var querystring = require('querystring');
var path = require('path');
var zlib = require('zlib');
+var readline = require('readline');
+var child_process = require('child_process');
+var delta = require('./js/json_delta.js');
// Constants.
+var HISTORY_TO_KEEP = 5;
+var MINIMUM_VERSION = null;
+var COUNT_FROM_VARNISH_LOG = true;
+
+// Filename to serve.
var json_filename = '/srv/analysis.sesse.net/www/analysis.json';
+if (process.argv.length >= 3) {
+ json_filename = process.argv[2];
+}
+
+// Expected destination filename.
+var serve_url = '/analysis.pl';
+if (process.argv.length >= 4) {
+ serve_url = process.argv[3];
+}
+
+// TCP port to listen on.
+var port = 5000;
+if (process.argv.length >= 5) {
+ port = parseInt(process.argv[4]);
+}
+
+// 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 = undefined;
-var json_contents_gz = undefined;
-var json_last_modified = undefined;
+var json = undefined;
-// 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 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.
+// 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 we need to get it from parsing varnishncsa.
+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] = {
+ parsed: diff,
+ plain: 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)) {
return;
}
+ if (json_lock >= 2) {
+ return;
+ }
+ 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;
if (err) throw err;
fs.close(fd, function() {
var new_json_contents = buffer.toString('utf8', 0, bytesRead);
- zlib.gzip(new_json_contents, function(err, buffer) {
- if (err) throw err;
- json_contents = new_json_contents;
- json_contents_gz = buffer;
- json_last_modified = st.mtime.getTime();
- possibly_wakeup_clients();
- });
+ 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);
- mark_recently_seen(sleeping_clients[request_id].unique);
- send_json(sleeping_clients[i].response, sleeping_clients[i].accept_gzip);
+ 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, accept_gzip) {
+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',
- 'Access-Control-Expose-Headers': 'X-Remoteglot-Last-Modified, X-Remoteglot-Num-Viewers',
- 'Expires': 'Mon, 01 Jan 1970 00:00:00 UTC',
+ 'X-RGLM': this_json.last_modified,
+ 'X-RGNV': num_viewers,
+ 'Access-Control-Expose-Headers': 'X-RGLM, X-RGNV, X-RGMV',
+ 'Vary': 'Accept-Encoding',
};
+ if (MINIMUM_VERSION) {
+ headers['X-RGMV'] = MINIMUM_VERSION;
+ }
+
if (accept_gzip) {
+ headers['Content-Length'] = this_json.gzip.length;
headers['Content-Encoding'] = 'gzip';
response.writeHead(200, headers);
- response.write(json_contents_gz);
+ response.write(this_json.gzip);
} else {
+ headers['Content-Length'] = this_json.plain.length;
response.writeHead(200, headers);
- response.write(json_contents);
+ response.write(this_json.plain);
}
response.end();
}
-var timeout_client = function(client) {
- mark_recently_seen(client.unique);
- send_json(client.response, client.accept_gzip);
- 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.
last_seen_clients = new_last_seen_clients;
return num_viewers;
}
+var log = function(str) {
+ console.log("[" + ((new Date).getTime()*1e-3).toFixed(3) + "] " + str);
+}
// 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(null, path.basename(json_filename));
+if (COUNT_FROM_VARNISH_LOG) {
+ // Note: We abuse serve_url as a regex.
+ var varnishncsa = child_process.spawn(
+ 'varnishncsa', ['-F', '%{%s}t %U %q tffb=%{Varnish:time_firstbyte}x',
+ '-q', 'ReqURL ~ "^' + serve_url + '"']);
+ var rl = readline.createInterface({
+ input: varnishncsa.stdout,
+ output: varnishncsa.stdin,
+ terminal: false
+ });
+
+ var uniques = [];
+ rl.on('line', function(line) {
+ var v = line.match(/(\d+) .*\?ims=\d+&unique=(.*) tffb=(.*)/);
+ if (v) {
+ uniques[v[2]] = {
+ last_seen: (parseInt(v[1]) + parseFloat(v[3])) * 1e3,
+ grace: null,
+ };
+ log(v[1] + " " + v[2] + " " + v[3]);
+ } else {
+ log("VARNISHNCSA UNPARSEABLE LINE: " + line);
+ }
+ });
+ setInterval(function() {
+ var mtime = json.last_modified - 1000; // Compensate for subsecond issues.
+ var now = (new Date).getTime();
+ var num_viewers = 0;
+
+ for (var unique in uniques) {
+ ++num_viewers;
+ var last_seen = uniques[unique].last_seen;
+ if (now - last_seen <= 5000) {
+ // We've seen this user in the last five seconds;
+ // it's okay.
+ continue;
+ }
+ if (last_seen >= mtime) {
+ // This user has the latest version;
+ // they are probably just hanging.
+ continue;
+ }
+ if (uniques[unique].grace === null) {
+ // They have five seconds after a new JSON has been
+ // provided to get get it, or they're out.
+ // We don't simply use mtime, since we don't want to
+ // reset the grace timer just because a new JSON is
+ // published.
+ uniques[unique].grace = mtime;
+ }
+ if (now - uniques[unique].grace > 5000) {
+ log("Timing out " + unique + " (last_seen=" + last_seen + ", now=" + now +
+ ", mtime=" + mtime, ", grace=" + uniques[unique].grace + ")");
+ delete uniques[unique];
+ --num_viewers;
+ }
+ }
+
+ log(num_viewers + " entries in hash, mtime=" + mtime);
+ viewer_count_override = num_viewers;
+ }, 1000);
+}
+
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 !== '/analysis.pl') {
+ log(request.url);
+ if (u.pathname !== serve_url) {
// This is not the request you are looking for.
send_404(response);
return;
// If we already have something newer than what the user has,
// just send it out and be done with it.
- if (json_last_modified !== undefined && (!ims || json_last_modified > ims)) {
- send_json(response, accept_gzip);
+ 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;
request.socket.client = client;
}
});
});
-server.listen(5000);
+
+server.listen(port);
projects / remoteglot / blobdiff