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August 3, 2012 05:16
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Simple Memcached server in Javascript with 100 lines of code
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/* Simple Memcached in Javascript | |
* @Author: Sun, Junyi | |
* @Email: ccnusjy@gmail.com | |
* @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(socket,header,body,call_back){ | |
var response="" | |
var tup = 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" | |
response += obj.data + "\r\n" | |
response += "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: body} | |
store[obj.key] = obj | |
response = "STORED\r\n" | |
break; | |
default: | |
response = "ERROR\r\n" | |
break; | |
} | |
socket.write(response,"binary",call_back) | |
} | |
var server = net.createServer(function (socket) { | |
console.log("client: ",socket.remoteAddress) | |
var user_state = 'reading_header' | |
var buf = "" | |
var header ="" | |
var body = "" | |
var expect_body_len = 0 | |
var CRLF_LEN = 2 | |
socket.setEncoding("binary") | |
socket.on('data',function(data){ | |
buf += data | |
socket.emit('user_event') | |
}) | |
socket.on('user_event',function(){ | |
switch(user_state){ | |
case "reading_header": | |
var pos =-1 | |
if((pos=buf.indexOf('\r\n'))!=-1){ | |
header = buf.slice(0,pos) | |
buf = buf.slice(pos+2) | |
CRLF_LEN =2 | |
} | |
else if((pos=buf.indexOf('\n'))!=-1){ | |
header = buf.slice(0,pos) | |
buf = buf.slice(pos+1) | |
CRLF_LEN =1 | |
} | |
if(pos!=-1){ | |
user_state = 'reading_body' | |
expect_body_len = handle_header(header,CRLF_LEN) | |
socket.emit("user_event") | |
} | |
break | |
case "reading_body": | |
if(expect_body_len <= buf.length){ | |
body = buf.slice(0,expect_body_len-CRLF_LEN) | |
buf = buf.slice(expect_body_len) | |
handle_body(socket,header,body, | |
function(){ | |
user_state = 'reading_header' | |
if(buf.length>0) | |
socket.emit("user_event") | |
} | |
) | |
} | |
break | |
} | |
}) | |
}); | |
var port = 11211 | |
console.log("listening at "+ port) | |
server.listen(port, '0.0.0.0') |
Don't reemit to 'user_event', use recursion and an iife in the 'data' event. Avoid putting string concatenation in separate statements in handle_body (just wrap after / before a '+'). Avoid coercing buffers to strings, iterate using charCodes and a 'for' loop (this is probably the biggest possible speed gain). The bottlenecks on something with this high of IO is probably String<->Buffer coercions and syscalls from my experience, so you can think about those.
big performance problem is probably in "buf += data". Try to keep list of incoming chunks ( buffers.push(data) ) instead. You can do this manually or re-use @substack's 'bufferlist' and/or 'binary' modules
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Hi guys,
I am studying node.js. It is a wonderful utility to write network-based application.
Now, I have written a memcached server using node.js. You can have a look at https://gist.github.com/3244607
I tested the program, and found it could reach 12000/s throughput. However, during the test, I found sometimes the speed suddenly decreased due to the GC pause from my mind.
Is there a way to improve my code ?
Thanks