pkg/analysis_server/lib/src/services/pub/pub_package_service.dart - sdk.git - Git at Google

 // Copyright (c) 2021, 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.

 /// @docImport 'package:analyzer/file_system/physical_file_system.dart';
 library;

 import 'dart:async';
 import 'dart:convert';

 import 'package:analysis_server/src/services/pub/pub_api.dart';
 import 'package:analysis_server/src/services/pub/pub_command.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/instrumentation/service.dart';
 import 'package:meta/meta.dart';

 /// Information about Pub packages that can be converted to/from JSON and
 /// cached to disk.
 class PackageDetailsCache {
   static const cacheVersion = 3;
   static const maxCacheAge = Duration(hours: 18);
   static const maxPackageDetailsRequestsInFlight = 5;

   /// Requests to write the cache from fetching package details will be
   /// debounced by this duration to prevent many writes while the user may be
   /// cursoring though completion requests that will trigger fetching
   /// descriptions/versions.
   static const _writeCacheDebounceDuration = Duration(seconds: 3);

   final Map<String, PubPackage> packages;
   DateTime lastUpdatedUtc;

   PackageDetailsCache._(this.packages, DateTime lastUpdated)
     : lastUpdatedUtc = lastUpdated.toUtc();

   Duration get cacheTimeRemaining {
     var cacheAge = DateTime.now().toUtc().difference(lastUpdatedUtc);
     var cacheTimeRemaining = maxCacheAge - cacheAge;
     return cacheTimeRemaining < Duration.zero
         ? Duration.zero
         : cacheTimeRemaining;
   }

   Map<String, Object> toJson() {
     return {
       'version': cacheVersion,
       'lastUpdated': lastUpdatedUtc.toIso8601String(),
       'packages': packages.values.toList(),
     };
   }

   static PackageDetailsCache empty() {
     return PackageDetailsCache._({}, DateTime.utc(2000));
   }

   static PackageDetailsCache fromApiResults(List<PubApiPackage> apiPackages) {
     var packages = Map.fromEntries(
       apiPackages.map(
         (package) =>
             MapEntry(package.packageName, PubPackage.fromName(package)),
       ),
     );

     return PackageDetailsCache._(packages, DateTime.now().toUtc());
   }

   /// Deserializes cached package data from JSON.
   ///
   /// If the JSON version does not match the current version, will return null.
   static PackageDetailsCache? fromJson(Map<String, Object?> json) {
     if (json['version'] != cacheVersion) {
       return null;
     }

     var packagesJson = json['packages'];
     if (packagesJson is! List<Object?>) {
       return null;
     }

     var packages = <PubPackage>[];
     for (var packageJson in packagesJson) {
       if (packageJson is! Map<String, Object?>) {
         return null;
       }
       var nameJson = packageJson['packageName'];
       if (nameJson is! String) {
         return null;
       }
       packages.add(PubPackage.fromJson(packageJson));
     }

     var packageMap = Map.fromEntries(
       packages.map((package) => MapEntry(package.packageName, package)),
     );

     var lastUpdatedJson = json['lastUpdated'];
     if (lastUpdatedJson is! String) {
       return null;
     }
     var lastUpdated = DateTime.tryParse(lastUpdatedJson);
     if (lastUpdated == null) {
       return null;
     }

     return PackageDetailsCache._(packageMap, lastUpdated);
   }
 }

 /// Information about a single Pub package.
 class PubPackage {
   String packageName;
   String? description;
   String? latestVersion;

   PubPackage.fromDetails(PubApiPackageDetails package)
     : packageName = package.packageName,
       description = package.description,
       latestVersion = package.latestVersion;

   PubPackage.fromJson(Map<String, Object?> json)
     : packageName = json['packageName'] as String,
       description = json['description'] as String?,
       latestVersion = json['latestVersion'] as String?;

   PubPackage.fromName(PubApiPackage package)
     : packageName = package.packageName;

   Map<String, Object> toJson() {
     return {
       'packageName': packageName,
       'description': ?description,
       'latestVersion': ?latestVersion,
     };
   }
 }

 /// A service for providing Pub package information.
 ///
 /// Uses a [PubApi] to communicate with the Pub API and a [PubCommand] to
 /// interact with the local `pub` command.
 ///
 /// Expensive results are cached to disk using [resourceProvider].
 class PubPackageService {
   final InstrumentationService _instrumentationService;
   final PubApi _api;

