Make sure we do not try to process more than one analysis.json update at a time.

diff --git a/www/serve-analysis.js b/www/serve-analysis.js
index 10a3e55545d18b9a5af7cc6143c5899a93ea0f5b..171ce82ac6b56d7ead0d6405ec07b41e580a4c64 100644 (file)
--- a/www/serve-analysis.js
+++ b/www/serve-analysis.js
@@ -14,6 +14,10 @@ var delta = require('./js/json_delta.js');
 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 = undefined;
 
@@ -69,6 +73,7 @@ var replace_json = function(new_json_contents, mtime) {
                        new_json.gzip = buffer;
                        json = new_json;
                        diff_json = new_diff_json;
+                       json_lock = 0;
 
                        // Finally, wake up any sleeping clients.
                        possibly_wakeup_clients();
@@ -101,6 +106,17 @@ 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;