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Fix an issue that clearing the image cache may cause resource leaks (#104527)

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This commit is contained in:
Yang Chao 2022-05-25 07:58:09 +08:00 committed by GitHub
parent a56c5e51ae
commit b5adbee145
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 38 additions and 12 deletions
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23
packages/flutter/lib/src/painting/image_cache.dart
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@ -397,16 +397,16 @@ class ImageCache {
if (!kReleaseMode) { if (!kReleaseMode) {
listenerTask = TimelineTask(parent: timelineTask)..start('listener'); listenerTask = TimelineTask(parent: timelineTask)..start('listener');
} }
// If we're doing tracing, we need to make sure that we don't try to finish // A multi-frame provider may call the listener more than once. We need do make
// the trace entry multiple times if we get re-entrant calls from a multi- // sure that some cleanup works won't run multiple times, such as finishing the
// frame provider here. // tracing task or removing the listeners
bool listenedOnce = false; bool listenedOnce = false;
// We shouldn't use the _pendingImages map if the cache is disabled, but we // 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 // will have to listen to the image at least once so we don't leak it in
// the live image tracking. // the live image tracking.
// If the cache is disabled, this variable will be set. final bool trackPendingImage = maximumSize > 0 && maximumSizeBytes > 0;
_PendingImage? untrackedPendingImage; late _PendingImage pendingImage;
void listener(ImageInfo? info, bool syncCall) { void listener(ImageInfo? info, bool syncCall) {
int? sizeBytes; int? sizeBytes;
if (info != null) { if (info != null) {
@ -421,14 +421,14 @@ class ImageCache {
_trackLiveImage(key, result, sizeBytes); _trackLiveImage(key, result, sizeBytes);
// Only touch if the cache was enabled when resolve was initially called. // Only touch if the cache was enabled when resolve was initially called.
if (untrackedPendingImage == null) { if (trackPendingImage) {
_touch(key, image, listenerTask); _touch(key, image, listenerTask);
} else { } else {
image.dispose(); image.dispose();
} }
final _PendingImage? pendingImage = untrackedPendingImage ?? _pendingImages.remove(key); _pendingImages.remove(key);
if (pendingImage != null) { if (!listenedOnce) {
pendingImage.removeListener(); pendingImage.removeListener();
} }
if (!kReleaseMode && !listenedOnce) { if (!kReleaseMode && !listenedOnce) {
@ -445,10 +445,9 @@ class ImageCache {
} }
final ImageStreamListener streamListener = ImageStreamListener(listener); final ImageStreamListener streamListener = ImageStreamListener(listener);
if (maximumSize > 0 && maximumSizeBytes > 0) { pendingImage = _PendingImage(result, streamListener);
_pendingImages[key] = _PendingImage(result, streamListener); if (trackPendingImage) {
} else { _pendingImages[key] = pendingImage;
untrackedPendingImage = _PendingImage(result, streamListener);
} }
// Listener is removed in [_PendingImage.removeListener]. // Listener is removed in [_PendingImage.removeListener].
result.addListener(streamListener); result.addListener(streamListener);

27
packages/flutter/test/painting/image_cache_test.dart
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@ -332,6 +332,33 @@ void main() {
expect(imageCache.liveImageCount, 0); expect(imageCache.liveImageCount, 0);
}); });
test('Clearing image cache does not leak live images', () async {
imageCache.maximumSize = 1;
final ui.Image testImage1 = await createTestImage(width: 8, height: 8);
final ui.Image testImage2 = await createTestImage(width: 10, height: 10);
final TestImageStreamCompleter completer1 = TestImageStreamCompleter();
final TestImageStreamCompleter completer2 = TestImageStreamCompleter()..testSetImage(testImage2);
imageCache.putIfAbsent(testImage1, () => completer1);
expect(imageCache.statusForKey(testImage1).pending, true);
expect(imageCache.statusForKey(testImage1).live, true);
imageCache.clear();
expect(imageCache.statusForKey(testImage1).pending, false);
expect(imageCache.statusForKey(testImage1).live, true);
completer1.testSetImage(testImage1);
expect(imageCache.statusForKey(testImage1).keepAlive, true);
expect(imageCache.statusForKey(testImage1).live, false);
imageCache.putIfAbsent(testImage2, () => completer2);
expect(imageCache.statusForKey(testImage1).tracked, false); // evicted
expect(imageCache.statusForKey(testImage2).tracked, true);
});
test('Evicting a pending image clears the live image by default', () async { test('Evicting a pending image clears the live image by default', () async {
final ui.Image testImage = await createTestImage(width: 8, height: 8); final ui.Image testImage = await createTestImage(width: 8, height: 8);