Index: imaps-frontend/node_modules/webpack/lib/FileSystemInfo.js
===================================================================
--- imaps-frontend/node_modules/webpack/lib/FileSystemInfo.js	(revision 79a03170cdde4e801d12257ee86723774970427b)
+++ imaps-frontend/node_modules/webpack/lib/FileSystemInfo.js	(revision 79a03170cdde4e801d12257ee86723774970427b)
@@ -0,0 +1,4041 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+const { create: createResolver } = require("enhanced-resolve");
+const nodeModule = require("module");
+const asyncLib = require("neo-async");
+const { isAbsolute } = require("path");
+const AsyncQueue = require("./util/AsyncQueue");
+const StackedCacheMap = require("./util/StackedCacheMap");
+const createHash = require("./util/createHash");
+const { join, dirname, relative, lstatReadlinkAbsolute } = require("./util/fs");
+const makeSerializable = require("./util/makeSerializable");
+const processAsyncTree = require("./util/processAsyncTree");
+
+/** @typedef {import("enhanced-resolve").Resolver} Resolver */
+/** @typedef {import("enhanced-resolve").ResolveRequest} ResolveRequest */
+/** @typedef {import("enhanced-resolve").ResolveFunctionAsync} ResolveFunctionAsync */
+/** @typedef {import("./WebpackError")} WebpackError */
+/** @typedef {import("./logging/Logger").Logger} Logger */
+/** @typedef {import("./serialization/ObjectMiddleware").ObjectDeserializerContext} ObjectDeserializerContext */
+/** @typedef {import("./serialization/ObjectMiddleware").ObjectSerializerContext} ObjectSerializerContext */
+/** @typedef {typeof import("./util/Hash")} Hash */
+/** @typedef {import("./util/fs").IStats} IStats */
+/** @typedef {import("./util/fs").InputFileSystem} InputFileSystem */
+/** @typedef {import("./util/fs").PathLike} PathLike */
+/** @typedef {import("./util/fs").StringCallback} StringCallback */
+/**
+ * @template T
+ * @typedef {import("./util/AsyncQueue").Callback<T>} ProcessorCallback
+ */
+/**
+ * @template T, R
+ * @typedef {import("./util/AsyncQueue").Processor<T, R>} Processor
+ */
+
+const supportsEsm = Number(process.versions.modules) >= 83;
+
+/** @type {Set<string>} */
+const builtinModules = new Set(nodeModule.builtinModules);
+
+let FS_ACCURACY = 2000;
+
+const EMPTY_SET = new Set();
+
+const RBDT_RESOLVE_CJS = 0;
+const RBDT_RESOLVE_ESM = 1;
+const RBDT_RESOLVE_DIRECTORY = 2;
+const RBDT_RESOLVE_CJS_FILE = 3;
+const RBDT_RESOLVE_CJS_FILE_AS_CHILD = 4;
+const RBDT_RESOLVE_ESM_FILE = 5;
+const RBDT_DIRECTORY = 6;
+const RBDT_FILE = 7;
+const RBDT_DIRECTORY_DEPENDENCIES = 8;
+const RBDT_FILE_DEPENDENCIES = 9;
+
+/** @typedef {RBDT_RESOLVE_CJS | RBDT_RESOLVE_ESM | RBDT_RESOLVE_DIRECTORY | RBDT_RESOLVE_CJS_FILE | RBDT_RESOLVE_CJS_FILE_AS_CHILD | RBDT_RESOLVE_ESM_FILE | RBDT_DIRECTORY | RBDT_FILE | RBDT_DIRECTORY_DEPENDENCIES | RBDT_FILE_DEPENDENCIES} JobType */
+
+const INVALID = Symbol("invalid");
+
+/**
+ * @typedef {object} FileSystemInfoEntry
+ * @property {number} safeTime
+ * @property {number=} timestamp
+ */
+
+/**
+ * @typedef {object} ResolvedContextFileSystemInfoEntry
+ * @property {number} safeTime
+ * @property {string=} timestampHash
+ */
+
+/**
+ * @typedef {object} ContextFileSystemInfoEntry
+ * @property {number} safeTime
+ * @property {string=} timestampHash
+ * @property {ResolvedContextFileSystemInfoEntry=} resolved
+ * @property {Set<string>=} symlinks
+ */
+
+/**
+ * @typedef {object} TimestampAndHash
+ * @property {number} safeTime
+ * @property {number=} timestamp
+ * @property {string} hash
+ */
+
+/**
+ * @typedef {object} ResolvedContextTimestampAndHash
+ * @property {number} safeTime
+ * @property {string=} timestampHash
+ * @property {string} hash
+ */
+
+/** @typedef {Set<string>} Symlinks */
+
+/**
+ * @typedef {object} ContextTimestampAndHash
+ * @property {number} safeTime
+ * @property {string=} timestampHash
+ * @property {string} hash
+ * @property {ResolvedContextTimestampAndHash=} resolved
+ * @property {Symlinks=} symlinks
+ */
+
+/**
+ * @typedef {object} ContextHash
+ * @property {string} hash
+ * @property {string=} resolved
+ * @property {Symlinks=} symlinks
+ */
+
+/** @typedef {Set<string>} SnapshotContent */
+
+/**
+ * @typedef {object} SnapshotOptimizationEntry
+ * @property {Snapshot} snapshot
+ * @property {number} shared
+ * @property {SnapshotContent | undefined} snapshotContent
+ * @property {Set<SnapshotOptimizationEntry> | undefined} children
+ */
+
+/**
+ * @typedef {object} ResolveBuildDependenciesResult
+ * @property {Set<string>} files list of files
+ * @property {Set<string>} directories list of directories
+ * @property {Set<string>} missing list of missing entries
+ * @property {Map<string, string | false | undefined>} resolveResults stored resolve results
+ * @property {object} resolveDependencies dependencies of the resolving
+ * @property {Set<string>} resolveDependencies.files list of files
+ * @property {Set<string>} resolveDependencies.directories list of directories
+ * @property {Set<string>} resolveDependencies.missing list of missing entries
+ */
+
+/**
+ * @typedef {object} SnapshotOptions
+ * @property {boolean=} hash should use hash to snapshot
+ * @property {boolean=} timestamp should use timestamp to snapshot
+ */
+
+const DONE_ITERATOR_RESULT = new Set().keys().next();
+
+// cspell:word tshs
+// Tsh = Timestamp + Hash
+// Tshs = Timestamp + Hash combinations
+
+class SnapshotIterator {
+	/**
+	 * @param {() => IteratorResult<string>} next next
+	 */
+	constructor(next) {
+		this.next = next;
+	}
+}
+
+/**
+ * @typedef {(snapshot: Snapshot) => (Map<string, any> | Set<string> | undefined)[]} GetMapsFunction
+ */
+
+class SnapshotIterable {
+	/**
+	 * @param {Snapshot} snapshot snapshot
+	 * @param {GetMapsFunction} getMaps get maps function
+	 */
+	constructor(snapshot, getMaps) {
+		this.snapshot = snapshot;
+		this.getMaps = getMaps;
+	}
+
+	[Symbol.iterator]() {
+		let state = 0;
+		/** @type {IterableIterator<string>} */
+		let it;
+		/** @type {(snapshot: Snapshot) => (Map<string, any> | Set<string> | undefined)[]} */
+		let getMaps;
+		/** @type {(Map<string, any> | Set<string> | undefined)[]} */
+		let maps;
+		/** @type {Snapshot} */
+		let snapshot;
+		/** @type {Snapshot[] | undefined} */
+		let queue;
+		return new SnapshotIterator(() => {
+			for (;;) {
+				switch (state) {
+					case 0:
+						snapshot = this.snapshot;
+						getMaps = this.getMaps;
+						maps = getMaps(snapshot);
+						state = 1;
+					/* falls through */
+					case 1:
+						if (maps.length > 0) {
+							const map = maps.pop();
+							if (map !== undefined) {
+								it = map.keys();
+								state = 2;
+							} else {
+								break;
+							}
+						} else {
+							state = 3;
+							break;
+						}
+					/* falls through */
+					case 2: {
+						const result = it.next();
+						if (!result.done) return result;
+						state = 1;
+						break;
+					}
+					case 3: {
+						const children = snapshot.children;
+						if (children !== undefined) {
+							if (children.size === 1) {
+								// shortcut for a single child
+								// avoids allocation of queue
+								for (const child of children) snapshot = child;
+								maps = getMaps(snapshot);
+								state = 1;
+								break;
+							}
+							if (queue === undefined) queue = [];
+							for (const child of children) {
+								queue.push(child);
+							}
+						}
+						if (queue !== undefined && queue.length > 0) {
+							snapshot = /** @type {Snapshot} */ (queue.pop());
+							maps = getMaps(snapshot);
+							state = 1;
+							break;
+						} else {
+							state = 4;
+						}
+					}
+					/* falls through */
+					case 4:
+						return DONE_ITERATOR_RESULT;
+				}
+			}
+		});
+	}
+}
+
+/** @typedef {Map<string, FileSystemInfoEntry | null>} FileTimestamps */
+/** @typedef {Map<string, string | null>} FileHashes */
+/** @typedef {Map<string, TimestampAndHash | string | null>} FileTshs */
+/** @typedef {Map<string, ResolvedContextFileSystemInfoEntry | null>} ContextTimestamps */
+/** @typedef {Map<string, string | null>} ContextHashes */
+/** @typedef {Map<string, ResolvedContextTimestampAndHash | null>} ContextTshs */
+/** @typedef {Map<string, boolean>} MissingExistence */
+/** @typedef {Map<string, string>} ManagedItemInfo */
+/** @typedef {Set<string>} ManagedFiles */
+/** @typedef {Set<string>} ManagedContexts */
+/** @typedef {Set<string>} ManagedMissing */
+/** @typedef {Set<Snapshot>} Children */
+
+class Snapshot {
+	constructor() {
+		this._flags = 0;
+		/** @type {Iterable<string> | undefined} */
+		this._cachedFileIterable = undefined;
+		/** @type {Iterable<string> | undefined} */
+		this._cachedContextIterable = undefined;
+		/** @type {Iterable<string> | undefined} */
+		this._cachedMissingIterable = undefined;
+		/** @type {number | undefined} */
+		this.startTime = undefined;
+		/** @type {FileTimestamps | undefined} */
+		this.fileTimestamps = undefined;
+		/** @type {FileHashes | undefined} */
+		this.fileHashes = undefined;
+		/** @type {FileTshs | undefined} */
+		this.fileTshs = undefined;
+		/** @type {ContextTimestamps | undefined} */
+		this.contextTimestamps = undefined;
+		/** @type {ContextHashes | undefined} */
+		this.contextHashes = undefined;
+		/** @type {ContextTshs | undefined} */
+		this.contextTshs = undefined;
+		/** @type {MissingExistence | undefined} */
+		this.missingExistence = undefined;
+		/** @type {ManagedItemInfo | undefined} */
+		this.managedItemInfo = undefined;
+		/** @type {ManagedFiles | undefined} */
+		this.managedFiles = undefined;
+		/** @type {ManagedContexts | undefined} */
+		this.managedContexts = undefined;
+		/** @type {ManagedMissing | undefined} */
+		this.managedMissing = undefined;
+		/** @type {Children | undefined} */
+		this.children = undefined;
+	}
+
+	hasStartTime() {
+		return (this._flags & 1) !== 0;
+	}
+
+	/**
+	 * @param {number} value start value
+	 */
+	setStartTime(value) {
+		this._flags = this._flags | 1;
+		this.startTime = value;
+	}
+
+	/**
+	 * @param {number | undefined} value value
+	 * @param {Snapshot} snapshot snapshot
+	 */
+	setMergedStartTime(value, snapshot) {
+		if (value) {
+			if (snapshot.hasStartTime()) {
+				this.setStartTime(
+					Math.min(
+						value,
+						/** @type {NonNullable<Snapshot["startTime"]>} */
+						(snapshot.startTime)
+					)
+				);
+			} else {
+				this.setStartTime(value);
+			}
+		} else if (snapshot.hasStartTime()) {
+			this.setStartTime(
+				/** @type {NonNullable<Snapshot["startTime"]>} */
+				(snapshot.startTime)
+			);
+		}
+	}
+
+	hasFileTimestamps() {
+		return (this._flags & 2) !== 0;
+	}
+
+	/**
+	 * @param {FileTimestamps} value file timestamps
+	 */
+	setFileTimestamps(value) {
+		this._flags = this._flags | 2;
+		this.fileTimestamps = value;
+	}
+
+	hasFileHashes() {
+		return (this._flags & 4) !== 0;
+	}
+
+	/**
+	 * @param {FileHashes} value file hashes
+	 */
+	setFileHashes(value) {
+		this._flags = this._flags | 4;
+		this.fileHashes = value;
+	}
+
+	hasFileTshs() {
+		return (this._flags & 8) !== 0;
+	}
+
+	/**
+	 * @param {FileTshs} value file tshs
+	 */
+	setFileTshs(value) {
+		this._flags = this._flags | 8;
+		this.fileTshs = value;
+	}
+
+	hasContextTimestamps() {
+		return (this._flags & 0x10) !== 0;
+	}
+
+	/**
+	 * @param {ContextTimestamps} value context timestamps
+	 */
+	setContextTimestamps(value) {
+		this._flags = this._flags | 0x10;
+		this.contextTimestamps = value;
+	}
+
+	hasContextHashes() {
+		return (this._flags & 0x20) !== 0;
+	}
+
+	/**
+	 * @param {ContextHashes} value context hashes
+	 */
+	setContextHashes(value) {
+		this._flags = this._flags | 0x20;
+		this.contextHashes = value;
+	}
+
+	hasContextTshs() {
+		return (this._flags & 0x40) !== 0;
+	}
+
+	/**
+	 * @param {ContextTshs} value context tshs
+	 */
+	setContextTshs(value) {
+		this._flags = this._flags | 0x40;
+		this.contextTshs = value;
+	}
+
+	hasMissingExistence() {
+		return (this._flags & 0x80) !== 0;
+	}
+
+	/**
+	 * @param {MissingExistence} value context tshs
+	 */
+	setMissingExistence(value) {
+		this._flags = this._flags | 0x80;
+		this.missingExistence = value;
+	}
+
+	hasManagedItemInfo() {
+		return (this._flags & 0x100) !== 0;
+	}
+
+	/**
+	 * @param {ManagedItemInfo} value managed item info
+	 */
+	setManagedItemInfo(value) {
+		this._flags = this._flags | 0x100;
+		this.managedItemInfo = value;
+	}
+
+	hasManagedFiles() {
+		return (this._flags & 0x200) !== 0;
+	}
+
+	/**
+	 * @param {ManagedFiles} value managed files
+	 */
+	setManagedFiles(value) {
+		this._flags = this._flags | 0x200;
+		this.managedFiles = value;
+	}
+
+	hasManagedContexts() {
+		return (this._flags & 0x400) !== 0;
+	}
+
+	/**
+	 * @param {ManagedContexts} value managed contexts
+	 */
+	setManagedContexts(value) {
+		this._flags = this._flags | 0x400;
+		this.managedContexts = value;
+	}
+
+	hasManagedMissing() {
+		return (this._flags & 0x800) !== 0;
+	}
+
+	/**
+	 * @param {ManagedMissing} value managed missing
+	 */
+	setManagedMissing(value) {
+		this._flags = this._flags | 0x800;
+		this.managedMissing = value;
+	}
+
+	hasChildren() {
+		return (this._flags & 0x1000) !== 0;
+	}
+
+	/**
+	 * @param {Children} value children
+	 */
+	setChildren(value) {
+		this._flags = this._flags | 0x1000;
+		this.children = value;
+	}
+
+	/**
+	 * @param {Snapshot} child children
+	 */
+	addChild(child) {
+		if (!this.hasChildren()) {
+			this.setChildren(new Set());
+		}
+		/** @type {Children} */
+		(this.children).add(child);
+	}
+
+	/**
+	 * @param {ObjectSerializerContext} context context
+	 */
+	serialize({ write }) {
+		write(this._flags);
+		if (this.hasStartTime()) write(this.startTime);
+		if (this.hasFileTimestamps()) write(this.fileTimestamps);
+		if (this.hasFileHashes()) write(this.fileHashes);
+		if (this.hasFileTshs()) write(this.fileTshs);
+		if (this.hasContextTimestamps()) write(this.contextTimestamps);
+		if (this.hasContextHashes()) write(this.contextHashes);
+		if (this.hasContextTshs()) write(this.contextTshs);