   /// A wrapper over the "pub" command line too.
   ///
   /// This can be null when not running on a real file system because it may
   /// try to interact with folders that don't really exist.
   final PubCommand? _command;

   Timer? _nextPackageNameListRequestTimer;
   Timer? _nextWriteDiskCacheTimer;

   /// [ResourceProvider] used for accessing the disk for caches and checking
   /// project types. This will be a [PhysicalResourceProvider] outside of tests.
   final ResourceProvider resourceProvider;

   /// The current cache of package information. Initially `null`, but
   /// overwritten after first read of cache from disk or fetch from the API.
   @visibleForTesting
   PackageDetailsCache? packageCache;

   int _packageDetailsRequestsInFlight = 0;

   /// A cache of version numbers from running the "pub outdated" command used
   /// for completion in pubspec.yaml.
   final _pubspecPackageVersions =
       <String, Map<String, PubOutdatedPackageDetails>>{};

   PubPackageService(
     this._instrumentationService,
     this.resourceProvider,
     this._api,
     this._command,
   );

   /// Gets the last set of package results from the Pub API or an empty List if
   /// no results.
   ///
   /// This data is used for completion of package names in pubspec.yaml
   /// and for clients that support lazy resolution of completion items may also
   /// include their descriptions and/or version numbers.
   List<PubPackage> get cachedPackages =>
       packageCache?.packages.values.toList() ?? [];

   @visibleForTesting
   bool get isPackageNamesTimerRunning =>
       _nextPackageNameListRequestTimer != null;

   @visibleForTesting
   File get packageCacheFile {
     var cacheFolder = resourceProvider.getStateLocation(
       '.pub-package-details-cache',
     )!..create();
     return cacheFolder.getChildAssumingFile('packages.json');
   }

   /// Begins preloading caches for package names and pub versions.
   void beginCachePreloads(List<String> pubspecs) {
     beginPackageNamePreload();
     for (var pubspec in pubspecs) {
       fetchPackageVersionsViaPubOutdated(pubspec, pubspecWasModified: false);
     }
   }

   /// Begin a timer to pre-load and update the package name list if one has not
   /// already been started.
   void beginPackageNamePreload() {
     if (isPackageNamesTimerRunning) {
       return;
     }

     // If first time, try to read from disk.
     var cache = packageCache;
     if (cache == null) {
       cache ??= readDiskCache() ?? PackageDetailsCache.empty();
       packageCache = cache;
     }

     // If there is no queued request, initialize one when the current cache expires.
     _nextPackageNameListRequestTimer ??= Timer(
       cache.cacheTimeRemaining,
       _fetchFromServer,
     );
   }

   /// Gets the latest cached package version fetched from the Pub API for the
   /// package [packageName].
   String? cachedPubApiLatestVersion(String packageName) =>
       packageCache?.packages[packageName]?.latestVersion;

   /// Gets the package versions cached using "pub outdated" for the package
   /// [packageName] for the project using [pubspecPath].
   ///
   /// Versions in here might only be available for packages that are in the
   /// pubspec on disk. Newly-added packages in the overlay might not be
   /// available.
   PubOutdatedPackageDetails? cachedPubOutdatedVersions(
     String pubspecPath,
     String packageName,
   ) {
     var pubspecCache = _pubspecPackageVersions[pubspecPath];
     return pubspecCache != null ? pubspecCache[packageName] : null;
   }

   /// Begin a request to pre-load package versions using the "pub outdated"
   /// command.
   ///
   /// If [pubspecWasModified] is true, the command will always be run. Otherwise it
   /// will only be run if data is not already cached.
   Future<void> fetchPackageVersionsViaPubOutdated(
     String pubspecPath, {
     required bool pubspecWasModified,
   }) async {
     var pubCommand = _command;
     if (pubCommand == null) {
       return;
     }

     // If we already have a cache for the file and it was not modified (only
     // opened) we do not need to re-run the command.
     if (!pubspecWasModified &&
         _pubspecPackageVersions.containsKey(pubspecPath)) {
       return;
     }

