var url = require('url');
var querystring = require('querystring');
var path = require('path');
+var zlib = require('zlib');
+var delta = require('./js/json_delta.js');
// Constants.
-var json_filename = '/srv/analysis.sesse.net/www/analysis.json';
+var JSON_FILENAME = '/srv/analysis.sesse.net/www/analysis.json';
+var HISTORY_TO_KEEP = 5;
+
+// If set to 1, we are already processing a JSON update and should not
+// start a new one. If set to 2, we are _also_ having one in the queue.
+var json_lock = 0;
// The current contents of the file to hand out, and its last modified time.
-var json_contents = null;
-var json_last_modified = null;
+var json = undefined;
+
+// The last five timestamps, and diffs from them to the latest version.
+var historic_json = [];
+var diff_json = {};
-// The list of clients that are waiting for new data to show up,
-// and their associated timers. Uniquely keyed by request_id
-// so that we can take them out of the queue if they time out.
+// The list of clients that are waiting for new data to show up.
+// Uniquely keyed by request_id so that we can take them out of
+// the queue if they close the socket.
var sleeping_clients = {};
var request_id = 0;
// Used to show a viewer count to the user.
var last_seen_clients = {};
+// The timer used to touch the file every 30 seconds if nobody
+// else does it for us. This makes sure we don't have clients
+// hanging indefinitely (which might have them return errors).
+var touch_timer = undefined;
+
+// If we are behind Varnish, we can't count the number of clients
+// ourselves, so some external log-tailing daemon needs to tell us.
+var viewer_count_override = undefined;
+
+var replace_json = function(new_json_contents, mtime) {
+ // Generate the list of diffs from the last five versions.
+ if (json !== undefined) {
+ // If two versions have the same mtime, clients could have either.
+ // Note the fact, so that we never insert it.
+ if (json.last_modified == mtime) {
+ json.invalid_base = true;
+ }
+ if (!json.invalid_base) {
+ historic_json.push(json);
+ if (historic_json.length > HISTORY_TO_KEEP) {
+ historic_json.shift();
+ }
+ }
+ }
+
+ var new_json = {
+ parsed: JSON.parse(new_json_contents),
+ plain: new_json_contents,
+ last_modified: mtime
+ };
+ create_json_historic_diff(new_json, historic_json.slice(0), {}, function(new_diff_json) {
+ // gzip the new version (non-delta), and put it into place.
+ zlib.gzip(new_json_contents, function(err, buffer) {
+ if (err) throw err;
+
+ new_json.gzip = buffer;
+ json = new_json;
+ diff_json = new_diff_json;
+ json_lock = 0;
+
+ // Finally, wake up any sleeping clients.
+ possibly_wakeup_clients();
+ });
+ });
+}
+
+var create_json_historic_diff = function(new_json, history_left, new_diff_json, cb) {
+ if (history_left.length == 0) {
+ cb(new_diff_json);
+ return;
+ }
+
+ var histobj = history_left.shift();
+ var diff = delta.JSON_delta.diff(histobj.parsed, new_json.parsed);
+ var diff_text = JSON.stringify(diff);
+ zlib.gzip(diff_text, function(err, buffer) {
+ if (err) throw err;
+ new_diff_json[histobj.last_modified] = {
+ plain: diff,
+ text: diff_text,
+ gzip: buffer,
+ last_modified: new_json.last_modified,
+ };
+ create_json_historic_diff(new_json, history_left, new_diff_json, cb);
+ });
+}
+
var reread_file = function(event, filename) {
- if (filename != path.basename(json_filename)) {
+ if (filename != path.basename(JSON_FILENAME)) {
+ return;
+ }
+ if (json_lock >= 2) {
return;
}
- console.log("Rereading " + json_filename);
- fs.open(json_filename, 'r+', function(err, fd) {
+ if (json_lock == 1) {
+ // Already processing; wait a bit.
+ json_lock = 2;
+ setTimeout(function() { json_lock = 1; reread_file(event, filename); }, 100);
+ return;
+ }
+ json_lock = 1;
+
+ console.log("Rereading " + JSON_FILENAME);
+ fs.open(JSON_FILENAME, 'r+', function(err, fd) {
if (err) throw err;
fs.fstat(fd, function(err, st) {
if (err) throw err;
fs.read(fd, buffer, 0, 1048576, 0, function(err, bytesRead, buffer) {
if (err) throw err;
fs.close(fd, function() {
- json_contents = buffer.toString('utf8', 0, bytesRead);
- json_last_modified = st.mtime.getTime();
- possibly_wakeup_clients();
+ var new_json_contents = buffer.toString('utf8', 0, bytesRead);
+ replace_json(new_json_contents, st.mtime.getTime());
});
});
});
});
+
+ if (touch_timer !== undefined) {
+ clearTimeout(touch_timer);
+ }
+ touch_timer = setTimeout(function() {
+ console.log("Touching analysis.json due to no other activity");
+ var now = Date.now() / 1000;
+ fs.utimes(JSON_FILENAME, now, now);
+ }, 30000);
}
var possibly_wakeup_clients = function() {
+ var num_viewers = count_viewers();
for (var i in sleeping_clients) {
- clearTimeout(sleeping_clients[i].timer);
- send_json(sleeping_clients[i].response);
+ mark_recently_seen(sleeping_clients[i].unique);
+ send_json(sleeping_clients[i].response,
+ sleeping_clients[i].ims,
+ sleeping_clients[i].accept_gzip,
+ num_viewers);
}
sleeping_clients = {};
}
response.write('Something went wrong. Sorry.');
response.end();
}
-var send_json = function(response) {
- response.writeHead(200, {
+var handle_viewer_override = function(request, u, response) {
+ // Only accept requests from localhost.
