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server.js
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server.js
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var sys = require('sys');
var http = require('http');
var url = require('url');
var cp = require('child_process');
var config = require('./config').config;
///////////////////////////////////////////////////////////////////////////////////////////////////////////////
function logTailer(id){
var self = this;
this.id = id;
this.buffer = "";
this.first_line = 1;
this.next_line = 1;
this.lines = {};
//
// launch the log tailer
//
var tailcmd = 'gtail';
var args = ['-F'];
for (var i=0; i<config.log_groups[id].length; i++) args.push(config.log_groups[id][i]);
this.proc = cp.spawn(tailcmd, args);
this.proc.stderr.on('data', function(data){
console.log('ERROR '+data);
});
this.proc.stdout.on('data', function(data){
self.buffer += data.toString('utf8');
self.consumeBuffer();
});
this.proc.on('exit', function(code){
console.log('tailing process exited');
});
//
// try and extract lines from `buffer` and stash them
// in the lines hash.
//
this.consumeBuffer = function(){
var sent = 0;
while (1){
var idx = self.buffer.indexOf("\n");
if (idx == -1){
if (sent){
self.cleanup();
self.emit('lines');
}
return;
}
var line = self.buffer.substr(0, idx);
self.buffer = self.buffer.substr(idx+1);
self.lines[self.next_line] = line;
//console.log('added line '+self.next_line);
self.next_line++;
sent++;
self.emit('line', self.next_line-1);
}
}
this.cleanup = function(){
// scrub old lines here
var min_start = self.next_line - config.max_lines;
if (self.first_line < min_start){
//console.log('pruning lines from '+self.first_line+' to '+min_start);
for (var i=self.first_line; i<min_start; i++){
delete self.lines[i];
}
self.first_line = min_start;
}
}
//
// get the index to start reading from (for a new connection)
//
this.getLines = function(start){
var lines = [];
if (!start){
start = self.next_line - config.send_on_fresh;
if (start < self.first_line) start = self.first_line;
}
// are they asking to start before we have logs?
if (start < self.first_line){
lines.push('[skipping forward]');
start = self.first_line;
}
// are they asking for stuff from the future?
if (start > self.next_line){
lines.push('[log server restarted]');
start = self.first_line;
}
// are they asking for what's about to come?
if (start == self.next_line){
return [];
}
// they must be asking for lines we have
for (var i=start; i<self.next_line; i++){
lines.push(self.lines[i]);
}
return lines;
}
}
sys.inherits(logTailer, process.EventEmitter);
///////////////////////////////////////////////////////////////////////////////////////////////////////////////
function logServer(tailers){
http.createServer(function (req, res){
res.writeHead(200, {
'Content-Type': 'text/plain',
'Access-Control-Allow-Origin': '*',
});
var _url = url.parse(req.url, true);
var get = _url.query || {};
// get the bit after the slash
var id = _url.pathname.substr(1);
if (!tailers[id]){
res.end(JSON.stringify({ok: 0, error: 'Log not found: '+id}));
return;
}
var tailer = tailers[id];
var lines = tailer.getLines(parseInt(get.l));
if (lines.length){
// return right away - we have lines!
res.end(JSON.stringify({ok: 1, lines: lines, l: tailer.next_line}));
return;
}
var new_idx = tailer.next_line;
var ended = false;
var listener = null;
var timer = setTimeout(function(){
if (ended) return;
ended = true;
res.end(JSON.stringify({ok :1, timeout: 1}));
tailer.removeListener('lines', listener);
}, config.idle_timeout);
listener = function(){
if (ended) return;
ended = true;
lines = tailer.getLines(new_idx);
res.end(JSON.stringify({ok: 1, lines: lines, l: tailer.next_line}));
clearTimeout(timer);
};
tailer.on('lines', listener);
}).listen(config.port, config.host);
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////
var tailers = {};
for (var i in config.log_groups){
tailers[i] = new logTailer(i);
}
var server = new logServer(tailers);