+		if (this.hasMissingExistence()) write(this.missingExistence);
+		if (this.hasManagedItemInfo()) write(this.managedItemInfo);
+		if (this.hasManagedFiles()) write(this.managedFiles);
+		if (this.hasManagedContexts()) write(this.managedContexts);
+		if (this.hasManagedMissing()) write(this.managedMissing);
+		if (this.hasChildren()) write(this.children);
+	}
+
+	/**
+	 * @param {ObjectDeserializerContext} context context
+	 */
+	deserialize({ read }) {
+		this._flags = read();
+		if (this.hasStartTime()) this.startTime = read();
+		if (this.hasFileTimestamps()) this.fileTimestamps = read();
+		if (this.hasFileHashes()) this.fileHashes = read();
+		if (this.hasFileTshs()) this.fileTshs = read();
+		if (this.hasContextTimestamps()) this.contextTimestamps = read();
+		if (this.hasContextHashes()) this.contextHashes = read();
+		if (this.hasContextTshs()) this.contextTshs = read();
+		if (this.hasMissingExistence()) this.missingExistence = read();
+		if (this.hasManagedItemInfo()) this.managedItemInfo = read();
+		if (this.hasManagedFiles()) this.managedFiles = read();
+		if (this.hasManagedContexts()) this.managedContexts = read();
+		if (this.hasManagedMissing()) this.managedMissing = read();
+		if (this.hasChildren()) this.children = read();
+	}
+
+	/**
+	 * @param {GetMapsFunction} getMaps first
+	 * @returns {Iterable<string>} iterable
+	 */
+	_createIterable(getMaps) {
+		return new SnapshotIterable(this, getMaps);
+	}
+
+	/**
+	 * @returns {Iterable<string>} iterable
+	 */
+	getFileIterable() {
+		if (this._cachedFileIterable === undefined) {
+			this._cachedFileIterable = this._createIterable(s => [
+				s.fileTimestamps,
+				s.fileHashes,
+				s.fileTshs,
+				s.managedFiles
+			]);
+		}
+		return this._cachedFileIterable;
+	}
+
+	/**
+	 * @returns {Iterable<string>} iterable
+	 */
+	getContextIterable() {
+		if (this._cachedContextIterable === undefined) {
+			this._cachedContextIterable = this._createIterable(s => [
+				s.contextTimestamps,
+				s.contextHashes,
+				s.contextTshs,
+				s.managedContexts
+			]);
+		}
+		return this._cachedContextIterable;
+	}
+
+	/**
+	 * @returns {Iterable<string>} iterable
+	 */
+	getMissingIterable() {
+		if (this._cachedMissingIterable === undefined) {
+			this._cachedMissingIterable = this._createIterable(s => [
+				s.missingExistence,
+				s.managedMissing
+			]);
+		}
+		return this._cachedMissingIterable;
+	}
+}
+
+makeSerializable(Snapshot, "webpack/lib/FileSystemInfo", "Snapshot");
+
+const MIN_COMMON_SNAPSHOT_SIZE = 3;
+
+/**
+ * @template U, T
+ * @typedef {U extends true ? Set<string> : Map<string, T>} SnapshotOptimizationValue
+ */
+
+/**
+ * @template T
+ * @template {boolean} [U=false]
+ */
+class SnapshotOptimization {
+	/**
+	 * @param {function(Snapshot): boolean} has has value
+	 * @param {function(Snapshot): SnapshotOptimizationValue<U, T> | undefined} get get value
+	 * @param {function(Snapshot, SnapshotOptimizationValue<U, T>): void} set set value
+	 * @param {boolean=} useStartTime use the start time of snapshots
+	 * @param {U=} isSet value is an Set instead of a Map
+	 */
+	constructor(
+		has,
+		get,
+		set,
+		useStartTime = true,
+		isSet = /** @type {U} */ (false)
+	) {
+		this._has = has;
+		this._get = get;
+		this._set = set;
+		this._useStartTime = useStartTime;
+		/** @type {U} */
+		this._isSet = isSet;
+		/** @type {Map<string, SnapshotOptimizationEntry>} */
+		this._map = new Map();
+		this._statItemsShared = 0;
+		this._statItemsUnshared = 0;
+		this._statSharedSnapshots = 0;
+		this._statReusedSharedSnapshots = 0;
+	}
+
+	getStatisticMessage() {
+		const total = this._statItemsShared + this._statItemsUnshared;
+		if (total === 0) return;
+		return `${
+			this._statItemsShared && Math.round((this._statItemsShared * 100) / total)
+		}% (${this._statItemsShared}/${total}) entries shared via ${
+			this._statSharedSnapshots
+		} shared snapshots (${
+			this._statReusedSharedSnapshots + this._statSharedSnapshots
+		} times referenced)`;
+	}
+
+	clear() {
+		this._map.clear();
+		this._statItemsShared = 0;
+		this._statItemsUnshared = 0;
+		this._statSharedSnapshots = 0;
+		this._statReusedSharedSnapshots = 0;
+	}
+
+	/**
+	 * @param {Snapshot} newSnapshot snapshot
+	 * @param {Set<string>} capturedFiles files to snapshot/share
+	 * @returns {void}
+	 */
+	optimize(newSnapshot, capturedFiles) {
+		/**
+		 * @param {SnapshotOptimizationEntry} entry optimization entry
+		 * @returns {void}
+		 */
+		const increaseSharedAndStoreOptimizationEntry = entry => {
+			if (entry.children !== undefined) {
+				for (const child of entry.children) {
+					increaseSharedAndStoreOptimizationEntry(child);
+				}
+			}
+			entry.shared++;
+			storeOptimizationEntry(entry);
+		};
+		/**
+		 * @param {SnapshotOptimizationEntry} entry optimization entry
+		 * @returns {void}
+		 */
+		const storeOptimizationEntry = entry => {
+			for (const path of /** @type {SnapshotContent} */ (
+				entry.snapshotContent
+			)) {
+				const old =
+					/** @type {SnapshotOptimizationEntry} */
+					(this._map.get(path));
+				if (old.shared < entry.shared) {
+					this._map.set(path, entry);
+				}
+				capturedFiles.delete(path);
+			}
+		};
+
+		/** @type {SnapshotOptimizationEntry | undefined} */
+		let newOptimizationEntry;
+
+		const capturedFilesSize = capturedFiles.size;
+
+		/** @type {Set<SnapshotOptimizationEntry> | undefined} */
+		const optimizationEntries = new Set();
+
+		for (const path of capturedFiles) {
+			const optimizationEntry = this._map.get(path);
+			if (optimizationEntry === undefined) {
+				if (newOptimizationEntry === undefined) {
+					newOptimizationEntry = {
+						snapshot: newSnapshot,
+						shared: 0,
+						snapshotContent: undefined,
+						children: undefined
+					};
+				}
+				this._map.set(path, newOptimizationEntry);
+				continue;
+			} else {
+				optimizationEntries.add(optimizationEntry);
+			}
+		}
+
+		optimizationEntriesLabel: for (const optimizationEntry of optimizationEntries) {
+			const snapshot = optimizationEntry.snapshot;
+			if (optimizationEntry.shared > 0) {
+				// It's a shared snapshot
+				// We can't change it, so we can only use it when all files match
+				// and startTime is compatible
+				if (
+					this._useStartTime &&
+					newSnapshot.startTime &&
+					(!snapshot.startTime || snapshot.startTime > newSnapshot.startTime)
+				) {
+					continue;
+				}
+				const nonSharedFiles = new Set();
+				const snapshotContent =
+					/** @type {NonNullable<SnapshotOptimizationEntry["snapshotContent"]>} */
+					(optimizationEntry.snapshotContent);
+				const snapshotEntries =
+					/** @type {SnapshotOptimizationValue<U, T>} */
+					(this._get(snapshot));
+				for (const path of snapshotContent) {
+					if (!capturedFiles.has(path)) {
+						if (!snapshotEntries.has(path)) {
+							// File is not shared and can't be removed from the snapshot
+							// because it's in a child of the snapshot
+							continue optimizationEntriesLabel;
+						}
+						nonSharedFiles.add(path);
+						continue;
+					}
+				}
+				if (nonSharedFiles.size === 0) {
+					// The complete snapshot is shared
+					// add it as child
+					newSnapshot.addChild(snapshot);
+					increaseSharedAndStoreOptimizationEntry(optimizationEntry);
+					this._statReusedSharedSnapshots++;
+				} else {
+					// Only a part of the snapshot is shared
+					const sharedCount = snapshotContent.size - nonSharedFiles.size;
+					if (sharedCount < MIN_COMMON_SNAPSHOT_SIZE) {
+						// Common part it too small
+						continue;
+					}
+					// Extract common timestamps from both snapshots
+					let commonMap;
+					if (this._isSet) {
+						commonMap = new Set();
+						for (const path of /** @type {Set<string>} */ (snapshotEntries)) {
+							if (nonSharedFiles.has(path)) continue;
+							commonMap.add(path);
+							snapshotEntries.delete(path);
+						}
+					} else {
+						commonMap = new Map();
+						const map = /** @type {Map<string, T>} */ (snapshotEntries);
+						for (const [path, value] of map) {
+							if (nonSharedFiles.has(path)) continue;
+							commonMap.set(path, value);
+							snapshotEntries.delete(path);
+						}
+					}
+					// Create and attach snapshot
+					const commonSnapshot = new Snapshot();
+					if (this._useStartTime) {
+						commonSnapshot.setMergedStartTime(newSnapshot.startTime, snapshot);
+					}
+					this._set(
+						commonSnapshot,
+						/** @type {SnapshotOptimizationValue<U, T>} */ (commonMap)
+					);
+					newSnapshot.addChild(commonSnapshot);
+					snapshot.addChild(commonSnapshot);
+					// Create optimization entry
+					const newEntry = {
+						snapshot: commonSnapshot,
+						shared: optimizationEntry.shared + 1,
+						snapshotContent: new Set(commonMap.keys()),
+						children: undefined
+					};
+					if (optimizationEntry.children === undefined)
+						optimizationEntry.children = new Set();
+					optimizationEntry.children.add(newEntry);
+					storeOptimizationEntry(newEntry);
+					this._statSharedSnapshots++;
+				}
+			} else {
+				// It's a unshared snapshot
+				// We can extract a common shared snapshot
+				// with all common files
+				const snapshotEntries = this._get(snapshot);
+				if (snapshotEntries === undefined) {
+					// Incomplete snapshot, that can't be used
+					continue;
+				}
+				let commonMap;
+				if (this._isSet) {
+					commonMap = new Set();
+					const set = /** @type {Set<string>} */ (snapshotEntries);
+					if (capturedFiles.size < set.size) {
+						for (const path of capturedFiles) {
+							if (set.has(path)) commonMap.add(path);
+						}
+					} else {
+						for (const path of set) {
+							if (capturedFiles.has(path)) commonMap.add(path);
+						}
+					}
+				} else {
+					commonMap = new Map();
+					const map = /** @type {Map<string, T>} */ (snapshotEntries);
+					for (const path of capturedFiles) {
+						const ts = map.get(path);
+						if (ts === undefined) continue;
+						commonMap.set(path, ts);
+					}
+				}
+
+				if (commonMap.size < MIN_COMMON_SNAPSHOT_SIZE) {
+					// Common part it too small
+					continue;
+				}
+				// Create and attach snapshot
+				const commonSnapshot = new Snapshot();
+				if (this._useStartTime) {
+					commonSnapshot.setMergedStartTime(newSnapshot.startTime, snapshot);
+				}
+				this._set(
+					commonSnapshot,
+					/** @type {SnapshotOptimizationValue<U, T>} */
+					(commonMap)
+				);
+				newSnapshot.addChild(commonSnapshot);
+				snapshot.addChild(commonSnapshot);
+				// Remove files from snapshot
+				for (const path of commonMap.keys()) snapshotEntries.delete(path);
+				const sharedCount = commonMap.size;
+				this._statItemsUnshared -= sharedCount;
+				this._statItemsShared += sharedCount;
+				// Create optimization entry
+				storeOptimizationEntry({
+					snapshot: commonSnapshot,
+					shared: 2,
+					snapshotContent: new Set(commonMap.keys()),
+					children: undefined
+				});
+				this._statSharedSnapshots++;
+			}
+		}
+		const unshared = capturedFiles.size;
+		this._statItemsUnshared += unshared;
+		this._statItemsShared += capturedFilesSize - unshared;
+	}
+}
+
+/**
+ * @param {string} str input
+ * @returns {string} result
+ */
+const parseString = str => {
+	if (str[0] === "'" || str[0] === "`")
+		str = `"${str.slice(1, -1).replace(/"/g, '\\"')}"`;
+	return JSON.parse(str);
+};
+
+/* istanbul ignore next */
+/**
+ * @param {number} mtime mtime
+ */
+const applyMtime = mtime => {
+	if (FS_ACCURACY > 1 && mtime % 2 !== 0) FS_ACCURACY = 1;
+	else if (FS_ACCURACY > 10 && mtime % 20 !== 0) FS_ACCURACY = 10;
+	else if (FS_ACCURACY > 100 && mtime % 200 !== 0) FS_ACCURACY = 100;
+	else if (FS_ACCURACY > 1000 && mtime % 2000 !== 0) FS_ACCURACY = 1000;
+};
+
+/**
+ * @template T
+ * @template K
+ * @param {Map<T, K> | undefined} a source map
+ * @param {Map<T, K> | undefined} b joining map
+ * @returns {Map<T, K>} joined map
+ */
+const mergeMaps = (a, b) => {
+	if (!b || b.size === 0) return /** @type {Map<T, K>} */ (a);
+	if (!a || a.size === 0) return /** @type {Map<T, K>} */ (b);
+	/** @type {Map<T, K>} */
+	const map = new Map(a);
+	for (const [key, value] of b) {
+		map.set(key, value);
+	}
+	return map;
+};
+
+/**
+ * @template T
+ * @param {Set<T> | undefined} a source map
+ * @param {Set<T> | undefined} b joining map
+ * @returns {Set<T>} joined map
+ */
+const mergeSets = (a, b) => {
+	if (!b || b.size === 0) return /** @type {Set<T>} */ (a);
+	if (!a || a.size === 0) return /** @type {Set<T>} */ (b);
+	/** @type {Set<T>} */
+	const map = new Set(a);
+	for (const item of b) {
+		map.add(item);
+	}
+	return map;
+};
+
+/**
+ * Finding file or directory to manage
+ * @param {string} managedPath path that is managing by {@link FileSystemInfo}
+ * @param {string} path path to file or directory
+ * @returns {string|null} managed item
+ * @example
+ * getManagedItem(
+ *   '/Users/user/my-project/node_modules/',
+ *   '/Users/user/my-project/node_modules/package/index.js'
+ * ) === '/Users/user/my-project/node_modules/package'
+ * getManagedItem(
+ *   '/Users/user/my-project/node_modules/',
+ *   '/Users/user/my-project/node_modules/package1/node_modules/package2'
+ * ) === '/Users/user/my-project/node_modules/package1/node_modules/package2'
+ * getManagedItem(
+ *   '/Users/user/my-project/node_modules/',
+ *   '/Users/user/my-project/node_modules/.bin/script.js'
+ * ) === null // hidden files are disallowed as managed items
+ * getManagedItem(
+ *   '/Users/user/my-project/node_modules/',
+ *   '/Users/user/my-project/node_modules/package'
+ * ) === '/Users/user/my-project/node_modules/package'
+ */
+const getManagedItem = (managedPath, path) => {
+	let i = managedPath.length;
+	let slashes = 1;
+	let startingPosition = true;
+	loop: while (i < path.length) {
+		switch (path.charCodeAt(i)) {
+			case 47: // slash
+			case 92: // backslash
+				if (--slashes === 0) break loop;
+				startingPosition = true;
+				break;
+			case 46: // .
