Implement Microtask Delivery Queue

test/mjsunit/harmony/microtask-delivery.js

Index: test/mjsunit/harmony/microtask-delivery.js
diff --git a/test/mjsunit/harmony/microtask-delivery.js b/test/mjsunit/harmony/microtask-delivery.js
new file mode 100644
index 0000000000000000000000000000000000000000..566a39d03e5f36ca1491981bdbc25539c5fe0936
--- /dev/null
+++ b/test/mjsunit/harmony/microtask-delivery.js
@@ -0,0 +1,168 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --harmony-observation --harmony-promises --allow-natives-syntax
+
+var ordering = [];
+function reset() {
+  ordering = [];
+}
+
+function assertArrayValues(expected, actual) {
+  assertEquals(expected.length, actual.length);
+  for (var i = 0; i < expected.length; i++) {
+    assertEquals(expected[i], actual[i]);
+  }
+}
+
+function assertOrdering(expected) {
+  %RunMicrotasks();
+  assertArrayValues(expected, ordering);
+}
+
+function newPromise(id, fn) {
+  var r;
+  var t = 1;
+  var promise = new Promise(function(resolve) {
+    r = resolve;
+    if (fn) fn();
+  });
+
+  var next = promise.then(function(value) {
+    ordering.push('p' + id);
+    return value;
+  });
+
+  return {
+    resolve: r,
+    then: function(fn) {
+      next = next.then(function(value) {
+        ordering.push('p' + id + ':' + t++);
+        return fn ? fn(value) : value;
+      });
+
+      return this;
+    }
+  };
+}
+
+function newObserver(id, fn, obj) {
+  var observer = {
+    value: 1,
+    recordCounts: []
+  };
+
+  Object.observe(observer, function(records) {
+    ordering.push('o' + id);
+    observer.recordCounts.push(records.length);
+    if (fn) fn();
+  });
+
+  return observer;
+}
+
+
+(function PromiseThens() {
+  reset();
+
+  var p1 = newPromise(1).then();
+  var p2 = newPromise(2).then();
+
+  p1.resolve();
+  p2.resolve();
+
+  assertOrdering(['p1', 'p2', 'p1:1', 'p2:1']);
+})();
+
+
+(function ObserversBatch() {
+  reset();
+
+  var p1 = newPromise(1);
+  var p2 = newPromise(2);
+  var p3 = newPromise(3);
+
+  var ob1 = newObserver(1);
+  var ob2 = newObserver(2, function() {
+    ob3.value++;
+    p3.resolve();
+    ob1.value++;
+  });
+  var ob3 = newObserver(3);
+
+  p1.resolve();
+  ob1.value++;
+  p2.resolve();
+  ob2.value++;
+
+  assertOrdering(['p1', 'o1', 'o2', 'p2', 'o1', 'o3', 'p3']);

[rossberg, 2014/02/04 13:50:08]

Whew, I had to stare at this for 10 minutes to figure out why this is the
expected outcome. I fear we are in for a major WTF from programmers with this
semantics...

[rafaelw, 2014/02/04 19:57:15]

Yeah. I know. My hope is that most developers won't ever have to care about
delivery order. For sure, those that do will be sad. If you have ideas about how
to improve this, don't be shy.

On 2014/02/04 13:50:08, rossberg wrote:

+  assertArrayValues([1, 1], ob1.recordCounts);
+  assertArrayValues([1], ob2.recordCounts);
+  assertArrayValues([1], ob3.recordCounts);
+})();
+
+
+(function ObserversGetAllRecords() {
+  reset();
+
+  var p1 = newPromise(1);
+  var p2 = newPromise(2);
+  var ob1 = newObserver(1, function() {
+    ob2.value++;
+  });
+  var ob2 = newObserver(2);
+
+  p1.resolve();
+  ob1.value++;
+  p2.resolve();
+  ob2.value++;
+
+  assertOrdering(['p1', 'o1', 'o2', 'p2']);
+  assertArrayValues([1], ob1.recordCounts);
+  assertArrayValues([2], ob2.recordCounts);
+})();
+
+
+(function NewObserverDeliveryGetsNewMicrotask() {
+  reset();
+
+  var p1 = newPromise(1);
+  var p2 = newPromise(2);
+  var ob1 = newObserver(1);
+  var ob2 = newObserver(2, function() {
+    ob1.value++;
+  });
+
+  p1.resolve();
+  ob1.value++;
+  p2.resolve();
+  ob2.value++;
+
+  assertOrdering(['p1', 'o1', 'o2', 'p2', 'o1']);
+  assertArrayValues([1, 1], ob1.recordCounts);
+  assertArrayValues([1], ob2.recordCounts);
+})();