Redis::ScriptManager

Redis::ScriptManager executes your Lua scripts in your Redis infrastructure while managing trade-offs between bandwidth and statefulness.

https://github.com/resque/resque-scheduler

Resque::Scheduler::Lock::Resiliant manages its scripts with load-on-init and EVALSHA-else-SCRIPT-LOAD-and-re-EVALSHA.

This is robust if there are no SCRIPT FLUSH or no pipelines, but it will fail if a SCRIPT FLUSH can happen after init, then we run in a pipeline.

The Lua scripts in resque-scheduler are only a few 100s of bytes in size, so there is little to be gained by avoiding simply using EVAL.

Warning: resque-scheduler embeds "#{timeout}" in its Lua scripts. One is unlikely to change resque-scheduler lock timeouts frequently, but if so it could be possible to fill the Redis script cache with tons of abandoned scripts.

https://github.com/Shopify/wolverine http://shopify.github.io/wolverine/

Wolverine does load-on-init and EVALSHA-only. Assuming you have only one Redis connection and SCRIPT FLUSH is never called, this is fine even in a pipeline.

If you juggle multiple Redis connections or are worried about inconsistent script cache contents, Wolverine might have some gaps.

Wolverine also has nice support for keeping your Lua scripts in a repository of related .lua files, with support for common code folding.

https://github.com/chanks/redis-lua

Redis-lua does EVALSHA-else-SCRIPT-LOAD-and-re-EVALSHA when not in a pipeline, simple EVAL otherwise.

This is great: this is always correct regardless of how many Redises you are talking to, and calls outside of a pipeline will tend toward minimal bandwith as the script cache gets warmed up.

However, if most of your scripting is done within a pipeline, bandwidth use will stay high.

Early iterations of redis-script_manager were inspired by redis-lua.

https://github.com/codekitchen/redis-rb-scripting

redis-rb-scripting does load-on-init plus EVALSHA-else-EVAL. It is correct when the script cache is inconsistent but does not tend to repopulate the cache in these cases.

redis-rb-scripting has no special provision for pipelines. Called in a pipeline it will fail to recover from a cold cache.

Like wolverine, redis-rb-scripting also supports a repository of .lua files, but without the common code folding.

https://github.com/ciconia/led

Like redis-rb-scripting, led does load-on-init plus EVALSHA-else-EVAL. It is correct when the script cache is inconsistent but does not tend to repopulate the cache in these cases. It has no special provision for pipelines. Called in a pipeline it will fail to recover from a cold cache.

Like wolverine, led also supports a repository of .lua files with common code folding.

Add this line to your application's Gemfile:

gem 'redis-script_manager'

And then execute:

$ bundle

Or install it yourself as:

$ gem install redis-script_manager

# Configure Redis::ScriptManager from the ENV.
#
Redis::ScriptManager.configure do |config|
  config.statsd             = $statsd
  config.stats_prefix       = 'profile.redis_util.'
  config.do_minify_lua      = 'true' == ENV['MY_PREF_MINIFY_LUA']
  config.max_tiny_lua       = ENV['MY_PREF_MAGIC_SIZE_LIMIT'] || 512
  config.do_preload         = 'true' == ENV['MY_PREF_PRELOADED_SHAS']
  config.preload_cache_size = ENV['MY_PREF_PRELOADED_SHAS_MAX_SIZE']
end

# Invoke Redis::ScriptManager.eval_gently just like Redis.eval.
#
Redis.eval('return KEYS',keys: ['k1'],argv: ['a1'])
Redis::ScriptManager.eval_gently('return KEYS',keys: ['k1'],argv: ['a1'])

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/redis-script_manager.