detect aborted requests and don't panic. References bug 706

The cause of bug 706 seems to be our own aborted requests,
mis-detected as XHR failures.

But there are other bad things that are still possible. User can abort
request by pressing Escape. And it seems there's no portable way to
distinguish that from not responding server.

Signed-off-by: Matt Ingenthron <ingenthr@cep.net>

deps/menelaus/priv/js/app.js

@@ -171,6 +171,14 @@ function addBasicAuth(xhr, login, password) {
 function onUnexpectedXHRError(xhr) {
   window.onUnexpectedXHRError = function () {}
 
+  if (Abortarium.isAborted(xhr))
+    return;
+
+  // for manual interception
+  if ('debuggerHook' in onUnexpectedXHRError) {
+    onUnexpectedXHRError['debuggerHook'](xhr);
+  }
+
   var status;
   try {status = xhr.status} catch (e) {};
 

deps/menelaus/priv/js/cells.js

@@ -41,7 +41,7 @@ future.get = function (ajaxOptions, valueTransformer, nowValue) {
   var options = {
     valueTransformer: valueTransformer,
     cancel: function () {
-      xhr.abort();
+      Abortarium.abortRequest(xhr);
     },
     nowValue: nowValue
   }

deps/menelaus/priv/js/misc.js

@@ -611,3 +611,33 @@ function collectBacktraceViaCaller() {
   }
   return rv.join('');
 }
+
+var Abortarium = {
+  recentlyAborted: [],
+  MAX_LENGTH: 50,
+  abortRequest: function (xhr) {
+    if (this.isAborted(xhr))
+      return;
+    console.log("aborting request:", xhr);
+    this.recentlyAborted.push(xhr);
+    if (this.recentlyAborted.length > this.MAX_LENGTH)
+      this.recentlyAborted = this.recentlyAborted.slice(-this.MAX_LENGTH);
+    try {
+      return xhr.abort();
+    } finally {
+      try {xhr.onreadystatechange = $.noop();} catch (e) {}
+    }
+  },
+  isAborted: function (xhr) {
+    return _.include(this.recentlyAborted, xhr);
+  },
+  wrapSuccessCallback: function (callback) {
+    if (!callback)
+      return callback;
+    return function (data, status, xhr) {
+      if (Abortarium.isAborted(xhr))
+        return;
+      return callback.apply(this, arguments);
+    }
+  }
+};