+				// hidden files are disallowed as managed items
+				// it's probably .yarn-integrity or .cache
+				if (startingPosition) return null;
+				break;
+			case 64: // @
+				if (!startingPosition) return null;
+				slashes++;
+				break;
+			default:
+				startingPosition = false;
+				break;
+		}
+		i++;
+	}
+	if (i === path.length) slashes--;
+	// return null when path is incomplete
+	if (slashes !== 0) return null;
+	// if (path.slice(i + 1, i + 13) === "node_modules")
+	if (
+		path.length >= i + 13 &&
+		path.charCodeAt(i + 1) === 110 &&
+		path.charCodeAt(i + 2) === 111 &&
+		path.charCodeAt(i + 3) === 100 &&
+		path.charCodeAt(i + 4) === 101 &&
+		path.charCodeAt(i + 5) === 95 &&
+		path.charCodeAt(i + 6) === 109 &&
+		path.charCodeAt(i + 7) === 111 &&
+		path.charCodeAt(i + 8) === 100 &&
+		path.charCodeAt(i + 9) === 117 &&
+		path.charCodeAt(i + 10) === 108 &&
+		path.charCodeAt(i + 11) === 101 &&
+		path.charCodeAt(i + 12) === 115
+	) {
+		// if this is the end of the path
+		if (path.length === i + 13) {
+			// return the node_modules directory
+			// it's special
+			return path;
+		}
+		const c = path.charCodeAt(i + 13);
+		// if next symbol is slash or backslash
+		if (c === 47 || c === 92) {
+			// Managed subpath
+			return getManagedItem(path.slice(0, i + 14), path);
+		}
+	}
+	return path.slice(0, i);
+};
+
+/**
+ * @template {ContextFileSystemInfoEntry | ContextTimestampAndHash} T
+ * @param {T | null} entry entry
+ * @returns {T["resolved"] | null | undefined} the resolved entry
+ */
+const getResolvedTimestamp = entry => {
+	if (entry === null) return null;
+	if (entry.resolved !== undefined) return entry.resolved;
+	return entry.symlinks === undefined ? entry : undefined;
+};
+
+/**
+ * @param {ContextHash | null} entry entry
+ * @returns {string | null | undefined} the resolved entry
+ */
+const getResolvedHash = entry => {
+	if (entry === null) return null;
+	if (entry.resolved !== undefined) return entry.resolved;
+	return entry.symlinks === undefined ? entry.hash : undefined;
+};
+
+/**
+ * @template T
+ * @param {Set<T>} source source
+ * @param {Set<T>} target target
+ */
+const addAll = (source, target) => {
+	for (const key of source) target.add(key);
+};
+
+/** @typedef {Set<string>} LoggedPaths */
+
+/**
+ * Used to access information about the filesystem in a cached way
+ */
+class FileSystemInfo {
+	/**
+	 * @param {InputFileSystem} fs file system
+	 * @param {object} options options
+	 * @param {Iterable<string | RegExp>=} options.unmanagedPaths paths that are not managed by a package manager and the contents are subject to change
+	 * @param {Iterable<string | RegExp>=} options.managedPaths paths that are only managed by a package manager
+	 * @param {Iterable<string | RegExp>=} options.immutablePaths paths that are immutable
+	 * @param {Logger=} options.logger logger used to log invalid snapshots
+	 * @param {string | Hash=} options.hashFunction the hash function to use
+	 */
+	constructor(
+		fs,
+		{
+			unmanagedPaths = [],
+			managedPaths = [],
+			immutablePaths = [],
+			logger,
+			hashFunction = "md4"
+		} = {}
+	) {
+		this.fs = fs;
+		this.logger = logger;
+		this._remainingLogs = logger ? 40 : 0;
+		/** @type {LoggedPaths | undefined} */
+		this._loggedPaths = logger ? new Set() : undefined;
+		this._hashFunction = hashFunction;
+		/** @type {WeakMap<Snapshot, boolean | (function((WebpackError | null)=, boolean=): void)[]>} */
+		this._snapshotCache = new WeakMap();
+		this._fileTimestampsOptimization = new SnapshotOptimization(
+			s => s.hasFileTimestamps(),
+			s => s.fileTimestamps,
+			(s, v) => s.setFileTimestamps(v)
+		);
+		this._fileHashesOptimization = new SnapshotOptimization(
+			s => s.hasFileHashes(),
+			s => s.fileHashes,
+			(s, v) => s.setFileHashes(v),
+			false
+		);
+		this._fileTshsOptimization = new SnapshotOptimization(
+			s => s.hasFileTshs(),
+			s => s.fileTshs,
+			(s, v) => s.setFileTshs(v)
+		);
+		this._contextTimestampsOptimization = new SnapshotOptimization(
+			s => s.hasContextTimestamps(),
+			s => s.contextTimestamps,
+			(s, v) => s.setContextTimestamps(v)
+		);
+		this._contextHashesOptimization = new SnapshotOptimization(
+			s => s.hasContextHashes(),
+			s => s.contextHashes,
+			(s, v) => s.setContextHashes(v),
+			false
+		);
+		this._contextTshsOptimization = new SnapshotOptimization(
+			s => s.hasContextTshs(),
+			s => s.contextTshs,
+			(s, v) => s.setContextTshs(v)
+		);
+		this._missingExistenceOptimization = new SnapshotOptimization(
+			s => s.hasMissingExistence(),
+			s => s.missingExistence,
+			(s, v) => s.setMissingExistence(v),
+			false
+		);
+		this._managedItemInfoOptimization = new SnapshotOptimization(
+			s => s.hasManagedItemInfo(),
+			s => s.managedItemInfo,
+			(s, v) => s.setManagedItemInfo(v),
+			false
+		);
+		this._managedFilesOptimization = new SnapshotOptimization(
+			s => s.hasManagedFiles(),
+			s => s.managedFiles,
+			(s, v) => s.setManagedFiles(v),
+			false,
+			true
+		);
+		this._managedContextsOptimization = new SnapshotOptimization(
+			s => s.hasManagedContexts(),
+			s => s.managedContexts,
+			(s, v) => s.setManagedContexts(v),
+			false,
+			true
+		);
+		this._managedMissingOptimization = new SnapshotOptimization(
+			s => s.hasManagedMissing(),
+			s => s.managedMissing,
+			(s, v) => s.setManagedMissing(v),
+			false,
+			true
+		);
+		/** @type {StackedCacheMap<string, FileSystemInfoEntry | "ignore" | null>} */
+		this._fileTimestamps = new StackedCacheMap();
+		/** @type {Map<string, string | null>} */
+		this._fileHashes = new Map();
+		/** @type {Map<string, TimestampAndHash | string>} */
+		this._fileTshs = new Map();
+		/** @type {StackedCacheMap<string, ContextFileSystemInfoEntry | "ignore" | null>} */
+		this._contextTimestamps = new StackedCacheMap();
+		/** @type {Map<string, ContextHash>} */
+		this._contextHashes = new Map();
+		/** @type {Map<string, ContextTimestampAndHash>} */
+		this._contextTshs = new Map();
+		/** @type {Map<string, string>} */
+		this._managedItems = new Map();
+		/** @type {AsyncQueue<string, string, FileSystemInfoEntry>} */
+		this.fileTimestampQueue = new AsyncQueue({
+			name: "file timestamp",
+			parallelism: 30,
+			processor: this._readFileTimestamp.bind(this)
+		});
+		/** @type {AsyncQueue<string, string, string>} */
+		this.fileHashQueue = new AsyncQueue({
+			name: "file hash",
+			parallelism: 10,
+			processor: this._readFileHash.bind(this)
+		});
+		/** @type {AsyncQueue<string, string, ContextFileSystemInfoEntry>} */
+		this.contextTimestampQueue = new AsyncQueue({
+			name: "context timestamp",
+			parallelism: 2,
+			processor: this._readContextTimestamp.bind(this)
+		});
+		/** @type {AsyncQueue<string, string, ContextHash>} */
+		this.contextHashQueue = new AsyncQueue({
+			name: "context hash",
+			parallelism: 2,
+			processor: this._readContextHash.bind(this)
+		});
+		/** @type {AsyncQueue<string, string, ContextTimestampAndHash>} */
+		this.contextTshQueue = new AsyncQueue({
+			name: "context hash and timestamp",
+			parallelism: 2,
+			processor: this._readContextTimestampAndHash.bind(this)
+		});
+		/** @type {AsyncQueue<string, string, string>} */
+		this.managedItemQueue = new AsyncQueue({
+			name: "managed item info",
+			parallelism: 10,
+			processor: this._getManagedItemInfo.bind(this)
+		});
+		/** @type {AsyncQueue<string, string, Set<string>>} */
+		this.managedItemDirectoryQueue = new AsyncQueue({
+			name: "managed item directory info",
+			parallelism: 10,
+			processor: this._getManagedItemDirectoryInfo.bind(this)
+		});
+		const _unmanagedPaths = Array.from(unmanagedPaths);
+		this.unmanagedPathsWithSlash = /** @type {string[]} */ (
+			_unmanagedPaths.filter(p => typeof p === "string")
+		).map(p => join(fs, p, "_").slice(0, -1));
+		this.unmanagedPathsRegExps = /** @type {RegExp[]} */ (
+			_unmanagedPaths.filter(p => typeof p !== "string")
+		);
+
+		this.managedPaths = Array.from(managedPaths);
+		this.managedPathsWithSlash = /** @type {string[]} */ (
+			this.managedPaths.filter(p => typeof p === "string")
+		).map(p => join(fs, p, "_").slice(0, -1));
+
+		this.managedPathsRegExps = /** @type {RegExp[]} */ (
+			this.managedPaths.filter(p => typeof p !== "string")
+		);
+		this.immutablePaths = Array.from(immutablePaths);
+		this.immutablePathsWithSlash = /** @type {string[]} */ (
+			this.immutablePaths.filter(p => typeof p === "string")
+		).map(p => join(fs, p, "_").slice(0, -1));
+		this.immutablePathsRegExps = /** @type {RegExp[]} */ (
+			this.immutablePaths.filter(p => typeof p !== "string")
+		);
+
+		this._cachedDeprecatedFileTimestamps = undefined;
+		this._cachedDeprecatedContextTimestamps = undefined;
+
+		this._warnAboutExperimentalEsmTracking = false;
+
+		this._statCreatedSnapshots = 0;
+		this._statTestedSnapshotsCached = 0;
+		this._statTestedSnapshotsNotCached = 0;
+		this._statTestedChildrenCached = 0;
+		this._statTestedChildrenNotCached = 0;
+		this._statTestedEntries = 0;
+	}
+
+	logStatistics() {
+		const logger = /** @type {Logger} */ (this.logger);
+		/**
+		 * @param {string} header header
+		 * @param {string | undefined} message message
+		 */
+		const logWhenMessage = (header, message) => {
+			if (message) {
+				logger.log(`${header}: ${message}`);
+			}
+		};
+		logger.log(`${this._statCreatedSnapshots} new snapshots created`);
+		logger.log(
+			`${
+				this._statTestedSnapshotsNotCached &&
+				Math.round(
+					(this._statTestedSnapshotsNotCached * 100) /
+						(this._statTestedSnapshotsCached +
+							this._statTestedSnapshotsNotCached)
+				)
+			}% root snapshot uncached (${this._statTestedSnapshotsNotCached} / ${
+				this._statTestedSnapshotsCached + this._statTestedSnapshotsNotCached
+			})`
+		);
+		logger.log(
+			`${
+				this._statTestedChildrenNotCached &&
+				Math.round(
+					(this._statTestedChildrenNotCached * 100) /
+						(this._statTestedChildrenCached + this._statTestedChildrenNotCached)
+				)
+			}% children snapshot uncached (${this._statTestedChildrenNotCached} / ${
+				this._statTestedChildrenCached + this._statTestedChildrenNotCached
+			})`
+		);
+		logger.log(`${this._statTestedEntries} entries tested`);
+		logger.log(
+			`File info in cache: ${this._fileTimestamps.size} timestamps ${this._fileHashes.size} hashes ${this._fileTshs.size} timestamp hash combinations`
+		);
+		logWhenMessage(
+			"File timestamp snapshot optimization",
+			this._fileTimestampsOptimization.getStatisticMessage()
+		);
+		logWhenMessage(
+			"File hash snapshot optimization",
+			this._fileHashesOptimization.getStatisticMessage()
+		);
+		logWhenMessage(
+			"File timestamp hash combination snapshot optimization",
+			this._fileTshsOptimization.getStatisticMessage()
+		);
+		logger.log(
+			`Directory info in cache: ${this._contextTimestamps.size} timestamps ${this._contextHashes.size} hashes ${this._contextTshs.size} timestamp hash combinations`
+		);
+		logWhenMessage(
+			"Directory timestamp snapshot optimization",
+			this._contextTimestampsOptimization.getStatisticMessage()
+		);
+		logWhenMessage(
+			"Directory hash snapshot optimization",
+			this._contextHashesOptimization.getStatisticMessage()
+		);
+		logWhenMessage(
+			"Directory timestamp hash combination snapshot optimization",
+			this._contextTshsOptimization.getStatisticMessage()
+		);
+		logWhenMessage(
+			"Missing items snapshot optimization",
+			this._missingExistenceOptimization.getStatisticMessage()
+		);
+		logger.log(`Managed items info in cache: ${this._managedItems.size} items`);
+		logWhenMessage(
+			"Managed items snapshot optimization",
+			this._managedItemInfoOptimization.getStatisticMessage()
+		);
+		logWhenMessage(
+			"Managed files snapshot optimization",
+			this._managedFilesOptimization.getStatisticMessage()
+		);
+		logWhenMessage(
+			"Managed contexts snapshot optimization",
+			this._managedContextsOptimization.getStatisticMessage()
+		);
+		logWhenMessage(
+			"Managed missing snapshot optimization",
+			this._managedMissingOptimization.getStatisticMessage()
+		);
+	}
+
+	/**
+	 * @param {string} path path
+	 * @param {string} reason reason
+	 * @param {any[]} args arguments
+	 */
+	_log(path, reason, ...args) {
+		const key = path + reason;
+		const loggedPaths = /** @type {LoggedPaths} */ (this._loggedPaths);
+		if (loggedPaths.has(key)) return;
+		loggedPaths.add(key);
+		/** @type {Logger} */
+		(this.logger).debug(`${path} invalidated because ${reason}`, ...args);
+		if (--this._remainingLogs === 0) {
+			/** @type {Logger} */
+			(this.logger).debug(
+				"Logging limit has been reached and no further logging will be emitted by FileSystemInfo"
+			);
+		}
+	}
+
+	clear() {
+		this._remainingLogs = this.logger ? 40 : 0;
+		if (this._loggedPaths !== undefined) this._loggedPaths.clear();
+
+		this._snapshotCache = new WeakMap();
+		this._fileTimestampsOptimization.clear();
+		this._fileHashesOptimization.clear();
+		this._fileTshsOptimization.clear();
+		this._contextTimestampsOptimization.clear();
+		this._contextHashesOptimization.clear();
+		this._contextTshsOptimization.clear();
+		this._missingExistenceOptimization.clear();
+		this._managedItemInfoOptimization.clear();
+		this._managedFilesOptimization.clear();
+		this._managedContextsOptimization.clear();
+		this._managedMissingOptimization.clear();
+		this._fileTimestamps.clear();
+		this._fileHashes.clear();
+		this._fileTshs.clear();
+		this._contextTimestamps.clear();
+		this._contextHashes.clear();
+		this._contextTshs.clear();
+		this._managedItems.clear();
+		this._managedItems.clear();
+
+		this._cachedDeprecatedFileTimestamps = undefined;
+		this._cachedDeprecatedContextTimestamps = undefined;
+
+		this._statCreatedSnapshots = 0;
+		this._statTestedSnapshotsCached = 0;
+		this._statTestedSnapshotsNotCached = 0;
+		this._statTestedChildrenCached = 0;
+		this._statTestedChildrenNotCached = 0;
+		this._statTestedEntries = 0;
+	}
+
+	/**
+	 * @param {ReadonlyMap<string, FileSystemInfoEntry | "ignore" | null>} map timestamps
+	 * @param {boolean=} immutable if 'map' is immutable and FileSystemInfo can keep referencing it
+	 * @returns {void}
+	 */
+	addFileTimestamps(map, immutable) {
+		this._fileTimestamps.addAll(map, immutable);
+		this._cachedDeprecatedFileTimestamps = undefined;
+	}
+
+	/**
+	 * @param {ReadonlyMap<string, FileSystemInfoEntry | "ignore" | null>} map timestamps
+	 * @param {boolean=} immutable if 'map' is immutable and FileSystemInfo can keep referencing it
+	 * @returns {void}
+	 */
+	addContextTimestamps(map, immutable) {
+		this._contextTimestamps.addAll(map, immutable);
+		this._cachedDeprecatedContextTimestamps = undefined;
+	}
+
+	/**
+	 * @param {string} path file path
+	 * @param {function((WebpackError | null)=, (FileSystemInfoEntry | "ignore" | null)=): void} callback callback function
+	 * @returns {void}
+	 */
+	getFileTimestamp(path, callback) {
+		const cache = this._fileTimestamps.get(path);
+		if (cache !== undefined) return callback(null, cache);
+		this.fileTimestampQueue.add(path, callback);
+	}
+
+	/**
+	 * @param {string} path context path
+	 * @param {function((WebpackError | null)=, (ResolvedContextFileSystemInfoEntry | "ignore" | null)=): void} callback callback function
+	 * @returns {void}
+	 */
+	getContextTimestamp(path, callback) {
+		const cache = this._contextTimestamps.get(path);
+		if (cache !== undefined) {
+			if (cache === "ignore") return callback(null, "ignore");
+			const resolved = getResolvedTimestamp(cache);
+			if (resolved !== undefined) return callback(null, resolved);
+			return this._resolveContextTimestamp(
+				/** @type {ResolvedContextFileSystemInfoEntry} */
+				(cache),
+				callback
+			);
+		}
+		this.contextTimestampQueue.add(path, (err, _entry) => {
+			if (err) return callback(err);
+			const entry = /** @type {ContextFileSystemInfoEntry} */ (_entry);
+			const resolved = getResolvedTimestamp(entry);
