NAME
Redis::ScriptCache - Cached Lua scripts on a Redis server
SYNOPSIS
use Redis;
use Redis::ScriptCache;
my $conn = Redis->new(server => ...);
my $cache = Redis::ScriptCache->new(redis_conn => $conn);
# some Lua script to execute on the server
my $script = q{
local x = redis.call('get', KEYS[1]);
redis.call('set', 'temp', x);
return x;
};
my $script_name = $cache->register_script('myscript', $script);
# later:
my ($value) = $cache->run_script('myscript', [1, 'somekey']);
# alternatively, if you have a script_dir
my $cache = Redis::ScriptCache->new(
redis_conn => $conn,
script_dir => 'path/to/lua/scripts',
);
$cache->register_all_scripts();
# path/to/lua/scripts/*.lua gets registered
$cache->run_script('myscript1', [1, 'somekey']); # myscript1.luaDESCRIPTION
Recent versions of Redis can execute Lua scripts on the server. This appears to be the most effective and efficient way to group interactions with Redis atomically. In order to avoid having to re-transmit (and compile) the scripts themselves on every request, Redis has a set of commands related to executing previously seen scripts again using the SHA-1 as identification.
This module offers a way to avoid re-transmission of the full script without checking for script existence on the server manually each time. For that purpose, it offers an interface that will load the given script onto the Redis server and on subsequent uses avoid doing so.
Do not use this module if it can happen that all scripts are flushed from the Redis instance during the life time of a script cache object.
METHODS
new
Expects key/value pairs of options. The only mandatory option is redis_conn, an instance of the Redis module to use to talk to the Redis server.
script_dir is optional, and can also be specified in register_all_scripts as well (see below).
register_script
Given a Lua script (as a scalar, or scalar ref) to register as the first argument, this makes sure that the script is available via its SHA-1 on the Redis server.
Returns the script's name, which will be used to invoke the script using run_script, see below. The SHA-1 is opaque to the user and is internally cached to avoid repeat registration and unnecessary roundtrips.
run_script
Given a registered script's name as first argument and an array reference as second argument, executes the corresponding Lua script on the Redis server and passes the contents of the array reference as parameters to the $redis->evalsha($sha, ...) call. Refer to http://redis.io/commands/evalsha for details.
If the second parameter is omitted, it's assumed to be a script call without parameters, so that
$cache->run_script($script_name);is the same as:
$cache->run_script($script_name, [0]);It is expected that the script is pre-registered via register_script, register_file, or register_all_scripts.
Returns the results of the evalsha call.
register_all_scripts
Given a script_dir (specified in new or register_all_scripts), will register them all under their Lua script names.
Returns an array of names all registered scripts.
register_file
Given a filename under script_dir will register that file and return the name of that script. Handy if you don't want to register everything, but just a select script on disk.
scripts
Returns an array of all scripts registered in the script cache.
flush_all_scripts
Flushes the Redis script cache, and the local script cache.
SEE ALSO
AUTHOR
Steffen Mueller, smueller@cpan.org
CONTRIBUTORS
Iftekharul Haque, iftekhar@cpan.org
Tom Rathborne, lsd@acm.org
Omar Othman, omar.m.othman@gmail.com
COPYRIGHT AND LICENSE
(C) 2012 Steffen Mueller. All rights reserved.
This code is available under the same license as Perl version
5.8.1 or higher.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.