git.sesse.net Git - remoteglot/blob - server/serve-analysis.js

   1 // node.js version of analysis.pl; hopefully scales a bit better
   2 // for this specific kind of task.
   3
   4 // Modules.
   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');
  11 var readline = require('readline');
  12 var child_process = require('child_process');
  13 var delta = require('../www/js/json_delta.js');
  14 var hash_lookup = require('./hash-lookup.js');
  15
  16 // Constants.
  17 var HISTORY_TO_KEEP = 5;
  18 var MINIMUM_VERSION = null;
  19 var COUNT_FROM_VARNISH_LOG = true;
  20
  21 // Filename to serve.
  22 var json_filename = '/srv/analysis.sesse.net/www/analysis.json';
  23 if (process.argv.length >= 3) {
  24         json_filename = process.argv[2];
  25 }
  26
  27 // Expected destination filenames.
  28 var serve_url = '/analysis.pl';
  29 var hash_serve_url = '/hash';
  30 if (process.argv.length >= 4) {
  31         serve_url = process.argv[3];
  32 }
  33 if (process.argv.length >= 5) {
  34         hash_serve_url = process.argv[4];
  35 }
  36
  37 // TCP port to listen on.
  38 var port = 5000;
  39 if (process.argv.length >= 6) {
  40         port = parseInt(process.argv[5]);
  41 }
  42
  43 // gRPC backends.
  44 var grpc_backends = ["localhost:50051", "localhost:50052"];
  45 if (process.argv.length >= 7) {
  46         grpc_backends = process.argv[6].split(",");
  47 }
  48 hash_lookup.init(grpc_backends);
  49
  50 // If set to 1, we are already processing a JSON update and should not
  51 // start a new one. If set to 2, we are _also_ having one in the queue.
  52 var json_lock = 0;
  53
  54 // The current contents of the file to hand out, and its last modified time.
  55 var json = undefined;
  56
  57 // The last five timestamps, and diffs from them to the latest version.
  58 var historic_json = [];
  59 var diff_json = {};
  60
  61 // The list of clients that are waiting for new data to show up.
  62 // Uniquely keyed by request_id so that we can take them out of
  63 // the queue if they close the socket.
  64 var sleeping_clients = {};
  65 var request_id = 0;
  66
  67 // List of when clients were last seen, keyed by their unique ID.
  68 // Used to show a viewer count to the user.
  69 var last_seen_clients = {};
  70
  71 // The timer used to touch the file every 30 seconds if nobody
  72 // else does it for us. This makes sure we don't have clients
  73 // hanging indefinitely (which might have them return errors).
  74 var touch_timer = undefined;
  75
  76 // If we are behind Varnish, we can't count the number of clients
  77 // ourselves, so we need to get it from parsing varnishncsa.
  78 var viewer_count_override = undefined;
  79
  80 var replace_json = function(new_json_contents, mtime) {
  81         // Generate the list of diffs from the last five versions.
  82         if (json !== undefined) {
  83                 // If two versions have the same mtime, clients could have either.
  84                 // Note the fact, so that we never insert it.
  85                 if (json.last_modified == mtime) {
  86                         json.invalid_base = true;
  87                 }
  88                 if (!json.invalid_base) {
  89                         historic_json.push(json);
  90                         if (historic_json.length > HISTORY_TO_KEEP) {
  91                                 historic_json.shift();
  92                         }
  93                 }
  94         }
  95
  96         var parsed = JSON.parse(new_json_contents);
  97
  98         if (parsed['internal']) {
  99                 if (parsed['internal']['grpc_backends'] &&
 100                     hash_lookup.need_reinit(parsed['internal']['grpc_backends'])) {
 101                         hash_lookup.init(parsed['internal']['grpc_backends']);
 102                 }
 103                 delete parsed['internal'];
 104         }
 105
 106         var new_json = {
 107                 parsed: parsed,
 108                 plain: new_json_contents,
 109                 last_modified: mtime
 110         };
 111         create_json_historic_diff(new_json, historic_json.slice(0), {}, function(new_diff_json) {
 112                 // gzip the new version (non-delta), and put it into place.
 113                 zlib.gzip(new_json_contents, function(err, buffer) {
 114                         if (err) throw err;
 115
 116                         new_json.gzip = buffer;
 117                         json = new_json;
 118                         diff_json = new_diff_json;
 119                         json_lock = 0;
 120
 121                         // Finally, wake up any sleeping clients.
 122                         possibly_wakeup_clients();
 123                 });
 124         });
 125 }
 126
 127 var create_json_historic_diff = function(new_json, history_left, new_diff_json, cb) {
 128         if (history_left.length == 0) {
 129                 cb(new_diff_json);
 130                 return;
 131         }
 132
 133         var histobj = history_left.shift();
 134         var diff = delta.JSON_delta.diff(histobj.parsed, new_json.parsed);
 135         var diff_text = JSON.stringify(diff);
 136         zlib.gzip(diff_text, function(err, buffer) {
 137                 if (err) throw err;
 138                 new_diff_json[histobj.last_modified] = {
 139                         parsed: diff,
 140                         plain: diff_text,
 141                         gzip: buffer,
 142                         last_modified: new_json.last_modified,
 143                 };
 144                 create_json_historic_diff(new_json, history_left, new_diff_json, cb);
 145         });
 146 }
 147
 148 var reread_file = function(event, filename) {
 149         if (filename != path.basename(json_filename)) {
 150                 return;
 151         }
 152         if (json_lock >= 2) {
 153                 return;
 154         }
 155         if (json_lock == 1) {
 156                 // Already processing; wait a bit.
 157                 json_lock = 2;
 158                 setTimeout(function() { if (json_lock == 2) json_lock = 1; reread_file(event, filename); }, 100);
 159                 return;
 160         }
 161         json_lock = 1;
 162
 163         console.log("Rereading " + json_filename);
 164         fs.open(json_filename, 'r', function(err, fd) {
 165                 if (err) throw err;
 166                 fs.fstat(fd, function(err, st) {
 167                         if (err) throw err;
 168                         var buffer = new Buffer(1048576);
 169                         fs.read(fd, buffer, 0, 1048576, 0, function(err, bytesRead, buffer) {
 170                                 if (err) throw err;
 171                                 fs.close(fd, function() {
 172                                         var new_json_contents = buffer.toString('utf8', 0, bytesRead);
 173                                         replace_json(new_json_contents, st.mtime.getTime());
 174                                 });
 175                         });
 176                 });
 177         });
 178
 179         if (touch_timer !== undefined) {
 180                 clearTimeout(touch_timer);
 181         }
 182         touch_timer = setTimeout(function() {
 183                 console.log("Touching analysis.json due to no other activity");
 184                 var now = Date.now() / 1000;
 185                 fs.utimes(json_filename, now, now);
 186         }, 30000);
 187 }
 188 var possibly_wakeup_clients = function() {
 189         var num_viewers = count_viewers();
 190         for (var i in sleeping_clients) {
 191                 mark_recently_seen(sleeping_clients[i].unique);
 192                 send_json(sleeping_clients[i].response,
 193                           sleeping_clients[i].ims,
 194                           sleeping_clients[i].accept_gzip,
 195                           num_viewers);
 196         }
 197         sleeping_clients = {};
 198 }
 199 var send_404 = function(response) {
 200         response.writeHead(404, {
 201                 'Content-Type': 'text/plain',
 202         });
 203         response.write('Something went wrong. Sorry.');
 204         response.end();
 205 }
 206 var send_json = function(response, ims, accept_gzip, num_viewers) {
 207         var this_json = diff_json[ims] || json;
 208
 209         var headers = {
 210                 'Content-Type': 'text/json',
 211                 'X-RGLM': this_json.last_modified,
 212                 'X-RGNV': num_viewers,
 213                 'Access-Control-Expose-Headers': 'X-RGLM, X-RGNV, X-RGMV',
 214                 'Vary': 'Accept-Encoding',
 215         };
 216
 217         if (MINIMUM_VERSION) {
 218                 headers['X-RGMV'] = MINIMUM_VERSION;
 219         }
 220
 221         if (accept_gzip) {
 222                 headers['Content-Length'] = this_json.gzip.length;
 223                 headers['Content-Encoding'] = 'gzip';
 224                 response.writeHead(200, headers);
 225                 response.write(this_json.gzip);
 226         } else {
 227                 headers['Content-Length'] = this_json.plain.length;
 228                 response.writeHead(200, headers);
 229                 response.write(this_json.plain);
 230         }
 231         response.end();
 232 }
 233 var mark_recently_seen = function(unique) {
 234         if (unique) {
 235                 last_seen_clients[unique] = (new Date).getTime();
 236         }
 237 }
 238 var count_viewers = function() {
 239         if (viewer_count_override !== undefined) {
 240                 return viewer_count_override;
 241         }
 242
 243         var now = (new Date).getTime();
 244
 245         // Go through and remove old viewers, and count them at the same time.
 246         var new_last_seen_clients = {};
 247         var num_viewers = 0;
 248         for (var unique in last_seen_clients) {
 249                 if (now - last_seen_clients[unique] < 5000) {
 250                         ++num_viewers;
 251                         new_last_seen_clients[unique] = last_seen_clients[unique];
 252                 }
 253         }
 254
 255         // Also add sleeping clients that we would otherwise assume timed out.
 256         for (var request_id in sleeping_clients) {
 257                 var unique = sleeping_clients[request_id].unique;
 258                 if (unique && !(unique in new_last_seen_clients)) {
 259                         ++num_viewers;
 260                 }
 261         }
 262
 263         last_seen_clients = new_last_seen_clients;
 264         return num_viewers;
 265 }
 266 var log = function(str) {
 267         console.log("[" + ((new Date).getTime()*1e-3).toFixed(3) + "] " + str);
 268 }
 269
 270 // Set up a watcher to catch changes to the file, then do an initial read
 271 // to make sure we have a copy.
