Gets selected database index.
utf8( [ $boolean ] )
Enables or disables UTF-8 mode.
connection_timeout( [ $fractional_seconds ] )
Gets or sets the "connection_timeout" of the client. The "undef" value resets the "connection_timeout" to
default value.
read_timeout( [ $fractional_seconds ] )
Gets or sets the "read_timeout" of the client.
reconnect( [ $boolean ] )
Enables or disables reconnection mode of the client.
reconnect_interval( [ $fractional_seconds ] )
Gets or sets "reconnect_interval" of the client.
on_connect( [ $callback ] )
Gets or sets the "on_connect" callback.
on_disconnect( [ $callback ] )
Gets or sets the "on_disconnect" callback.
on_error( [ $callback ] )
Gets or sets the "on_error" callback.
SEE ALSO
AnyEvent::RipeRedis::Cluster, AnyEvent, Redis::hiredis, Redis, RedisDB
AUTHOR
Eugene Ponizovsky, <ponizovsky@gmail.com> Sponsored by SMS Online, <dev.opensource@sms-online.com> Special thanks • Alexey Shrub • Vadim Vlasov • Konstantin Uvarin • Ivan Kruglov
COPYRIGHT AND LICENSE
Copyright (c) 2012-2021, 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.