Tweaks to error reporting in Tracker.

History.md

@@ -33,6 +33,11 @@
 * Yield to the event loop during the flush cycle, unless we're executing a
   synchronous `Tracker.flush()`.  #3901
 
+* Fix error reporting not being source-mapped properly. #3655
+
+* Introduce a new option for `Tracker.autorun` - `onError`. This callback can be
+  used to handle errors caught in the reactive computations. #3822
+
 
 ### `meteor` command-line tool
 

docs/client/data.js

@@ -494,7 +494,17 @@ DocsData = {
     "longname": "Accounts.setPassword",
     "memberof": "Accounts",
     "name": "setPassword",
-    "options": [],
+    "options": [
+      {
+        "description": "<p>Logout all current connections with this userId (default: true)</p>",
+        "name": "logout",
+        "type": {
+          "names": [
+            "Object"
+          ]
+        }
+      }
+    ],
     "params": [
       {
         "description": "<p>The id of the user to update.</p>",
@@ -513,6 +523,15 @@ DocsData = {
             "String"
           ]
         }
+      },
+      {
+        "name": "options",
+        "optional": true,
+        "type": {
+          "names": [
+            "Object"
+          ]
+        }
       }
     ],
     "scope": "static",
@@ -5392,7 +5411,7 @@ DocsData = {
     "options": [],
     "params": [],
     "scope": "static",
-    "summary": "- Inside an `onCreated`, `onRendered`, or `onDestroyed` callback, returns\nthe data context of the template.\n- Inside a helper, returns the data context of the DOM node where the helper\nwas used.\n- Inside an event handler, returns the data context of the element that fired\nthe event.\n\nEstablishes a reactive dependency on the result."
+    "summary": "- Inside an `onCreated`, `onRendered`, or `onDestroyed` callback, returns\nthe data context of the template.\n- Inside an event handler, returns the data context of the template on which\nthis event handler was defined.\n- Inside a helper, returns the data context of the DOM node where the helper\nwas used.\n\nEstablishes a reactive dependency on the result."
   },
   "Template.dynamic": {
     "istemplate": "true",
@@ -5730,16 +5749,35 @@ DocsData = {
     "longname": "Tracker.autorun",
     "memberof": "Tracker",
     "name": "autorun",
-    "options": [],
+    "options": [
+      {
+        "description": "<p>Optional. The function to run when an error\nhappens in the Computation. The only argument it recieves is the Error\nthrown. Defaults to the error being logged to the console.</p>",
+        "name": "onError",
+        "type": {
+          "names": [
+            "function"
+          ]
+        }
+      }
+    ],
     "params": [
       {
-        "description": "<p>The function to run. It receives one argument: the Computation object that will be returned.</p>",
+        "description": "<p>The function to run. It receives\none argument: the Computation object that will be returned.</p>",
         "name": "runFunc",
         "type": {
           "names": [
             "Tracker.ComputationFunction"
           ]
         }
+      },
+      {
+        "name": "options",
+        "optional": true,
+        "type": {
+          "names": [
+            "Object"
+          ]
+        }
       }
     ],
     "returns": [
@@ -5752,7 +5790,7 @@ DocsData = {
       }
     ],
     "scope": "static",
-    "summary": "Run a function now and rerun it later whenever its dependencies change. Returns a Computation object that can be used to stop or observe the rerunning."
+    "summary": "Run a function now and rerun it later whenever its dependencies\nchange. Returns a Computation object that can be used to stop or observe the\nrerunning."
   },
   "Tracker.currentComputation": {
     "kind": "member",

packages/meteor/debug.js

@@ -60,3 +60,8 @@ Meteor._debug = function (/* arguments */) {
 Meteor._suppress_log = function (count) {
   suppress += count;
 };
+
+Meteor._supressed_log_expected = function () {
+  return suppress !== 0;
+};
+

packages/tracker/package.js

@@ -12,6 +12,7 @@ Package.onUse(function (api) {
 
 Package.onTest(function (api) {
   api.use('tinytest');
+  api.use('test-helpers');
   api.use('tracker');
   api.addFiles('tracker_tests.js', 'client');
 });

packages/tracker/tracker.js

@@ -45,28 +45,42 @@ var _debugFunc = function () {
   //
   // Lazy evaluation because `Meteor` does not exist right away.(??)
   return (typeof Meteor !== "undefined" ? Meteor._debug :
-          ((typeof console !== "undefined") && console.log ?
-           function () { console.log.apply(console, arguments); } :
+          ((typeof console !== "undefined") && console.error ?
+           function () { console.error.apply(console, arguments); } :
            function () {}));
 };
 
