Live image cache (#51485)
* Reland "Live image cache" (#51441)
This reverts commit 419a2853a8e4ac846524afeb49b866d4cdaa7d9d.
* Make evict safer
diff --git a/dev/tracing_tests/test/image_cache_tracing_test.dart b/dev/tracing_tests/test/image_cache_tracing_test.dart
index e4d786d..6eac376 100644
--- a/dev/tracing_tests/test/image_cache_tracing_test.dart
+++ b/dev/tracing_tests/test/image_cache_tracing_test.dart
@@ -20,7 +20,7 @@
final developer.ServiceProtocolInfo info = await developer.Service.getInfo();
if (info.serverUri == null) {
- throw TestFailure('This test _must_ be run with --enable-vmservice.');
+ fail('This test _must_ be run with --enable-vmservice.');
}
await timelineObtainer.connect(info.serverUri);
await timelineObtainer.setDartFlags();
@@ -58,7 +58,8 @@
'name': 'ImageCache.clear',
'args': <String, dynamic>{
'pendingImages': 1,
- 'cachedImages': 0,
+ 'keepAliveImages': 0,
+ 'liveImages': 1,
'currentSizeInBytes': 0,
'isolateId': isolateId,
}
@@ -149,7 +150,7 @@
Future<void> close() async {
expect(_completers, isEmpty);
- await _observatorySocket.close();
+ await _observatorySocket?.close();
}
}
diff --git a/packages/flutter/lib/src/painting/binding.dart b/packages/flutter/lib/src/painting/binding.dart
index cbdb882..d5f00a9 100644
--- a/packages/flutter/lib/src/painting/binding.dart
+++ b/packages/flutter/lib/src/painting/binding.dart
@@ -96,6 +96,7 @@
void evict(String asset) {
super.evict(asset);
imageCache.clear();
+ imageCache.clearLiveImages();
}
/// Listenable that notifies when the available fonts on the system have
diff --git a/packages/flutter/lib/src/painting/image_cache.dart b/packages/flutter/lib/src/painting/image_cache.dart
index 63034db..44e0268 100644
--- a/packages/flutter/lib/src/painting/image_cache.dart
+++ b/packages/flutter/lib/src/painting/image_cache.dart
@@ -3,6 +3,7 @@
// found in the LICENSE file.
import 'dart:developer';
+import 'dart:ui' show hashValues;
import 'package:flutter/foundation.dart';
@@ -15,18 +16,24 @@
///
/// Implements a least-recently-used cache of up to 1000 images, and up to 100
/// MB. The maximum size can be adjusted using [maximumSize] and
-/// [maximumSizeBytes]. Images that are actively in use (i.e. to which the
-/// application is holding references, either via [ImageStream] objects,
-/// [ImageStreamCompleter] objects, [ImageInfo] objects, or raw [dart:ui.Image]
-/// objects) may get evicted from the cache (and thus need to be refetched from
-/// the network if they are referenced in the [putIfAbsent] method), but the raw
-/// bits are kept in memory for as long as the application is using them.
+/// [maximumSizeBytes].
+///
+/// The cache also holds a list of "live" references. An image is considered
+/// live if its [ImageStreamCompleter]'s listener count has never dropped to
+/// zero after adding at least one listener. The cache uses
+/// [ImageStreamCompleter.addOnLastListenerRemovedCallback] to determine when
+/// this has happened.
///
/// The [putIfAbsent] method is the main entry-point to the cache API. It
/// returns the previously cached [ImageStreamCompleter] for the given key, if
/// available; if not, it calls the given callback to obtain it first. In either
/// case, the key is moved to the "most recently used" position.
///
+/// A caller can determine whether an image is already in the cache by using
+/// [containsKey], which will return true if the image is tracked by the cache
+/// in a pending or compelted state. More fine grained information is available
+/// by using the [statusForKey] method.
+///
/// Generally this class is not used directly. The [ImageProvider] class and its
/// subclasses automatically handle the caching of images.
///
@@ -71,6 +78,11 @@
class ImageCache {
final Map<Object, _PendingImage> _pendingImages = <Object, _PendingImage>{};
final Map<Object, _CachedImage> _cache = <Object, _CachedImage>{};
+ /// ImageStreamCompleters with at least one listener. These images may or may
+ /// not fit into the _pendingImages or _cache objects.
+ ///
+ /// Unlike _cache, the [_CachedImage] for this may have a null byte size.
+ final Map<Object, _CachedImage> _liveImages = <Object, _CachedImage>{};
/// Maximum number of entries to store in the cache.
///
@@ -150,20 +162,27 @@
int get currentSizeBytes => _currentSizeBytes;
int _currentSizeBytes = 0;
- /// Evicts all entries from the cache.
+ /// Evicts all pending and keepAlive entries from the cache.
///
/// This is useful if, for instance, the root asset bundle has been updated
/// and therefore new images must be obtained.
///
/// Images which have not finished loading yet will not be removed from the
/// cache, and when they complete they will be inserted as normal.
+ ///
+ /// This method does not clear live references to images, since clearing those
+ /// would not reduce memory pressure. Such images still have listeners in the
+ /// application code, and will still remain resident in memory.
+ ///
+ /// To clear live references, use [clearLiveImages].
void clear() {
if (!kReleaseMode) {
Timeline.instantSync(
'ImageCache.clear',
arguments: <String, dynamic>{
'pendingImages': _pendingImages.length,
- 'cachedImages': _cache.length,
+ 'keepAliveImages': _cache.length,
+ 'liveImages': _liveImages.length,
'currentSizeInBytes': _currentSizeBytes,
},
);
@@ -174,11 +193,23 @@
}
/// Evicts a single entry from the cache, returning true if successful.
- /// Pending images waiting for completion are removed as well, returning true
- /// if successful.
///
- /// When a pending image is removed the listener on it is removed as well to
- /// prevent it from adding itself to the cache if it eventually completes.
+ /// Pending images waiting for completion are removed as well, returning true
+ /// if successful. When a pending image is removed the listener on it is
+ /// removed as well to prevent it from adding itself to the cache if it
+ /// eventually completes.
+ ///
+ /// If this method removes a pending image, it will also remove
+ /// the corresponding live tracking of the image, since it is no longer clear
+ /// if the image will ever complete or have any listeners, and failing to
+ /// remove the live reference could leave the cache in a state where all
+ /// subsequent calls to [putIfAbsent] will return an [ImageStreamCompleter]
+ /// that will never complete.
+ ///
+ /// If this method removes a completed image, it will _not_ remove the live
+ /// reference to the image, which will only be cleared when the listener
+ /// count on the completer drops to zero. To clear live image references,
+ /// whether completed or not, use [clearLiveImages].
///
/// The `key` must be equal to an object used to cache an image in
/// [ImageCache.putIfAbsent].
@@ -186,10 +217,28 @@
/// If the key is not immediately available, as is common, consider using
/// [ImageProvider.evict] to call this method indirectly instead.
