redis-lua-helper

A helper package to load lua scripts for redis featuring a #include macro

Purpose

This small package is intended to help out with managing Lua scripts for redis as those scripts need to be sent via the client and can profit from a wrapper. More importantly, this wrapper allows for scripts to include code that is in other script files via #include 'file.lua' which promotes code reusability.

Note that this package is client agnostic and still requires you to create a wrapper for your client. You may also want to write the created code to new files for debugging purposes.

Usage

Install this module via npm..

npm install redis-lua-helper

.. and include is as such:

var RedisLuaHelper = require('redis-lua-helper');
var rlh = RedisLuaHelper(options);

#include macro

In your lua script files, you may use a #include 'filename' macro. This macro will include a different script at the place where this macro was placed. File paths are relative to the current file. Included files may contain macros as well, but circular dependencies will raise errors.

Example of one Lua script including the other via #include:

File foo.lua:

print('This is foo!')
#include 'bar'

File bar.lua:

print('This is bar!')

Processed contents when loading foo script:

print('This is foo!')
 
-- #include bar:
print('This is bar!')
-- End of bar

API

Create a new instance of the RedisLuaHelper class, expects either the path of your script folder or a full configuration object. Below are all possible options and there default values:

var RedisLuaHelper = require('redis-lua-helper');
 
// using an options object 
var rlh = RedisLuaHelper({
    'root':         __dirname + '/scripts',
    'macro':        '#include',
    'extension':    'lua',
    'encoding':     'utf8'
});
 
// just provide the script path 
var rlh2 = RedisLuaHelper(__dirname + '/scripts');

The root field defines the path relative from which scripts will be loaded. The extension forces that script files may only be loaded if they share that extension. File encoding defaults to utf8 but can be overridden. The macro option allows you to override the default #include 'file' to something else.

Load one or more Lua script files into the instance cache. The callback function should expect an error argument and an array of loaded script files. Examples:

// load a single script
rlh.load('myscript', function (err, scripts) {} );

// you can load any amount of scripts in this fashion
rlh.load('myscript1', 'myscript2', function (err, scripts) {} );

// filenames can be provided as an array as well
rlh.load(['myscript3', 'myscript4'], function (err, scripts) {} );

Notice: Right now, checking for circular dependencies may cause problems if you try to call load multiple times in a row before awaiting the first call to finish. To avoid this, you should place all filenames that you wish to load in an array and call load once.

Loads all script files in a given directory, relative to the root directory. Does not include files in subdirectories. If the dirpath argument is omitted, the root directory will be used instead.

// load all files in the root directory (not including subdirectories)
rlh.loadDir( function (err, scripts) {} );

// load all files in /root/subdir
rlh.loadDir( 'subdir', function (err, scripts) {} );

Returns the code of a previously loaded script. You must load a script first before you can access its code.

var code = rlh.code('myscript');

Returns the shasum of a previously loaded script. You must load a script first before you can access its shasum.

// returns the scripts shasum
// i.e. 6b1bf486c81ceb7edf3c093f4c48582e38c0e791
var shasum = rlh.shasum('myscript');

Clears the entire cache, is the same as creating a fresh instance.

// clear the script cache
rlh.clearCache();

TODO

  • Create a loading queue so you can issue multiple load commands in parallel.
  • Scan code for KEYS[*] and store information to be accessed via helper.keys('script').
  • Allow to create compiled files and store them in filesystem for debugging and caching.
  • Add bindings for popular redis clients, .sync() and .eval(), with config options to provide a 'client' and 'adapter' (=client type).
  • Reformat README.md for linebreaks -.-

Changelog

Initial release.

License

MIT License, see LICENSE file.