     // Check if this pubspec is inside a DEPS-managed folder, and if so
     // just cache an empty set of results since Pub is not managing
     // dependencies.
     if (_hasAncestorDEPSFile(pubspecPath)) {
       _pubspecPackageVersions.putIfAbsent(pubspecPath, () => {});
       return;
     }

     var results = await pubCommand.outdatedVersions(pubspecPath);
     var cache = _pubspecPackageVersions.putIfAbsent(pubspecPath, () => {});
     for (var package in results) {
       // We use the versions from the "pub outdated" results but only cache them
       // in-memory for this specific pubspec, as the resolved version may be
       // restricted by constraints/dependencies in the pubspec. The "pub"
       // command does caching of the JSON versions to make "pub outdated" fast.
       cache[package.packageName] = package;
     }
   }

   /// Clears package caches for [pubspecPath].
   ///
   /// Does not remove other caches that are not pubspec-specific (for example
   /// the latest version pulled directly from the Pub API independent of
   /// pubspec).
   Future<void> flushPackageCaches(String pubspecPath) async {
     _pubspecPackageVersions.remove(pubspecPath);
   }

   /// Gets package details for package [packageName].
   ///
   /// If the package details are not cached, will call the Pub API and cache
   /// the result. Results are cached for the same period as the main package
   /// list cache - that is, when the package list cache expires, all cached
   /// package details will go with it.
   Future<PubPackage?> packageDetails(String packageName) async {
     var packageData = packageCache?.packages[packageName];
     // If we don't have the version for this package, we don't have its full details.
     if (packageData?.latestVersion == null &&
         // Limit the number of package details requests that can be in-flight at
         // once since an editor may send many of these requests as the user
         // cursors through the results (a good editor will cancel the resolve
         // requests, but we may have already started the requests synchronously
         // before handling a cancellation).
         _packageDetailsRequestsInFlight <=
             PackageDetailsCache.maxPackageDetailsRequestsInFlight) {
       _packageDetailsRequestsInFlight++;
       try {
         var details = await _api.packageInfo(packageName);
         if (details != null) {
           packageData = PubPackage.fromDetails(details);
           packageCache?.packages[packageName] = packageData;
           _writeDiskCacheDebounced();
         }
       } finally {
         _packageDetailsRequestsInFlight--;
       }
     }
     return packageData;
   }

   @visibleForTesting
   PackageDetailsCache? readDiskCache() {
     var file = packageCacheFile;
     if (!file.exists) {
       return null;
     }
     try {
       var contents = file.readAsStringSync();
       var json = jsonDecode(contents);
       if (json is Map<String, Object?>) {
         return PackageDetailsCache.fromJson(json);
       } else {
         return null;
       }
     } catch (e) {
       _instrumentationService.logError('Error reading pub cache file: $e');
       return null;
     }
   }

   void shutdown() {
     _nextPackageNameListRequestTimer?.cancel();
     _command?.shutdown();
   }

   @visibleForTesting
   void writeDiskCache([PackageDetailsCache? cache]) {
     cache ??= packageCache;
     if (cache == null) {
       return;
     }
     var file = packageCacheFile;
     file.writeAsStringSync(jsonEncode(cache.toJson()));
   }

   Future<void> _fetchFromServer() async {
     try {
       var packages = await _api.allPackages();

       // If we never got a valid response, just skip until the next refresh.
       if (packages == null) {
         return;
       }

       var packageCache = PackageDetailsCache.fromApiResults(packages);
       this.packageCache = packageCache;
       writeDiskCache();
     } catch (e) {
       _instrumentationService.logError('Failed to fetch packages from Pub: $e');
     } finally {
       _nextPackageNameListRequestTimer = Timer(
         PackageDetailsCache.maxCacheAge,
         _fetchFromServer,
       );
     }
   }

   /// Checks whether there is a DEPS file in any folder walking up from the
   /// pubspec at [pubspecPath].
   bool _hasAncestorDEPSFile(String pubspecPath) {
     var pathContext = resourceProvider.pathContext;
     var folder = pathContext.dirname(pubspecPath);
     do {
       if (resourceProvider.getFile(pathContext.join(folder, 'DEPS')).exists) {
         return true;
       }
       folder = pathContext.dirname(folder);
     } while (folder != pathContext.dirname(folder));
     return false;
   }

   /// Writes the package cache to disk after
   /// [PackageDetailsCache._writeCacheDebounceDuration] has elapsed, restarting
   /// the timer each time this method is called.
   void _writeDiskCacheDebounced() {
     _nextWriteDiskCacheTimer?.cancel();
     _nextWriteDiskCacheTimer = Timer(
       PackageDetailsCache._writeCacheDebounceDuration,
       writeDiskCache,
     );
   }
 }
	// Copyright (c) 2021, 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.

