redis-lua.coffee

Copyright 2010 Paul Shirren shirro@shirro.com

MIT licenced

Patch lua commands into node-redis prototype. Does not assume node-redis has been patched with scripting support so can use standard version.

The source is on github

 
createHash = require('crypto').createHash

sha = (str) ->
  createHash('sha1').update(str).digest('hex')

Example usage

redis = require('redis')
require('redis_lua').attachLua(redis)
r = redis.createClient()

redis.lua 'mycmd', num_keys, lua_script

r.mycmd 'key', 'value', callback

RedisClient = null


lua = (name, keys, script) ->

  script_sha = null

Use send_command to work with unpatched node-db without eval, evalsha

 
  eval_cmd = (db, params, cb) ->
    params.unshift script
    params.unshift 'eval'
    params.push cb
    db.send_command.apply db, params

  evalsha_cmd = (db, params, cb) ->
    params.unshift script_sha
    params.unshift 'evalsha'
    params.push cb
    db.send_command.apply db, params

Add our new Lua command into the RedisClient prototype so it looks like native db

 
  RedisClient.prototype[name] = (params..., cb) ->
    db = this
    params.unshift keys

    if script_sha
      evalsha_cmd db, params, (err, res) ->

Is this really the right way to test?

 
        if err and err.message.indexOf('NOSCRIPT') > 0
          eval_cmd db, params.slice(1,-1), cb
        else
          cb err, res
    else
      script_sha = script_sha or sha script
      eval_cmd db, params, cb

exports.attachLua = (redis) ->
  RedisClient = redis.RedisClient
  redis.lua = lua
  redis