///
+ /// The `includeLive` argument determines whether images that still have
+ /// listeners in the tree should be evicted as well. This parameter should be
+ /// set to true in cases where the image may be corrupted and needs to be
+ /// completely discarded by the cache. It should be set to false when calls
+ /// to evict are trying to relieve memory pressure, since an image with a
+ /// listener will not actually be evicted from memory, and subsequent attempts
+ /// to load it will end up allocating more memory for the image again. The
+ /// argument must not be null.
+ ///
/// See also:
///
/// * [ImageProvider], for providing images to the [Image] widget.
- bool evict(Object key) {
+ bool evict(Object key, { bool includeLive = true }) {
+ assert(includeLive != null);
+ if (includeLive) {
+ // Remove from live images - the cache will not be able to mark
+ // it as complete, and it might be getting evicted because it
+ // will never complete, e.g. it was loaded in a FakeAsync zone.
+ // In such a case, we need to make sure subsequent calls to
+ // putIfAbsent don't return this image that may never complete.
+ _liveImages.remove(key);
+ }
final _PendingImage pendingImage = _pendingImages.remove(key);
if (pendingImage != null) {
if (!kReleaseMode) {
@@ -204,7 +253,7 @@
if (image != null) {
if (!kReleaseMode) {
Timeline.instantSync('ImageCache.evict', arguments: <String, dynamic>{
- 'type': 'completed',
+ 'type': 'keepAlive',
'sizeiInBytes': image.sizeBytes,
});
}
@@ -219,6 +268,37 @@
return false;
}
+ /// Updates the least recently used image cache with this image, if it is
+ /// less than the [maximumSizeBytes] of this cache.
+ ///
+ /// Resizes the cache as appropriate to maintain the constraints of
+ /// [maximumSize] and [maximumSizeBytes].
+ void _touch(Object key, _CachedImage image, TimelineTask timelineTask) {
+ // TODO(dnfield): Some customers test in release mode with asserts enabled.
+ // This is bound to cause problems, b/150295238 is tracking that. For now,
+ // avoid this being a point of failure.
+ assert(kReleaseMode || timelineTask != null);
+ if (image.sizeBytes != null && image.sizeBytes <= maximumSizeBytes) {
+ _currentSizeBytes += image.sizeBytes;
+ _cache[key] = image;
+ _checkCacheSize(timelineTask);
+ }
+ }
+
+ void _trackLiveImage(Object key, _CachedImage image) {
+ // Avoid adding unnecessary callbacks to the completer.
+ _liveImages.putIfAbsent(key, () {
+ // Even if no callers to ImageProvider.resolve have listened to the stream,
+ // the cache is listening to the stream and will remove itself once the
+ // image completes to move it from pending to keepAlive.
+ // Even if the cache size is 0, we still add this listener.
+ image.completer.addOnLastListenerRemovedCallback(() {
+ _liveImages.remove(key);
+ });
+ return image;
+ });
+ }
+
/// Returns the previously cached [ImageStream] for the given key, if available;
/// if not, calls the given callback to obtain it first. In either case, the
/// key is moved to the "most recently used" position.
@@ -252,17 +332,32 @@
}
// Remove the provider from the list so that we can move it to the
// recently used position below.
+ // Don't use _touch here, which would trigger a check on cache size that is
+ // not needed since this is just moving an existing cache entry to the head.
final _CachedImage image = _cache.remove(key);
if (image != null) {
if (!kReleaseMode) {
- timelineTask.finish(arguments: <String, dynamic>{'result': 'completed'});
+ timelineTask.finish(arguments: <String, dynamic>{'result': 'keepAlive'});
}
+ // The image might have been keptAlive but had no listeners (so not live).
+ // Make sure the cache starts tracking it as live again.
+ _trackLiveImage(key, image);
_cache[key] = image;
return image.completer;
}
+ final _CachedImage liveImage = _liveImages[key];
+ if (liveImage != null) {
+ _touch(key, liveImage, timelineTask);
+ if (!kReleaseMode) {
+ timelineTask.finish(arguments: <String, dynamic>{'result': 'keepAlive'});
+ }
+ return liveImage.completer;
+ }
+
try {
result = loader();
+ _trackLiveImage(key, _CachedImage(result, null));
} catch (error, stackTrace) {
if (!kReleaseMode) {
timelineTask.finish(arguments: <String, dynamic>{
@@ -282,21 +377,37 @@
if (!kReleaseMode) {
listenerTask = TimelineTask(parent: timelineTask)..start('listener');
}
+ // If we're doing tracing, we need to make sure that we don't try to finish
+ // the trace entry multiple times if we get re-entrant calls from a multi-
+ // frame provider here.
bool listenedOnce = false;
+
+ // We shouldn't use the _pendingImages map if the cache is disabled, but we
+ // will have to listen to the image at least once so we don't leak it in
+ // the live image tracking.
+ // If the cache is disabled, this variable will be set.
+ _PendingImage untrackedPendingImage;
void listener(ImageInfo info, bool syncCall) {
// Images that fail to load don't contribute to cache size.
final int imageSize = info?.image == null ? 0 : info.image.height * info.image.width * 4;
+
final _CachedImage image = _CachedImage(result, imageSize);
- final _PendingImage pendingImage = _pendingImages.remove(key);
+ if (!_liveImages.containsKey(key)) {
+ assert(syncCall);
+ result.addOnLastListenerRemovedCallback(() {
+ _liveImages.remove(key);
+ });
+ }
+ _liveImages[key] = image;
+ final _PendingImage pendingImage = untrackedPendingImage ?? _pendingImages.remove(key);
if (pendingImage != null) {
pendingImage.removeListener();
}
-
- if (imageSize <= maximumSizeBytes) {
- _currentSizeBytes += imageSize;
- _cache[key] = image;
- _checkCacheSize(listenerTask);
+ // Only touch if the cache was enabled when resolve was initially called.
+ if (untrackedPendingImage == null) {
+ _touch(key, image, listenerTask);
}
+
if (!kReleaseMode && !listenedOnce) {
listenerTask.finish(arguments: <String, dynamic>{
'syncCall': syncCall,
@@ -309,20 +420,58 @@
}
listenedOnce = true;
}
+
+ final ImageStreamListener streamListener = ImageStreamListener(listener);
if (maximumSize > 0 && maximumSizeBytes > 0) {
- final ImageStreamListener streamListener = ImageStreamListener(listener);
_pendingImages[key] = _PendingImage(result, streamListener);
- // Listener is removed in [_PendingImage.removeListener].
- result.addListener(streamListener);
+ } else {
+ untrackedPendingImage = _PendingImage(result, streamListener);
}
+ // Listener is removed in [_PendingImage.removeListener].
+ result.addListener(streamListener);
+
return result;
}
+ /// The [ImageCacheStatus] information for the given `key`.