	/// @docImport 'package:analyzer/file_system/physical_file_system.dart';
	library;

	import 'dart:async';
	import 'dart:convert';

	import 'package:analysis_server/src/services/pub/pub_api.dart';
	import 'package:analysis_server/src/services/pub/pub_command.dart';
	import 'package:analyzer/file_system/file_system.dart';
	import 'package:analyzer/instrumentation/service.dart';
	import 'package:meta/meta.dart';

	/// Information about Pub packages that can be converted to/from JSON and
	/// cached to disk.
	class PackageDetailsCache {
	static const cacheVersion = 3;
	static const maxCacheAge = Duration(hours: 18);
	static const maxPackageDetailsRequestsInFlight = 5;

	/// Requests to write the cache from fetching package details will be
	/// debounced by this duration to prevent many writes while the user may be
	/// cursoring though completion requests that will trigger fetching
	/// descriptions/versions.
	static const _writeCacheDebounceDuration = Duration(seconds: 3);

	final Map<String, PubPackage> packages;
	DateTime lastUpdatedUtc;

	PackageDetailsCache._(this.packages, DateTime lastUpdated)
	: lastUpdatedUtc = lastUpdated.toUtc();

	Duration get cacheTimeRemaining {
	var cacheAge = DateTime.now().toUtc().difference(lastUpdatedUtc);
	var cacheTimeRemaining = maxCacheAge - cacheAge;
	return cacheTimeRemaining < Duration.zero
	? Duration.zero
	: cacheTimeRemaining;
	}

	Map<String, Object> toJson() {
	return {
	'version': cacheVersion,
	'lastUpdated': lastUpdatedUtc.toIso8601String(),
	'packages': packages.values.toList(),
	};
	}

	static PackageDetailsCache empty() {
	return PackageDetailsCache._({}, DateTime.utc(2000));
	}

	static PackageDetailsCache fromApiResults(List<PubApiPackage> apiPackages) {
	var packages = Map.fromEntries(
	apiPackages.map(
	(package) =>
	MapEntry(package.packageName, PubPackage.fromName(package)),
	),
	);

	return PackageDetailsCache._(packages, DateTime.now().toUtc());
	}

	/// Deserializes cached package data from JSON.
	///
	/// If the JSON version does not match the current version, will return null.
	static PackageDetailsCache? fromJson(Map<String, Object?> json) {
	if (json['version'] != cacheVersion) {
	return null;
	}

	var packagesJson = json['packages'];
	if (packagesJson is! List<Object?>) {
	return null;
	}

	var packages = <PubPackage>[];
	for (var packageJson in packagesJson) {
	if (packageJson is! Map<String, Object?>) {
	return null;
	}
	var nameJson = packageJson['packageName'];
	if (nameJson is! String) {
	return null;
	}
	packages.add(PubPackage.fromJson(packageJson));
	}

	var packageMap = Map.fromEntries(
	packages.map((package) => MapEntry(package.packageName, package)),
	);

	var lastUpdatedJson = json['lastUpdated'];
	if (lastUpdatedJson is! String) {
	return null;
	}
	var lastUpdated = DateTime.tryParse(lastUpdatedJson);
	if (lastUpdated == null) {
	return null;
	}

	return PackageDetailsCache._(packageMap, lastUpdated);
	}
	}

	/// Information about a single Pub package.
	class PubPackage {
	String packageName;
	String? description;
	String? latestVersion;

	PubPackage.fromDetails(PubApiPackageDetails package)
	: packageName = package.packageName,
	description = package.description,
	latestVersion = package.latestVersion;

	PubPackage.fromJson(Map<String, Object?> json)
	: packageName = json['packageName'] as String,
	description = json['description'] as String?,
	latestVersion = json['latestVersion'] as String?;

	PubPackage.fromName(PubApiPackage package)
	: packageName = package.packageName;

	Map<String, Object> toJson() {
	return {
	'packageName': packageName,
	'description': ?description,
	'latestVersion': ?latestVersion,
	};
	}
	}

	/// A service for providing Pub package information.
	///
	/// Uses a [PubApi] to communicate with the Pub API and a [PubCommand] to
	/// interact with the local `pub` command.
	///
	/// Expensive results are cached to disk using [resourceProvider].
	class PubPackageService {
	final InstrumentationService _instrumentationService;
	final PubApi _api;

