X-Git-Url: https://git.sesse.net/?p=remoteglot;a=blobdiff_plain;f=www%2Fserve-analysis.js;h=edb4a18a9db7b6a933d77771f244806995525304;hp=56845eef01f7d0d37391392a1810605441b51dca;hb=f958c7696910d2d096d5662689ba133876d5dabe;hpb=a66c165f94e06a675b392d133f60c3dbbab22c60 diff --git a/www/serve-analysis.js b/www/serve-analysis.js index 56845ee..edb4a18 100644 --- a/www/serve-analysis.js +++ b/www/serve-analysis.js @@ -6,17 +6,28 @@ var http = require('http'); var fs = require('fs'); 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; @@ -24,8 +35,90 @@ var request_id = 0; // Used to show a viewer count to the user. var last_seen_clients = {}; -var reread_file = function() { - fs.open(json_filename, 'r+', function(err, fd) { +// 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)) { + 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; fs.fstat(fd, function(err, st) { if (err) throw err; @@ -33,18 +126,30 @@ var reread_file = function() { 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 = {}; } @@ -55,73 +160,134 @@ var send_404 = function(response) { 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(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);