+ ImageCacheStatus statusForKey(Object key) {
+ return ImageCacheStatus._(
+ pending: _pendingImages.containsKey(key),
+ keepAlive: _cache.containsKey(key),
+ live: _liveImages.containsKey(key),
+ );
+ }
+
/// Returns whether this `key` has been previously added by [putIfAbsent].
bool containsKey(Object key) {
return _pendingImages[key] != null || _cache[key] != null;
}
+ /// The number of live images being held by the [ImageCache].
+ ///
+ /// Compare with [ImageCache.currentSize] for keepAlive images.
+ int get liveImageCount => _liveImages.length;
+
+ /// The number of images being tracked as pending in the [ImageCache].
+ ///
+ /// Compare with [ImageCache.currentSize] for keepAlive images.
+ int get pendingImageCount => _pendingImages.length;
+
+ /// Clears any live references to images in this cache.
+ ///
+ /// An image is considered live if its [ImageStreamCompleter] has never hit
+ /// zero listeners after adding at least one listener. The
+ /// [ImageStreamCompleter.addOnLastListenerRemovedCallback] is used to
+ /// determine when this has happened.
+ ///
+ /// This is called after a hot reload to evict any stale references to image
+ /// data for assets that have changed. Calling this method does not relieve
+ /// memory pressure, since the live image caching only tracks image instances
+ /// that are also being held by at least one other object.
+ void clearLiveImages() {
+ _liveImages.clear();
+ }
+
// Remove images from the cache until both the length and bytes are below
// maximum, or the cache is empty.
void _checkCacheSize(TimelineTask timelineTask) {
@@ -354,6 +503,76 @@
}
}
+/// Information about how the [ImageCache] is tracking an image.
+///
+/// A [pending] image is one that has not completed yet. It may also be tracked
+/// as [live] because something is listening to it.
+///
+/// A [keepAlive] image is being held in the cache, which uses Least Recently
+/// Used semantics to determine when to evict an image. These images are subject
+/// to eviction based on [ImageCache.maximumSizeBytes] and
+/// [ImageCache.maximumSize]. It may be [live], but not [pending].
+///
+/// A [live] image is being held until its [ImageStreamCompleter] has no more
+/// listeners. It may also be [pending] or [keepAlive].
+///
+/// An [untracked] image is not being cached.
+///
+/// To obtain an [ImageCacheStatus], use [ImageCache.statusForKey] or
+/// [ImageProvider.obtainCacheStatus].
+class ImageCacheStatus {
+ const ImageCacheStatus._({
+ this.pending = false,
+ this.keepAlive = false,
+ this.live = false,
+ }) : assert(!pending || !keepAlive);
+
+ /// An image that has been submitted to [ImageCache.putIfAbsent], but
+ /// not yet completed.
+ final bool pending;
+
+ /// An image that has been submitted to [ImageCache.putIfAbsent], has
+ /// completed, fits based on the sizing rules of the cache, and has not been
+ /// evicted.
+ ///
+ /// Such images will be kept alive even if [live] is false, as long
+ /// as they have not been evicted from the cache based on its sizing rules.
+ final bool keepAlive;
+
+ /// An image that has been submitted to [ImageCache.putIfAbsent] and has at
+ /// least one listener on its [ImageStreamCompleter].
+ ///
+ /// Such images may also be [keepAlive] if they fit in the cache based on its
+ /// sizing rules. They may also be [pending] if they have not yet resolved.
+ final bool live;
+
+ /// An image that is tracked in some way by the [ImageCache], whether
+ /// [pending], [keepAlive], or [live].
+ bool get tracked => pending || keepAlive || live;
+
+ /// An image that either has not been submitted to
+ /// [ImageCache.putIfAbsent] or has otherwise been evicted from the
+ /// [keepAlive] and [live] caches.
+ bool get untracked => !pending && !keepAlive && !live;
+
+ @override
+ bool operator ==(Object other) {
+ if (other.runtimeType != runtimeType) {
+ return false;
+ }
+ return other is ImageCacheStatus
+ && other.pending == pending
+ && other.keepAlive == keepAlive
+ && other.live == live;
+ }
+
+ @override
+ int get hashCode => hashValues(pending, keepAlive, live);
+
+ @override
+ String toString() => '${objectRuntimeType(this, 'ImageCacheStatus')}(pending: $pending, live: $live, keepAlive: $keepAlive)';
+}
+
class _CachedImage {
_CachedImage(this.completer, this.sizeBytes);
diff --git a/packages/flutter/lib/src/painting/image_provider.dart b/packages/flutter/lib/src/painting/image_provider.dart
index a0e65a0..87c29ff 100644
--- a/packages/flutter/lib/src/painting/image_provider.dart
+++ b/packages/flutter/lib/src/painting/image_provider.dart
@@ -17,6 +17,12 @@
import 'image_cache.dart';
import 'image_stream.dart';
+/// Signature for the callback taken by [_createErrorHandlerAndKey].
+typedef _KeyAndErrorHandlerCallback<T> = void Function(T key, ImageErrorListener handleError);
+
+/// Signature used for error handling by [_createErrorHandlerAndKey].
+typedef _AsyncKeyErrorHandler<T> = Future<void> Function(T key, dynamic exception, StackTrace stack);
+
/// Configuration information passed to the [ImageProvider.resolve] method to
/// select a specific image.
///
@@ -318,7 +324,28 @@
final ImageStream stream = createStream(configuration);
// Load the key (potentially asynchronously), set up an error handling zone,
// and call resolveStreamForKey.
- _createErrorHandlerAndKey(configuration, stream);
+ _createErrorHandlerAndKey(
+ configuration,
+ (T key, ImageErrorListener errorHandler) {
+ resolveStreamForKey(configuration, stream, key, errorHandler);
+ },
+ (T key, dynamic exception, StackTrace stack) async {
+ await null; // wait an event turn in case a listener has been added to the image stream.
+ final _ErrorImageCompleter imageCompleter = _ErrorImageCompleter();
+ stream.setCompleter(imageCompleter);
+ imageCompleter.setError(
+ exception: exception,
+ stack: stack,
+ context: ErrorDescription('while resolving an image'),
+ silent: true, // could be a network error or whatnot
+ informationCollector: () sync* {
+ yield DiagnosticsProperty<ImageProvider>('Image provider', this);
+ yield DiagnosticsProperty<ImageConfiguration>('Image configuration', configuration);
+ yield DiagnosticsProperty<T>('Image key', key, defaultValue: null);
+ },
+ );
+ },
+ );
return stream;
}
@@ -332,30 +359,66 @@
return ImageStream();
}
- void _createErrorHandlerAndKey(ImageConfiguration configuration, ImageStream stream) {
+ /// Returns the cache location for the key that this [ImageProvider] creates.
+ ///
+ /// The location may be [ImageCacheStatus.untracked], indicating that this
+ /// image provider's key is not available in the [ImageCache].
