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/** * @module LRUCache */ const perf = typeof performance === 'object' && performance && typeof performance.now === 'function' ? performance : Date; const warned = new Set(); /* c8 ignore start */ const PROCESS = (typeof process === 'object' && !!process ? process : {}); /* c8 ignore start */ const emitWarning = (msg, type, code, fn) => { typeof PROCESS.emitWarning === 'function' ? PROCESS.emitWarning(msg, type, code, fn) : console.error(`[${code}] ${type}: ${msg}`); }; let AC = globalThis.AbortController; let AS = globalThis.AbortSignal; /* c8 ignore start */ if (typeof AC === 'undefined') { //@ts-ignore AS = class AbortSignal { onabort; _onabort = []; reason; aborted = false; addEventListener(_, fn) { this._onabort.push(fn); } }; //@ts-ignore AC = class AbortController { constructor() { warnACPolyfill(); } signal = new AS(); abort(reason) { if (this.signal.aborted) return; //@ts-ignore this.signal.reason = reason; //@ts-ignore this.signal.aborted = true; //@ts-ignore for (const fn of this.signal._onabort) { fn(reason); } this.signal.onabort?.(reason); } }; let printACPolyfillWarning = PROCESS.env?.LRU_CACHE_IGNORE_AC_WARNING !== '1'; const warnACPolyfill = () => { if (!printACPolyfillWarning) return; printACPolyfillWarning = false; emitWarning('AbortController is not defined. If using lru-cache in ' + 'node 14, load an AbortController polyfill from the ' + '`node-abort-controller` package. A minimal polyfill is ' + 'provided for use by LRUCache.fetch(), but it should not be ' + 'relied upon in other contexts (eg, passing it to other APIs that ' + 'use AbortController/AbortSignal might have undesirable effects). ' + 'You may disable this with LRU_CACHE_IGNORE_AC_WARNING=1 in the env.', 'NO_ABORT_CONTROLLER', 'ENOTSUP', warnACPolyfill); }; } /* c8 ignore stop */ const shouldWarn = (code) => !warned.has(code); const TYPE = Symbol('type'); const isPosInt = (n) => n && n === Math.floor(n) && n > 0 && isFinite(n); /* c8 ignore start */ // This is a little bit ridiculous, tbh. // The maximum array length is 2^32-1 or thereabouts on most JS impls. // And well before that point, you're caching the entire world, I mean, // that's ~32GB of just integers for the next/prev links, plus whatever // else to hold that many keys and values. Just filling the memory with // zeroes at init time is brutal when you get that big. // But why not be complete? // Maybe in the future, these limits will have expanded. const getUintArray = (max) => !isPosInt(max) ? null : max <= Math.pow(2, 8) ? Uint8Array : max <= Math.pow(2, 16) ? Uint16Array : max <= Math.pow(2, 32) ? Uint32Array : max <= Number.MAX_SAFE_INTEGER ? ZeroArray : null; /* c8 ignore stop */ class ZeroArray extends Array { constructor(size) { super(size); this.fill(0); } } class Stack { heap; length; // private constructor static #constructing = false; static create(max) { const HeapCls = getUintArray(max); if (!HeapCls) return []; Stack.#constructing = true; const s = new Stack(max, HeapCls); Stack.#constructing = false; return s; } constructor(max, HeapCls) { /* c8 ignore start */ if (!Stack.