 272 fs.watch(path.dirname(json_filename), reread_file);
 273 reread_file(null, path.basename(json_filename));
 274
 275 if (COUNT_FROM_VARNISH_LOG) {
 276         // Note: We abuse serve_url as a regex.
 277         var varnishncsa = child_process.spawn(
 278                 'varnishncsa', ['-F', '%{%s}t %U %q tffb=%{Varnish:time_firstbyte}x',
 279                 '-q', 'ReqURL ~ "^' + serve_url + '"']);
 280         var rl = readline.createInterface({
 281                 input: varnishncsa.stdout,
 282                 output: varnishncsa.stdin,
 283                 terminal: false
 284         });
 285
 286         var uniques = [];
 287         rl.on('line', function(line) {
 288                 var v = line.match(/(\d+) .*\?ims=\d+&unique=(.*) tffb=(.*)/);
 289                 if (v) {
 290                         uniques[v[2]] = {
 291                                 last_seen: (parseInt(v[1]) + parseFloat(v[3])) * 1e3,
 292                                 grace: null,
 293                         };
 294                         log(v[1] + " " + v[2] + " " + v[3]);
 295                 } else {
 296                         log("VARNISHNCSA UNPARSEABLE LINE: " + line);
 297                 }
 298         });
 299         setInterval(function() {
 300                 var mtime = json.last_modified - 1000;  // Compensate for subsecond issues.
 301                 var now = (new Date).getTime();
 302                 var num_viewers = 0;
 303
 304                 for (var unique in uniques) {
 305                         ++num_viewers;
 306                         var last_seen = uniques[unique].last_seen;
 307                         if (now - last_seen <= 5000) {
 308                                 // We've seen this user in the last five seconds;
 309                                 // it's okay.
 310                                 continue;
 311                         }
 312                         if (last_seen >= mtime) {
 313                                 // This user has the latest version;
 314                                 // they are probably just hanging.
 315                                 continue;
 316                         }
 317                         if (uniques[unique].grace === null) {
 318                                 // They have five seconds after a new JSON has been
 319                                 // provided to get get it, or they're out.
 320                                 // We don't simply use mtime, since we don't want to
 321                                 // reset the grace timer just because a new JSON is
 322                                 // published.
 323                                 uniques[unique].grace = mtime;
 324                         }
 325                         if (now - uniques[unique].grace > 5000) {
 326                                 log("Timing out " + unique + " (last_seen=" + last_seen + ", now=" + now +
 327                                         ", mtime=" + mtime, ", grace=" + uniques[unique].grace + ")");
 328                                 delete uniques[unique];
 329                                 --num_viewers;
 330                         }
 331                 }
 332
 333                 log(num_viewers + " entries in hash, mtime=" + mtime);
 334                 viewer_count_override = num_viewers;
 335         }, 1000);
 336 }
 337
 338 var server = http.createServer();
 339 server.on('request', function(request, response) {
 340         var u = url.parse(request.url, true);
 341         var ims = (u.query)['ims'];
 342         var unique = (u.query)['unique'];
 343
 344         log(request.url);
 345         if (u.pathname === hash_serve_url) {
 346                 var fen = (u.query)['fen'];
 347                 hash_lookup.handle_request(fen, response);
 348                 return;
 349         }
 350         if (u.pathname !== serve_url) {
 351                 // This is not the request you are looking for.
 352                 send_404(response);
 353                 return;
 354         }
 355
 356         mark_recently_seen(unique);
 357
 358         var accept_encoding = request.headers['accept-encoding'];
 359         var accept_gzip;
 360         if (accept_encoding !== undefined && accept_encoding.match(/\bgzip\b/)) {
 361                 accept_gzip = true;
 362         } else {
 363                 accept_gzip = false;
 364         }
 365
 366         // If we already have something newer than what the user has,
 367         // just send it out and be done with it.
 368         if (json !== undefined && (!ims || json.last_modified > ims)) {
 369                 send_json(response, ims, accept_gzip, count_viewers());
 370                 return;
 371         }
 372
 373         // OK, so we need to hang until we have something newer.
 374         // Put the user on the wait list.
 375         var client = {};
 376         client.response = response;
 377         client.request_id = request_id;
 378         client.accept_gzip = accept_gzip;
 379         client.unique = unique;
 380         client.ims = ims;
 381         sleeping_clients[request_id++] = client;
 382
 383         request.socket.client = client;
 384 });
 385 server.on('connection', function(socket) {
 386         socket.on('close', function() {
 387                 var client = socket.client;
 388                 if (client) {
 389                         mark_recently_seen(client.unique);
 390                         delete sleeping_clients[client.request_id];
 391                 }
 392         });
 393 });
 394
 395 server.listen(port);