	/// A wrapper over the "pub" command line too.
	///
	/// This can be null when not running on a real file system because it may
	/// try to interact with folders that don't really exist.
	final PubCommand? _command;

	Timer? _nextPackageNameListRequestTimer;
	Timer? _nextWriteDiskCacheTimer;

	/// [ResourceProvider] used for accessing the disk for caches and checking
	/// project types. This will be a [PhysicalResourceProvider] outside of tests.
	final ResourceProvider resourceProvider;

	/// The current cache of package information. Initially `null`, but
	/// overwritten after first read of cache from disk or fetch from the API.
	@visibleForTesting
	PackageDetailsCache? packageCache;

	int _packageDetailsRequestsInFlight = 0;

	/// A cache of version numbers from running the "pub outdated" command used
	/// for completion in pubspec.yaml.
	final _pubspecPackageVersions =
	<String, Map<String, PubOutdatedPackageDetails>>{};

	PubPackageService(
	this._instrumentationService,
	this.resourceProvider,
	this._api,
	this._command,
	);

	/// Gets the last set of package results from the Pub API or an empty List if
	/// no results.
	///
	/// This data is used for completion of package names in pubspec.yaml
	/// and for clients that support lazy resolution of completion items may also
	/// include their descriptions and/or version numbers.
	List<PubPackage> get cachedPackages =>
	packageCache?.packages.values.toList() ?? [];

	@visibleForTesting
	bool get isPackageNamesTimerRunning =>
	_nextPackageNameListRequestTimer != null;

	@visibleForTesting
	File get packageCacheFile {
	var cacheFolder = resourceProvider.getStateLocation(
	'.pub-package-details-cache',
	)!..create();
	return cacheFolder.getChildAssumingFile('packages.json');
	}

	/// Begins preloading caches for package names and pub versions.
	void beginCachePreloads(List<String> pubspecs) {
	beginPackageNamePreload();
	for (var pubspec in pubspecs) {
	fetchPackageVersionsViaPubOutdated(pubspec, pubspecWasModified: false);
	}
	}

	/// Begin a timer to pre-load and update the package name list if one has not
	/// already been started.
	void beginPackageNamePreload() {
	if (isPackageNamesTimerRunning) {
	return;
	}

	// If first time, try to read from disk.
	var cache = packageCache;
	if (cache == null) {
	cache ??= readDiskCache() ?? PackageDetailsCache.empty();
	packageCache = cache;
	}

	// If there is no queued request, initialize one when the current cache expires.
	_nextPackageNameListRequestTimer ??= Timer(
	cache.cacheTimeRemaining,
	_fetchFromServer,
	);
	}

	/// Gets the latest cached package version fetched from the Pub API for the
	/// package [packageName].
	String? cachedPubApiLatestVersion(String packageName) =>
	packageCache?.packages[packageName]?.latestVersion;

	/// Gets the package versions cached using "pub outdated" for the package
	/// [packageName] for the project using [pubspecPath].
	///
	/// Versions in here might only be available for packages that are in the
	/// pubspec on disk. Newly-added packages in the overlay might not be
	/// available.
	PubOutdatedPackageDetails? cachedPubOutdatedVersions(
	String pubspecPath,
	String packageName,
	) {
	var pubspecCache = _pubspecPackageVersions[pubspecPath];
	return pubspecCache != null ? pubspecCache[packageName] : null;
	}

	/// Begin a request to pre-load package versions using the "pub outdated"
	/// command.
	///
	/// If [pubspecWasModified] is true, the command will always be run. Otherwise it
	/// will only be run if data is not already cached.
	Future<void> fetchPackageVersionsViaPubOutdated(
	String pubspecPath, {
	required bool pubspecWasModified,
	}) async {
	var pubCommand = _command;
	if (pubCommand == null) {
	return;
	}

	// If we already have a cache for the file and it was not modified (only
	// opened) we do not need to re-run the command.
	if (!pubspecWasModified &&
	_pubspecPackageVersions.containsKey(pubspecPath)) {
	return;
	}