#constructing) { throw new TypeError('instantiate Stack using Stack.create(n)'); } /* c8 ignore stop */ this.heap = new HeapCls(max); this.length = 0; } push(n) { this.heap[this.length++] = n; } pop() { return this.heap[--this.length]; } } /** * Default export, the thing you're using this module to get. * * All properties from the options object (with the exception of * {@link OptionsBase.max} and {@link OptionsBase.maxSize}) are added as * normal public members. (`max` and `maxBase` are read-only getters.) * Changing any of these will alter the defaults for subsequent method calls, * but is otherwise safe. */ export class LRUCache { // properties coming in from the options of these, only max and maxSize // really *need* to be protected. The rest can be modified, as they just // set defaults for various methods. #max; #maxSize; #dispose; #disposeAfter; #fetchMethod; /** * {@link LRUCache.OptionsBase.ttl} */ ttl; /** * {@link LRUCache.OptionsBase.ttlResolution} */ ttlResolution; /** * {@link LRUCache.OptionsBase.ttlAutopurge} */ ttlAutopurge; /** * {@link LRUCache.OptionsBase.updateAgeOnGet} */ updateAgeOnGet; /** * {@link LRUCache.OptionsBase.updateAgeOnHas} */ updateAgeOnHas; /** * {@link LRUCache.OptionsBase.allowStale} */ allowStale; /** * {@link LRUCache.OptionsBase.noDisposeOnSet} */ noDisposeOnSet; /** * {@link LRUCache.OptionsBase.noUpdateTTL} */ noUpdateTTL; /** * {@link LRUCache.OptionsBase.maxEntrySize} */ maxEntrySize; /** * {@link LRUCache.OptionsBase.sizeCalculation} */ sizeCalculation; /** * {@link LRUCache.OptionsBase.noDeleteOnFetchRejection} */ noDeleteOnFetchRejection; /** * {@link LRUCache.OptionsBase.noDeleteOnStaleGet} */ noDeleteOnStaleGet; /** * {@link LRUCache.OptionsBase.allowStaleOnFetchAbort} */ allowStaleOnFetchAbort; /** * {@link LRUCache.OptionsBase.allowStaleOnFetchRejection} */ allowStaleOnFetchRejection; /** * {@link LRUCache.OptionsBase.ignoreFetchAbort} */ ignoreFetchAbort; // computed properties #size; #calculatedSize; #keyMap; #keyList; #valList; #next; #prev; #head; #tail; #free; #disposed; #sizes; #starts; #ttls; #hasDispose; #hasFetchMethod; #hasDisposeAfter; /** * Do not call this method unless you need to inspect the * inner workings of the cache. If anything returned by this * object is modified in any way, strange breakage may occur. * * These fields are private for a reason! * * @internal */ static unsafeExposeInternals(c) { return { // properties starts: c.#starts, ttls: c.#ttls, sizes: c.#sizes, keyMap: c.#keyMap, keyList: c.#keyList, valList: c.#valList, next: c.#next, prev: c.#prev, get head() { return c.#head; }, get tail() { return c.#tail; }, free: c.#free, // methods isBackgroundFetch: (p) => c.#isBackgroundFetch(p), backgroundFetch: (k, index, options, context) => c.#backgroundFetch(k, index, options, context), moveToTail: (index) => c.#moveToTail(index), indexes: (options) => c.#indexes(options), rindexes: (options) => c.#rindexes(options), isStale: (index) => c.#isStale(index), }; } // Protected read-only members /** * {@link LRUCache.OptionsBase.max} (read-only) */ get max() { return this.#max; } /** * {@link LRUCache.OptionsBase.maxSize} (read-only) */ get maxSize() { return this.#maxSize; } /** * The total computed size of items in the cache (read-only) */ get calculatedSize() { return this.#calculatedSize; } /** * The number of items stored in the cache (read-only) */ get size() { return this.#size; } /** * {@link LRUCache.OptionsBase.fetchMethod} (read-only) */ get fetchMethod() { return this.#fetchMethod; } /** * {@link LRUCache.OptionsBase.dispose} (read-only) */ get dispose() { return this.#dispose; } /** * {@link LRUCache.OptionsBase.disposeAfter} (read-only) */ get disposeAfter() { return this.#disposeAfter; } constructor(options) { const { max = 0, ttl, ttlResolution = 1, ttlAutopurge, updateAgeOnGet, updateAgeOnHas, allowStale, dispose, disposeAfter, noDisposeOnSet, noUpdateTTL, maxSize = 0, maxEntrySize = 0, sizeCalculation, fetchMethod, noDeleteOnFetchRejection, noDeleteOnStaleGet, allowStaleOnFetchRejection, allowStaleOnFetchAbort, ignoreFetchAbort, } = options; if (max !