+			if (resolved !== undefined) return callback(null, resolved);
+			this._resolveContextTimestamp(entry, callback);
+		});
+	}
+
+	/**
+	 * @param {string} path context path
+	 * @param {function((WebpackError | null)=, (ContextFileSystemInfoEntry | "ignore" | null)=): void} callback callback function
+	 * @returns {void}
+	 */
+	_getUnresolvedContextTimestamp(path, callback) {
+		const cache = this._contextTimestamps.get(path);
+		if (cache !== undefined) return callback(null, cache);
+		this.contextTimestampQueue.add(path, callback);
+	}
+
+	/**
+	 * @param {string} path file path
+	 * @param {function((WebpackError | null)=, (string | null)=): void} callback callback function
+	 * @returns {void}
+	 */
+	getFileHash(path, callback) {
+		const cache = this._fileHashes.get(path);
+		if (cache !== undefined) return callback(null, cache);
+		this.fileHashQueue.add(path, callback);
+	}
+
+	/**
+	 * @param {string} path context path
+	 * @param {function((WebpackError | null)=, string=): void} callback callback function
+	 * @returns {void}
+	 */
+	getContextHash(path, callback) {
+		const cache = this._contextHashes.get(path);
+		if (cache !== undefined) {
+			const resolved = getResolvedHash(cache);
+			if (resolved !== undefined)
+				return callback(null, /** @type {string} */ (resolved));
+			return this._resolveContextHash(cache, callback);
+		}
+		this.contextHashQueue.add(path, (err, _entry) => {
+			if (err) return callback(err);
+			const entry = /** @type {ContextHash} */ (_entry);
+			const resolved = getResolvedHash(entry);
+			if (resolved !== undefined)
+				return callback(null, /** @type {string} */ (resolved));
+			this._resolveContextHash(entry, callback);
+		});
+	}
+
+	/**
+	 * @param {string} path context path
+	 * @param {function((WebpackError | null)=, (ContextHash | null)=): void} callback callback function
+	 * @returns {void}
+	 */
+	_getUnresolvedContextHash(path, callback) {
+		const cache = this._contextHashes.get(path);
+		if (cache !== undefined) return callback(null, cache);
+		this.contextHashQueue.add(path, callback);
+	}
+
+	/**
+	 * @param {string} path context path
+	 * @param {function((WebpackError | null)=, (ResolvedContextTimestampAndHash | null)=): void} callback callback function
+	 * @returns {void}
+	 */
+	getContextTsh(path, callback) {
+		const cache = this._contextTshs.get(path);
+		if (cache !== undefined) {
+			const resolved = getResolvedTimestamp(cache);
+			if (resolved !== undefined) return callback(null, resolved);
+			return this._resolveContextTsh(cache, callback);
+		}
+		this.contextTshQueue.add(path, (err, _entry) => {
+			if (err) return callback(err);
+			const entry = /** @type {ContextTimestampAndHash} */ (_entry);
+			const resolved = getResolvedTimestamp(entry);
+			if (resolved !== undefined) return callback(null, resolved);
+			this._resolveContextTsh(entry, callback);
+		});
+	}
+
+	/**
+	 * @param {string} path context path
+	 * @param {function((WebpackError | null)=, (ContextTimestampAndHash | null)=): void} callback callback function
+	 * @returns {void}
+	 */
+	_getUnresolvedContextTsh(path, callback) {
+		const cache = this._contextTshs.get(path);
+		if (cache !== undefined) return callback(null, cache);
+		this.contextTshQueue.add(path, callback);
+	}
+
+	_createBuildDependenciesResolvers() {
+		const resolveContext = createResolver({
+			resolveToContext: true,
+			exportsFields: [],
+			fileSystem: this.fs
+		});
+		const resolveCjs = createResolver({
+			extensions: [".js", ".json", ".node"],
+			conditionNames: ["require", "node"],
+			exportsFields: ["exports"],
+			fileSystem: this.fs
+		});
+		const resolveCjsAsChild = createResolver({
+			extensions: [".js", ".json", ".node"],
+			conditionNames: ["require", "node"],
+			exportsFields: [],
+			fileSystem: this.fs
+		});
+		const resolveEsm = createResolver({
+			extensions: [".js", ".json", ".node"],
+			fullySpecified: true,
+			conditionNames: ["import", "node"],
+			exportsFields: ["exports"],
+			fileSystem: this.fs
+		});
+		return { resolveContext, resolveEsm, resolveCjs, resolveCjsAsChild };
+	}
+
+	/**
+	 * @param {string} context context directory
+	 * @param {Iterable<string>} deps dependencies
+	 * @param {function((Error | null)=, ResolveBuildDependenciesResult=): void} callback callback function
+	 * @returns {void}
+	 */
+	resolveBuildDependencies(context, deps, callback) {
+		const { resolveContext, resolveEsm, resolveCjs, resolveCjsAsChild } =
+			this._createBuildDependenciesResolvers();
+
+		/** @type {Set<string>} */
+		const files = new Set();
+		/** @type {Set<string>} */
+		const fileSymlinks = new Set();
+		/** @type {Set<string>} */
+		const directories = new Set();
+		/** @type {Set<string>} */
+		const directorySymlinks = new Set();
+		/** @type {Set<string>} */
+		const missing = new Set();
+		/** @type {Set<string>} */
+		const resolveFiles = new Set();
+		/** @type {Set<string>} */
+		const resolveDirectories = new Set();
+		/** @type {Set<string>} */
+		const resolveMissing = new Set();
+		/** @type {Map<string, string | false | undefined>} */
+		const resolveResults = new Map();
+		const invalidResolveResults = new Set();
+		const resolverContext = {
+			fileDependencies: resolveFiles,
+			contextDependencies: resolveDirectories,
+			missingDependencies: resolveMissing
+		};
+		/**
+		 * @param {undefined | boolean | string} expected expected result
+		 * @returns {string} expected result
+		 */
+		const expectedToString = expected =>
+			expected ? ` (expected ${expected})` : "";
+		/** @typedef {{ type: JobType, context: string | undefined, path: string, issuer: Job | undefined, expected: undefined | boolean | string }} Job */
+
+		/**
+		 * @param {Job} job job
+		 * @returns {`resolve commonjs file ${string}${string}`|`resolve esm file ${string}${string}`|`resolve esm ${string}${string}`|`resolve directory ${string}`|`file ${string}`|`unknown ${string} ${string}`|`resolve commonjs ${string}${string}`|`directory ${string}`|`file dependencies ${string}`|`directory dependencies ${string}`} result
+		 */
+		const jobToString = job => {
+			switch (job.type) {
+				case RBDT_RESOLVE_CJS:
+					return `resolve commonjs ${job.path}${expectedToString(
+						job.expected
+					)}`;
+				case RBDT_RESOLVE_ESM:
+					return `resolve esm ${job.path}${expectedToString(job.expected)}`;
+				case RBDT_RESOLVE_DIRECTORY:
+					return `resolve directory ${job.path}`;
+				case RBDT_RESOLVE_CJS_FILE:
+					return `resolve commonjs file ${job.path}${expectedToString(
+						job.expected
+					)}`;
+				case RBDT_RESOLVE_ESM_FILE:
+					return `resolve esm file ${job.path}${expectedToString(
+						job.expected
+					)}`;
+				case RBDT_DIRECTORY:
+					return `directory ${job.path}`;
+				case RBDT_FILE:
+					return `file ${job.path}`;
+				case RBDT_DIRECTORY_DEPENDENCIES:
+					return `directory dependencies ${job.path}`;
+				case RBDT_FILE_DEPENDENCIES:
+					return `file dependencies ${job.path}`;
+			}
+			return `unknown ${job.type} ${job.path}`;
+		};
+		/**
+		 * @param {Job} job job
+		 * @returns {string} string value
+		 */
+		const pathToString = job => {
+			let result = ` at ${jobToString(job)}`;
+			/** @type {Job | undefined} */
+			(job) = job.issuer;
+			while (job !== undefined) {
+				result += `\n at ${jobToString(job)}`;
+				job = /** @type {Job} */ (job.issuer);
+			}
+			return result;
+		};
+		const logger = /** @type {Logger} */ (this.logger);
+		processAsyncTree(
+			Array.from(
+				deps,
+				dep =>
+					/** @type {Job} */ ({
+						type: RBDT_RESOLVE_CJS,
+						context,
+						path: dep,
+						expected: undefined,
+						issuer: undefined
+					})
+			),
+			20,
+			(job, push, callback) => {
+				const { type, context, path, expected } = job;
+				/**
+				 * @param {string} path path
+				 * @returns {void}
+				 */
+				const resolveDirectory = path => {
+					const key = `d\n${context}\n${path}`;
+					if (resolveResults.has(key)) {
+						return callback();
+					}
+					resolveResults.set(key, undefined);
+					resolveContext(
+						/** @type {string} */ (context),
+						path,
+						resolverContext,
+						(err, _, result) => {
+							if (err) {
+								if (expected === false) {
+									resolveResults.set(key, false);
+									return callback();
+								}
+								invalidResolveResults.add(key);
+								err.message += `\nwhile resolving '${path}' in ${context} to a directory`;
+								return callback(err);
+							}
+							const resultPath = /** @type {ResolveRequest} */ (result).path;
+							resolveResults.set(key, resultPath);
+							push({
+								type: RBDT_DIRECTORY,
+								context: undefined,
+								path: /** @type {string} */ (resultPath),
+								expected: undefined,
+								issuer: job
+							});
+							callback();
+						}
+					);
+				};
+				/**
+				 * @param {string} path path
+				 * @param {("f" | "c" | "e")=} symbol symbol
+				 * @param {(ResolveFunctionAsync)=} resolve resolve fn
+				 * @returns {void}
+				 */
+				const resolveFile = (path, symbol, resolve) => {
+					const key = `${symbol}\n${context}\n${path}`;
+					if (resolveResults.has(key)) {
+						return callback();
+					}
+					resolveResults.set(key, undefined);
+					/** @type {ResolveFunctionAsync} */
+					(resolve)(
+						/** @type {string} */ (context),
+						path,
+						resolverContext,
+						(err, _, result) => {
+							if (typeof expected === "string") {
+								if (!err && result && result.path === expected) {
+									resolveResults.set(key, result.path);
+								} else {
+									invalidResolveResults.add(key);
+									logger.warn(
+										`Resolving '${path}' in ${context} for build dependencies doesn't lead to expected result '${expected}', but to '${
+											err || (result && result.path)
+										}' instead. Resolving dependencies are ignored for this path.\n${pathToString(
+											job
+										)}`
+									);
+								}
+							} else {
+								if (err) {
+									if (expected === false) {
+										resolveResults.set(key, false);
+										return callback();
+									}
+									invalidResolveResults.add(key);
+									err.message += `\nwhile resolving '${path}' in ${context} as file\n${pathToString(
+										job
+									)}`;
+									return callback(err);
+								}
+								const resultPath = /** @type {ResolveRequest} */ (result).path;
+								resolveResults.set(key, resultPath);
+								push({
+									type: RBDT_FILE,
+									context: undefined,
+									path: /** @type {string} */ (resultPath),
+									expected: undefined,
+									issuer: job
+								});
+							}
+							callback();
+						}
+					);
+				};
+				switch (type) {
+					case RBDT_RESOLVE_CJS: {
+						const isDirectory = /[\\/]$/.test(path);
+						if (isDirectory) {
+							resolveDirectory(path.slice(0, -1));
+						} else {
+							resolveFile(path, "f", resolveCjs);
+						}
+						break;
+					}
+					case RBDT_RESOLVE_ESM: {
+						const isDirectory = /[\\/]$/.test(path);
+						if (isDirectory) {
+							resolveDirectory(path.slice(0, -1));
+						} else {
+							resolveFile(path);
+						}
+						break;
+					}
+					case RBDT_RESOLVE_DIRECTORY: {
+						resolveDirectory(path);
+						break;
+					}
+					case RBDT_RESOLVE_CJS_FILE: {
+						resolveFile(path, "f", resolveCjs);
+						break;
+					}
+					case RBDT_RESOLVE_CJS_FILE_AS_CHILD: {
+						resolveFile(path, "c", resolveCjsAsChild);
+						break;
+					}
+					case RBDT_RESOLVE_ESM_FILE: {
+						resolveFile(path, "e", resolveEsm);
+						break;
+					}
+					case RBDT_FILE: {
+						if (files.has(path)) {
+							callback();
+							break;
+						}
+						files.add(path);
+						/** @type {NonNullable<InputFileSystem["realpath"]>} */
+						(this.fs.realpath)(path, (err, _realPath) => {
+							if (err) return callback(err);
+							const realPath = /** @type {string} */ (_realPath);
+							if (realPath !== path) {
+								fileSymlinks.add(path);
+								resolveFiles.add(path);
+								if (files.has(realPath)) return callback();
+								files.add(realPath);
+							}
+							push({
+								type: RBDT_FILE_DEPENDENCIES,
+								context: undefined,
+								path: realPath,
+								expected: undefined,
+								issuer: job
+							});
+							callback();
+						});
+						break;
+					}
+					case RBDT_DIRECTORY: {
+						if (directories.has(path)) {
+							callback();
+							break;
+						}
+						directories.add(path);
+						/** @type {NonNullable<InputFileSystem["realpath"]>} */
+						(this.fs.realpath)(path, (err, _realPath) => {
+							if (err) return callback(err);
+							const realPath = /** @type {string} */ (_realPath);
+							if (realPath !== path) {
+								directorySymlinks.add(path);
+								resolveFiles.add(path);
+								if (directories.has(realPath)) return callback();
+								directories.add(realPath);
+							}
+							push({
+								type: RBDT_DIRECTORY_DEPENDENCIES,
+								context: undefined,
+								path: realPath,
+								expected: undefined,
+								issuer: job
+							});
+							callback();
+						});
+						break;
+					}
+					case RBDT_FILE_DEPENDENCIES: {
+						// Check for known files without dependencies
+						if (/\.json5?$|\.yarn-integrity$|yarn\.lock$|\.ya?ml/.test(path)) {
+							process.nextTick(callback);
+							break;
+						}
+						// Check commonjs cache for the module
+						/** @type {NodeModule | undefined} */
+						const module = require.cache[path];
+						if (module && Array.isArray(module.children)) {
+							children: for (const child of module.children) {
+								const childPath = child.filename;
+								if (childPath) {
+									push({
+										type: RBDT_FILE,
+										context: undefined,
+										path: childPath,
+										expected: undefined,
+										issuer: job
+									});
+									const context = dirname(this.fs, path);
+									for (const modulePath of module.paths) {
+										if (childPath.startsWith(modulePath)) {
+											const subPath = childPath.slice(modulePath.length + 1);
+											const packageMatch = /^(@[^\\/]+[\\/])[^\\/]+/.exec(
+												subPath
+											);
+											if (packageMatch) {
+												push({
+													type: RBDT_FILE,
+													context: undefined,
+													path: `${
+														modulePath +
+														childPath[modulePath.length] +
+														packageMatch[0] +
+														childPath[modulePath.length]
+													}package.json`,
+													expected: false,
+													issuer: job
+												});
+											}
+											let request = subPath.replace(/\\/g, "/");
+											if (request.endsWith(".js"))
+												request = request.slice(0, -3);
+											push({
+												type: RBDT_RESOLVE_CJS_FILE_AS_CHILD,
+												context,
+												path: request,
+												expected: child.filename,
+												issuer: job
+											});
+											continue children;
+										}
+									}
+									let request = relative(this.fs, context, childPath);
+									if (request.endsWith(".js")) request = request.slice(0, -3);
+									request = request.replace(/\\/g, "/");
+									if (!request.startsWith("../") && !isAbsolute(request)) {
+										request = `./${request}`;
+									}
+									push({
+										type: RBDT_RESOLVE_CJS_FILE,
+										context,
+										path: request,
+										expected: child.filename,
+										issuer: job
+									});
+								}
+							}
+						} else if (supportsEsm && /\.m?js$/.test(path)) {
+							if (!this._warnAboutExperimentalEsmTracking) {
+								logger.log(
+									"Node.js doesn't offer a (nice) way to introspect the ESM dependency graph yet.\n" +
+										"Until a full solution is available webpack uses an experimental ESM tracking based on parsing.\n" +
+										"As best effort webpack parses the ESM files to guess dependencies. But this can lead to expensive and incorrect tracking."