	// Check if this pubspec is inside a DEPS-managed folder, and if so
	// just cache an empty set of results since Pub is not managing
	// dependencies.
	if (_hasAncestorDEPSFile(pubspecPath)) {
	_pubspecPackageVersions.putIfAbsent(pubspecPath, () => {});
	return;
	}

	var results = await pubCommand.outdatedVersions(pubspecPath);
	var cache = _pubspecPackageVersions.putIfAbsent(pubspecPath, () => {});
	for (var package in results) {
	// We use the versions from the "pub outdated" results but only cache them
	// in-memory for this specific pubspec, as the resolved version may be
	// restricted by constraints/dependencies in the pubspec. The "pub"
	// command does caching of the JSON versions to make "pub outdated" fast.
	cache[package.packageName] = package;
	}
	}

	/// Clears package caches for [pubspecPath].
	///
	/// Does not remove other caches that are not pubspec-specific (for example
	/// the latest version pulled directly from the Pub API independent of
	/// pubspec).
	Future<void> flushPackageCaches(String pubspecPath) async {
	_pubspecPackageVersions.remove(pubspecPath);
	}

	/// Gets package details for package [packageName].
	///
	/// If the package details are not cached, will call the Pub API and cache
	/// the result. Results are cached for the same period as the main package
	/// list cache - that is, when the package list cache expires, all cached
	/// package details will go with it.
	Future<PubPackage?> packageDetails(String packageName) async {
	var packageData = packageCache?.packages[packageName];
	// If we don't have the version for this package, we don't have its full details.
	if (packageData?.latestVersion == null &&
	// Limit the number of package details requests that can be in-flight at
	// once since an editor may send many of these requests as the user
	// cursors through the results (a good editor will cancel the resolve
	// requests, but we may have already started the requests synchronously
	// before handling a cancellation).
	_packageDetailsRequestsInFlight <=
	PackageDetailsCache.maxPackageDetailsRequestsInFlight) {
	_packageDetailsRequestsInFlight++;
	try {
	var details = await _api.packageInfo(packageName);
	if (details != null) {
	packageData = PubPackage.fromDetails(details);
	packageCache?.packages[packageName] = packageData;
	_writeDiskCacheDebounced();
	}
	} finally {
	_packageDetailsRequestsInFlight--;
	}
	}
	return packageData;
	}

	@visibleForTesting
	PackageDetailsCache? readDiskCache() {
	var file = packageCacheFile;
	if (!file.exists) {
	return null;
	}
	try {
	var contents = file.readAsStringSync();
	var json = jsonDecode(contents);
	if (json is Map<String, Object?>) {
	return PackageDetailsCache.fromJson(json);
	} else {
	return null;
	}
	} catch (e) {
	_instrumentationService.logError('Error reading pub cache file: $e');
	return null;
	}
	}

	void shutdown() {
	_nextPackageNameListRequestTimer?.cancel();
	_command?.shutdown();
	}

	@visibleForTesting
	void writeDiskCache([PackageDetailsCache? cache]) {
	cache ??= packageCache;
	if (cache == null) {
	return;
	}
	var file = packageCacheFile;
	file.writeAsStringSync(jsonEncode(cache.toJson()));
	}

	Future<void> _fetchFromServer() async {
	try {
	var packages = await _api.allPackages();

	// If we never got a valid response, just skip until the next refresh.
	if (packages == null) {
	return;
	}

	var packageCache = PackageDetailsCache.fromApiResults(packages);
	this.packageCache = packageCache;
	writeDiskCache();
	} catch (e) {
	_instrumentationService.logError('Failed to fetch packages from Pub: $e');
	} finally {
	_nextPackageNameListRequestTimer = Timer(
	PackageDetailsCache.maxCacheAge,
	_fetchFromServer,
	);
	}
	}

	/// Checks whether there is a DEPS file in any folder walking up from the
	/// pubspec at [pubspecPath].
	bool _hasAncestorDEPSFile(String pubspecPath) {
	var pathContext = resourceProvider.pathContext;
	var folder = pathContext.dirname(pubspecPath);
	do {
	if (resourceProvider.getFile(pathContext.join(folder, 'DEPS')).exists) {
	return true;
	}
	folder = pathContext.dirname(folder);
	} while (folder != pathContext.dirname(folder));
	return false;
	}

	/// Writes the package cache to disk after
	/// [PackageDetailsCache._writeCacheDebounceDuration] has elapsed, restarting
	/// the timer each time this method is called.
	void _writeDiskCacheDebounced() {
	_nextWriteDiskCacheTimer?.cancel();
	_nextWriteDiskCacheTimer = Timer(
	PackageDetailsCache._writeCacheDebounceDuration,
	writeDiskCache,
	);
	}
	}