== 0 && !isPosInt(max)) { throw new TypeError('max option must be a nonnegative integer'); } const UintArray = max ? getUintArray(max) : Array; if (!UintArray) { throw new Error('invalid max value: ' + max); } this.#max = max; this.#maxSize = maxSize; this.maxEntrySize = maxEntrySize || this.#maxSize; this.sizeCalculation = sizeCalculation; if (this.sizeCalculation) { if (!this.#maxSize && !this.maxEntrySize) { throw new TypeError('cannot set sizeCalculation without setting maxSize or maxEntrySize'); } if (typeof this.sizeCalculation !== 'function') { throw new TypeError('sizeCalculation set to non-function'); } } if (fetchMethod !== undefined && typeof fetchMethod !== 'function') { throw new TypeError('fetchMethod must be a function if specified'); } this.#fetchMethod = fetchMethod; this.#hasFetchMethod = !!fetchMethod; this.#keyMap = new Map(); this.#keyList = new Array(max).fill(undefined); this.#valList = new Array(max).fill(undefined); this.#next = new UintArray(max); this.#prev = new UintArray(max); this.#head = 0; this.#tail = 0; this.#free = Stack.create(max); this.#size = 0; this.#calculatedSize = 0; if (typeof dispose === 'function') { this.#dispose = dispose; } if (typeof disposeAfter === 'function') { this.#disposeAfter = disposeAfter; this.#disposed = []; } else { this.#disposeAfter = undefined; this.#disposed = undefined; } this.#hasDispose = !!this.#dispose; this.#hasDisposeAfter = !!this.#disposeAfter; this.noDisposeOnSet = !!noDisposeOnSet; this.noUpdateTTL = !!noUpdateTTL; this.noDeleteOnFetchRejection = !!noDeleteOnFetchRejection; this.allowStaleOnFetchRejection = !!allowStaleOnFetchRejection; this.allowStaleOnFetchAbort = !!allowStaleOnFetchAbort; this.ignoreFetchAbort = !!ignoreFetchAbort; // NB: maxEntrySize is set to maxSize if it's set if (this.maxEntrySize !== 0) { if (this.#maxSize !== 0) { if (!isPosInt(this.#maxSize)) { throw new TypeError('maxSize must be a positive integer if specified'); } } if (!isPosInt(this.maxEntrySize)) { throw new TypeError('maxEntrySize must be a positive integer if specified'); } this.#initializeSizeTracking(); } this.allowStale = !!allowStale; this.noDeleteOnStaleGet = !!noDeleteOnStaleGet; this.updateAgeOnGet = !!updateAgeOnGet; this.updateAgeOnHas = !!updateAgeOnHas; this.ttlResolution = isPosInt(ttlResolution) || ttlResolution === 0 ? ttlResolution : 1; this.ttlAutopurge = !!ttlAutopurge; this.ttl = ttl || 0; if (this.ttl) { if (!isPosInt(this.ttl)) { throw new TypeError('ttl must be a positive integer if specified'); } this.#initializeTTLTracking(); } // do not allow completely unbounded caches if (this.#max === 0 && this.ttl === 0 && this.#maxSize === 0) { throw new TypeError('At least one of max, maxSize, or ttl is required'); } if (!this.ttlAutopurge && !this.#max && !this.#maxSize) { const code = 'LRU_CACHE_UNBOUNDED'; if (shouldWarn(code)) { warned.add(code); const msg = 'TTL caching without ttlAutopurge, max, or maxSize can ' + 'result in unbounded memory consumption.'; emitWarning(msg, 'UnboundedCacheWarning', code, LRUCache); } } } /** * Return the remaining TTL time for a given entry key */ getRemainingTTL(key) { return this.#keyMap.has(key) ? Infinity : 0; } #initializeTTLTracking() { const ttls = new ZeroArray(this.#max); const starts = new ZeroArray(this.#max); this.#ttls = ttls; this.#starts = starts; this.#setItemTTL = (index, ttl, start = perf.now()) => { starts[index] = ttl !== 0 ? start : 0; ttls[index] = ttl; if (ttl !== 0 && this.ttlAutopurge) { const t = setTimeout(() => { if (this.