1 // node.js version of analysis.pl; hopefully scales a bit better
2 // for this specific kind of task.
5 var http = require('http');
6 var fs = require('fs');
7 var url = require('url');
8 var querystring = require('querystring');
9 var path = require('path');
10 var zlib = require('zlib');
13 var json_filename = '/srv/analysis.sesse.net/www/analysis.json';
15 // The current contents of the file to hand out, and its last modified time.
16 var json_contents = undefined;
17 var json_contents_gz = undefined;
18 var json_last_modified = undefined;
20 // The list of clients that are waiting for new data to show up,
21 // and their associated timers. Uniquely keyed by request_id
22 // so that we can take them out of the queue if they time out.
23 var sleeping_clients = {};
26 // List of when clients were last seen, keyed by their unique ID.
27 // Used to show a viewer count to the user.
28 var last_seen_clients = {};
30 var reread_file = function(event, filename) {
31 if (filename != path.basename(json_filename)) {
34 console.log("Rereading " + json_filename);
35 fs.open(json_filename, 'r+', function(err, fd) {
37 fs.fstat(fd, function(err, st) {
39 var buffer = new Buffer(1048576);
40 fs.read(fd, buffer, 0, 1048576, 0, function(err, bytesRead, buffer) {
42 fs.close(fd, function() {
43 var new_json_contents = buffer.toString('utf8', 0, bytesRead);
44 zlib.gzip(new_json_contents, function(err, buffer) {
46 json_contents = new_json_contents;
47 json_contents_gz = buffer;
48 json_last_modified = st.mtime.getTime();
49 possibly_wakeup_clients();
56 var possibly_wakeup_clients = function() {
57 for (var i in sleeping_clients) {
58 clearTimeout(sleeping_clients[i].timer);
59 send_json(sleeping_clients[i].response, sleeping_clients[i].accept_gzip);
61 sleeping_clients = {};
63 var send_404 = function(response) {
64 response.writeHead(404, {
65 'Content-Type': 'text/plain',
67 response.write('Something went wrong. Sorry.');
70 var send_json = function(response, accept_gzip) {
72 'Content-Type': 'text/json',
73 'X-Remoteglot-Last-Modified': json_last_modified,
74 'X-Remoteglot-Num-Viewers': count_viewers(),
75 'Access-Control-Allow-Origin': 'http://analysis.sesse.net',
76 'Access-Control-Expose-Headers': 'X-Remoteglot-Last-Modified, X-Remoteglot-Num-Viewers',
77 'Expires': 'Mon, 01 Jan 1970 00:00:00 UTC',
81 headers['Content-Encoding'] = 'gzip';
82 response.writeHead(200, headers);
83 response.write(json_contents_gz);
85 response.writeHead(200, headers);
86 response.write(json_contents);
90 var timeout_client = function(client) {
91 send_json(client.response, client.accept_gzip);
92 delete sleeping_clients[client.request_id];
94 var count_viewers = function() {
95 var now = (new Date).getTime();
97 // Go through and remove old viewers, and count them at the same time.
98 var new_last_seen_clients = {};
100 for (var unique in last_seen_clients) {
101 if (now - last_seen_clients[unique] < 60000) {
103 new_last_seen_clients[unique] = last_seen_clients[unique];
106 last_seen_clients = new_last_seen_clients;
110 // Set up a watcher to catch changes to the file, then do an initial read
111 // to make sure we have a copy.
112 fs.watch(path.dirname(json_filename), reread_file);
113 reread_file(null, path.basename(json_filename));
115 http.createServer(function(request, response) {
116 var u = url.parse(request.url, true);
117 var ims = (u.query)['ims'];
118 var unique = (u.query)['unique'];
120 console.log((new Date).getTime()*1e-3 + " " + request.url);
122 if (u.pathname !== '/analysis.pl') {
123 // This is not the request you are looking for.
129 last_seen_clients[unique] = (new Date).getTime();
132 var accept_encoding = request.headers['accept-encoding'];
134 if (accept_encoding !== undefined && accept_encoding.match(/\bgzip\b/)) {
140 // If we already have something newer than what the user has,
141 // just send it out and be done with it.
142 if (json_last_modified !== undefined && (!ims || json_last_modified > ims)) {
143 send_json(response, accept_gzip);
147 // OK, so we need to hang until we have something newer.
148 // Put the user on the wait list; if we don't get anything
149 // in 30 seconds, though, we'll send something anyway.
151 client.response = response;
152 client.timer = setTimeout(function() { timeout_client(client); }, 30000);
153 client.request_id = request_id;
154 client.accept_gzip = accept_gzip;
155 sleeping_clients[request_id++] = client;