+ ///
+ /// The `cache` and `configuration` parameters must not be null. If the
+ /// `handleError` parameter is null, errors will be reported to
+ /// [FlutterError.onError], and the method will return null.
+ ///
+ /// A completed return value of null indicates that an error has occurred.
+ Future<ImageCacheStatus> obtainCacheStatus({
+ @required ImageConfiguration configuration,
+ ImageErrorListener handleError,
+ }) {
assert(configuration != null);
- assert(stream != null);
+ final Completer<ImageCacheStatus> completer = Completer<ImageCacheStatus>();
+ _createErrorHandlerAndKey(
+ configuration,
+ (T key, ImageErrorListener innerHandleError) {
+ completer.complete(PaintingBinding.instance.imageCache.statusForKey(key));
+ },
+ (T key, dynamic exception, StackTrace stack) async {
+ if (handleError != null) {
+ handleError(exception, stack);
+ } else {
+ FlutterError.onError(FlutterErrorDetails(
+ context: ErrorDescription('while checking the cache location of an image'),
+ informationCollector: () sync* {
+ yield DiagnosticsProperty<ImageProvider>('Image provider', this);
+ yield DiagnosticsProperty<ImageConfiguration>('Image configuration', configuration);
+ yield DiagnosticsProperty<T>('Image key', key, defaultValue: null);
+ },
+ exception: exception,
+ stack: stack,
+ ));
+ completer.complete(null);
+ }
+ },
+ );
+ return completer.future;
+ }
+
+ /// This method is used by both [resolve] and [obtainCacheStatus] to ensure
+ /// that errors thrown during key creation are handled whether synchronous or
+ /// asynchronous.
+ void _createErrorHandlerAndKey(
+ ImageConfiguration configuration,
+ _KeyAndErrorHandlerCallback<T> successCallback,
+ _AsyncKeyErrorHandler<T> errorCallback,
+ ) {
T obtainedKey;
bool didError = false;
Future<void> handleError(dynamic exception, StackTrace stack) async {
if (didError) {
return;
}
+ if (!didError) {
+ errorCallback(obtainedKey, exception, stack);
+ }
didError = true;
- await null; // wait an event turn in case a listener has been added to the image stream.
- final _ErrorImageCompleter imageCompleter = _ErrorImageCompleter();
- stream.setCompleter(imageCompleter);
- imageCompleter.setError(
- exception: exception,
- stack: stack,
- context: ErrorDescription('while resolving an image'),
- silent: true, // could be a network error or whatnot
- informationCollector: () sync* {
- yield DiagnosticsProperty<ImageProvider>('Image provider', this);
- yield DiagnosticsProperty<ImageConfiguration>('Image configuration', configuration);
- yield DiagnosticsProperty<T>('Image key', obtainedKey, defaultValue: null);
- },
- );
}
// If an error is added to a synchronous completer before a listener has been
@@ -384,7 +447,7 @@
key.then<void>((T key) {
obtainedKey = key;
try {
- resolveStreamForKey(configuration, stream, key, handleError);
+ successCallback(key, handleError);
} catch (error, stackTrace) {
handleError(error, stackTrace);
}
diff --git a/packages/flutter/lib/src/painting/image_stream.dart b/packages/flutter/lib/src/painting/image_stream.dart
index 7b5c263..5db8bac 100644
--- a/packages/flutter/lib/src/painting/image_stream.dart
+++ b/packages/flutter/lib/src/painting/image_stream.dart
@@ -203,6 +203,11 @@
///
/// ImageStream objects are backed by [ImageStreamCompleter] objects.
///
+/// The [ImageCache] will consider an image to be live until the listener count
+/// drops to zero after adding at least one listener. The
+/// [addOnLastListenerRemovedCallback] method is used for tracking this
+/// information.
+///
/// See also:
///
/// * [ImageProvider], which has an example that includes the use of an
@@ -392,6 +397,23 @@
break;
}
}
+ if (_listeners.isEmpty) {
+ for (final VoidCallback callback in _onLastListenerRemovedCallbacks) {
+ callback();
+ }
+ _onLastListenerRemovedCallbacks.clear();
+ }
+ }
+
+ final List<VoidCallback> _onLastListenerRemovedCallbacks = <VoidCallback>[];
+
+ /// Adds a callback to call when [removeListener] results in an empty
+ /// list of listeners.
+ ///
+ /// This callback will never fire if [removeListener] is never called.
+ void addOnLastListenerRemovedCallback(VoidCallback callback) {
+ assert(callback != null);
+ _onLastListenerRemovedCallbacks.add(callback);
}
/// Calls all the registered listeners to notify them of a new image.
diff --git a/packages/flutter/lib/src/widgets/image.dart b/packages/flutter/lib/src/widgets/image.dart
index f373af5..12a947e 100644
--- a/packages/flutter/lib/src/widgets/image.dart
+++ b/packages/flutter/lib/src/widgets/image.dart
@@ -8,6 +8,7 @@
import 'package:flutter/foundation.dart';
import 'package:flutter/painting.dart';
+import 'package:flutter/scheduler.dart';
import 'package:flutter/services.dart';
import 'package:flutter/semantics.dart';
@@ -65,7 +66,30 @@
/// If the image is later used by an [Image] or [BoxDecoration] or [FadeInImage],
/// it will probably be loaded faster. The consumer of the image does not need
/// to use the same [ImageProvider] instance. The [ImageCache] will find the image
-/// as long as both images share the same key.
+/// as long as both images share the same key, and the image is held by the
+/// cache.
+///
+/// The cache may refuse to hold the image if it is disabled, the image is too
+/// large, or some other criteria implemented by a custom [ImageCache]
+/// implementation.
+///
+/// The [ImageCache] holds a reference to all images passed to [putIfAbsent] as
+/// long as their [ImageStreamCompleter] has at least one listener. This method
+/// will wait until the end of the frame after its future completes before
+/// releasing its own listener. This gives callers a chance to listen to the
+/// stream if necessary. A caller can determine if the image ended up in the
+/// cache by calling [ImageProvider.obtainCacheStatus]. If it is only held as
+/// [ImageCacheStatus.live], and the caller wishes to keep the resolved
+/// image in memory, the caller should immediately call `provider.resolve` and
+/// add a listener to the returned [ImageStream]. The image will remain pinned
+/// in memory at least until the caller removes its listener from the stream,
+/// even if it would not otherwise fit into the cache.
+///
+/// Callers should be cautious about pinning large images or a large number of
+/// images in memory, as this can result in running out of memory and being
+/// killed by the operating system. The lower the avilable physical memory, the
+/// more susceptible callers will be to running into OOM issues. These issues
+/// manifest as immediate process death, sometimes with no other error messages.
///
/// The [BuildContext] and [Size] are used to select an image configuration
/// (see [createLocalImageConfiguration]).
@@ -91,7 +115,12 @@
if (!completer.isCompleted) {
completer.complete();
}
- stream.removeListener(listener);
+ // Give callers until at least the end of the frame to subscribe to the
+ // image stream.
+ // See ImageCache._liveImages
+ SchedulerBinding.instance.addPostFrameCallback((Duration timeStamp) {
+ stream.removeListener(listener);
+ });
},
onError: (dynamic exception, StackTrace stackTrace) {
if (!completer.isCompleted) {
diff --git a/packages/flutter/test/painting/binding_test.dart b/packages/flutter/test/painting/binding_test.dart
index 0c0e7dc..f216b1a 100644
--- a/packages/flutter/test/painting/binding_test.dart
+++ b/packages/flutter/test/painting/binding_test.dart
@@ -3,7 +3,10 @@
// found in the LICENSE file.
import 'dart:typed_data' show Uint8List;
+import 'dart:ui';
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter/painting.dart';
@@ -24,4 +27,88 @@
});
expect(binding.instantiateImageCodecCalledCount, 1);
});
+
+ test('evict clears live references', () async {
+ final TestPaintingBinding binding = TestPaintingBinding();
+ expect(binding.imageCache.clearCount, 0);
+ expect(binding.imageCache.liveClearCount, 0);
+
+ binding.evict('/path/to/asset.png');
+ expect(binding.imageCache.clearCount, 1);
+ expect(binding.imageCache.liveClearCount, 1);
+ });
}
+
+class TestBindingBase implements BindingBase {
+ @override
+ void initInstances() {}
+
+ @override
+ void initServiceExtensions() {}
+
+ @override
+ Future<void> lockEvents(Future<void> Function() callback) async {}
+
+ @override
+ bool get locked => throw UnimplementedError();
+
+ @override
+ Future<void> performReassemble() {
+ throw UnimplementedError();
+ }
+
+ @override
+ void postEvent(String eventKind, Map<String, dynamic> eventData) {}
+
+ @override
+ Future<void> reassembleApplication() {
+ throw UnimplementedError();
+ }
+
+ @override
+ void registerBoolServiceExtension({String name, AsyncValueGetter<bool> getter, AsyncValueSetter<bool> setter}) {}
+
+ @override
+ void registerNumericServiceExtension({String name, AsyncValueGetter<double> getter, AsyncValueSetter<double> setter}) {}
+
+ @override
+ void registerServiceExtension({String name, ServiceExtensionCallback callback}) {}
+
+ @override
+ void registerSignalServiceExtension({String name, AsyncCallback callback}) {}
+
+ @override
+ void registerStringServiceExtension({String name, AsyncValueGetter<String> getter, AsyncValueSetter<String> setter}) {}
+
+ @override
+ void unlocked() {}
+
+ @override
+ Window get window => throw UnimplementedError();
+}
+
+class TestPaintingBinding extends TestBindingBase with ServicesBinding, PaintingBinding {
+
+ @override
+ final FakeImageCache imageCache = FakeImageCache();
+
+ @override
+ ImageCache createImageCache() => imageCache;
+}
+
+class FakeImageCache extends ImageCache {
+ int clearCount = 0;
+ int liveClearCount = 0;
+
+ @override
+ void clear() {
+ clearCount += 1;
+ super.clear();
+ }
+
+ @override
+ void clearLiveImages() {
+ liveClearCount += 1;
+ super.clearLiveImages();
+ }
+}
\ No newline at end of file
diff --git a/packages/flutter/test/painting/image_cache_test.dart b/packages/flutter/test/painting/image_cache_test.dart
index 39f3a2a..39a9369 100644
--- a/packages/flutter/test/painting/image_cache_test.dart
+++ b/packages/flutter/test/painting/image_cache_test.dart
@@ -9,13 +9,14 @@
import 'mocks_for_image_cache.dart';
void main() {
- group(ImageCache, () {
+ group('ImageCache', () {
setUpAll(() {
TestRenderingFlutterBinding(); // initializes the imageCache
});
tearDown(() {
imageCache.clear();
+ imageCache.clearLiveImages();
imageCache.maximumSize = 1000;
imageCache.maximumSizeBytes = 10485760;
});
@@ -169,7 +170,14 @@
return completer1;
}) as TestImageStreamCompleter;
+ expect(imageCache.statusForKey(testImage).pending, true);
+ expect(imageCache.statusForKey(testImage).live, true);
imageCache.clear();
+ expect(imageCache.statusForKey(testImage).pending, false);
+ expect(imageCache.statusForKey(testImage).live, true);
+ imageCache.clearLiveImages();
+ expect(imageCache.statusForKey(testImage).pending, false);
+ expect(imageCache.statusForKey(testImage).live, false);
final TestImageStreamCompleter resultingCompleter2 = imageCache.putIfAbsent(testImage, () {
return completer2;
@@ -240,7 +248,155 @@
expect(resultingCompleter1, completer1);
expect(imageCache.containsKey(testImage), true);
+ });
+ test('putIfAbsent updates LRU properties of a live image', () async {
+ imageCache.maximumSize = 1;
+ const TestImage testImage = TestImage(width: 8, height: 8);
+ const TestImage testImage2 = TestImage(width: 10, height: 10);
+
+ final TestImageStreamCompleter completer1 = TestImageStreamCompleter()..testSetImage(testImage);
+ final TestImageStreamCompleter completer2 = TestImageStreamCompleter()..testSetImage(testImage2);
+
+ completer1.addListener(ImageStreamListener((ImageInfo info, bool syncCall) {}));
+
+ final TestImageStreamCompleter resultingCompleter1 = imageCache.putIfAbsent(testImage, () {
+ return completer1;
+ }) as TestImageStreamCompleter;
+
+ expect(imageCache.statusForKey(testImage).pending, false);
+ expect(imageCache.statusForKey(testImage).keepAlive, true);
+ expect(imageCache.statusForKey(testImage).live, true);
+ expect(imageCache.statusForKey(testImage2).untracked, true);
+ final TestImageStreamCompleter resultingCompleter2 = imageCache.putIfAbsent(testImage2, () {
+ return completer2;
+ }) as TestImageStreamCompleter;
+
+
+ expect(imageCache.statusForKey(testImage).pending, false);
+ expect(imageCache.statusForKey(testImage).keepAlive, false); // evicted
+ expect(imageCache.statusForKey(testImage).live, true);
+ expect(imageCache.statusForKey(testImage2).pending, false);
+ expect(imageCache.statusForKey(testImage2).keepAlive, true); // took the LRU spot.