#isStale(index)) { this.delete(this.#keyList[index]); } }, ttl + 1); // unref() not supported on all platforms /* c8 ignore start */ if (t.unref) { t.unref(); } /* c8 ignore stop */ } }; this.#updateItemAge = index => { starts[index] = ttls[index] !== 0 ? perf.now() : 0; }; this.#statusTTL = (status, index) => { if (ttls[index]) { const ttl = ttls[index]; const start = starts[index]; /* c8 ignore next */ if (!ttl || !start) return; status.ttl = ttl; status.start = start; status.now = cachedNow || getNow(); const age = status.now - start; status.remainingTTL = ttl - age; } }; // debounce calls to perf.now() to 1s so we're not hitting // that costly call repeatedly. let cachedNow = 0; const getNow = () => { const n = perf.now(); if (this.ttlResolution > 0) { cachedNow = n; const t = setTimeout(() => (cachedNow = 0), this.ttlResolution); // not available on all platforms /* c8 ignore start */ if (t.unref) { t.unref(); } /* c8 ignore stop */ } return n; }; this.getRemainingTTL = key => { const index = this.#keyMap.get(key); if (index === undefined) { return 0; } const ttl = ttls[index]; const start = starts[index]; if (!ttl || !start) { return Infinity; } const age = (cachedNow || getNow()) - start; return ttl - age; }; this.#isStale = index => { const s = starts[index]; const t = ttls[index]; return !!t && !!s && (cachedNow || getNow()) - s > t; }; } // conditionally set private methods related to TTL #updateItemAge = () => { }; #statusTTL = () => { }; #setItemTTL = () => { }; /* c8 ignore stop */ #isStale = () => false; #initializeSizeTracking() { const sizes = new ZeroArray(this.#max); this.#calculatedSize = 0; this.#sizes = sizes; this.#removeItemSize = index => { this.#calculatedSize -= sizes[index]; sizes[index] = 0; }; this.#requireSize = (k, v, size, sizeCalculation) => { // provisionally accept background fetches. // actual value size will be checked when they return. if (this.#isBackgroundFetch(v)) { return 0; } if (!isPosInt(size)) { if (sizeCalculation) { if (typeof sizeCalculation !== 'function') { throw new TypeError('sizeCalculation must be a function'); } size = sizeCalculation(v, k); if (!isPosInt(size)) { throw new TypeError('sizeCalculation return invalid (expect positive integer)'); } } else { throw new TypeError('invalid size value (must be positive integer). ' + 'When maxSize or maxEntrySize is used, sizeCalculation ' + 'or size must be set.'); } } return size; }; this.#addItemSize = (index, size, status) => { sizes[index] = size; if (this.#maxSize) { const maxSize = this.#maxSize - sizes[index]; while (this.#calculatedSize > maxSize) { this.#evict(true); } } this.#calculatedSize += sizes[index]; if (status) { status.entrySize = size; status.totalCalculatedSize = this.#calculatedSize; } }; } #removeItemSize = _i => { }; #addItemSize = (_i, _s, _st) => { }; #requireSize = (_k, _v, size, sizeCalculation) => { if (size || sizeCalculation) { throw new TypeError('cannot set size without setting maxSize or maxEntrySize on cache'); } return 0; }; *#indexes({ allowStale = this.allowStale } = {}) { if (this.#size) { for (let i = this.#tail; true;) { if (!this.#isValidIndex(i)) { break; } if (allowStale || !this.#isStale(i)) { yield i; } if (i === this.#head) { break; } else { i = this.#prev[i]; } } } } *#rindexes({ allowStale = this.allowStale } = {}) { if (this.#size) { for (let i = this.#head; true;) { if (!this.#isValidIndex(i)) { break; } if (allowStale || !this.#isStale(i)) { yield i; } if (i === this.#tail) { break; } else { i = this.#next[i]; } } } } #isValidIndex(index) { return (index !== undefined && this.#keyMap.get(this.#keyList[index]) === index); } /** * Return a generator yielding `[key, value]` pairs, * in order from most recently used to least recently used. */ *entries() { for (const i of this.#indexes()) { if (this.#valList[i] !== undefined && this.#keyList[i] !== undefined && !this.#isBackgroundFetch(this.#valList[i])) { yield [this.#keyList[i], this.#valList[i]]; } } } /** * Inverse order version of {@link LRUCache.entries} * * Return a generator yielding `[key, value]` pairs, * in order from least recently used to most recently used. */ *rentries() { for (const i of this.#rindexes()) { if (this.#valList[i] !== undefined && this.#keyList[i] !== undefined && !this.#isBackgroundFetch(this.#valList[i])) { yield [this.#keyList[i], this.#valList[i]]; } } } /** * Return a generator yielding the keys in the cache, * in order from most recently used to least recently used. */ *keys() { for (const i of this.#indexes()) { const k = this.#keyList[i]; if (k !== undefined && !this.#isBackgroundFetch(this.#valList[i])) { yield k; } } } /** * Inverse order version of {@link LRUCache.keys} * * Return a generator yielding the keys in the cache, * in order from least recently used to most recently used. */ *rkeys() { for (const i of this.#rindexes()) { const k = this.#keyList[i]; if (k !== undefined && !this.#isBackgroundFetch(this.#valList[i])) { yield k; } } } /** * Return a generator yielding the values in the cache, * in order from most recently used to least recently used. */ *values() { for (const i of this.#indexes()) { const v = this.#valList[i]; if (v !== undefined && !this.#isBackgroundFetch(this.#valList[i])) { yield this.#valList[i]; } } } /** * Inverse order version of {@link LRUCache.values} * * Return a generator yielding the values in the cache, * in order from least recently used to most recently used. */ *rvalues() { for (const i of this.#rindexes()) { const v = this.#valList[i]; if (v !== undefined && !this.#isBackgroundFetch(this.#valList[i])) { yield this.#valList[i]; } } } /** * Iterating over the cache itself yields the same results as * {@link LRUCache.entries} */ [Symbol.iterator]() { return this.entries(); } /** * A String value that is used in the creation of the default string description of an object. * Called by the built-in method Object.prototype.toString. */ [Symbol.toStringTag] = 'LRUCache'; /** * Find a value for which the supplied fn method returns a truthy value, * similar to Array.find(). fn is called as fn(value, key, cache). */ find(fn, getOptions = {}) { for (const i of this.#indexes()) { const v = this.#valList[i]; const value = this.#isBackgroundFetch(v) ? v.__staleWhileFetching : v; if (value === undefined) continue; if (fn(value, this.#keyList[i], this)) { return this.get(this.#keyList[i], getOptions); } } } /** * Call the supplied function on each item in the cache, in order from * most recently used to least recently used. fn is called as * fn(value, key, cache). Does not update age or recenty of use. * Does not iterate over stale values. */ forEach(fn, thisp = this) { for (const i of this.#indexes()) { const v = this.#valList[i]; const value = this.#isBackgroundFetch(v) ? v.__staleWhileFetching : v; if (value === undefined) continue; fn.call(thisp, value, this.#keyList[i], this); } } /** * The same as {@link LRUCache.forEach} but items are iterated over in * reverse order. (ie, less recently used items are iterated over first.) */ rforEach(fn, thisp = this) { for (const i of this.#rindexes()) { const v = this.#valList[i]; const value = this.#isBackgroundFetch(v) ? v.