+								);
+								this._warnAboutExperimentalEsmTracking = true;
+							}
+							const lexer = require("es-module-lexer");
+							lexer.init.then(() => {
+								this.fs.readFile(path, (err, content) => {
+									if (err) return callback(err);
+									try {
+										const context = dirname(this.fs, path);
+										const source = /** @type {Buffer} */ (content).toString();
+										const [imports] = lexer.parse(source);
+										for (const imp of imports) {
+											try {
+												let dependency;
+												if (imp.d === -1) {
+													// import ... from "..."
+													dependency = parseString(
+														source.substring(imp.s - 1, imp.e + 1)
+													);
+												} else if (imp.d > -1) {
+													// import()
+													const expr = source.substring(imp.s, imp.e).trim();
+													dependency = parseString(expr);
+												} else {
+													// e.g. import.meta
+													continue;
+												}
+
+												// we should not track Node.js build dependencies
+												if (dependency.startsWith("node:")) continue;
+												if (builtinModules.has(dependency)) continue;
+
+												push({
+													type: RBDT_RESOLVE_ESM_FILE,
+													context,
+													path: dependency,
+													expected: imp.d > -1 ? false : undefined,
+													issuer: job
+												});
+											} catch (err1) {
+												logger.warn(
+													`Parsing of ${path} for build dependencies failed at 'import(${source.substring(
+														imp.s,
+														imp.e
+													)})'.\n` +
+														"Build dependencies behind this expression are ignored and might cause incorrect cache invalidation."
+												);
+												logger.debug(pathToString(job));
+												logger.debug(/** @type {Error} */ (err1).stack);
+											}
+										}
+									} catch (err2) {
+										logger.warn(
+											`Parsing of ${path} for build dependencies failed and all dependencies of this file are ignored, which might cause incorrect cache invalidation..`
+										);
+										logger.debug(pathToString(job));
+										logger.debug(/** @type {Error} */ (err2).stack);
+									}
+									process.nextTick(callback);
+								});
+							}, callback);
+							break;
+						} else {
+							logger.log(
+								`Assuming ${path} has no dependencies as we were unable to assign it to any module system.`
+							);
+							logger.debug(pathToString(job));
+						}
+						process.nextTick(callback);
+						break;
+					}
+					case RBDT_DIRECTORY_DEPENDENCIES: {
+						const match =
+							/(^.+[\\/]node_modules[\\/](?:@[^\\/]+[\\/])?[^\\/]+)/.exec(path);
+						const packagePath = match ? match[1] : path;
+						const packageJson = join(this.fs, packagePath, "package.json");
+						this.fs.readFile(packageJson, (err, content) => {
+							if (err) {
+								if (err.code === "ENOENT") {
+									resolveMissing.add(packageJson);
+									const parent = dirname(this.fs, packagePath);
+									if (parent !== packagePath) {
+										push({
+											type: RBDT_DIRECTORY_DEPENDENCIES,
+											context: undefined,
+											path: parent,
+											expected: undefined,
+											issuer: job
+										});
+									}
+									callback();
+									return;
+								}
+								return callback(err);
+							}
+							resolveFiles.add(packageJson);
+							let packageData;
+							try {
+								packageData = JSON.parse(
+									/** @type {Buffer} */ (content).toString("utf-8")
+								);
+							} catch (parseErr) {
+								return callback(/** @type {Error} */ (parseErr));
+							}
+							const depsObject = packageData.dependencies;
+							const optionalDepsObject = packageData.optionalDependencies;
+							const allDeps = new Set();
+							const optionalDeps = new Set();
+							if (typeof depsObject === "object" && depsObject) {
+								for (const dep of Object.keys(depsObject)) {
+									allDeps.add(dep);
+								}
+							}
+							if (
+								typeof optionalDepsObject === "object" &&
+								optionalDepsObject
+							) {
+								for (const dep of Object.keys(optionalDepsObject)) {
+									allDeps.add(dep);
+									optionalDeps.add(dep);
+								}
+							}
+							for (const dep of allDeps) {
+								push({
+									type: RBDT_RESOLVE_DIRECTORY,
+									context: packagePath,
+									path: dep,
+									expected: !optionalDeps.has(dep),
+									issuer: job
+								});
+							}
+							callback();
+						});
+						break;
+					}
+				}
+			},
+			err => {
+				if (err) return callback(err);
+				for (const l of fileSymlinks) files.delete(l);
+				for (const l of directorySymlinks) directories.delete(l);
+				for (const k of invalidResolveResults) resolveResults.delete(k);
+				callback(null, {
+					files,
+					directories,
+					missing,
+					resolveResults,
+					resolveDependencies: {
+						files: resolveFiles,
+						directories: resolveDirectories,
+						missing: resolveMissing
+					}
+				});
+			}
+		);
+	}
+
+	/**
+	 * @param {Map<string, string | false>} resolveResults results from resolving
+	 * @param {function((Error | null)=, boolean=): void} callback callback with true when resolveResults resolve the same way
+	 * @returns {void}
+	 */
+	checkResolveResultsValid(resolveResults, callback) {
+		const { resolveCjs, resolveCjsAsChild, resolveEsm, resolveContext } =
+			this._createBuildDependenciesResolvers();
+		asyncLib.eachLimit(
+			resolveResults,
+			20,
+			([key, expectedResult], callback) => {
+				const [type, context, path] = key.split("\n");
+				switch (type) {
+					case "d":
+						resolveContext(context, path, {}, (err, _, result) => {
+							if (expectedResult === false)
+								return callback(err ? undefined : INVALID);
+							if (err) return callback(err);
+							const resultPath = /** @type {ResolveRequest} */ (result).path;
+							if (resultPath !== expectedResult) return callback(INVALID);
+							callback();
+						});
+						break;
+					case "f":
+						resolveCjs(context, path, {}, (err, _, result) => {
+							if (expectedResult === false)
+								return callback(err ? undefined : INVALID);
+							if (err) return callback(err);
+							const resultPath = /** @type {ResolveRequest} */ (result).path;
+							if (resultPath !== expectedResult) return callback(INVALID);
+							callback();
+						});
+						break;
+					case "c":
+						resolveCjsAsChild(context, path, {}, (err, _, result) => {
+							if (expectedResult === false)
+								return callback(err ? undefined : INVALID);
+							if (err) return callback(err);
+							const resultPath = /** @type {ResolveRequest} */ (result).path;
+							if (resultPath !== expectedResult) return callback(INVALID);
+							callback();
+						});
+						break;
+					case "e":
+						resolveEsm(context, path, {}, (err, _, result) => {
+							if (expectedResult === false)
+								return callback(err ? undefined : INVALID);
+							if (err) return callback(err);
+							const resultPath = /** @type {ResolveRequest} */ (result).path;
+							if (resultPath !== expectedResult) return callback(INVALID);
+							callback();
+						});
+						break;
+					default:
+						callback(new Error("Unexpected type in resolve result key"));
+						break;
+				}
+			},
+			/**
+			 * @param {Error | typeof INVALID=} err error or invalid flag
+			 * @returns {void}
+			 */
+			err => {
+				if (err === INVALID) {
+					return callback(null, false);
+				}
+				if (err) {
+					return callback(err);
+				}
+				return callback(null, true);
+			}
+		);
+	}
+
+	/**
+	 * @param {number | null | undefined} startTime when processing the files has started
+	 * @param {Iterable<string> | null} files all files
+	 * @param {Iterable<string> | null} directories all directories
+	 * @param {Iterable<string> | null} missing all missing files or directories
+	 * @param {SnapshotOptions | null | undefined} options options object (for future extensions)
+	 * @param {function(WebpackError | null, Snapshot | null): void} callback callback function
+	 * @returns {void}
+	 */
+	createSnapshot(startTime, files, directories, missing, options, callback) {
+		/** @type {FileTimestamps} */
+		const fileTimestamps = new Map();
+		/** @type {FileHashes} */
+		const fileHashes = new Map();
+		/** @type {FileTshs} */
+		const fileTshs = new Map();
+		/** @type {ContextTimestamps} */
+		const contextTimestamps = new Map();
+		/** @type {ContextHashes} */
+		const contextHashes = new Map();
+		/** @type {ContextTshs} */
+		const contextTshs = new Map();
+		/** @type {MissingExistence} */
+		const missingExistence = new Map();
+		/** @type {ManagedItemInfo} */
+		const managedItemInfo = new Map();
+		/** @type {ManagedFiles} */
+		const managedFiles = new Set();
+		/** @type {ManagedContexts} */
+		const managedContexts = new Set();
+		/** @type {ManagedMissing} */
+		const managedMissing = new Set();
+		/** @type {Children} */
+		const children = new Set();
+
+		const snapshot = new Snapshot();
+		if (startTime) snapshot.setStartTime(startTime);
+
+		/** @type {Set<string>} */
+		const managedItems = new Set();
+
+		/** 1 = timestamp, 2 = hash, 3 = timestamp + hash */
+		const mode = options && options.hash ? (options.timestamp ? 3 : 2) : 1;
+
+		let jobs = 1;
+		const jobDone = () => {
+			if (--jobs === 0) {
+				if (fileTimestamps.size !== 0) {
+					snapshot.setFileTimestamps(fileTimestamps);
+				}
+				if (fileHashes.size !== 0) {
+					snapshot.setFileHashes(fileHashes);
+				}
+				if (fileTshs.size !== 0) {
+					snapshot.setFileTshs(fileTshs);
+				}
+				if (contextTimestamps.size !== 0) {
+					snapshot.setContextTimestamps(contextTimestamps);
+				}
+				if (contextHashes.size !== 0) {
+					snapshot.setContextHashes(contextHashes);
+				}
+				if (contextTshs.size !== 0) {
+					snapshot.setContextTshs(contextTshs);
+				}
+				if (missingExistence.size !== 0) {
+					snapshot.setMissingExistence(missingExistence);
+				}
+				if (managedItemInfo.size !== 0) {
+					snapshot.setManagedItemInfo(managedItemInfo);
+				}
+				this._managedFilesOptimization.optimize(snapshot, managedFiles);
+				if (managedFiles.size !== 0) {
+					snapshot.setManagedFiles(managedFiles);
+				}
+				this._managedContextsOptimization.optimize(snapshot, managedContexts);
+				if (managedContexts.size !== 0) {
+					snapshot.setManagedContexts(managedContexts);
+				}
+				this._managedMissingOptimization.optimize(snapshot, managedMissing);
+				if (managedMissing.size !== 0) {
+					snapshot.setManagedMissing(managedMissing);
+				}
+				if (children.size !== 0) {
+					snapshot.setChildren(children);
+				}
+				this._snapshotCache.set(snapshot, true);
+				this._statCreatedSnapshots++;
+
+				callback(null, snapshot);
+			}
+		};
+		const jobError = () => {
+			if (jobs > 0) {
+				// large negative number instead of NaN or something else to keep jobs to stay a SMI (v8)
+				jobs = -100000000;
+				callback(null, null);
+			}
+		};
+		/**
+		 * @param {string} path path
+		 * @param {Set<string>} managedSet managed set
+		 * @returns {boolean} true when managed
+		 */
+		const checkManaged = (path, managedSet) => {
+			for (const unmanagedPath of this.unmanagedPathsRegExps) {
+				if (unmanagedPath.test(path)) return false;
+			}
+			for (const unmanagedPath of this.unmanagedPathsWithSlash) {
+				if (path.startsWith(unmanagedPath)) return false;
+			}
+			for (const immutablePath of this.immutablePathsRegExps) {
+				if (immutablePath.test(path)) {
+					managedSet.add(path);
+					return true;
+				}
+			}
+			for (const immutablePath of this.immutablePathsWithSlash) {
+				if (path.startsWith(immutablePath)) {
+					managedSet.add(path);
+					return true;
+				}
+			}
+			for (const managedPath of this.managedPathsRegExps) {
+				const match = managedPath.exec(path);
+				if (match) {
+					const managedItem = getManagedItem(match[1], path);
+					if (managedItem) {
+						managedItems.add(managedItem);
+						managedSet.add(path);
+						return true;
+					}
+				}
+			}
+			for (const managedPath of this.managedPathsWithSlash) {
+				if (path.startsWith(managedPath)) {
+					const managedItem = getManagedItem(managedPath, path);
+					if (managedItem) {
+						managedItems.add(managedItem);
+						managedSet.add(path);
+						return true;
+					}
+				}
+			}
+			return false;
+		};
+		/**
+		 * @param {Iterable<string>} items items
+		 * @param {Set<string>} managedSet managed set
+		 * @returns {Set<string>} result
+		 */
+		const captureNonManaged = (items, managedSet) => {
+			const capturedItems = new Set();
+			for (const path of items) {
+				if (!checkManaged(path, managedSet)) capturedItems.add(path);
+			}
+			return capturedItems;
+		};
+		/**
+		 * @param {Set<string>} capturedFiles captured files
+		 */
+		const processCapturedFiles = capturedFiles => {
+			switch (mode) {
+				case 3:
+					this._fileTshsOptimization.optimize(snapshot, capturedFiles);
+					for (const path of capturedFiles) {
+						const cache = this._fileTshs.get(path);
+						if (cache !== undefined) {
+							fileTshs.set(path, cache);
+						} else {
+							jobs++;
+							this._getFileTimestampAndHash(path, (err, entry) => {
+								if (err) {
+									if (this.logger) {
+										this.logger.debug(
+											`Error snapshotting file timestamp hash combination of ${path}: ${err.stack}`
+										);
+									}
+									jobError();
+								} else {
+									fileTshs.set(path, /** @type {TimestampAndHash} */ (entry));
+									jobDone();
+								}
+							});
+						}
+					}
+					break;
+				case 2:
+					this._fileHashesOptimization.optimize(snapshot, capturedFiles);
+					for (const path of capturedFiles) {
+						const cache = this._fileHashes.get(path);
+						if (cache !== undefined) {
+							fileHashes.set(path, cache);
+						} else {
+							jobs++;
+							this.fileHashQueue.add(path, (err, entry) => {
+								if (err) {
+									if (this.logger) {
+										this.logger.debug(
+											`Error snapshotting file hash of ${path}: ${err.stack}`
+										);
+									}
+									jobError();
+								} else {
+									fileHashes.set(path, /** @type {string} */ (entry));
+									jobDone();
+								}
+							});
+						}
+					}
+					break;
+				case 1:
+					this._fileTimestampsOptimization.optimize(snapshot, capturedFiles);
+					for (const path of capturedFiles) {
+						const cache = this._fileTimestamps.get(path);
+						if (cache !== undefined) {
+							if (cache !== "ignore") {
+								fileTimestamps.set(path, cache);
+							}
+						} else {
+							jobs++;
+							this.fileTimestampQueue.add(path, (err, entry) => {
+								if (err) {
+									if (this.logger) {
+										this.logger.debug(
+											`Error snapshotting file timestamp of ${path}: ${err.stack}`
+										);
+									}
+									jobError();
+								} else {
+									fileTimestamps.set(
+										path,
+										/** @type {FileSystemInfoEntry} */
+										(entry)
+									);
+									jobDone();
+								}
+							});
+						}
+					}
+					break;
+			}
+		};
+		if (files) {
+			processCapturedFiles(captureNonManaged(files, managedFiles));
+		}
+		/**
+		 * @param {Set<string>} capturedDirectories captured directories
+		 */
+		const processCapturedDirectories = capturedDirectories => {
+			switch (mode) {
+				case 3:
+					this._contextTshsOptimization.optimize(snapshot, capturedDirectories);
+					for (const path of capturedDirectories) {
+						const cache = this._contextTshs.get(path);
+						/** @type {ResolvedContextTimestampAndHash | null | undefined} */
+						let resolved;
+						if (
+							cache !== undefined &&
+							(resolved = getResolvedTimestamp(cache)) !== undefined
+						) {
+							contextTshs.set(path, resolved);
+						} else {
+							jobs++;
+							/**
+							 * @param {(WebpackError | null)=} err error
+							 * @param {(ResolvedContextTimestampAndHash | null)=} entry entry
