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| 1 // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file | |
| 2 // for details. All rights reserved. Use of this source code is governed by a | |
| 3 // BSD-style license that can be found in the LICENSE file. | |
| 4 | |
| 5 /// *Warning*: this library is **internal**, and APIs are subject to change. | |
| 6 /// | |
| 7 /// Tracks observable objects for dirty checking and testing purposes. | |
| 8 /// | |
| 9 /// It can collect all observed objects, which can be used to trigger | |
| 10 /// predictable delivery of all pending changes in a test, including objects | |
| 11 /// allocated internally to another library, such as those in | |
| 12 /// `package:template_binding`. | |
| 13 library observe.src.dirty_check; | |
| 14 | |
| 15 import 'dart:async'; | |
| 16 import 'package:logging/logging.dart'; | |
| 17 import 'package:observe/observe.dart' show Observable; | |
| 18 | |
| 19 /// The number of active observables in the system. | |
| 20 int get allObservablesCount => _allObservablesCount; | |
| 21 | |
| 22 int _allObservablesCount = 0; | |
| 23 | |
| 24 List<Observable> _allObservables = null; | |
| 25 | |
| 26 bool _delivering = false; | |
| 27 | |
| 28 void registerObservable(Observable obj) { | |
| 29 if (_allObservables == null) _allObservables = <Observable>[]; | |
| 30 _allObservables.add(obj); | |
| 31 _allObservablesCount++; | |
| 32 } | |
| 33 | |
| 34 /// Synchronously deliver all change records for known observables. | |
| 35 /// | |
| 36 /// This will execute [Observable.deliverChanges] on objects that inherit from | |
| 37 /// [Observable]. | |
| 38 // Note: this is called performMicrotaskCheckpoint in change_summary.js. | |
| 39 void dirtyCheckObservables() { | |
| 40 if (_delivering) return; | |
| 41 if (_allObservables == null) return; | |
| 42 | |
| 43 _delivering = true; | |
| 44 | |
| 45 int cycles = 0; | |
| 46 bool anyChanged = false; | |
| 47 List debugLoop = null; | |
| 48 do { | |
| 49 cycles++; | |
| 50 if (cycles == MAX_DIRTY_CHECK_CYCLES) { | |
| 51 debugLoop = []; | |
| 52 } | |
| 53 | |
| 54 var toCheck = _allObservables; | |
| 55 _allObservables = <Observable>[]; | |
| 56 anyChanged = false; | |
| 57 | |
| 58 for (int i = 0; i < toCheck.length; i++) { | |
| 59 final observer = toCheck[i]; | |
| 60 if (observer.hasObservers) { | |
| 61 if (observer.deliverChanges()) { | |
| 62 anyChanged = true; | |
| 63 if (debugLoop != null) debugLoop.add([i, observer]); | |
| 64 } | |
| 65 _allObservables.add(observer); | |
| 66 } | |
| 67 } | |
| 68 } while (cycles < MAX_DIRTY_CHECK_CYCLES && anyChanged); | |
| 69 | |
| 70 if (debugLoop != null && anyChanged) { | |
| 71 _logger.warning('Possible loop in Observable.dirtyCheck, stopped ' | |
| 72 'checking.'); | |
| 73 for (final info in debugLoop) { | |
| 74 _logger.warning('In last iteration Observable changed at index ' | |
| 75 '${info[0]}, object: ${info[1]}.'); | |
| 76 } | |
| 77 } | |
| 78 | |
| 79 _allObservablesCount = _allObservables.length; | |
| 80 _delivering = false; | |
| 81 } | |
| 82 | |
| 83 const MAX_DIRTY_CHECK_CYCLES = 1000; | |
| 84 | |
| 85 /// Log for messages produced at runtime by this library. Logging can be | |
| 86 /// configured by accessing Logger.root from the logging library. | |
| 87 final Logger _logger = new Logger('Observable.dirtyCheck'); | |
| 88 | |
| 89 /// Creates a [ZoneSpecification] to set up automatic dirty checking after each | |
| 90 /// batch of async operations. This ensures that change notifications are always | |
| 91 /// delivered. Typically used via [dirtyCheckZone]. | |
| 92 ZoneSpecification dirtyCheckZoneSpec() { | |
| 93 bool pending = false; | |
| 94 | |
| 95 enqueueDirtyCheck(ZoneDelegate parent, Zone zone) { | |
| 96 // Only schedule one dirty check per microtask. | |
| 97 if (pending) return; | |
| 98 | |
| 99 pending = true; | |
| 100 parent.scheduleMicrotask(zone, () { | |
| 101 pending = false; | |
| 102 Observable.dirtyCheck(); | |
| 103 }); | |
| 104 } | |
| 105 | |
| 106 wrapCallback(Zone self, ZoneDelegate parent, Zone zone, f()) { | |
| 107 // TODO(jmesserly): why does this happen? | |
| 108 if (f == null) return f; | |
| 109 return () { | |
| 110 enqueueDirtyCheck(parent, zone); | |
| 111 return f(); | |
| 112 }; | |
| 113 } | |
| 114 | |
| 115 wrapUnaryCallback(Zone self, ZoneDelegate parent, Zone zone, f(x)) { | |
| 116 // TODO(jmesserly): why does this happen? | |
| 117 if (f == null) return f; | |
| 118 return (x) { | |
| 119 enqueueDirtyCheck(parent, zone); | |
| 120 return f(x); | |
| 121 }; | |
| 122 } | |
| 123 | |
| 124 return new ZoneSpecification( | |
| 125 registerCallback: wrapCallback, | |
| 126 registerUnaryCallback: wrapUnaryCallback); | |
| 127 } | |
| 128 | |
| 129 /// Forks a [Zone] off the current one that does dirty-checking automatically | |
| 130 /// after each batch of async operations. Equivalent to: | |
| 131 /// | |
| 132 /// Zone.current.fork(specification: dirtyCheckZoneSpec()); | |
| 133 Zone dirtyCheckZone() => Zone.current.fork(specification: dirtyCheckZoneSpec()); | |
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Chromium Code Reviews
Issue 817483003:
delete observe from the repo (Closed)
Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart