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fix infinite loop in findMinimumFontsForCodeunits (flutter/engine#24441)

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Yegor 2021-02-16 14:38:03 -08:00 committed by GitHub
parent adbe5b3cd7
commit 04067ddd57
4 changed files with 210 additions and 53 deletions
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111
engine/src/flutter/lib/web_ui/lib/src/engine/canvaskit/font_fallbacks.dart
View File

@ -12,7 +12,7 @@ bool _registeredSymbolsAndEmoji = false;
final Set<int> codeUnitsWithNoKnownFont = <int>{};
Future<void> _findFontsForMissingCodeunits(List<int> codeunits) async {
Future<void> findFontsForMissingCodeunits(List<int> codeunits) async {
_ensureNotoFontTreeCreated();
// If all of the code units are known to have no Noto Font which covers them,
@ -20,11 +20,11 @@ Future<void> _findFontsForMissingCodeunits(List<int> codeunits) async {
if (codeunits.every((u) => codeUnitsWithNoKnownFont.contains(u))) {
return;
}
Set<_NotoFont> fonts = <_NotoFont>{};
Set<NotoFont> fonts = <NotoFont>{};
Set<int> coveredCodeUnits = <int>{};
Set<int> missingCodeUnits = <int>{};
for (int codeunit in codeunits) {
List<_NotoFont> fontsForUnit = _notoTree!.intersections(codeunit);
List<NotoFont> fontsForUnit = _notoTree!.intersections(codeunit);
fonts.addAll(fontsForUnit);
if (fontsForUnit.isNotEmpty) {
coveredCodeUnits.add(codeunit);
@ -33,15 +33,15 @@ Future<void> _findFontsForMissingCodeunits(List<int> codeunits) async {
}
}
fonts = _findMinimumFontsForCodeunits(coveredCodeUnits, fonts);
fonts = findMinimumFontsForCodeunits(coveredCodeUnits, fonts);
for (_NotoFont font in fonts) {
for (NotoFont font in fonts) {
await font.ensureResolved();
}
Set<_ResolvedNotoSubset> resolvedFonts = <_ResolvedNotoSubset>{};
for (int codeunit in coveredCodeUnits) {
for (_NotoFont font in fonts) {
for (NotoFont font in fonts) {
if (font.resolvedFont == null) {
// We failed to resolve the font earlier.
continue;
@ -232,18 +232,20 @@ Future<void> _registerSymbolsAndEmoji() async {
/// which finds the font which covers the most codeunits. If multiple CJK
/// fonts match the same number of codeunits, we choose one based on the user's
/// locale.
Set<_NotoFont> _findMinimumFontsForCodeunits(
Iterable<int> codeunits, Set<_NotoFont> fonts) {
Set<NotoFont> findMinimumFontsForCodeunits(
Iterable<int> codeunits, Set<NotoFont> fonts) {
assert(fonts.isNotEmpty || codeunits.isEmpty);
List<int> unmatchedCodeunits = List<int>.from(codeunits);
Set<_NotoFont> minimumFonts = <_NotoFont>{};
List<_NotoFont> bestFonts = <_NotoFont>[];
int maxCodeunitsCovered = 0;
Set<NotoFont> minimumFonts = <NotoFont>{};
List<NotoFont> bestFonts = <NotoFont>[];
String language = html.window.navigator.language;
// This is guaranteed to terminate because [codeunits] is a list of fonts
// which we've already determined are covered by [fonts].
while (unmatchedCodeunits.isNotEmpty) {
int maxCodeunitsCovered = 0;
bestFonts.clear();
for (var font in fonts) {
int codeunitsCovered = 0;
for (int codeunit in unmatchedCodeunits) {
@ -259,10 +261,13 @@ Set<_NotoFont> _findMinimumFontsForCodeunits(
bestFonts.add(font);
}
}
assert(bestFonts.isNotEmpty);
assert(
bestFonts.isNotEmpty,
'Did not find any fonts that cover code units: ${unmatchedCodeunits.join(', ')}',
);
// If the list of best fonts are all CJK fonts, choose the best one based
// on locale. Otherwise just choose the first font.
_NotoFont bestFont = bestFonts.first;
NotoFont bestFont = bestFonts.first;
if (bestFonts.length > 1) {
if (bestFonts.every((font) => _cjkFonts.contains(font))) {
if (language == 'zh-Hans' ||
@ -301,19 +306,19 @@ void _ensureNotoFontTreeCreated() {
return;
}
Map<_NotoFont, List<CodeunitRange>> ranges =
<_NotoFont, List<CodeunitRange>>{};
Map<NotoFont, List<CodeunitRange>> ranges =
<NotoFont, List<CodeunitRange>>{};
for (_NotoFont font in _notoFonts) {
for (NotoFont font in _notoFonts) {
for (CodeunitRange range in font.unicodeRanges) {
ranges.putIfAbsent(font, () => <CodeunitRange>[]).add(range);
}
}
_notoTree = IntervalTree<_NotoFont>.createFromRanges(ranges);
_notoTree = IntervalTree<NotoFont>.createFromRanges(ranges);
}
class _NotoFont {
class NotoFont {
final String name;
final List<CodeunitRange> unicodeRanges;
@ -321,7 +326,7 @@ class _NotoFont {
_ResolvedNotoFont? resolvedFont;
_NotoFont(this.name, this.unicodeRanges);
NotoFont(this.name, this.unicodeRanges);
bool matchesCodeunit(int codeunit) {
for (CodeunitRange range in unicodeRanges) {
@ -397,7 +402,7 @@ class _ResolvedNotoSubset {
String toString() => '_ResolvedNotoSubset($family, $url)';
}
_NotoFont _notoSansSC = _NotoFont('Noto Sans SC', <CodeunitRange>[
NotoFont _notoSansSC = NotoFont('Noto Sans SC', <CodeunitRange>[
CodeunitRange(12288, 12591),
CodeunitRange(12800, 13311),
CodeunitRange(19968, 40959),
@ -405,37 +410,37 @@ _NotoFont _notoSansSC = _NotoFont('Noto Sans SC', <CodeunitRange>[
CodeunitRange(65280, 65519),
]);
_NotoFont _notoSansTC = _NotoFont('Noto Sans TC', <CodeunitRange>[
NotoFont _notoSansTC = NotoFont('Noto Sans TC', <CodeunitRange>[
CodeunitRange(12288, 12351),
CodeunitRange(12549, 12585),
CodeunitRange(19968, 40959),
]);
_NotoFont _notoSansHK = _NotoFont('Noto Sans HK', <CodeunitRange>[
NotoFont _notoSansHK = NotoFont('Noto Sans HK', <CodeunitRange>[
CodeunitRange(12288, 12351),
CodeunitRange(12549, 12585),
CodeunitRange(19968, 40959),
]);
_NotoFont _notoSansJP = _NotoFont('Noto Sans JP', <CodeunitRange>[
NotoFont _notoSansJP = NotoFont('Noto Sans JP', <CodeunitRange>[
CodeunitRange(12288, 12543),
CodeunitRange(19968, 40959),
CodeunitRange(65280, 65519),
]);
List<_NotoFont> _cjkFonts = <_NotoFont>[
List<NotoFont> _cjkFonts = <NotoFont>[
_notoSansSC,
_notoSansTC,
_notoSansHK,
_notoSansJP,
];
List<_NotoFont> _notoFonts = <_NotoFont>[
List<NotoFont> _notoFonts = <NotoFont>[
_notoSansSC,
_notoSansTC,
_notoSansHK,
_notoSansJP,
_NotoFont('Noto Naskh Arabic UI', <CodeunitRange>[
NotoFont('Noto Naskh Arabic UI', <CodeunitRange>[
CodeunitRange(1536, 1791),
CodeunitRange(8204, 8206),
CodeunitRange(8208, 8209),
@ -444,36 +449,36 @@ List<_NotoFont> _notoFonts = <_NotoFont>[
CodeunitRange(64336, 65023),
CodeunitRange(65132, 65276),
]),
_NotoFont('Noto Sans Armenian', <CodeunitRange>[
NotoFont('Noto Sans Armenian', <CodeunitRange>[
CodeunitRange(1328, 1424),
CodeunitRange(64275, 64279),
]),
_NotoFont('Noto Sans Bengali UI', <CodeunitRange>[
NotoFont('Noto Sans Bengali UI', <CodeunitRange>[
CodeunitRange(2404, 2405),
CodeunitRange(2433, 2555),
CodeunitRange(8204, 8205),
CodeunitRange(8377, 8377),
CodeunitRange(9676, 9676),
]),
_NotoFont('Noto Sans Myanmar UI', <CodeunitRange>[
NotoFont('Noto Sans Myanmar UI', <CodeunitRange>[
CodeunitRange(4096, 4255),
CodeunitRange(8204, 8205),
CodeunitRange(9676, 9676),
]),
_NotoFont('Noto Sans Egyptian Hieroglyphs', <CodeunitRange>[
NotoFont('Noto Sans Egyptian Hieroglyphs', <CodeunitRange>[
CodeunitRange(77824, 78894),
]),
_NotoFont('Noto Sans Ethiopic', <CodeunitRange>[
NotoFont('Noto Sans Ethiopic', <CodeunitRange>[
CodeunitRange(4608, 5017),
CodeunitRange(11648, 11742),
CodeunitRange(43777, 43822),
]),
_NotoFont('Noto Sans Georgian', <CodeunitRange>[
NotoFont('Noto Sans Georgian', <CodeunitRange>[
CodeunitRange(1417, 1417),
CodeunitRange(4256, 4351),
CodeunitRange(11520, 11567),
]),
_NotoFont('Noto Sans Gujarati UI', <CodeunitRange>[
NotoFont('Noto Sans Gujarati UI', <CodeunitRange>[
CodeunitRange(2404, 2405),
CodeunitRange(2688, 2815),
CodeunitRange(8204, 8205),
@ -481,7 +486,7 @@ List<_NotoFont> _notoFonts = <_NotoFont>[
CodeunitRange(9676, 9676),
CodeunitRange(43056, 43065),
]),
_NotoFont('Noto Sans Gurmukhi UI', <CodeunitRange>[
NotoFont('Noto Sans Gurmukhi UI', <CodeunitRange>[
CodeunitRange(2404, 2405),
CodeunitRange(2561, 2677),
CodeunitRange(8204, 8205),
@ -490,13 +495,13 @@ List<_NotoFont> _notoFonts = <_NotoFont>[
CodeunitRange(9772, 9772),
CodeunitRange(43056, 43065),
]),
_NotoFont('Noto Sans Hebrew', <CodeunitRange>[
NotoFont('Noto Sans Hebrew', <CodeunitRange>[
CodeunitRange(1424, 1535),
CodeunitRange(8362, 8362),
CodeunitRange(9676, 9676),
CodeunitRange(64285, 64335),
]),
_NotoFont('Noto Sans Devanagari UI', <CodeunitRange>[
NotoFont('Noto Sans Devanagari UI', <CodeunitRange>[
CodeunitRange(2304, 2431),
CodeunitRange(7376, 7414),
CodeunitRange(7416, 7417),
@ -507,29 +512,29 @@ List<_NotoFont> _notoFonts = <_NotoFont>[
CodeunitRange(43056, 43065),
CodeunitRange(43232, 43259),
]),
_NotoFont('Noto Sans Kannada UI', <CodeunitRange>[
NotoFont('Noto Sans Kannada UI', <CodeunitRange>[
CodeunitRange(2404, 2405),
CodeunitRange(3202, 3314),
CodeunitRange(8204, 8205),
CodeunitRange(8377, 8377),
CodeunitRange(9676, 9676),
]),
_NotoFont('Noto Sans Khmer UI', <CodeunitRange>[
NotoFont('Noto Sans Khmer UI', <CodeunitRange>[
CodeunitRange(6016, 6143),
CodeunitRange(8204, 8204),
CodeunitRange(9676, 9676),
]),
_NotoFont('Noto Sans KR', <CodeunitRange>[
NotoFont('Noto Sans KR', <CodeunitRange>[
CodeunitRange(12593, 12686),
CodeunitRange(12800, 12828),
CodeunitRange(12896, 12923),
CodeunitRange(44032, 55215),
]),
_NotoFont('Noto Sans Lao UI', <CodeunitRange>[
NotoFont('Noto Sans Lao UI', <CodeunitRange>[
CodeunitRange(3713, 3807),
CodeunitRange(9676, 9676),
]),
_NotoFont('Noto Sans Malayalam UI', <CodeunitRange>[
NotoFont('Noto Sans Malayalam UI', <CodeunitRange>[
CodeunitRange(775, 775),
CodeunitRange(803, 803),
CodeunitRange(2404, 2405),
@ -538,20 +543,20 @@ List<_NotoFont> _notoFonts = <_NotoFont>[
CodeunitRange(8377, 8377),
CodeunitRange(9676, 9676),
]),
_NotoFont('Noto Sans Sinhala', <CodeunitRange>[
NotoFont('Noto Sans Sinhala', <CodeunitRange>[
CodeunitRange(2404, 2405),
CodeunitRange(3458, 3572),
CodeunitRange(8204, 8205),
CodeunitRange(9676, 9676),
]),
_NotoFont('Noto Sans Tamil UI', <CodeunitRange>[
NotoFont('Noto Sans Tamil UI', <CodeunitRange>[
CodeunitRange(2404, 2405),
CodeunitRange(2946, 3066),
CodeunitRange(8204, 8205),
CodeunitRange(8377, 8377),
CodeunitRange(9676, 9676),
]),
_NotoFont('Noto Sans Telugu UI', <CodeunitRange>[
NotoFont('Noto Sans Telugu UI', <CodeunitRange>[
CodeunitRange(2385, 2386),
CodeunitRange(2404, 2405),
CodeunitRange(3072, 3199),
@ -559,12 +564,12 @@ List<_NotoFont> _notoFonts = <_NotoFont>[
CodeunitRange(8204, 8205),
CodeunitRange(9676, 9676),
]),
_NotoFont('Noto Sans Thai UI', <CodeunitRange>[
NotoFont('Noto Sans Thai UI', <CodeunitRange>[
CodeunitRange(3585, 3675),
CodeunitRange(8204, 8205),
CodeunitRange(9676, 9676),
]),
_NotoFont('Noto Sans', <CodeunitRange>[
NotoFont('Noto Sans', <CodeunitRange>[
CodeunitRange(0, 255),
CodeunitRange(305, 305),
CodeunitRange(338, 339),
@ -639,7 +644,7 @@ class FallbackFontDownloadQueue {
downloads.add(Future<void>(() async {
ByteBuffer buffer;
try {
buffer = await downloader.downloadAsBytes(subset.url);
buffer = await downloader.downloadAsBytes(subset.url, debugDescription: subset.family);
} catch (e) {
html.window.console
.warn('Failed to load font ${subset.family} at ${subset.url}');
@ -695,7 +700,7 @@ class NotoDownloader {
/// Downloads the [url] and returns it as a [ByteBuffer].
///
/// Override this for testing.
Future<ByteBuffer> downloadAsBytes(String url) {
Future<ByteBuffer> downloadAsBytes(String url, {String? debugDescription}) {
if (assertionsEnabled) {
_debugActiveDownloadCount += 1;
}
@ -714,7 +719,7 @@ class NotoDownloader {
/// Downloads the [url] and returns is as a [String].
///
/// Override this for testing.
Future<String> downloadAsString(String url) {
Future<String> downloadAsString(String url, {String? debugDescription}) {
if (assertionsEnabled) {
_debugActiveDownloadCount += 1;
}
@ -731,6 +736,12 @@ class NotoDownloader {
}
/// The Noto font interval tree.
IntervalTree<_NotoFont>? _notoTree;
IntervalTree<NotoFont>? _notoTree;
/// Returns the tree of Noto fonts for tests.
IntervalTree<NotoFont> get debugNotoTree {
_ensureNotoFontTreeCreated();
return _notoTree!;
}
FallbackFontDownloadQueue notoDownloadQueue = FallbackFontDownloadQueue();

12
engine/src/flutter/lib/web_ui/lib/src/engine/canvaskit/interval_tree.dart
View File

@ -18,7 +18,7 @@ class IntervalTree<T> {
/// have a range which contains the point.
factory IntervalTree.createFromRanges(Map<T, List<CodeunitRange>> rangesMap) {
// Get a list of all the ranges ordered by start index.
List<IntervalTreeNode<T>> intervals = <IntervalTreeNode<T>>[];
final List<IntervalTreeNode<T>> intervals = <IntervalTreeNode<T>>[];
rangesMap.forEach((T key, List<CodeunitRange> rangeList) {
for (CodeunitRange range in rangeList) {
intervals.add(IntervalTreeNode<T>(key, range.start, range.end));
@ -93,6 +93,16 @@ class IntervalTreeNode<T> {
IntervalTreeNode(this.value, this.low, this.high) : computedHigh = high;
Iterable<T> enumerateAllElements() sync* {
if (left != null) {
yield* left!.enumerateAllElements();
}
yield value;
if (right != null) {
yield* right!.enumerateAllElements();
}
}
bool contains(int x) {
return low <= x && x <= high;
}

2
engine/src/flutter/lib/web_ui/lib/src/engine/canvaskit/text.dart
View File

@ -714,7 +714,7 @@ class CkParagraphBuilder implements ui.ParagraphBuilder {
missingCodeUnits.add(codeUnits[i]);
}
}
_findFontsForMissingCodeunits(missingCodeUnits);
findFontsForMissingCodeunits(missingCodeUnits);
}
}

138
engine/src/flutter/lib/web_ui/test/canvaskit/fallback_fonts_golden_test.dart
View File

@ -4,6 +4,7 @@
// @dart = 2.12
import 'dart:async';
import 'dart:math' as math;
import 'dart:typed_data';
import 'package:ui/ui.dart' as ui;
@ -206,6 +207,116 @@ void testMain() {
expect(notoDownloadQueue.isPending, isFalse);
expect(skiaFontCollection.globalFontFallbacks, ['Roboto']);
});
// Regression test for https://github.com/flutter/flutter/issues/75836
// When we had this bug our font fallback resolution logic would end up in an
// infinite loop and this test would freeze and time out.
test('Can find fonts for two adjacent unmatched code units from different fonts', () async {
final LoggingDownloader loggingDownloader = LoggingDownloader(NotoDownloader());
notoDownloadQueue.downloader = loggingDownloader;
// Try rendering text that requires fallback fonts, initially before the fonts are loaded.
CkParagraphBuilder(CkParagraphStyle()).addText('ヽಠ');
await notoDownloadQueue.downloader.debugWhenIdle();
expect(
loggingDownloader.log,
<String>[
'https://fonts.googleapis.com/css2?family=Noto+Sans+SC',
'https://fonts.googleapis.com/css2?family=Noto+Sans+Kannada+UI',
'Noto Sans SC',
'Noto Sans Kannada UI',
],
);
// Do the same thing but this time with loaded fonts.
loggingDownloader.log.clear();
CkParagraphBuilder(CkParagraphStyle()).addText('ヽಠ');
await notoDownloadQueue.downloader.debugWhenIdle();
expect(loggingDownloader.log, isEmpty);
});
test('findMinimumFontsForCodeunits for all supported code units', () async {
final LoggingDownloader loggingDownloader = LoggingDownloader(NotoDownloader());
notoDownloadQueue.downloader = loggingDownloader;
// Collect all supported code units from all fallback fonts in the Noto
// font tree.
final Set<String> testedFonts = <String>{};
final Set<int> supportedUniqueCodeUnits = <int>{};
for (NotoFont font in debugNotoTree.root.enumerateAllElements()) {
testedFonts.add(font.name);
for (CodeunitRange range in font.unicodeRanges) {
for (int codeUnit = range.start; codeUnit < range.end; codeUnit += 1) {
supportedUniqueCodeUnits.add(codeUnit);
}
}
}
expect(supportedUniqueCodeUnits.length, greaterThan(10000)); // sanity check
expect(testedFonts, unorderedEquals(<String>{
'Noto Sans',
'Noto Sans Malayalam UI',
'Noto Sans Armenian',
'Noto Sans Georgian',
'Noto Sans Hebrew',
'Noto Naskh Arabic UI',
'Noto Sans Devanagari UI',
'Noto Sans Telugu UI',
'Noto Sans Tamil UI',
'Noto Sans Kannada UI',
'Noto Sans Sinhala',
'Noto Sans Gurmukhi UI',
'Noto Sans Gujarati UI',
'Noto Sans Bengali UI',
'Noto Sans Thai UI',
'Noto Sans Lao UI',
'Noto Sans Myanmar UI',
'Noto Sans Ethiopic',
'Noto Sans Khmer UI',
'Noto Sans SC',
'Noto Sans JP',
'Noto Sans TC',
'Noto Sans HK',
'Noto Sans KR',
'Noto Sans Egyptian Hieroglyphs',
}));
// Construct random paragraphs out of supported code units.
final math.Random random = math.Random(0);
final List<int> supportedCodeUnits = supportedUniqueCodeUnits.toList()..shuffle(random);
const int paragraphLength = 3;
for (int batchStart = 0; batchStart < supportedCodeUnits.length; batchStart += paragraphLength) {
final int batchEnd = math.min(batchStart + paragraphLength, supportedCodeUnits.length);
final List<int> codeUnits = <int>[];
for (int i = batchStart; i < batchEnd; i += 1) {
codeUnits.add(supportedCodeUnits[i]);
}
final Set<NotoFont> fonts = <NotoFont>{};
for (int codeunit in codeUnits) {
List<NotoFont> fontsForUnit = debugNotoTree.intersections(codeunit);
// All code units are extracted from the same tree, so there must
// be at least one font supporting each code unit
expect(fontsForUnit, isNotEmpty);
// Make sure that every returned font indeed covers the code unit.
expect(fontsForUnit.every((font) => font.matchesCodeunit(codeunit)), isTrue);
fonts.addAll(fontsForUnit);
}
try {
findMinimumFontsForCodeunits(codeUnits, fonts);
} catch (e) {
print(
'findMinimumFontsForCodeunits failed:\n'
' Code units: ${codeUnits.join(', ')}\n'
' Fonts: ${fonts.map((f) => f.name).join(', ')}',
);
rethrow;
}
}
});
// TODO: https://github.com/flutter/flutter/issues/60040
}, skip: isIosSafari);
}
@ -213,7 +324,7 @@ void testMain() {
class TestDownloader extends NotoDownloader {
static final Map<String, String> mockDownloads = <String, String>{};
@override
Future<String> downloadAsString(String url) async {
Future<String> downloadAsString(String url, {String? debugDescription}) async {
if (mockDownloads.containsKey(url)) {
return mockDownloads[url]!;
} else {
@ -221,3 +332,28 @@ class TestDownloader extends NotoDownloader {
}
}
}
class LoggingDownloader implements NotoDownloader {
final List<String> log = <String>[];
LoggingDownloader(this.delegate);
final NotoDownloader delegate;
@override
Future<void> debugWhenIdle() {
return delegate.debugWhenIdle();
}
@override
Future<ByteBuffer> downloadAsBytes(String url, {String? debugDescription}) {
log.add(debugDescription ?? url);
return delegate.downloadAsBytes(url);
}
@override
Future<String> downloadAsString(String url, {String? debugDescription}) {
log.add(debugDescription ?? url);
return delegate.downloadAsString(url);
}
}