Simple Memcached server in Javascript with 100 lines of code

gistfile1.js

/* Simple Memcached in Javascript 
 * @Author: Sun, Junyi
 * @Email:  [email protected]
 * @Date:   2012-8-3
*/
var net = require('net');
var store = {}

function handle_header(header, crlf_len){
	var tup = header.split(" ")
	var expect_body_len = 0
	switch(tup[0]) {
		case 'get':
		case 'delete':
			expect_body_len = 0
			break
		case 'set':
			expect_body_len = parseInt(tup[4]) + crlf_len
			break
	}
	return expect_body_len
}

function handle_body(state, call_back){
	var response
	var tup = state.header.split(" ")
	switch(tup[0]){
		case 'get':
			var key = tup[1]
			var obj = store[key]
			if(obj){
				response = "VALUE "+ obj.key+" " + obj.flag+" "  + obj.data.length + "\r\n" +
                            obj.data + "\r\n" +
                            "END\r\n"
			}
			else
				response = "NOT_FOUND\r\n"
			break;
		case 'delete':
			var key = tup[1]
			delete store[key]
			response = "DELETED\r\n"
			break;
		case 'set':
			var obj = {key: tup[1], flag: tup[2], data: state.body}
			store[obj.key] = obj
			response = "STORED\r\n"
			break;
		default:
			response = "ERROR\r\n"
			break;
	}
	socket.write(response,"binary",call_back)
}

function processState(state) {
    switch(state.id){
        case "reading_header":
            var pos = -1
            if((pos = state.buf.indexOf('\r\n')) != -1){
                state.header = state.buf.slice(0, pos)
                state.buf = state.buf.slice(pos+2)
                state.CRLF_LEN = 2
            }
            else if((pos = state.buf.indexOf('\n')) != -1){
                state.header = state.buf.slice(0, pos)
                state.buf = state.buf.slice(pos+1)
                CRLF_LEN = 1
            }
            if(pos != -1){
                state.id = 'reading_body'
                state.expect_body_len = handle_header(state.header, CRLF_LEN)
                processState(state)
            }
            break
        case "reading_body":
            if(state.expect_body_len <= state.buf.length){
                state.body = state.buf.slice(0, state.expect_body_len - state.CRLF_LEN)
                state.buf = state.buf.slice(state.expect_body_len)
                handle_body(state, function(){
                    state.id = 'reading_header'
                    if(buf.length > 0)
                        processState(state)
                })
                
            }
            break
    }
}

var server = net.createServer(function (socket) {
	console.log("client: ",socket.remoteAddress)
    socket.setEncoding("binary")
    
    var state = { id: 'reading_header', socket: socket, buf: "", header: "", body: "", expect_body_len: 0, CRLF_LEN: 2 }

 	socket.on('data',function(data){
 		buf += data
        processState(state);
 	})
});
var port = 11211
console.log("listening at "+ port)
server.listen(port, '0.0.0.0')