+							 * @returns {void}
+							 */
+							const callback = (err, entry) => {
+								if (err) {
+									if (this.logger) {
+										this.logger.debug(
+											`Error snapshotting context timestamp hash combination of ${path}: ${err.stack}`
+										);
+									}
+									jobError();
+								} else {
+									contextTshs.set(
+										path,
+										/** @type {ResolvedContextTimestampAndHash | null} */
+										(entry)
+									);
+									jobDone();
+								}
+							};
+							if (cache !== undefined) {
+								this._resolveContextTsh(cache, callback);
+							} else {
+								this.getContextTsh(path, callback);
+							}
+						}
+					}
+					break;
+				case 2:
+					this._contextHashesOptimization.optimize(
+						snapshot,
+						capturedDirectories
+					);
+					for (const path of capturedDirectories) {
+						const cache = this._contextHashes.get(path);
+						let resolved;
+						if (
+							cache !== undefined &&
+							(resolved = getResolvedHash(cache)) !== undefined
+						) {
+							contextHashes.set(path, resolved);
+						} else {
+							jobs++;
+							/**
+							 * @param {(WebpackError | null)=} err err
+							 * @param {string=} entry entry
+							 */
+							const callback = (err, entry) => {
+								if (err) {
+									if (this.logger) {
+										this.logger.debug(
+											`Error snapshotting context hash of ${path}: ${err.stack}`
+										);
+									}
+									jobError();
+								} else {
+									contextHashes.set(path, /** @type {string} */ (entry));
+									jobDone();
+								}
+							};
+							if (cache !== undefined) {
+								this._resolveContextHash(cache, callback);
+							} else {
+								this.getContextHash(path, callback);
+							}
+						}
+					}
+					break;
+				case 1:
+					this._contextTimestampsOptimization.optimize(
+						snapshot,
+						capturedDirectories
+					);
+					for (const path of capturedDirectories) {
+						const cache = this._contextTimestamps.get(path);
+						if (cache === "ignore") continue;
+						let resolved;
+						if (
+							cache !== undefined &&
+							(resolved = getResolvedTimestamp(cache)) !== undefined
+						) {
+							contextTimestamps.set(path, resolved);
+						} else {
+							jobs++;
+							/**
+							 * @param {(Error | null)=} err error
+							 * @param {(FileSystemInfoEntry | "ignore" | null)=} entry entry
+							 * @returns {void}
+							 */
+							const callback = (err, entry) => {
+								if (err) {
+									if (this.logger) {
+										this.logger.debug(
+											`Error snapshotting context timestamp of ${path}: ${err.stack}`
+										);
+									}
+									jobError();
+								} else {
+									contextTimestamps.set(
+										path,
+										/** @type {FileSystemInfoEntry | null} */
+										(entry)
+									);
+									jobDone();
+								}
+							};
+							if (cache !== undefined) {
+								this._resolveContextTimestamp(
+									/** @type {ContextFileSystemInfoEntry} */
+									(cache),
+									callback
+								);
+							} else {
+								this.getContextTimestamp(path, callback);
+							}
+						}
+					}
+					break;
+			}
+		};
+		if (directories) {
+			processCapturedDirectories(
+				captureNonManaged(directories, managedContexts)
+			);
+		}
+		/**
+		 * @param {Set<string>} capturedMissing captured missing
+		 */
+		const processCapturedMissing = capturedMissing => {
+			this._missingExistenceOptimization.optimize(snapshot, capturedMissing);
+			for (const path of capturedMissing) {
+				const cache = this._fileTimestamps.get(path);
+				if (cache !== undefined) {
+					if (cache !== "ignore") {
+						missingExistence.set(path, Boolean(cache));
+					}
+				} else {
+					jobs++;
+					this.fileTimestampQueue.add(path, (err, entry) => {
+						if (err) {
+							if (this.logger) {
+								this.logger.debug(
+									`Error snapshotting missing timestamp of ${path}: ${err.stack}`
+								);
+							}
+							jobError();
+						} else {
+							missingExistence.set(path, Boolean(entry));
+							jobDone();
+						}
+					});
+				}
+			}
+		};
+		if (missing) {
+			processCapturedMissing(captureNonManaged(missing, managedMissing));
+		}
+		this._managedItemInfoOptimization.optimize(snapshot, managedItems);
+		for (const path of managedItems) {
+			const cache = this._managedItems.get(path);
+			if (cache !== undefined) {
+				if (!cache.startsWith("*")) {
+					managedFiles.add(join(this.fs, path, "package.json"));
+				} else if (cache === "*nested") {
+					managedMissing.add(join(this.fs, path, "package.json"));
+				}
+				managedItemInfo.set(path, cache);
+			} else {
+				jobs++;
+				this.managedItemQueue.add(path, (err, entry) => {
+					if (err) {
+						if (this.logger) {
+							this.logger.debug(
+								`Error snapshotting managed item ${path}: ${err.stack}`
+							);
+						}
+						jobError();
+					} else if (entry) {
+						if (!entry.startsWith("*")) {
+							managedFiles.add(join(this.fs, path, "package.json"));
+						} else if (cache === "*nested") {
+							managedMissing.add(join(this.fs, path, "package.json"));
+						}
+						managedItemInfo.set(path, entry);
+						jobDone();
+					} else {
+						// Fallback to normal snapshotting
+						/**
+						 * @param {Set<string>} set set
+						 * @param {function(Set<string>): void} fn fn
+						 */
+						const process = (set, fn) => {
+							if (set.size === 0) return;
+							const captured = new Set();
+							for (const file of set) {
+								if (file.startsWith(path)) captured.add(file);
+							}
+							if (captured.size > 0) fn(captured);
+						};
+						process(managedFiles, processCapturedFiles);
+						process(managedContexts, processCapturedDirectories);
+						process(managedMissing, processCapturedMissing);
+						jobDone();
+					}
+				});
+			}
+		}
+		jobDone();
+	}
+
+	/**
+	 * @param {Snapshot} snapshot1 a snapshot
+	 * @param {Snapshot} snapshot2 a snapshot
+	 * @returns {Snapshot} merged snapshot
+	 */
+	mergeSnapshots(snapshot1, snapshot2) {
+		const snapshot = new Snapshot();
+		if (snapshot1.hasStartTime() && snapshot2.hasStartTime()) {
+			snapshot.setStartTime(
+				Math.min(
+					/** @type {NonNullable<Snapshot["startTime"]>} */
+					(snapshot1.startTime),
+					/** @type {NonNullable<Snapshot["startTime"]>} */
+					(snapshot2.startTime)
+				)
+			);
+		} else if (snapshot2.hasStartTime()) {
+			snapshot.startTime = snapshot2.startTime;
+		} else if (snapshot1.hasStartTime()) {
+			snapshot.startTime = snapshot1.startTime;
+		}
+		if (snapshot1.hasFileTimestamps() || snapshot2.hasFileTimestamps()) {
+			snapshot.setFileTimestamps(
+				mergeMaps(snapshot1.fileTimestamps, snapshot2.fileTimestamps)
+			);
+		}
+		if (snapshot1.hasFileHashes() || snapshot2.hasFileHashes()) {
+			snapshot.setFileHashes(
+				mergeMaps(snapshot1.fileHashes, snapshot2.fileHashes)
+			);
+		}
+		if (snapshot1.hasFileTshs() || snapshot2.hasFileTshs()) {
+			snapshot.setFileTshs(mergeMaps(snapshot1.fileTshs, snapshot2.fileTshs));
+		}
+		if (snapshot1.hasContextTimestamps() || snapshot2.hasContextTimestamps()) {
+			snapshot.setContextTimestamps(
+				mergeMaps(snapshot1.contextTimestamps, snapshot2.contextTimestamps)
+			);
+		}
+		if (snapshot1.hasContextHashes() || snapshot2.hasContextHashes()) {
+			snapshot.setContextHashes(
+				mergeMaps(snapshot1.contextHashes, snapshot2.contextHashes)
+			);
+		}
+		if (snapshot1.hasContextTshs() || snapshot2.hasContextTshs()) {
+			snapshot.setContextTshs(
+				mergeMaps(snapshot1.contextTshs, snapshot2.contextTshs)
+			);
+		}
+		if (snapshot1.hasMissingExistence() || snapshot2.hasMissingExistence()) {
+			snapshot.setMissingExistence(
+				mergeMaps(snapshot1.missingExistence, snapshot2.missingExistence)
+			);
+		}
+		if (snapshot1.hasManagedItemInfo() || snapshot2.hasManagedItemInfo()) {
+			snapshot.setManagedItemInfo(
+				mergeMaps(snapshot1.managedItemInfo, snapshot2.managedItemInfo)
+			);
+		}
+		if (snapshot1.hasManagedFiles() || snapshot2.hasManagedFiles()) {
+			snapshot.setManagedFiles(
+				mergeSets(snapshot1.managedFiles, snapshot2.managedFiles)
+			);
+		}
+		if (snapshot1.hasManagedContexts() || snapshot2.hasManagedContexts()) {
+			snapshot.setManagedContexts(
+				mergeSets(snapshot1.managedContexts, snapshot2.managedContexts)
+			);
+		}
+		if (snapshot1.hasManagedMissing() || snapshot2.hasManagedMissing()) {
+			snapshot.setManagedMissing(
+				mergeSets(snapshot1.managedMissing, snapshot2.managedMissing)
+			);
+		}
+		if (snapshot1.hasChildren() || snapshot2.hasChildren()) {
+			snapshot.setChildren(mergeSets(snapshot1.children, snapshot2.children));
+		}
+		if (
+			this._snapshotCache.get(snapshot1) === true &&
+			this._snapshotCache.get(snapshot2) === true
+		) {
+			this._snapshotCache.set(snapshot, true);
+		}
+		return snapshot;
+	}
+
+	/**
+	 * @param {Snapshot} snapshot the snapshot made
+	 * @param {function((WebpackError | null)=, boolean=): void} callback callback function
+	 * @returns {void}
+	 */
+	checkSnapshotValid(snapshot, callback) {
+		const cachedResult = this._snapshotCache.get(snapshot);
+		if (cachedResult !== undefined) {
+			this._statTestedSnapshotsCached++;
+			if (typeof cachedResult === "boolean") {
+				callback(null, cachedResult);
+			} else {
+				cachedResult.push(callback);
+			}
+			return;
+		}
+		this._statTestedSnapshotsNotCached++;
+		this._checkSnapshotValidNoCache(snapshot, callback);
+	}
+
+	/**
+	 * @param {Snapshot} snapshot the snapshot made
+	 * @param {function((WebpackError | null)=, boolean=): void} callback callback function
+	 * @returns {void}
+	 */
+	_checkSnapshotValidNoCache(snapshot, callback) {
+		/** @type {number | undefined} */
+		let startTime;
+		if (snapshot.hasStartTime()) {
+			startTime = snapshot.startTime;
+		}
+		let jobs = 1;
+		const jobDone = () => {
+			if (--jobs === 0) {
+				this._snapshotCache.set(snapshot, true);
+				callback(null, true);
+			}
+		};
+		const invalid = () => {
+			if (jobs > 0) {
+				// large negative number instead of NaN or something else to keep jobs to stay a SMI (v8)
+				jobs = -100000000;
+				this._snapshotCache.set(snapshot, false);
+				callback(null, false);
+			}
+		};
+		/**
+		 * @param {string} path path
+		 * @param {WebpackError} err err
+		 */
+		const invalidWithError = (path, err) => {
+			if (this._remainingLogs > 0) {
+				this._log(path, "error occurred: %s", err);
+			}
+			invalid();
+		};
+		/**
+		 * @param {string} path file path
+		 * @param {string | null} current current hash
+		 * @param {string | null} snap snapshot hash
+		 * @returns {boolean} true, if ok
+		 */
+		const checkHash = (path, current, snap) => {
+			if (current !== snap) {
+				// If hash differ it's invalid
+				if (this._remainingLogs > 0) {
+					this._log(path, "hashes differ (%s != %s)", current, snap);
+				}
+				return false;
+			}
+			return true;
+		};
+		/**
+		 * @param {string} path file path
+		 * @param {boolean} current current entry
+		 * @param {boolean} snap entry from snapshot
+		 * @returns {boolean} true, if ok
+		 */
+		const checkExistence = (path, current, snap) => {
+			if (!current !== !snap) {
+				// If existence of item differs
+				// it's invalid
+				if (this._remainingLogs > 0) {
+					this._log(
+						path,
+						current ? "it didn't exist before" : "it does no longer exist"
+					);
+				}
+				return false;
+			}
+			return true;
+		};
+		/**
+		 * @param {string} path file path
+		 * @param {FileSystemInfoEntry | null} c current entry
+		 * @param {FileSystemInfoEntry | null} s entry from snapshot
+		 * @param {boolean} log log reason
+		 * @returns {boolean} true, if ok
+		 */
+		const checkFile = (path, c, s, log = true) => {
+			if (c === s) return true;
+			if (!checkExistence(path, Boolean(c), Boolean(s))) return false;
+			if (c) {
+				// For existing items only
+				if (typeof startTime === "number" && c.safeTime > startTime) {
+					// If a change happened after starting reading the item
+					// this may no longer be valid
+					if (log && this._remainingLogs > 0) {
+						this._log(
+							path,
+							"it may have changed (%d) after the start time of the snapshot (%d)",
+							c.safeTime,
+							startTime
+						);
+					}
+					return false;
+				}
+				const snap = /** @type {FileSystemInfoEntry} */ (s);
+				if (snap.timestamp !== undefined && c.timestamp !== snap.timestamp) {
+					// If we have a timestamp (it was a file or symlink) and it differs from current timestamp
+					// it's invalid
+					if (log && this._remainingLogs > 0) {
+						this._log(
+							path,
+							"timestamps differ (%d != %d)",
+							c.timestamp,
+							snap.timestamp
+						);
+					}
+					return false;
+				}
+			}
+			return true;
+		};
+		/**
+		 * @param {string} path file path
+		 * @param {ResolvedContextFileSystemInfoEntry | null} c current entry
+		 * @param {ResolvedContextFileSystemInfoEntry | null} s entry from snapshot
+		 * @param {boolean} log log reason
+		 * @returns {boolean} true, if ok
+		 */
+		const checkContext = (path, c, s, log = true) => {
+			if (c === s) return true;
+			if (!checkExistence(path, Boolean(c), Boolean(s))) return false;
+			if (c) {
+				// For existing items only
+				if (typeof startTime === "number" && c.safeTime > startTime) {
+					// If a change happened after starting reading the item
+					// this may no longer be valid
+					if (log && this._remainingLogs > 0) {
+						this._log(
+							path,
+							"it may have changed (%d) after the start time of the snapshot (%d)",
+							c.safeTime,
+							startTime
+						);
+					}
+					return false;
+				}
+				const snap = /** @type {ResolvedContextFileSystemInfoEntry} */ (s);
+				if (
+					snap.timestampHash !== undefined &&
+					c.timestampHash !== snap.timestampHash
+				) {
+					// If we have a timestampHash (it was a directory) and it differs from current timestampHash
+					// it's invalid
+					if (log && this._remainingLogs > 0) {
+						this._log(
+							path,
+							"timestamps hashes differ (%s != %s)",
+							c.timestampHash,
+							snap.timestampHash
+						);
+					}
+					return false;
+				}
+			}
+			return true;
+		};
+		if (snapshot.hasChildren()) {
+			/**
+			 * @param {(WebpackError | null)=} err err
+			 * @param {boolean=} result result
+			 * @returns {void}
+			 */
+			const childCallback = (err, result) => {
+				if (err || !result) return invalid();
+				jobDone();
+			};
+			for (const child of /** @type {Children} */ (snapshot.children)) {
+				const cache = this._snapshotCache.get(child);
+				if (cache !== undefined) {
+					this._statTestedChildrenCached++;
+					/* istanbul ignore else */
+					if (typeof cache === "boolean") {
+						if (cache === false) {
+							invalid();
+							return;
+						}
+					} else {
+						jobs++;
+						cache.push(childCallback);
+					}
+				} else {
+					this._statTestedChildrenNotCached++;
+					jobs++;
+					this._checkSnapshotValidNoCache(child, childCallback);
+				}
+			}
+		}
+		if (snapshot.hasFileTimestamps()) {
+			const fileTimestamps =
+				/** @type {FileTimestamps} */
+				(snapshot.fileTimestamps);
+			this._statTestedEntries += fileTimestamps.size;
+			for (const [path, ts] of fileTimestamps) {
+				const cache = this._fileTimestamps.get(path);
+				if (cache !== undefined) {
+					if (cache !== "ignore" && !checkFile(path, cache, ts)) {
+						invalid();
+						return;
+					}
+				} else {
+					jobs++;
+					this.fileTimestampQueue.add(path, (err, entry) => {
+						if (err) return invalidWithError(path, err);
+						if (
+							!checkFile(
+								path,
+								/** @type {FileSystemInfoEntry | null} */ (entry),
+								ts
+							)
+						) {
+							invalid();
+						} else {
+							jobDone();
+						}
+					});
+				}
+			}
+		}
+		/**
+		 * @param {string} path file path
+		 * @param {string | null} hash hash
+		 */
+		const processFileHashSnapshot = (path, hash) => {
