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nodule.js
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nodule.js
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var net = require('net'),
sys = require('sys');
var LOGGING = true;
var PORT = 13823;
var STATUS_OK = 0;
var E_INVALID_REQUEST = 1,
E_UNKNOWN_CMD = 2,
E_INVALID_PATTERN = 3;
/*
* Handle logging to STDOUT if LOGGING == true.
*/
var logger = new function() {
this.log = function(msg) {
if(LOGGING) sys.log(msg);
};
};
/*
* An entry in the key-value store.
*/
function Entry(value) {
this.value = value;
this.modified_at = new Date();
}
Entry.prototype.getValue = function() {
return this.value;
}
Entry.prototype.setValue = function(value) {
this.value = value;
this.modified_at = new Date();
return this;
}
/*
* A key space, which contains Entires and subscription patterns.
*/
function Space(name) {
this.name = name;
this.entries = {};
this.patterns = {};
}
Space.prototype.addSubscription = function(pattern, session_id) {
try {
new RegExp(pattern);
} catch(err) {
return E_INVALID_PATTERN;
}
logger.log('Space: ' + this.name + ' ' + session_id + ' SUBSCRIBE ' + pattern);
if(!this.patterns[pattern]) this.patterns[pattern] = {};
this.patterns[pattern][session_id] = null;
return STATUS_OK;
};
Space.prototype.publish = function(key, entry) {
for(var p in this.patterns) {
var regex = new RegExp(p);
if(key.match(regex)) {
for(var id in this.patterns[p]) {
// publish this key to the session
sessions[id].sendAsJSON({space: this.name, key: key, value: entry.getValue()});
}
}
}
};
Space.prototype.gcSession = function(session_id) {
for(var p in this.patterns) {
delete this.patterns[p][session_id];
}
};
/*
* A session for a connected client.
*/
function Session(stream) {
this.stream = stream;
this.id = Math.floor(Math.random()*99999999999).toString();
}
Session.prototype.sendAsJSON = function(data) {
this.stream.write(JSON.stringify(data) + "\n");
};
var sessions = {}; // track all connected sessions
/*
* Store the entries and mitigate access.
*/
var store = new function() {
var spaces = {};
this.gcSession = function(session_id) {
for(var i in spaces) {
spaces[i].gcSession(session_id);
}
};
this.get = function(space_name, key) {
logger.log('Store: GET Space:' + space_name + ' Key:' + key);
var space = spaces[space_name];
if(!space) return null;
var entry = space.entries[key];
if(!entry) return null;
return entry.getValue();
};
this.set = function(space_name, key, value) {
logger.log('Store: SET Space:' + space_name + ' Key:' + key + ' Value:' + value);
var space = spaces[space_name];
if(!space) space = spaces[space_name] = new Space(space_name);
var entry = space.entries[key];
if(entry) {
entry.setValue(value);
} else {
entry = space.entries[key] = new Entry(value);
}
space.publish(key, entry);
return STATUS_OK;
};
this.sub = function(space_name, pattern, session_id) {
logger.log('Store: SUB Space:' + space_name + ' Pattern: ' + pattern);
var space = spaces[space_name];
if(!space) space = spaces[space_name] = new Space(space_name);
return space.addSubscription(pattern, session_id);
};
};
/*
* Parse and process incoming requests.
*/
var processor = new function() {
this.process = function(data, session) {
try {
var cmd = JSON.parse(data);
} catch(err) {
this.error(E_INVALID_REQUEST, session);
return;
}
if(!cmd.hasOwnProperty('op')) return;
switch(cmd['op']) {
case 'get': this.get(cmd, session); break;
case 'set': this.set(cmd, session); break;
case 'sub': this.sub(cmd, session); break;
default:
logger.log('Processor: Unknown command "' + cmd['op'] + '"');
this.error(E_UNKNOWN_CMD, session);
}
};
this.error = function(errno, session) {
logger.log('Processor: ERROR ' + errno);
session.sendAsJSON({'status': errno});
};
this.get = function(cmd, session) {
logger.log('Processor: GET');
var value = store.get(cmd['space'], cmd['key']);
session.sendAsJSON({'value': value});
};
this.set = function(cmd, session) {
logger.log('Processor: SET');
var r = store.set(cmd['space'], cmd['key'], cmd['value']);
session.sendAsJSON({'status': r});
};
this.sub = function(cmd, session) {
logger.log('Processor: SUB');
var r = store.sub(cmd['space'], cmd['pattern'], session.id);
session.sendAsJSON({'status': r});
};
};
/*
* Listen for connections and data events.
*/
var server = net.createServer(function (stream) {
stream.setEncoding('utf8');
stream.addListener('connect', function() {
// create a session for this client
stream.session = new Session(stream);
sessions[stream.session.id] = stream.session;
logger.log('Server: CONNECT ' + stream.session.id + ' from ' + stream.remoteAddress);
});
stream.addListener('data', function(data) {
logger.log('Server: RECEIVE ' + stream.session.id + ' from ' + stream.remoteAddress + ' ' + data);
processor.process(data, stream.session);
});
stream.addListener('end', function() {
logger.log('Server: DISCONNECT ' + stream.session.id + ' from ' + stream.remoteAddress);
stream.end();
});
stream.addListener('close', function() {
// GC the session
var session_id = stream.session.id;
store.gcSession(session_id);
delete sessions[session_id];
delete stream.session;
});
});
// Start the server on PORT
server.listen(PORT, "localhost");