+ expect(imageCache.statusForKey(testImage2).live, false); // no listeners
+
+ expect(resultingCompleter1, completer1);
+ expect(resultingCompleter2, completer2);
+ });
+
+ test('Live image cache avoids leaks of unlistened streams', () async {
+ imageCache.maximumSize = 3;
+
+ const TestImageProvider(1, 1)..resolve(ImageConfiguration.empty);
+ const TestImageProvider(2, 2)..resolve(ImageConfiguration.empty);
+ const TestImageProvider(3, 3)..resolve(ImageConfiguration.empty);
+ const TestImageProvider(4, 4)..resolve(ImageConfiguration.empty);
+ const TestImageProvider(5, 5)..resolve(ImageConfiguration.empty);
+ const TestImageProvider(6, 6)..resolve(ImageConfiguration.empty);
+
+ // wait an event loop to let image resolution process.
+ await null;
+
+ expect(imageCache.currentSize, 3);
+ expect(imageCache.liveImageCount, 0);
+ });
+
+ test('Disabled image cache does not leak live images', () async {
+ imageCache.maximumSize = 0;
+
+ const TestImageProvider(1, 1)..resolve(ImageConfiguration.empty);
+ const TestImageProvider(2, 2)..resolve(ImageConfiguration.empty);
+ const TestImageProvider(3, 3)..resolve(ImageConfiguration.empty);
+ const TestImageProvider(4, 4)..resolve(ImageConfiguration.empty);
+ const TestImageProvider(5, 5)..resolve(ImageConfiguration.empty);
+ const TestImageProvider(6, 6)..resolve(ImageConfiguration.empty);
+
+ // wait an event loop to let image resolution process.
+ await null;
+
+ expect(imageCache.currentSize, 0);
+ expect(imageCache.liveImageCount, 0);
+ });
+
+ test('Evicting a pending image clears the live image by default', () async {
+ const TestImage testImage = TestImage(width: 8, height: 8);
+
+ final TestImageStreamCompleter completer1 = TestImageStreamCompleter();
+
+ imageCache.putIfAbsent(testImage, () => completer1);
+ expect(imageCache.statusForKey(testImage).pending, true);
+ expect(imageCache.statusForKey(testImage).live, true);
+ expect(imageCache.statusForKey(testImage).keepAlive, false);
+
+ imageCache.evict(testImage);
+ expect(imageCache.statusForKey(testImage).untracked, true);
+ });
+
+ test('Evicting a pending image does clear the live image when includeLive is false and only cache listening', () async {
+ const TestImage testImage = TestImage(width: 8, height: 8);
+
+ final TestImageStreamCompleter completer1 = TestImageStreamCompleter();
+
+ imageCache.putIfAbsent(testImage, () => completer1);
+ expect(imageCache.statusForKey(testImage).pending, true);
+ expect(imageCache.statusForKey(testImage).live, true);
+ expect(imageCache.statusForKey(testImage).keepAlive, false);
+
+ imageCache.evict(testImage, includeLive: false);
+ expect(imageCache.statusForKey(testImage).pending, false);
+ expect(imageCache.statusForKey(testImage).live, false);
+ expect(imageCache.statusForKey(testImage).keepAlive, false);
+ });
+
+ test('Evicting a pending image does clear the live image when includeLive is false and some other listener', () async {
+ const TestImage testImage = TestImage(width: 8, height: 8);
+
+ final TestImageStreamCompleter completer1 = TestImageStreamCompleter();
+
+ imageCache.putIfAbsent(testImage, () => completer1);
+ expect(imageCache.statusForKey(testImage).pending, true);
+ expect(imageCache.statusForKey(testImage).live, true);
+ expect(imageCache.statusForKey(testImage).keepAlive, false);
+
+ completer1.addListener(ImageStreamListener((_, __) {}));
+ imageCache.evict(testImage, includeLive: false);
+ expect(imageCache.statusForKey(testImage).pending, false);
+ expect(imageCache.statusForKey(testImage).live, true);
+ expect(imageCache.statusForKey(testImage).keepAlive, false);
+ });
+
+ test('Evicting a completed image does clear the live image by default', () async {
+ const TestImage testImage = TestImage(width: 8, height: 8);
+
+ final TestImageStreamCompleter completer1 = TestImageStreamCompleter()
+ ..testSetImage(testImage)
+ ..addListener(ImageStreamListener((ImageInfo info, bool syncCall) {}));
+
+ imageCache.putIfAbsent(testImage, () => completer1);
+ expect(imageCache.statusForKey(testImage).pending, false);
+ expect(imageCache.statusForKey(testImage).live, true);
+ expect(imageCache.statusForKey(testImage).keepAlive, true);
+
+ imageCache.evict(testImage);
+ expect(imageCache.statusForKey(testImage).untracked, true);
+ });
+
+ test('Evicting a completed image does not clear the live image when includeLive is set to false', () async {
+ const TestImage testImage = TestImage(width: 8, height: 8);
+
+ final TestImageStreamCompleter completer1 = TestImageStreamCompleter()
+ ..testSetImage(testImage)
+ ..addListener(ImageStreamListener((ImageInfo info, bool syncCall) {}));
+
+ imageCache.putIfAbsent(testImage, () => completer1);
+ expect(imageCache.statusForKey(testImage).pending, false);
+ expect(imageCache.statusForKey(testImage).live, true);
+ expect(imageCache.statusForKey(testImage).keepAlive, true);
+
+ imageCache.evict(testImage, includeLive: false);
+ expect(imageCache.statusForKey(testImage).pending, false);
+ expect(imageCache.statusForKey(testImage).live, true);
+ expect(imageCache.statusForKey(testImage).keepAlive, false);
});
});
}
diff --git a/packages/flutter/test/painting/image_provider_test.dart b/packages/flutter/test/painting/image_provider_test.dart
index 148912c..47371be 100644
--- a/packages/flutter/test/painting/image_provider_test.dart
+++ b/packages/flutter/test/painting/image_provider_test.dart
@@ -36,6 +36,7 @@
tearDown(() {
FlutterError.onError = oldError;
PaintingBinding.instance.imageCache.clear();
+ PaintingBinding.instance.imageCache.clearLiveImages();
});
group('ImageProvider', () {
@@ -52,15 +53,18 @@
const ImageProvider provider = ExactAssetImage('does-not-exist');
final Object key = await provider.obtainKey(ImageConfiguration.empty);
- expect(imageCache.containsKey(provider), false);
+ expect(imageCache.statusForKey(provider).untracked, true);
+ expect(imageCache.pendingImageCount, 0);
provider.resolve(ImageConfiguration.empty);
- expect(imageCache.containsKey(key), true);
+ expect(imageCache.statusForKey(key).pending, true);
+ expect(imageCache.pendingImageCount, 1);
await error.future;
- expect(imageCache.containsKey(provider), false);
+ expect(imageCache.statusForKey(provider).untracked, true);
+ expect(imageCache.pendingImageCount, 0);
}, skip: isBrowser);
test('AssetImageProvider - evicts on null load', () async {
@@ -71,15 +75,18 @@
final ImageProvider provider = ExactAssetImage('does-not-exist', bundle: TestAssetBundle());
final Object key = await provider.obtainKey(ImageConfiguration.empty);
- expect(imageCache.containsKey(key), false);
+ expect(imageCache.statusForKey(provider).untracked, true);
+ expect(imageCache.pendingImageCount, 0);
provider.resolve(ImageConfiguration.empty);
- expect(imageCache.containsKey(key), true);
+ expect(imageCache.statusForKey(key).pending, true);
+ expect(imageCache.pendingImageCount, 1);
await error.future;
- expect(imageCache.containsKey(key), false);
+ expect(imageCache.statusForKey(provider).untracked, true);
+ expect(imageCache.pendingImageCount, 0);
}, skip: isBrowser);
test('ImageProvider can evict images', () async {
