Only truncate history if needed.

[remoteglot] / www / serve-analysis.js

diff --git a/www/serve-analysis.js b/www/serve-analysis.js
index 5b08484d1693fb85f0c969a45a389a314308c256..d1f0bae22eb144deed50d6143ae30f6e0349bf48 100644 (file)
--- a/www/serve-analysis.js
+++ b/www/serve-analysis.js
@@ -7,13 +7,15 @@ var fs = require('fs');
 var url = require('url');
 var querystring = require('querystring');
 var path = require('path');
+var zlib = require('zlib');
 
 // Constants.
 var json_filename = '/srv/analysis.sesse.net/www/analysis.json';
 
 // 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_contents = undefined;
+var json_contents_gz = undefined;
+var json_last_modified = undefined;
 
 // The list of clients that are waiting for new data to show up,
 // and their associated timers. Uniquely keyed by request_id
@@ -38,9 +40,14 @@ var reread_file = function(event, filename) {
                        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);
+                                       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();
+                                       });
                                });
                        });
                });
@@ -49,7 +56,7 @@ var reread_file = function(event, filename) {
 var possibly_wakeup_clients = function() {
        for (var i in sleeping_clients) {
                clearTimeout(sleeping_clients[i].timer);
-               send_json(sleeping_clients[i].response);
+               send_json(sleeping_clients[i].response, sleeping_clients[i].accept_gzip);
        }
        sleeping_clients = {};
 }
@@ -60,20 +67,28 @@ var send_404 = function(response) {
        response.write('Something went wrong. Sorry.');
        response.end();
 }
-var send_json = function(response) {
-       response.writeHead(200, {
+var send_json = function(response, accept_gzip) {
+       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',
-       });
-       response.write(json_contents);
+       };
+
+       if (accept_gzip) {
+               headers['Content-Encoding'] = 'gzip';
+               response.writeHead(200, headers);
+               response.write(json_contents_gz);
+       } else {
+               response.writeHead(200, headers);
+               response.write(json_contents);
+       }
        response.end();
 }
 var timeout_client = function(client) {
-       send_json(client.response);
+       send_json(client.response, client.accept_gzip);
        delete sleeping_clients[client.request_id];
 }
 var count_viewers = function() {
@@ -95,7 +110,7 @@ var count_viewers = function() {
 // 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();
+reread_file(null, path.basename(json_filename));
 
 http.createServer(function(request, response) {
        var u = url.parse(request.url, true);
@@ -114,10 +129,18 @@ http.createServer(function(request, response) {
                last_seen_clients[unique] = (new Date).getTime();
        }
 
+       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_last_modified !== undefined && (!ims || json_last_modified > ims)) {
+               send_json(response, accept_gzip);
                return;
        }
 
@@ -128,5 +151,6 @@ http.createServer(function(request, response) {
        client.response = response;
        client.timer = setTimeout(function() { timeout_client(client); }, 30000);
        client.request_id = request_id;
+       client.accept_gzip = accept_gzip;
        sleeping_clients[request_id++] = client;
 }).listen(5000);