+var _maybeSupressMoreLogs = function (messagesLength) {
+  // Sometimes when running tests, we intentionally supress logs on expected
+  // printed errors. Since the current implementation of _throwOrLog can log
+  // multiple separate log messages, supress all of them if at least one supress
+  // is expected as we still want them to count as one.
+  if (typeof Meteor !== "undefined") {
+    if (Meteor._supressed_log_expected()) {
+      Meteor._suppress_log(messagesLength - 1);
+    }
+  }
+};
+
 var _throwOrLog = function (from, e) {
   if (throwFirstError) {
     throw e;
   } else {
-    var messageAndStack;
-    if (e.stack && e.message) {
+    var printArgs = ["Exception from Tracker " + from + " function:"];
+    if (e.stack && e.message && e.name) {
       var idx = e.stack.indexOf(e.message);
-      if (idx >= 0 && idx <= 10) // allow for "Error: " (at least 7)
-        messageAndStack = e.stack; // message is part of e.stack, as in Chrome
-      else
-        messageAndStack = e.message +
-        (e.stack.charAt(0) === '\n' ? '' : '\n') + e.stack; // e.g. Safari
-    } else {
-      messageAndStack = e.stack || e.message;
+      if (idx < 0 || idx > e.name.length + 2) { // check for "Error: "
+        // message is not part of the stack
+        var message = e.name + ": " + e.message;
+        printArgs.push(message);
+      }
+    }
+    printArgs.push(e.stack);
+    _maybeSupressMoreLogs(printArgs.length);
+
+    for (var i = 0; i < printArgs.length; i++) {
+      _debugFunc()(printArgs[i]);
     }
-    _debugFunc()("Exception from Tracker " + from + " function:",
-                 messageAndStack);
   }
 };
 
@@ -136,7 +150,7 @@ var constructingComputation = false;
  * computation.
  * @instancename computation
  */
-Tracker.Computation = function (f, parent) {
+Tracker.Computation = function (f, parent, onError) {
   if (! constructingComputation)
     throw new Error(
       "Tracker.Computation constructor is private; use Tracker.autorun");
@@ -185,6 +199,7 @@ Tracker.Computation = function (f, parent) {
   // to constrain the order that computations are processed
   self._parent = parent;
   self._func = f;
+  self._onError = onError;
   self._recomputing = false;
 
   // Register the computation within the global Tracker.
@@ -297,7 +312,11 @@ Tracker.Computation.prototype._recompute = function () {
       try {
         self._compute();
       } catch (e) {
-        _throwOrLog("recompute", e);
+        if (self._onError) {
+          self._onError(e);
+        } else {
+          _throwOrLog("recompute", e);
+        }
       }
     }
   } finally {
@@ -492,17 +511,27 @@ Tracker._runFlush = function (options) {
  * @param {Tracker.Computation}
  */
 /**
- * @summary Run a function now and rerun it later whenever its dependencies change. Returns a Computation object that can be used to stop or observe the rerunning.
+ * @summary Run a function now and rerun it later whenever its dependencies
+ * change. Returns a Computation object that can be used to stop or observe the
+ * rerunning.
  * @locus Client
- * @param {Tracker.ComputationFunction} runFunc The function to run. It receives one argument: the Computation object that will be returned.
+ * @param {Tracker.ComputationFunction} runFunc The function to run. It receives
+ * one argument: the Computation object that will be returned.
+ * @param {Object} [options]
+ * @param {Function} options.onError Optional. The function to run when an error
+ * happens in the Computation. The only argument it recieves is the Error
+ * thrown. Defaults to the error being logged to the console.
  * @returns {Tracker.Computation}
  */
-Tracker.autorun = function (f) {
+Tracker.autorun = function (f, options) {
   if (typeof f !== 'function')
     throw new Error('Tracker.autorun requires a function argument');
 
+  options = options || {};
+
   constructingComputation = true;
-  var c = new Tracker.Computation(f, Tracker.currentComputation);
+  var c = new Tracker.Computation(
+    f, Tracker.currentComputation, options.onError);
 
   if (Tracker.active)
     Tracker.onInvalidate(function () {

packages/tracker/tracker_tests.js

@@ -469,3 +469,21 @@ Tinytest.add('tracker - Tracker.flush finishes', function (test) {
   Tracker.flush();
   test.equal(n, 2000);
 });
+
+testAsyncMulti('tracker - Tracker.autorun, onError option', [function (test, expect) {
+  var d = new Tracker.Dependency;
+  var c = Tracker.autorun(function (c) {
+    d.depend();
+
+    if (! c.firstRun)
+      throw new Error("foo");
+  }, {
+    onError: expect(function (err) {
+      test.equal(err.message, "foo");
+    })
+  });
+
+  d.changed();
+  Tracker.flush();
+}]);
+