@@ -151,6 +158,17 @@
expect(await caughtError.future, true);
});
+ test('obtainKey errors will be caught - check location', () async {
+ final ImageProvider imageProvider = ObtainKeyErrorImageProvider();
+ final Completer<bool> caughtError = Completer<bool>();
+ FlutterError.onError = (FlutterErrorDetails details) {
+ caughtError.complete(true);
+ };
+ await imageProvider.obtainCacheStatus(configuration: ImageConfiguration.empty);
+
+ expect(await caughtError.future, true);
+ });
+
test('resolve sync errors will be caught', () async {
bool uncaught = false;
final Zone testZone = Zone.current.fork(specification: ZoneSpecification(
@@ -200,24 +218,26 @@
test('File image with empty file throws expected error and evicts from cache', () async {
final Completer<StateError> error = Completer<StateError>();
FlutterError.onError = (FlutterErrorDetails details) {
- print(details.exception);
error.complete(details.exception as StateError);
};
final MemoryFileSystem fs = MemoryFileSystem();
final File file = fs.file('/empty.png')..createSync(recursive: true);
final FileImage provider = FileImage(file);
- expect(imageCache.containsKey(provider), false);
+ expect(imageCache.statusForKey(provider).untracked, true);
+ expect(imageCache.pendingImageCount, 0);
provider.resolve(ImageConfiguration.empty);
- expect(imageCache.containsKey(provider), true);
+ expect(imageCache.statusForKey(provider).pending, true);
+ expect(imageCache.pendingImageCount, 1);
expect(await error.future, isStateError);
- expect(imageCache.containsKey(provider), false);
+ expect(imageCache.statusForKey(provider).untracked, true);
+ expect(imageCache.pendingImageCount, 0);
});
- group(NetworkImage, () {
+ group('NetworkImage', () {
MockHttpClient httpClient;
setUp(() {
@@ -242,11 +262,13 @@
final Completer<dynamic> caughtError = Completer<dynamic>();
final ImageProvider imageProvider = NetworkImage(nonconst(requestUrl));
- expect(imageCache.containsKey(imageProvider), false);
+ expect(imageCache.pendingImageCount, 0);
+ expect(imageCache.statusForKey(imageProvider).untracked, true);
final ImageStream result = imageProvider.resolve(ImageConfiguration.empty);
- expect(imageCache.containsKey(imageProvider), true);
+ expect(imageCache.pendingImageCount, 1);
+ expect(imageCache.statusForKey(imageProvider).pending, true);
result.addListener(ImageStreamListener((ImageInfo info, bool syncCall) {
}, onError: (dynamic error, StackTrace stackTrace) {
@@ -255,7 +277,8 @@
final dynamic err = await caughtError.future;
- expect(imageCache.containsKey(imageProvider), false);
+ expect(imageCache.pendingImageCount, 0);
+ expect(imageCache.statusForKey(imageProvider).untracked, true);
expect(
err,
diff --git a/packages/flutter/test/widgets/image_test.dart b/packages/flutter/test/widgets/image_test.dart
index cd4a342..6279d13 100644
--- a/packages/flutter/test/widgets/image_test.dart
+++ b/packages/flutter/test/widgets/image_test.dart
@@ -8,6 +8,7 @@
import 'package:flutter/foundation.dart';
import 'package:flutter/rendering.dart';
+import 'package:flutter/scheduler.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
@@ -23,6 +24,18 @@
}
void main() {
+ int originalCacheSize;
+
+ setUp(() {
+ originalCacheSize = imageCache.maximumSize;
+ imageCache.clear();
+ imageCache.clearLiveImages();
+ });
+
+ tearDown(() {
+ imageCache.maximumSize = originalCacheSize;
+ });
+
testWidgets('Verify Image resets its RenderImage when changing providers', (WidgetTester tester) async {
final GlobalKey key = GlobalKey();
final TestImageProvider imageProvider1 = TestImageProvider();
@@ -763,7 +776,7 @@
expect(isSync, isTrue);
});
- testWidgets('Precache remove listeners immediately after future completes, does not crash on successive calls #25143', (WidgetTester tester) async {
+ testWidgets('Precache removes original listener immediately after future completes, does not crash on successive calls #25143', (WidgetTester tester) async {
final TestImageStreamCompleter imageStreamCompleter = TestImageStreamCompleter();
final TestImageProvider provider = TestImageProvider(streamCompleter: imageStreamCompleter);
@@ -1364,6 +1377,197 @@
expect(imageProviders.skip(309 - 15).every(loadCalled), true);
expect(imageProviders.take(309 - 15).every(loadNotCalled), true);
});
+
+ testWidgets('Same image provider in multiple parts of the tree, no cache room left', (WidgetTester tester) async {
+ imageCache.maximumSize = 0;
+
+ final ui.Image image = await tester.runAsync(createTestImage);
+ final TestImageProvider provider1 = TestImageProvider();
+ final TestImageProvider provider2 = TestImageProvider();
+
+ expect(provider1.loadCallCount, 0);
+ expect(provider2.loadCallCount, 0);
+ expect(imageCache.liveImageCount, 0);
+
+ await tester.pumpWidget(Column(
+ children: <Widget>[
+ Image(image: provider1),
+ Image(image: provider2),
+ Image(image: provider1),
+ Image(image: provider1),
+ Image(image: provider2),
+ ],
+ ));
+
+ expect(imageCache.liveImageCount, 2);
+ expect(imageCache.statusForKey(provider1).live, true);
+ expect(imageCache.statusForKey(provider1).pending, false);
+ expect(imageCache.statusForKey(provider1).keepAlive, false);
+ expect(imageCache.statusForKey(provider2).live, true);
+ expect(imageCache.statusForKey(provider2).pending, false);
+ expect(imageCache.statusForKey(provider2).keepAlive, false);
+
+ expect(provider1.loadCallCount, 1);
+ expect(provider2.loadCallCount, 1);
+
+ provider1.complete(image);
+ await tester.idle();
+
+ provider2.complete(image);
+ await tester.idle();
+
+ expect(imageCache.liveImageCount, 2);
+ expect(imageCache.currentSize, 0);
+
+ await tester.pumpWidget(Image(image: provider2));
+ await tester.idle();
+ expect(imageCache.statusForKey(provider1).untracked, true);
+ expect(imageCache.statusForKey(provider2).live, true);
+ expect(imageCache.statusForKey(provider2).pending, false);
+ expect(imageCache.statusForKey(provider2).keepAlive, false);
+ expect(imageCache.liveImageCount, 1);
+
+ await tester.pumpWidget(const SizedBox());
+ await tester.idle();
+ expect(provider1.loadCallCount, 1);
+ expect(provider2.loadCallCount, 1);
+ expect(imageCache.liveImageCount, 0);
+ });
+
+ testWidgets('precacheImage does not hold weak ref for more than a frame', (WidgetTester tester) async {
+ imageCache.maximumSize = 0;
+ final TestImageProvider provider = TestImageProvider();
+ Future<void> precache;
+ await tester.pumpWidget(
+ Builder(
+ builder: (BuildContext context) {
+ precache = precacheImage(provider, context);
+ return Container();
+ }
+ )
+ );
+ provider.complete();
+ await precache;
+
+ // Should have ended up with only a weak ref, not in cache because cache size is 0
+ expect(imageCache.liveImageCount, 1);
+ expect(imageCache.containsKey(provider), false);
+
+ final ImageCacheStatus providerLocation = await provider.obtainCacheStatus(configuration: ImageConfiguration.empty);
+
+ expect(providerLocation, isNotNull);
+ expect(providerLocation.live, true);
+ expect(providerLocation.keepAlive, false);
+ expect(providerLocation.pending, false);
+
+ // Check that a second resolve of the same image is synchronous.
