From 93b05bdf638e1e26fa568e4fbd2c0da3b3637bcd Mon Sep 17 00:00:00 2001
From: Marko Vuksanovic <markovuksanovic@gmail.com>
Date: Tue, 29 Apr 2014 16:42:14 +1000
Subject: [PATCH] feat(VmTurnZone): VmTurnZone can handle scheduling
 microtasks.

To customize how VmTurnZone handles microtasks assign a function to
VmTurnZone.onScheduleMicrotask. This method will then be used whenever
a microtask is scheduled instead of the default implementation.

Closes #976
---
 lib/core/zone.dart       |  8 +++++
 test/core/zone_spec.dart | 74 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/lib/core/zone.dart b/lib/core/zone.dart
index 737e6de6c..ba63c70ff 100644
--- a/lib/core/zone.dart
+++ b/lib/core/zone.dart
@@ -10,6 +10,8 @@ typedef void ZoneOnTurnDone();
  */
 typedef void ZoneOnTurnStart();
 
+typedef void ZoneScheduleMicrotask(fn());
+
 /**
  * Handles an [VmTurnZone] onError event.
  */
@@ -58,6 +60,8 @@ class VmTurnZone {
   /// an "inner" [Zone], which is a child of the outer [Zone].
   async.Zone _innerZone;
 
+  ZoneScheduleMicrotask onScheduleMicrotask;
+
   /**
    * Associates with this
    *
@@ -108,6 +112,10 @@ class VmTurnZone {
 
   _onScheduleMicrotask(async.Zone self, async.ZoneDelegate delegate,
                        async.Zone zone, fn()) {
+    if (onScheduleMicrotask != null) {
+      return onScheduleMicrotask(fn);
+    }
+
     _asyncQueue.add(() => delegate.run(zone, fn));
     if (_runningInTurn == 0 && !_inFinishTurn)  _finishTurn(zone, delegate);
   }
diff --git a/test/core/zone_spec.dart b/test/core/zone_spec.dart
index 9e33ae62d..9845a2004 100644
--- a/test/core/zone_spec.dart
+++ b/test/core/zone_spec.dart
@@ -435,5 +435,79 @@ void main() {
         microLeap();
       })).toThrow('ssertion');  // Support both dart2js and the VM with half a word.
     });
+
+    it('should allow Scope to handle scheduling of microtasks', async((Logger log) {
+      var microtaskResult = false;
+      zone.onTurnStart = () {
+        log('onTurnStart(begin)');
+        log('onTurnStart(end)');
+      };
+      zone.onTurnDone = () {
+        log('onTurnDone(begin)');
+        scheduleMicrotask(() {
+          log('executeMicrotask');
+          return true;
+        });
+        log('onTurnDone(end)');
+      };
+      zone.onScheduleMicrotask = (microTaskFn) {
+        log('onScheduleMicrotask(begin)');
+        microtaskResult = microTaskFn();
+        log('onScheduleMicrotask(end)');
+      };
+      zone.run(() {
+        log('run');
+      });
+      microLeap();
+
+      expect(log.result()).toEqual('onTurnStart(begin); onTurnStart(end); run; onTurnDone(begin); onScheduleMicrotask(begin); executeMicrotask; onScheduleMicrotask(end); onTurnDone(end)');
+      expect(microtaskResult).toBeTruthy();
+    }));
+
+    it('should allow Scope to handle Future.microtask too', async((Logger log) {
+      zone.onTurnStart = () {
+        log('onTurnStart(begin)');
+        log('onTurnStart(end)');
+      };
+      zone.onTurnDone = () {
+        log('onTurnDone(begin)');
+        new Future.microtask(() => log('schedule from future'));
+        log('onTurnDone(end)');
+      };
+      zone.onScheduleMicrotask = (microTaskFn) {
+        log('onScheduleMicrotask(begin)');
+        microTaskFn();
+        log('onScheduleMicrotask(end)');
+      };
+      zone.run(() {
+        log('run');
+      });
+      microLeap();
+
+      expect(log.result()).toEqual('onTurnStart(begin); onTurnStart(end); run; onTurnDone(begin); onScheduleMicrotask(begin); schedule from future; onScheduleMicrotask(end); onTurnDone(end)');
+    }));
+
+    it('should allow Scope to handle Future.value too', async((Logger log) {
+      zone.onTurnStart = () {
+        log('onTurnStart(begin)');
+        log('onTurnStart(end)');
+      };
+      zone.onTurnDone = () {
+        log('onTurnDone(begin)');
+        new Future.value('async').then((v) => log('executed ${v}'));
+        log('onTurnDone(end)');
+      };
+      zone.onScheduleMicrotask = (microTaskFn) {
+        log('onScheduleMicrotask(begin)');
+        microTaskFn();
+        log('onScheduleMicrotask(end)');
+      };
+      zone.run(() {
+        log('run');
+      });
+      microLeap();
+
+      expect(log.result()).toEqual('onTurnStart(begin); onTurnStart(end); run; onTurnDone(begin); onScheduleMicrotask(begin); onScheduleMicrotask(end); onScheduleMicrotask(begin); executed async; onScheduleMicrotask(end); onTurnDone(end)');
+    }));
   });
 }