Index: client/html/src/Measurement.dart |
diff --git a/client/html/src/Measurement.dart b/client/html/src/Measurement.dart |
index e92a46c82b7d82ebd44be89fded51e59a5e56b91..fa2a37fe40dc39772a01bf391fa4fa671ae2743f 100644 |
--- a/client/html/src/Measurement.dart |
+++ b/client/html/src/Measurement.dart |
@@ -1,20 +1,12 @@ |
-// Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file |
+// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
// for details. All rights reserved. Use of this source code is governed by a |
// BSD-style license that can be found in the LICENSE file. |
-typedef Object ComputeValue(); |
- |
-class _MeasurementRequest<T> { |
- final ComputeValue computeValue; |
- final Completer<T> completer; |
- Object value; |
- bool exception = false; |
- _MeasurementRequest(this.computeValue, this.completer); |
-} |
+bool _inMeasurementFrame = false; |
final _MEASUREMENT_MESSAGE = "DART-MEASURE"; |
-List<_MeasurementRequest> _pendingRequests; |
-List<TimeoutHandler> _pendingMeasurementFrameCallbacks; |
+ |
+Queue<MeasurementCallback> _pendingMeasurementFrameCallbacks; |
bool _nextMeasurementFrameScheduled = false; |
bool _firstMeasurementRequest = true; |
@@ -27,9 +19,9 @@ void _maybeScheduleMeasurementFrame() { |
if (_firstMeasurementRequest) { |
// Messages from other windows do not cause a security risk as |
// all we care about is that _onCompleteMeasurementRequests is called |
- // after the current event loop is unwound and calling the function is |
- // a noop when zero requests are pending. |
- window.on.message.add((e) => _completeMeasurementFutures()); |
+ // after the current event loop is unwound and calling |
+ // _runMeasurementFrames is a noop when zero requests are pending. |
+ window.on.message.add((e) => _runMeasurementFrames()); |
_firstMeasurementRequest = false; |
} |
@@ -46,75 +38,52 @@ void _maybeScheduleMeasurementFrame() { |
* when they would have completed to avoid confusing bugs if it happened that |
* no measurements were actually requested. |
*/ |
-void _addMeasurementFrameCallback(TimeoutHandler callback) { |
+void _addMeasurementFrameCallback(MeasurementCallback callback) { |
+ assert(callback != null); |
if (_pendingMeasurementFrameCallbacks === null) { |
- _pendingMeasurementFrameCallbacks = <TimeoutHandler>[]; |
- _maybeScheduleMeasurementFrame(); |
+ _pendingMeasurementFrameCallbacks = new Queue<MeasurementCallback>(); |
} |
+ _maybeScheduleMeasurementFrame(); |
_pendingMeasurementFrameCallbacks.add(callback); |
} |
/** |
- * Returns a [Future] whose value will be the result of evaluating |
- * [computeValue] during the next safe measurement interval. |
- * The next safe measurement interval is after the current event loop has |
- * unwound but before the browser has rendered the page. |
- * It is important that the [computeValue] function only queries the html |
- * layout and html in any way. |
- */ |
-Future _createMeasurementFuture(ComputeValue computeValue, |
- Completer completer) { |
- if (_pendingRequests === null) { |
- _pendingRequests = <_MeasurementRequest>[]; |
- _maybeScheduleMeasurementFrame(); |
- } |
- _pendingRequests.add(new _MeasurementRequest(computeValue, completer)); |
- return completer.future; |
-} |
- |
-/** |
- * Complete all pending measurement futures evaluating them in a single batch |
+ * Run all pending measurement frames evaluating them in a single batch |
* so that the the browser is guaranteed to avoid multiple layouts. |
*/ |
-void _completeMeasurementFutures() { |
- if (_nextMeasurementFrameScheduled == false) { |
+void _runMeasurementFrames() { |
+ if (_nextMeasurementFrameScheduled == false || _inMeasurementFrame) { |
// Ignore spurious call to this function. |
return; |
} |
- _nextMeasurementFrameScheduled = false; |
- // We must compute all new values before fulfilling the futures as |
- // the onComplete callbacks for the futures could modify the DOM making |
- // subsequent measurement calculations expensive to compute. |
- if (_pendingRequests !== null) { |
- for (_MeasurementRequest request in _pendingRequests) { |
- try { |
- request.value = request.computeValue(); |
- } catch(var e) { |
- request.value = e; |
- request.exception = true; |
- } |
- } |
- } |
+ _inMeasurementFrame = true; |
- final completedRequests = _pendingRequests; |
- final readyMeasurementFrameCallbacks = _pendingMeasurementFrameCallbacks; |
- _pendingRequests = null; |
- _pendingMeasurementFrameCallbacks = null; |
- if (completedRequests !== null) { |
- for (_MeasurementRequest request in completedRequests) { |
- if (request.exception) { |
- request.completer.completeException(request.value); |
- } else { |
- request.completer.complete(request.value); |
+ final layoutCallbacks = <LayoutCallback>[]; |
+ while (!_pendingMeasurementFrameCallbacks.isEmpty()) { |
+ MeasurementCallback measurementCallback = |
+ _pendingMeasurementFrameCallbacks.removeFirst(); |
+ try { |
+ final layoutCallback = measurementCallback(); |
+ if (layoutCallback != null) { |
+ layoutCallbacks.add(layoutCallback); |
} |
+ } catch (Object e) { |
+ window.console.error( |
+ 'Caught exception in measurement frame callback: ${e}'); |
+ // TODO(jacobr): throw this exception again in the correct way. |
} |
} |
- if (readyMeasurementFrameCallbacks !== null) { |
- for (TimeoutHandler handler in readyMeasurementFrameCallbacks) { |
- // TODO(jacobr): wrap each call to a handler in a try-catch block. |
- handler(); |
+ _inMeasurementFrame = false; |
+ _nextMeasurementFrameScheduled = false; |
+ |
+ for (LayoutCallback layoutCallback in layoutCallbacks) { |
+ try { |
+ layoutCallback(); |
+ } catch (Object e) { |
+ window.console.error('Caught exception in layout callback: ${e}'); |
+ // TODO(jacobr): throw this exception again in the correct way. |
} |
} |
} |