+ expect(provider._lastResolvedConfiguration, isNotNull);
+ final ImageStream stream = provider.resolve(provider._lastResolvedConfiguration);
+ bool isSync;
+ final ImageStreamListener listener = ImageStreamListener((ImageInfo image, bool syncCall) { isSync = syncCall; });
+
+ // Still have live ref because frame has not pumped yet.
+ await tester.pump();
+ expect(imageCache.liveImageCount, 1);
+
+ SchedulerBinding.instance.scheduleFrame();
+ await tester.pump();
+ // Live ref should be gone - we didn't listen to the stream.
+ expect(imageCache.liveImageCount, 0);
+ expect(imageCache.currentSize, 0);
+
+ stream.addListener(listener);
+ expect(isSync, true); // because the stream still has the image.
+
+ expect(imageCache.liveImageCount, 0);
+ expect(imageCache.currentSize, 0);
+
+ expect(provider.loadCallCount, 1);
+ });
+
+ testWidgets('precacheImage allows time to take over weak refernce', (WidgetTester tester) async {
+ final TestImageProvider provider = TestImageProvider();
+ Future<void> precache;
+ await tester.pumpWidget(
+ Builder(
+ builder: (BuildContext context) {
+ precache = precacheImage(provider, context);
+ return Container();
+ }
+ )
+ );
+ provider.complete();
+ await precache;
+
+ // Should have ended up in the cache and have a weak reference.
+ expect(imageCache.liveImageCount, 1);
+ expect(imageCache.currentSize, 1);
+ expect(imageCache.containsKey(provider), true);
+
+ // Check that a second resolve of the same image is synchronous.
+ expect(provider._lastResolvedConfiguration, isNotNull);
+ final ImageStream stream = provider.resolve(provider._lastResolvedConfiguration);
+ bool isSync;
+ final ImageStreamListener listener = ImageStreamListener((ImageInfo image, bool syncCall) { isSync = syncCall; });
+
+ // Should have ended up in the cache and still have a weak reference.
+ expect(imageCache.liveImageCount, 1);
+ expect(imageCache.currentSize, 1);
+ expect(imageCache.containsKey(provider), true);
+
+ stream.addListener(listener);
+ expect(isSync, true);
+
+ expect(imageCache.liveImageCount, 1);
+ expect(imageCache.currentSize, 1);
+ expect(imageCache.containsKey(provider), true);
+
+ SchedulerBinding.instance.scheduleFrame();
+ await tester.pump();
+
+ expect(imageCache.liveImageCount, 1);
+ expect(imageCache.currentSize, 1);
+ expect(imageCache.containsKey(provider), true);
+ stream.removeListener(listener);
+
+ expect(imageCache.liveImageCount, 0);
+ expect(imageCache.currentSize, 1);
+ expect(imageCache.containsKey(provider), true);
+ expect(provider.loadCallCount, 1);
+ });
+
+ testWidgets('evict an image during precache', (WidgetTester tester) async {
+ // This test checks that the live image tracking does not hold on to a
+ // pending image that will never complete because it has been evicted from
+ // the cache.
+ // The scenario may arise in a test harness that is trying to load real
+ // images using `tester.runAsync()`, and wants to make sure that widgets
+ // under test have not also tried to resolve the image in a FakeAsync zone.
+ // The image loaded in the FakeAsync zone will never complete, and the
+ // runAsync call wants to make sure it gets a load attempt from the correct
+ // zone.
+ final Uint8List bytes = Uint8List.fromList(kTransparentImage);
+ final MemoryImage provider = MemoryImage(bytes);
+
+ await tester.runAsync(() async {
+ final List<Future<void>> futures = <Future<void>>[];
+ await tester.pumpWidget(Builder(builder: (BuildContext context) {
+ futures.add(precacheImage(provider, context));
+ imageCache.evict(provider);
+ futures.add(precacheImage(provider, context));
+ return const SizedBox.expand();
+ }));
+ await Future.wait<void>(futures);
+ expect(imageCache.statusForKey(provider).keepAlive, true);
+ expect(imageCache.statusForKey(provider).live, true);
+
+ // Schedule a frame to get precacheImage to stop listening.
+ SchedulerBinding.instance.scheduleFrame();
+ await tester.pump();
+ expect(imageCache.statusForKey(provider).keepAlive, true);
+ expect(imageCache.statusForKey(provider).live, false);
+ });
+ });
}
class ConfigurationAwareKey {
@@ -1405,8 +1609,9 @@
ImageStreamCompleter _streamCompleter;
ImageConfiguration _lastResolvedConfiguration;
- bool get loadCalled => _loadCalled;
- bool _loadCalled = false;
+ bool get loadCalled => _loadCallCount > 0;
+ int get loadCallCount => _loadCallCount;
+ int _loadCallCount = 0;
@override
Future<Object> obtainKey(ImageConfiguration configuration) {
@@ -1421,12 +1626,13 @@
@override
ImageStreamCompleter load(Object key, DecoderCallback decode) {
- _loadCalled = true;
+ _loadCallCount += 1;
return _streamCompleter;
}
- void complete() {
- _completer.complete(ImageInfo(image: TestImage()));
+ void complete([ui.Image image]) {
+ image ??= TestImage();
+ _completer.complete(ImageInfo(image: image));
}
void fail(dynamic exception, StackTrace stackTrace) {
