Introduce an optional configurable request timeout

docs/config.rst

@@ -215,6 +215,12 @@ Those configuration options are documented below:
     onFailure
         Callback to be invoked upon a failed request.
 
+.. describe:: timeout
+
+    By default, Raven.js requests do not time out. By setting this options, you can enforce that the request
+    is aborted after a number of milliseconds, e.g. set ``timeout: 500`` to abort after half a second during
+    configuration. Once the timeout occurs, the ``ravenTimeout`` event is triggered.
+
 .. describe:: allowSecretKey
 
     By default, Raven.js will throw an error if configured with a Sentry DSN that contains a secret key.

src/raven.js

@@ -1039,9 +1039,10 @@ Raven.prototype = {
     },
 
     _makeXhrRequest: function(opts) {
-        var request;
+        var request,
+            self = this,
+            url = opts.url;
 
-        var url = opts.url;
         function handler() {
             if (request.status === 200) {
                 if (opts.onSuccess) {
@@ -1070,6 +1071,13 @@ Raven.prototype = {
             request.onload = handler;
         }
 
+        // Allow limiting request duration to ensure that logging something will always reach a finished state. By
+        // default, the timeout is 0, which is unlimited.
+        request.timeout = opts.options.timeout || 0;
+        request.ontimeout = function () {
+            self._triggerEvent('timeout');
+        };
+
         // NOTE: auth is intentionally sent as part of query string (NOT as custom
         //       HTTP header) so as to avoid preflight CORS requests
         request.open('POST', url + '?' + urlencode(opts.auth));
@@ -1081,7 +1089,7 @@ Raven.prototype = {
             'withCredentials' in new XMLHttpRequest() ||
             typeof XDomainRequest !== 'undefined';
 
-        return (hasCORS ? this._makeXhrRequest : this._makeImageRequest)(opts);
+        return (hasCORS ? this._makeXhrRequest : this._makeImageRequest).call(this, opts);
     },
 
     // Note: this is shitty, but I can't figure out how to get

test/raven.test.js

@@ -1249,6 +1249,50 @@ describe('globals', function() {
             assert.equal(lastXhr.requestBody, '{"foo":"bar"}');
             assert.equal(lastXhr.url, 'http://localhost/?a=1&b=2');
         });
+
+        it('should set the request timeout if configured', function() {
+            var optionsWithTimeout = JSON.parse(JSON.stringify(Raven._globalOptions)),
+                expectedTimeout = 500;
+
+            optionsWithTimeout.timeout = expectedTimeout;
+            Raven._makeXhrRequest({
+                url: 'http://localhost/',
+                auth: {a: '1', b: '2'},
+                data: {foo: 'bar'},
+                options: optionsWithTimeout
+            });
+
+            var lastXhr = this.requests[this.requests.length - 1];
+            assert.equal(lastXhr.timeout, expectedTimeout);
+        });
+
+        it('should trigger a timeout event once timeout occurs', function () {
+            Raven._makeXhrRequest({
+                url: 'http://localhost/',
+                auth: {a: '1', b: '2'},
+                data: {foo: 'bar'},
+                options: Raven._globalOptions
+            });
+            this.sinon.stub(Raven, '_triggerEvent');
+
+            var lastXhr = this.requests[this.requests.length - 1];
+            assert.typeOf(lastXhr.ontimeout, 'function');
+
+            lastXhr.ontimeout();
+            assert.isTrue(Raven._triggerEvent.calledWith('timeout'));
+        });
+
+        it('should use an infinite request timeout by default', function() {
+            Raven._makeXhrRequest({
+                url: 'http://localhost/',
+                auth: {a: '1', b: '2'},
+                data: {foo: 'bar'},
+                options: Raven._globalOptions
+            });
+
+            var lastXhr = this.requests[this.requests.length - 1];
+            assert.equal(lastXhr.timeout, 0);
+        });
     });
 
     describe('makeImageRequest', function() {