redis function - redis scripts in javascript

Notice: this module is under heavy development and not yet ready for production. Also, a great part of the js syntax is not yet supported.

This is an interface for transpiling Javascript functions to Lua code and running them on the Redis scripting engine.

It is designed to work as a companion to the excellent node_redis module, although it is of course possible to use it with any other redis client library.

Install with:

npm install redis-function

Usage

Simple example, included as example.js:

    var redis = require('redis'),
        RedisFunction = require('redis-function');

    RedisFunction.mixin(redis.RedisClient);

    function compareAndDelete (key, cmp) {
      'use redis';

      var val = this.call('get', key);
      if (val == cmp) {
        this.call('del', key);
      }
      return val;

    }

    var client = redis.createClient();
    client.set('foo', 'bar', redis.print);
    client.eval(compareAndDelete, 1, 'foo', 'baz', redis.print);
    client.eval(compareAndDelete, 1, 'foo', 'bar', redis.print);
    client.quit();

This will display:

Reply: OK
Reply: bar
Reply: bar

API

Mixins (via RedisFunction.mixin(client))

client.eval(fn, arity, args..., cb)

Compiles the given function to lua code, and executes it on the redis scripting engine.

RedisFunction

RedisFunction.mixin(client)

Replaces the RedisClient.eval method with one which intercepts calls that pass Function objects, and compiles the function on-the-fly to lua code.

new RedisFunction(fn, arity)

Compiles the given function to lua code, and returns an object which represents the compiled lua script.

function.eval(redisClient, args..., cb)

Executes the function on the redis scripting engine.

function.name

The name of the function that was compiled. In the simple example (above), it equals 'compareAndDelete'.

function.arity

The number of key parameters that should be passed to the function.

function.script

The lua code the function was transpiled to.

function.sha1

The SHA-1 hash of the lua code. You can use this with the redis EVALSHA command. Note, however, that RedisClient already handles this for you, and there is no need to do it manually.

RedisFunction.eval(redisClient, fn, arity, args..., cb)

Convenience method for RedisFunction(fn, arity).eval(redisClient, args..., cb).