cache-storage/src/Storage/Async/RedisStorage.coffee

[ABANDONED] Advanced cache storage for node js

Storage = require './Storage'

redis = require 'redis'
assert = require 'assert'

class RedisStorage extends Storage


	@META_KEY: '__redis__storage__meta__key__'


	client: null


	constructor: ->
		if typeof window != 'undefined'
			throw new Error 'FileStorage: Can not use this storage in browser'

		@client = redis.createClient()


	selectDatabase: (database, fn) ->
		@client.SELECT database, fn


	_read: (name, fn, defaults = null) ->
		@client.GET name, (err, data) =>
			if err
				fn(err, null)
			else if data == null
				if defaults == null
					fn(null, null)
				else
					@_write name, defaults, (err) =>
						if err
							fn(err, null)
						else
							@_read name, (err, data) ->
								if err
									fn(err, null)
								else
									fn(null, data)
			else
				fn(null, JSON.parse(data))


	_write: (name, data, fn) ->
		@client.SET name, JSON.stringify(data), (err) ->
			if err
				fn(err)
			else
				fn(null)


	_remove: (name, fn) ->
		@client.DEL name, fn


	_removeAll: (fn) ->
		@client.FLUSHDB fn


	getMeta: (fn) ->
		@_read RedisStorage.META_KEY, fn, {}



	read: (key, fn) ->
		@_read key, (err, data) =>
			if err
				fn(err, null)
			else if data == null
				fn(null, null)
			else
				@findMeta(key, (err, meta) =>
					if err
						fn(err, null)
					else
						@verify(meta, (err, state) =>
							if err
								fn(err, null)
							else if state
								fn(null, data)
							else
								@remove(key, ->
									fn(null, null)
								)
						)
				)


	write: (key, data, dependencies = {}, fn) ->
		@_write key, data, (err) =>
			if err
				fn(err)
			else
				@getMeta( (err, meta) =>
					if err
						fn(err)
					else
						meta[key] = dependencies
						@_write RedisStorage.META_KEY, meta, fn
				)


	remove: (key, fn) ->
		@getMeta( (err, meta) =>
			if err
				fn(err)
			else
				if typeof meta[key] != 'undefined'
					delete meta[key]

				@_remove key, (err) =>
					if err
						fn(err)
					else
						@_write RedisStorage.META_KEY, meta, fn
		)


	removeAll: (fn) ->
		@_removeAll(fn)


module.exports = RedisStorage