+			const cache = this._fileHashes.get(path);
+			if (cache !== undefined) {
+				if (cache !== "ignore" && !checkHash(path, cache, hash)) {
+					invalid();
+				}
+			} else {
+				jobs++;
+				this.fileHashQueue.add(path, (err, entry) => {
+					if (err) return invalidWithError(path, err);
+					if (!checkHash(path, /** @type {string} */ (entry), hash)) {
+						invalid();
+					} else {
+						jobDone();
+					}
+				});
+			}
+		};
+		if (snapshot.hasFileHashes()) {
+			const fileHashes = /** @type {FileHashes} */ (snapshot.fileHashes);
+			this._statTestedEntries += fileHashes.size;
+			for (const [path, hash] of fileHashes) {
+				processFileHashSnapshot(path, hash);
+			}
+		}
+		if (snapshot.hasFileTshs()) {
+			const fileTshs = /** @type {FileTshs} */ (snapshot.fileTshs);
+			this._statTestedEntries += fileTshs.size;
+			for (const [path, tsh] of fileTshs) {
+				if (typeof tsh === "string") {
+					processFileHashSnapshot(path, tsh);
+				} else {
+					const cache = this._fileTimestamps.get(path);
+					if (cache !== undefined) {
+						if (cache === "ignore" || !checkFile(path, cache, tsh, false)) {
+							processFileHashSnapshot(path, tsh && tsh.hash);
+						}
+					} else {
+						jobs++;
+						this.fileTimestampQueue.add(path, (err, entry) => {
+							if (err) return invalidWithError(path, err);
+							if (
+								!checkFile(
+									path,
+									/** @type {FileSystemInfoEntry | null} */
+									(entry),
+									tsh,
+									false
+								)
+							) {
+								processFileHashSnapshot(path, tsh && tsh.hash);
+							}
+							jobDone();
+						});
+					}
+				}
+			}
+		}
+		if (snapshot.hasContextTimestamps()) {
+			const contextTimestamps =
+				/** @type {ContextTimestamps} */
+				(snapshot.contextTimestamps);
+			this._statTestedEntries += contextTimestamps.size;
+			for (const [path, ts] of contextTimestamps) {
+				const cache = this._contextTimestamps.get(path);
+				if (cache === "ignore") continue;
+				let resolved;
+				if (
+					cache !== undefined &&
+					(resolved = getResolvedTimestamp(cache)) !== undefined
+				) {
+					if (!checkContext(path, resolved, ts)) {
+						invalid();
+						return;
+					}
+				} else {
+					jobs++;
+					/**
+					 * @param {(WebpackError | null)=} err error
+					 * @param {(ResolvedContextFileSystemInfoEntry | "ignore" | null)=} entry entry
+					 * @returns {void}
+					 */
+					const callback = (err, entry) => {
+						if (err) return invalidWithError(path, err);
+						if (
+							!checkContext(
+								path,
+								/** @type {ResolvedContextFileSystemInfoEntry | null} */
+								(entry),
+								ts
+							)
+						) {
+							invalid();
+						} else {
+							jobDone();
+						}
+					};
+					if (cache !== undefined) {
+						this._resolveContextTimestamp(
+							/** @type {ContextFileSystemInfoEntry} */
+							(cache),
+							callback
+						);
+					} else {
+						this.getContextTimestamp(path, callback);
+					}
+				}
+			}
+		}
+		/**
+		 * @param {string} path path
+		 * @param {string | null} hash hash
+		 */
+		const processContextHashSnapshot = (path, hash) => {
+			const cache = this._contextHashes.get(path);
+			let resolved;
+			if (
+				cache !== undefined &&
+				(resolved = getResolvedHash(cache)) !== undefined
+			) {
+				if (!checkHash(path, resolved, hash)) {
+					invalid();
+				}
+			} else {
+				jobs++;
+				/**
+				 * @param {(WebpackError | null)=} err err
+				 * @param {string=} entry entry
+				 * @returns {void}
+				 */
+				const callback = (err, entry) => {
+					if (err) return invalidWithError(path, err);
+					if (!checkHash(path, /** @type {string} */ (entry), hash)) {
+						invalid();
+					} else {
+						jobDone();
+					}
+				};
+				if (cache !== undefined) {
+					this._resolveContextHash(cache, callback);
+				} else {
+					this.getContextHash(path, callback);
+				}
+			}
+		};
+		if (snapshot.hasContextHashes()) {
+			const contextHashes =
+				/** @type {ContextHashes} */
+				(snapshot.contextHashes);
+			this._statTestedEntries += contextHashes.size;
+			for (const [path, hash] of contextHashes) {
+				processContextHashSnapshot(path, hash);
+			}
+		}
+		if (snapshot.hasContextTshs()) {
+			const contextTshs = /** @type {ContextTshs} */ (snapshot.contextTshs);
+			this._statTestedEntries += contextTshs.size;
+			for (const [path, tsh] of contextTshs) {
+				if (typeof tsh === "string") {
+					processContextHashSnapshot(path, tsh);
+				} else {
+					const cache = this._contextTimestamps.get(path);
+					if (cache === "ignore") continue;
+					let resolved;
+					if (
+						cache !== undefined &&
+						(resolved = getResolvedTimestamp(cache)) !== undefined
+					) {
+						if (
+							!checkContext(
+								path,
+								/** @type {ResolvedContextFileSystemInfoEntry | null} */
+								(resolved),
+								tsh,
+								false
+							)
+						) {
+							processContextHashSnapshot(path, tsh && tsh.hash);
+						}
+					} else {
+						jobs++;
+						/**
+						 * @param {(WebpackError | null)=} err error
+						 * @param {(ResolvedContextFileSystemInfoEntry | "ignore" | null)=} entry entry
+						 * @returns {void}
+						 */
+						const callback = (err, entry) => {
+							if (err) return invalidWithError(path, err);
+							if (
+								!checkContext(
+									path,
+									// TODO: test with `"ignore"`
+									/** @type {ResolvedContextFileSystemInfoEntry | null} */
+									(entry),
+									tsh,
+									false
+								)
+							) {
+								processContextHashSnapshot(path, tsh && tsh.hash);
+							}
+							jobDone();
+						};
+						if (cache !== undefined) {
+							this._resolveContextTimestamp(
+								/** @type {ContextFileSystemInfoEntry} */
+								(cache),
+								callback
+							);
+						} else {
+							this.getContextTimestamp(path, callback);
+						}
+					}
+				}
+			}
+		}
+		if (snapshot.hasMissingExistence()) {
+			const missingExistence =
+				/** @type {MissingExistence} */
+				(snapshot.missingExistence);
+			this._statTestedEntries += missingExistence.size;
+			for (const [path, existence] of missingExistence) {
+				const cache = this._fileTimestamps.get(path);
+				if (cache !== undefined) {
+					if (
+						cache !== "ignore" &&
+						!checkExistence(path, Boolean(cache), Boolean(existence))
+					) {
+						invalid();
+						return;
+					}
+				} else {
+					jobs++;
+					this.fileTimestampQueue.add(path, (err, entry) => {
+						if (err) return invalidWithError(path, err);
+						if (!checkExistence(path, Boolean(entry), Boolean(existence))) {
+							invalid();
+						} else {
+							jobDone();
+						}
+					});
+				}
+			}
+		}
+		if (snapshot.hasManagedItemInfo()) {
+			const managedItemInfo =
+				/** @type {ManagedItemInfo} */
+				(snapshot.managedItemInfo);
+			this._statTestedEntries += managedItemInfo.size;
+			for (const [path, info] of managedItemInfo) {
+				const cache = this._managedItems.get(path);
+				if (cache !== undefined) {
+					if (!checkHash(path, cache, info)) {
+						invalid();
+						return;
+					}
+				} else {
+					jobs++;
+					this.managedItemQueue.add(path, (err, entry) => {
+						if (err) return invalidWithError(path, err);
+						if (!checkHash(path, /** @type {string} */ (entry), info)) {
+							invalid();
+						} else {
+							jobDone();
+						}
+					});
+				}
+			}
+		}
+		jobDone();
+
+		// if there was an async action
+		// try to join multiple concurrent request for this snapshot
+		if (jobs > 0) {
+			const callbacks = [callback];
+			callback = (err, result) => {
+				for (const callback of callbacks) callback(err, result);
+			};
+			this._snapshotCache.set(snapshot, callbacks);
+		}
+	}
+
+	/**
+	 * @type {Processor<string, FileSystemInfoEntry>}
+	 * @private
+	 */
+	_readFileTimestamp(path, callback) {
+		this.fs.stat(path, (err, _stat) => {
+			if (err) {
+				if (err.code === "ENOENT") {
+					this._fileTimestamps.set(path, null);
+					this._cachedDeprecatedFileTimestamps = undefined;
+					return callback(null, null);
+				}
+				return callback(/** @type {WebpackError} */ (err));
+			}
+			const stat = /** @type {IStats} */ (_stat);
+			let ts;
+			if (stat.isDirectory()) {
+				ts = {
+					safeTime: 0,
+					timestamp: undefined
+				};
+			} else {
+				const mtime = Number(stat.mtime);
+
+				if (mtime) applyMtime(mtime);
+
+				ts = {
+					safeTime: mtime ? mtime + FS_ACCURACY : Infinity,
+					timestamp: mtime
+				};
+			}
+
+			this._fileTimestamps.set(path, ts);
+			this._cachedDeprecatedFileTimestamps = undefined;
+
+			callback(null, ts);
+		});
+	}
+
+	/**
+	 * @type {Processor<string, string>}
+	 * @private
+	 */
+	_readFileHash(path, callback) {
+		this.fs.readFile(path, (err, content) => {
+			if (err) {
+				if (err.code === "EISDIR") {
+					this._fileHashes.set(path, "directory");
+					return callback(null, "directory");
+				}
+				if (err.code === "ENOENT") {
+					this._fileHashes.set(path, null);
+					return callback(null, null);
+				}
+				if (err.code === "ERR_FS_FILE_TOO_LARGE") {
+					/** @type {Logger} */
+					(this.logger).warn(`Ignoring ${path} for hashing as it's very large`);
+					this._fileHashes.set(path, "too large");
+					return callback(null, "too large");
+				}
+				return callback(/** @type {WebpackError} */ (err));
+			}
+
+			const hash = createHash(this._hashFunction);
+
+			hash.update(/** @type {string | Buffer} */ (content));
+
+			const digest = /** @type {string} */ (hash.digest("hex"));
+
+			this._fileHashes.set(path, digest);
+
+			callback(null, digest);
+		});
+	}
+
+	/**
+	 * @param {string} path path
+	 * @param {function(WebpackError | null, TimestampAndHash=) : void} callback callback
+	 * @private
+	 */
+	_getFileTimestampAndHash(path, callback) {
+		/**
+		 * @param {string} hash hash
+		 * @returns {void}
+		 */
+		const continueWithHash = hash => {
+			const cache = this._fileTimestamps.get(path);
+			if (cache !== undefined) {
+				if (cache !== "ignore") {
+					/** @type {TimestampAndHash} */
+					const result = {
+						.../** @type {FileSystemInfoEntry} */ (cache),
+						hash
+					};
+					this._fileTshs.set(path, result);
+					return callback(null, result);
+				}
+				this._fileTshs.set(path, hash);
+				return callback(null, /** @type {TODO} */ (hash));
+			}
+			this.fileTimestampQueue.add(path, (err, entry) => {
+				if (err) {
+					return callback(err);
+				}
+				/** @type {TimestampAndHash} */
+				const result = {
+					.../** @type {FileSystemInfoEntry} */ (entry),
+					hash
+				};
+				this._fileTshs.set(path, result);
+				return callback(null, result);
+			});
+		};
+
+		const cache = this._fileHashes.get(path);
+		if (cache !== undefined) {
+			continueWithHash(/** @type {string} */ (cache));
+		} else {
+			this.fileHashQueue.add(path, (err, entry) => {
+				if (err) {
+					return callback(err);
+				}
+				continueWithHash(/** @type {string} */ (entry));
+			});
+		}
+	}
+
+	/**
+	 * @template T
+	 * @template ItemType
+	 * @param {object} options options
+	 * @param {string} options.path path
+	 * @param {function(string): ItemType} options.fromImmutablePath called when context item is an immutable path
+	 * @param {function(string): ItemType} options.fromManagedItem called when context item is a managed path
+	 * @param {function(string, string, function((WebpackError | null)=, ItemType=): void): void} options.fromSymlink called when context item is a symlink
+	 * @param {function(string, IStats, function((WebpackError | null)=, (ItemType | null)=): void): void} options.fromFile called when context item is a file
+	 * @param {function(string, IStats, function((WebpackError | null)=, ItemType=): void): void} options.fromDirectory called when context item is a directory
+	 * @param {function(string[], ItemType[]): T} options.reduce called from all context items
+	 * @param {function((Error | null)=, (T | null)=): void} callback callback
+	 */
+	_readContext(
+		{
+			path,
+			fromImmutablePath,
+			fromManagedItem,
+			fromSymlink,
+			fromFile,
+			fromDirectory,
+			reduce
+		},
+		callback
+	) {
+		this.fs.readdir(path, (err, _files) => {
+			if (err) {
+				if (err.code === "ENOENT") {
+					return callback(null, null);
+				}
+				return callback(err);
+			}
+			const files = /** @type {string[]} */ (_files)
+				.map(file => file.normalize("NFC"))
+				.filter(file => !/^\./.test(file))
+				.sort();
+			asyncLib.map(
+				files,
+				(file, callback) => {
+					const child = join(this.fs, path, file);
+					for (const immutablePath of this.immutablePathsRegExps) {
+						if (immutablePath.test(path)) {
+							// ignore any immutable path for timestamping
+							return callback(null, fromImmutablePath(path));
+						}
+					}
+					for (const immutablePath of this.immutablePathsWithSlash) {
+						if (path.startsWith(immutablePath)) {
+							// ignore any immutable path for timestamping
+							return callback(null, fromImmutablePath(path));
+						}
+					}
+					for (const managedPath of this.managedPathsRegExps) {
+						const match = managedPath.exec(path);
+						if (match) {
+							const managedItem = getManagedItem(match[1], path);
+							if (managedItem) {
+								// construct timestampHash from managed info
+								return this.managedItemQueue.add(managedItem, (err, info) => {
+									if (err) return callback(err);
+									return callback(
+										null,
+										fromManagedItem(/** @type {string} */ (info))
+									);
+								});
+							}
+						}
+					}
+					for (const managedPath of this.managedPathsWithSlash) {
+						if (path.startsWith(managedPath)) {
+							const managedItem = getManagedItem(managedPath, child);
+							if (managedItem) {
+								// construct timestampHash from managed info
+								return this.managedItemQueue.add(managedItem, (err, info) => {
+									if (err) return callback(err);
+									return callback(
+										null,
+										fromManagedItem(/** @type {string} */ (info))
+									);
+								});
+							}
+						}
+					}
+
+					lstatReadlinkAbsolute(this.fs, child, (err, _stat) => {
+						if (err) return callback(err);
+
+						const stat = /** @type {IStats | string} */ (_stat);
+
+						if (typeof stat === "string") {
+							return fromSymlink(child, stat, callback);
+						}
+
+						if (stat.isFile()) {
+							return fromFile(child, stat, callback);
+						}
+						if (stat.isDirectory()) {
+							return fromDirectory(child, stat, callback);
+						}
+						callback(null, null);
+					});
+				},
+				(err, results) => {
+					if (err) return callback(err);
+					const result = reduce(files, /** @type {ItemType[]} */ (results));
+					callback(null, result);
+				}
+			);
+		});
+	}
+
+	/**
+	 * @type {Processor<string, ContextFileSystemInfoEntry>}
+	 * @private
+	 */
+	_readContextTimestamp(path, callback) {
+		this._readContext(
+			{
+				path,
+				fromImmutablePath: () =>
+					/** @type {ContextFileSystemInfoEntry | FileSystemInfoEntry | "ignore" | null} */
+					(null),
+				fromManagedItem: info => ({
+					safeTime: 0,
+					timestampHash: info
+				}),
+				fromSymlink: (file, target, callback) => {
+					callback(
+						null,
+						/** @type {ContextFileSystemInfoEntry} */
+						({
+							timestampHash: target,
+							symlinks: new Set([target])
+						})
+					);
+				},
+				fromFile: (file, stat, callback) => {
+					// Prefer the cached value over our new stat to report consistent results
+					const cache = this._fileTimestamps.get(file);
+					if (cache !== undefined)
+						return callback(null, cache === "ignore" ? null : cache);
+
+					const mtime = Number(stat.mtime);
+
+					if (mtime) applyMtime(mtime);
+
+					/** @type {FileSystemInfoEntry} */
+					const ts = {
+						safeTime: mtime ? mtime + FS_ACCURACY : Infinity,
+						timestamp: mtime
+					};
+
+					this._fileTimestamps.set(file, ts);
+					this._cachedDeprecatedFileTimestamps = undefined;
+					callback(null, ts);