+ var peer = request.socket.localAddress;
+ if ((peer != '127.0.0.1' && peer != '::1') || request.headers['x-forwarded-for']) {
+ console.log("Refusing viewer override from " + peer);
+ send_404(response);
+ } else {
+ viewer_count_override = (u.query)['num'];
+ response.writeHead(200, {
+ 'Content-Type': 'text/plain',
+ });
+ response.write('OK.');
+ response.end();
+ }
+}
+var send_json = function(response, ims, accept_gzip, num_viewers) {
+ var this_json = diff_json[ims] || json;
+
+ var headers = {
'Content-Type': 'text/json',
- 'X-Remoteglot-Last-Modified': json_last_modified,
- 'X-Remoteglot-Num-Viewers': count_viewers(),
- 'Access-Control-Allow-Origin': 'http://analysis.sesse.net',
+ 'X-Remoteglot-Last-Modified': this_json.last_modified,
+ 'X-Remoteglot-Num-Viewers': num_viewers,
'Access-Control-Expose-Headers': 'X-Remoteglot-Last-Modified, X-Remoteglot-Num-Viewers',
'Expires': 'Mon, 01 Jan 1970 00:00:00 UTC',
- });
- response.write(json_contents);
+ 'Vary': 'Accept-Encoding',
+ };
+
+ if (accept_gzip) {
+ headers['Content-Encoding'] = 'gzip';
+ response.writeHead(200, headers);
+ response.write(this_json.gzip);
+ } else {
+ response.writeHead(200, headers);
+ response.write(this_json.text);
+ }
response.end();
}
-var timeout_client = function(client) {
- send_json(client.response);
- delete sleeping_clients[client.request_id];
+var mark_recently_seen = function(unique) {
+ if (unique) {
+ last_seen_clients[unique] = (new Date).getTime();
+ }
}
var count_viewers = function() {
+ if (viewer_count_override !== undefined) {
+ return viewer_count_override;
+ }
+
var now = (new Date).getTime();
// Go through and remove old viewers, and count them at the same time.
var new_last_seen_clients = {};
var num_viewers = 0;
for (var unique in last_seen_clients) {
- if (now - last_seen_clients[unique] < 60000) {
+ if (now - last_seen_clients[unique] < 5000) {
++num_viewers;
new_last_seen_clients[unique] = last_seen_clients[unique];
}
}
+
+ // Also add sleeping clients that we would otherwise assume timed out.
+ for (var request_id in sleeping_clients) {
+ var unique = sleeping_clients[request_id].unique;
+ if (unique && !(unique in new_last_seen_clients)) {
+ ++num_viewers;
+ }
+ }
+
last_seen_clients = new_last_seen_clients;
return num_viewers;
}
// Set up a watcher to catch changes to the file, then do an initial read
// to make sure we have a copy.
-fs.watch(path.dirname(json_filename), reread_file);
-reread_file();
+fs.watch(path.dirname(JSON_FILENAME), reread_file);
+reread_file(null, path.basename(JSON_FILENAME));
-http.createServer(function(request, response) {
+var server = http.createServer();
+server.on('request', function(request, response) {
var u = url.parse(request.url, true);
var ims = (u.query)['ims'];
var unique = (u.query)['unique'];
console.log((new Date).getTime()*1e-3 + " " + request.url);
-
+ if (u.pathname === '/override-num-viewers') {
+ handle_viewer_override(request, u, response);
+ return;
+ }
if (u.pathname !== '/analysis.pl') {
// This is not the request you are looking for.
send_404(response);
return;
}
- if (unique) {
- last_seen_clients[unique] = (new Date).getTime();
+ mark_recently_seen(unique);
+
+ var accept_encoding = request.headers['accept-encoding'];
+ var accept_gzip;
+ if (accept_encoding !== undefined && accept_encoding.match(/\bgzip\b/)) {
+ accept_gzip = true;
+ } else {
+ accept_gzip = false;
}
// If we already have something newer than what the user has,
// just send it out and be done with it.
- if (!ims || json_last_modified > ims) {
- send_json(response);
+ if (json !== undefined && (!ims || json.last_modified > ims)) {
+ send_json(response, ims, accept_gzip, count_viewers());
return;
}
// OK, so we need to hang until we have something newer.
- // Put the user on the wait list; if we don't get anything
- // in 30 seconds, though, we'll send something anyway.
+ // Put the user on the wait list.
var client = {};
client.response = response;
- client.timer = setTimeout(function() { timeout_client(client); }, 30000);
client.request_id = request_id;
+ client.accept_gzip = accept_gzip;
+ client.unique = unique;
+ client.ims = ims;
sleeping_clients[request_id++] = client;
-}).listen(5000);
+
+ request.socket.client = client;
+});
+server.on('connection', function(socket) {
+ socket.on('close', function() {
+ var client = socket.client;
+ if (client) {
+ mark_recently_seen(client.unique);
+ delete sleeping_clients[client.request_id];
+ }
+ });
+});
+server.listen(5000);
projects / remoteglot / blobdiff