+				},
+				fromDirectory: (directory, stat, callback) => {
+					this.contextTimestampQueue.increaseParallelism();
+					this._getUnresolvedContextTimestamp(directory, (err, tsEntry) => {
+						this.contextTimestampQueue.decreaseParallelism();
+						callback(err, tsEntry);
+					});
+				},
+				reduce: (files, tsEntries) => {
+					let symlinks;
+
+					const hash = createHash(this._hashFunction);
+
+					for (const file of files) hash.update(file);
+					let safeTime = 0;
+					for (const _e of tsEntries) {
+						if (!_e) {
+							hash.update("n");
+							continue;
+						}
+						const entry =
+							/** @type {FileSystemInfoEntry | ContextFileSystemInfoEntry} */
+							(_e);
+						if (/** @type {FileSystemInfoEntry} */ (entry).timestamp) {
+							hash.update("f");
+							hash.update(
+								`${/** @type {FileSystemInfoEntry} */ (entry).timestamp}`
+							);
+						} else if (
+							/** @type {ContextFileSystemInfoEntry} */ (entry).timestampHash
+						) {
+							hash.update("d");
+							hash.update(
+								`${/** @type {ContextFileSystemInfoEntry} */ (entry).timestampHash}`
+							);
+						}
+						if (
+							/** @type {ContextFileSystemInfoEntry} */
+							(entry).symlinks !== undefined
+						) {
+							if (symlinks === undefined) symlinks = new Set();
+							addAll(
+								/** @type {ContextFileSystemInfoEntry} */ (entry).symlinks,
+								symlinks
+							);
+						}
+						if (entry.safeTime) {
+							safeTime = Math.max(safeTime, entry.safeTime);
+						}
+					}
+
+					const digest = /** @type {string} */ (hash.digest("hex"));
+					/** @type {ContextFileSystemInfoEntry} */
+					const result = {
+						safeTime,
+						timestampHash: digest
+					};
+					if (symlinks) result.symlinks = symlinks;
+					return result;
+				}
+			},
+			(err, result) => {
+				if (err) return callback(/** @type {WebpackError} */ (err));
+				this._contextTimestamps.set(path, result);
+				this._cachedDeprecatedContextTimestamps = undefined;
+
+				callback(null, result);
+			}
+		);
+	}
+
+	/**
+	 * @param {ContextFileSystemInfoEntry} entry entry
+	 * @param {function((WebpackError | null)=, (ResolvedContextFileSystemInfoEntry | "ignore" | null)=): void} callback callback
+	 * @returns {void}
+	 */
+	_resolveContextTimestamp(entry, callback) {
+		/** @type {string[]} */
+		const hashes = [];
+		let safeTime = 0;
+		processAsyncTree(
+			/** @type {NonNullable<ContextHash["symlinks"]>} */ (entry.symlinks),
+			10,
+			(target, push, callback) => {
+				this._getUnresolvedContextTimestamp(target, (err, entry) => {
+					if (err) return callback(err);
+					if (entry && entry !== "ignore") {
+						hashes.push(/** @type {string} */ (entry.timestampHash));
+						if (entry.safeTime) {
+							safeTime = Math.max(safeTime, entry.safeTime);
+						}
+						if (entry.symlinks !== undefined) {
+							for (const target of entry.symlinks) push(target);
+						}
+					}
+					callback();
+				});
+			},
+			err => {
+				if (err) return callback(/** @type {WebpackError} */ (err));
+				const hash = createHash(this._hashFunction);
+				hash.update(/** @type {string} */ (entry.timestampHash));
+				if (entry.safeTime) {
+					safeTime = Math.max(safeTime, entry.safeTime);
+				}
+				hashes.sort();
+				for (const h of hashes) {
+					hash.update(h);
+				}
+				callback(
+					null,
+					(entry.resolved = {
+						safeTime,
+						timestampHash: /** @type {string} */ (hash.digest("hex"))
+					})
+				);
+			}
+		);
+	}
+
+	/**
+	 * @type {Processor<string, ContextHash>}
+	 * @private
+	 */
+	_readContextHash(path, callback) {
+		this._readContext(
+			{
+				path,
+				fromImmutablePath: () => /** @type {ContextHash | ""} */ (""),
+				fromManagedItem: info => info || "",
+				fromSymlink: (file, target, callback) => {
+					callback(
+						null,
+						/** @type {ContextHash} */
+						({
+							hash: target,
+							symlinks: new Set([target])
+						})
+					);
+				},
+				fromFile: (file, stat, callback) =>
+					this.getFileHash(file, (err, hash) => {
+						callback(err, hash || "");
+					}),
+				fromDirectory: (directory, stat, callback) => {
+					this.contextHashQueue.increaseParallelism();
+					this._getUnresolvedContextHash(directory, (err, hash) => {
+						this.contextHashQueue.decreaseParallelism();
+						callback(err, hash || "");
+					});
+				},
+				/**
+				 * @param {string[]} files files
+				 * @param {(string | ContextHash)[]} fileHashes hashes
+				 * @returns {ContextHash} reduced hash
+				 */
+				reduce: (files, fileHashes) => {
+					let symlinks;
+					const hash = createHash(this._hashFunction);
+
+					for (const file of files) hash.update(file);
+					for (const entry of fileHashes) {
+						if (typeof entry === "string") {
+							hash.update(entry);
+						} else {
+							hash.update(entry.hash);
+							if (entry.symlinks) {
+								if (symlinks === undefined) symlinks = new Set();
+								addAll(entry.symlinks, symlinks);
+							}
+						}
+					}
+
+					/** @type {ContextHash} */
+					const result = {
+						hash: /** @type {string} */ (hash.digest("hex"))
+					};
+					if (symlinks) result.symlinks = symlinks;
+					return result;
+				}
+			},
+			(err, _result) => {
+				if (err) return callback(/** @type {WebpackError} */ (err));
+				const result = /** @type {ContextHash} */ (_result);
+				this._contextHashes.set(path, result);
+				return callback(null, result);
+			}
+		);
+	}
+
+	/**
+	 * @param {ContextHash} entry context hash
+	 * @param {function(WebpackError | null, string=): void} callback callback
+	 * @returns {void}
+	 */
+	_resolveContextHash(entry, callback) {
+		/** @type {string[]} */
+		const hashes = [];
+		processAsyncTree(
+			/** @type {NonNullable<ContextHash["symlinks"]>} */ (entry.symlinks),
+			10,
+			(target, push, callback) => {
+				this._getUnresolvedContextHash(target, (err, hash) => {
+					if (err) return callback(err);
+					if (hash) {
+						hashes.push(hash.hash);
+						if (hash.symlinks !== undefined) {
+							for (const target of hash.symlinks) push(target);
+						}
+					}
+					callback();
+				});
+			},
+			err => {
+				if (err) return callback(/** @type {WebpackError} */ (err));
+				const hash = createHash(this._hashFunction);
+				hash.update(entry.hash);
+				hashes.sort();
+				for (const h of hashes) {
+					hash.update(h);
+				}
+				callback(
+					null,
+					(entry.resolved = /** @type {string} */ (hash.digest("hex")))
+				);
+			}
+		);
+	}
+
+	/**
+	 * @type {Processor<string, ContextTimestampAndHash>}
+	 * @private
+	 */
+	_readContextTimestampAndHash(path, callback) {
+		/**
+		 * @param {ContextFileSystemInfoEntry | "ignore" | null} timestamp timestamp
+		 * @param {ContextHash} hash hash
+		 */
+		const finalize = (timestamp, hash) => {
+			const result =
+				/** @type {ContextTimestampAndHash} */
+				(timestamp === "ignore" ? hash : { ...timestamp, ...hash });
+			this._contextTshs.set(path, result);
+			callback(null, result);
+		};
+		const cachedHash = this._contextHashes.get(path);
+		const cachedTimestamp = this._contextTimestamps.get(path);
+		if (cachedHash !== undefined) {
+			if (cachedTimestamp !== undefined) {
+				finalize(cachedTimestamp, cachedHash);
+			} else {
+				this.contextTimestampQueue.add(path, (err, entry) => {
+					if (err) return callback(err);
+					finalize(
+						/** @type {ContextFileSystemInfoEntry} */
+						(entry),
+						cachedHash
+					);
+				});
+			}
+		} else if (cachedTimestamp !== undefined) {
+			this.contextHashQueue.add(path, (err, entry) => {
+				if (err) return callback(err);
+				finalize(cachedTimestamp, /** @type {ContextHash} */ (entry));
+			});
+		} else {
+			this._readContext(
+				{
+					path,
+					fromImmutablePath: () =>
+						/** @type {ContextTimestampAndHash | null} */ (null),
+					fromManagedItem: info => ({
+						safeTime: 0,
+						timestampHash: info,
+						hash: info || ""
+					}),
+					fromSymlink: (file, target, callback) => {
+						callback(
+							null,
+							/** @type {TODO} */
+							({
+								timestampHash: target,
+								hash: target,
+								symlinks: new Set([target])
+							})
+						);
+					},
+					fromFile: (file, stat, callback) => {
+						this._getFileTimestampAndHash(file, callback);
+					},
+					fromDirectory: (directory, stat, callback) => {
+						this.contextTshQueue.increaseParallelism();
+						this.contextTshQueue.add(directory, (err, result) => {
+							this.contextTshQueue.decreaseParallelism();
+							callback(err, result);
+						});
+					},
+					/**
+					 * @param {string[]} files files
+					 * @param {(Partial<TimestampAndHash> & Partial<ContextTimestampAndHash> | string | null)[]} results results
+					 * @returns {ContextTimestampAndHash} tsh
+					 */
+					reduce: (files, results) => {
+						let symlinks;
+
+						const tsHash = createHash(this._hashFunction);
+						const hash = createHash(this._hashFunction);
+
+						for (const file of files) {
+							tsHash.update(file);
+							hash.update(file);
+						}
+						let safeTime = 0;
+						for (const entry of results) {
+							if (!entry) {
+								tsHash.update("n");
+								continue;
+							}
+							if (typeof entry === "string") {
+								tsHash.update("n");
+								hash.update(entry);
+								continue;
+							}
+							if (entry.timestamp) {
+								tsHash.update("f");
+								tsHash.update(`${entry.timestamp}`);
+							} else if (entry.timestampHash) {
+								tsHash.update("d");
+								tsHash.update(`${entry.timestampHash}`);
+							}
+							if (entry.symlinks !== undefined) {
+								if (symlinks === undefined) symlinks = new Set();
+								addAll(entry.symlinks, symlinks);
+							}
+							if (entry.safeTime) {
+								safeTime = Math.max(safeTime, entry.safeTime);
+							}
+							hash.update(/** @type {string} */ (entry.hash));
+						}
+
+						/** @type {ContextTimestampAndHash} */
+						const result = {
+							safeTime,
+							timestampHash: /** @type {string} */ (tsHash.digest("hex")),
+							hash: /** @type {string} */ (hash.digest("hex"))
+						};
+						if (symlinks) result.symlinks = symlinks;
+						return result;
+					}
+				},
+				(err, _result) => {
+					if (err) return callback(/** @type {WebpackError} */ (err));
+					const result = /** @type {ContextTimestampAndHash} */ (_result);
+					this._contextTshs.set(path, result);
+					return callback(null, result);
+				}
+			);
+		}
+	}
+
+	/**
+	 * @param {ContextTimestampAndHash} entry entry
+	 * @param {ProcessorCallback<ResolvedContextTimestampAndHash>} callback callback
+	 * @returns {void}
+	 */
+	_resolveContextTsh(entry, callback) {
+		/** @type {string[]} */
+		const hashes = [];
+		/** @type {string[]} */
+		const tsHashes = [];
+		let safeTime = 0;
+		processAsyncTree(
+			/** @type {NonNullable<ContextHash["symlinks"]>} */ (entry.symlinks),
+			10,
+			(target, push, callback) => {
+				this._getUnresolvedContextTsh(target, (err, entry) => {
+					if (err) return callback(err);
+					if (entry) {
+						hashes.push(entry.hash);
+						if (entry.timestampHash) tsHashes.push(entry.timestampHash);
+						if (entry.safeTime) {
+							safeTime = Math.max(safeTime, entry.safeTime);
+						}
+						if (entry.symlinks !== undefined) {
+							for (const target of entry.symlinks) push(target);
+						}
+					}
+					callback();
+				});
+			},
+			err => {
+				if (err) return callback(/** @type {WebpackError} */ (err));
+				const hash = createHash(this._hashFunction);
+				const tsHash = createHash(this._hashFunction);
+				hash.update(entry.hash);
+				if (entry.timestampHash) tsHash.update(entry.timestampHash);
+				if (entry.safeTime) {
+					safeTime = Math.max(safeTime, entry.safeTime);
+				}
+				hashes.sort();
+				for (const h of hashes) {
+					hash.update(h);
+				}
+				tsHashes.sort();
+				for (const h of tsHashes) {
+					tsHash.update(h);
+				}
+				callback(
+					null,
+					(entry.resolved = {
+						safeTime,
+						timestampHash: /** @type {string} */ (tsHash.digest("hex")),
+						hash: /** @type {string} */ (hash.digest("hex"))
+					})
+				);
+			}
+		);
+	}
+
+	/**
+	 * @type {Processor<string, Set<string>>}
+	 * @private
+	 */
+	_getManagedItemDirectoryInfo(path, callback) {
+		this.fs.readdir(path, (err, elements) => {
+			if (err) {
+				if (err.code === "ENOENT" || err.code === "ENOTDIR") {
+					return callback(null, EMPTY_SET);
+				}
+				return callback(/** @type {WebpackError} */ (err));
+			}
+			const set = new Set(
+				/** @type {string[]} */ (elements).map(element =>
+					join(this.fs, path, element)
+				)
+			);
+			callback(null, set);
+		});
+	}
+
+	/**
+	 * @type {Processor<string, string>}
+	 * @private
+	 */
+	_getManagedItemInfo(path, callback) {
+		const dir = dirname(this.fs, path);
+		this.managedItemDirectoryQueue.add(dir, (err, elements) => {
+			if (err) {
+				return callback(err);
+			}
+			if (!(/** @type {Set<string>} */ (elements).has(path))) {
+				// file or directory doesn't exist
+				this._managedItems.set(path, "*missing");
+				return callback(null, "*missing");
+			}
+			// something exists
+			// it may be a file or directory
+			if (
+				path.endsWith("node_modules") &&
+				(path.endsWith("/node_modules") || path.endsWith("\\node_modules"))
+			) {
+				// we are only interested in existence of this special directory
+				this._managedItems.set(path, "*node_modules");
+				return callback(null, "*node_modules");
+			}
+
+			// we assume it's a directory, as files shouldn't occur in managed paths
+			const packageJsonPath = join(this.fs, path, "package.json");
+			this.fs.readFile(packageJsonPath, (err, content) => {
+				if (err) {
+					if (err.code === "ENOENT" || err.code === "ENOTDIR") {
+						// no package.json or path is not a directory
+						this.fs.readdir(path, (err, elements) => {
+							if (
+								!err &&
+								/** @type {string[]} */ (elements).length === 1 &&
+								/** @type {string[]} */ (elements)[0] === "node_modules"
+							) {
+								// This is only a grouping folder e.g. used by yarn
+								// we are only interested in existence of this special directory
+								this._managedItems.set(path, "*nested");
+								return callback(null, "*nested");
+							}
+							/** @type {Logger} */
+							(this.logger).warn(
+								`Managed item ${path} isn't a directory or doesn't contain a package.json (see snapshot.managedPaths option)`
+							);
+							return callback();
+						});
+						return;
+					}
+					return callback(/** @type {WebpackError} */ (err));
+				}
+				let data;
+				try {
+					data = JSON.parse(/** @type {Buffer} */ (content).toString("utf-8"));
+				} catch (parseErr) {
+					return callback(/** @type {WebpackError} */ (parseErr));
+				}
+				if (!data.name) {
+					/** @type {Logger} */
+					(this.logger).warn(
+						`${packageJsonPath} doesn't contain a "name" property (see snapshot.managedPaths option)`
+					);
+					return callback();
+				}
+				const info = `${data.name || ""}@${data.version || ""}`;
+				this._managedItems.set(path, info);
+				callback(null, info);
+			});
+		});
+	}
+
+	getDeprecatedFileTimestamps() {
+		if (this._cachedDeprecatedFileTimestamps !== undefined)
+			return this._cachedDeprecatedFileTimestamps;
+		const map = new Map();
+		for (const [path, info] of this._fileTimestamps) {
+			if (info) map.set(path, typeof info === "object" ? info.safeTime : null);
+		}
+		return (this._cachedDeprecatedFileTimestamps = map);
+	}
+
+	getDeprecatedContextTimestamps() {
+		if (this._cachedDeprecatedContextTimestamps !== undefined)
+			return this._cachedDeprecatedContextTimestamps;
+		const map = new Map();
+		for (const [path, info] of this._contextTimestamps) {
+			if (info) map.set(path, typeof info === "object" ? info.safeTime : null);
+		}
+		return (this._cachedDeprecatedContextTimestamps = map);
+	}
+}
+
+module.exports = FileSystemInfo;
+module.exports.Snapshot = Snapshot;