__staleWhileFetching : v; if (value === undefined) continue; fn.call(thisp, value, this.#keyList[i], this); } } /** * Delete any stale entries. Returns true if anything was removed, * false otherwise. */ purgeStale() { let deleted = false; for (const i of this.#rindexes({ allowStale: true })) { if (this.#isStale(i)) { this.delete(this.#keyList[i]); deleted = true; } } return deleted; } /** * Get the extended info about a given entry, to get its value, size, and * TTL info simultaneously. Like {@link LRUCache#dump}, but just for a * single key. Always returns stale values, if their info is found in the * cache, so be sure to check for expired TTLs if relevant. */ info(key) { const i = this.#keyMap.get(key); if (i === undefined) return undefined; const v = this.#valList[i]; const value = this.#isBackgroundFetch(v) ? v.__staleWhileFetching : v; if (value === undefined) return undefined; const entry = { value }; if (this.#ttls && this.#starts) { const ttl = this.#ttls[i]; const start = this.#starts[i]; if (ttl && start) { const remain = ttl - (perf.now() - start); entry.ttl = remain; entry.start = Date.now(); } } if (this.#sizes) { entry.size = this.#sizes[i]; } return entry; } /** * Return an array of [key, {@link LRUCache.Entry}] tuples which can be * passed to cache.load() */ dump() { const arr = []; for (const i of this.#indexes({ allowStale: true })) { const key = this.#keyList[i]; const v = this.#valList[i]; const value = this.#isBackgroundFetch(v) ? v.__staleWhileFetching : v; if (value === undefined || key === undefined) continue; const entry = { value }; if (this.#ttls && this.#starts) { entry.ttl = this.#ttls[i]; // always dump the start relative to a portable timestamp // it's ok for this to be a bit slow, it's a rare operation. const age = perf.now() - this.#starts[i]; entry.start = Math.floor(Date.now() - age); } if (this.#sizes) { entry.size = this.#sizes[i]; } arr.unshift([key, entry]); } return arr; } /** * Reset the cache and load in the items in entries in the order listed. * Note that the shape of the resulting cache may be different if the * same options are not used in both caches. */ load(arr) { this.clear(); for (const [key, entry] of arr) { if (entry.start) { // entry.start is a portable timestamp, but we may be using // node's performance.now(), so calculate the offset, so that // we get the intended remaining TTL, no matter how long it's // been on ice. // // it's ok for this to be a bit slow, it's a rare operation. const age = Date.now() - entry.start; entry.start = perf.now() - age; } this.set(key, entry.value, entry); } } /** * Add a value to the cache. * * Note: if `undefined` is specified as a value, this is an alias for * {@link LRUCache#delete} */ set(k, v, setOptions = {}) { if (v === undefined) { this.delete(k); return this; } const { ttl = this.ttl, start, noDisposeOnSet = this.noDisposeOnSet, sizeCalculation = this.sizeCalculation, status, } = setOptions; let { noUpdateTTL = this.noUpdateTTL } = setOptions; const size = this.#requireSize(k, v, setOptions.size || 0, sizeCalculation); // if the item doesn't fit, don't do anything // NB: maxEntrySize set to maxSize by default if (this.maxEntrySize && size > this.maxEntrySize) { if (status) { status.set = 'miss'; status.maxEntrySizeExceeded = true; } // have to delete, in case something is there already. this.delete(k); return this; } let index = this.#size === 0 ? undefined : this.#keyMap.get(k); if (index === undefined) { // addition index = (this.#size === 0 ? this.#tail : this.#free.length !== 0 ? this.#free.pop() : this.#size === this.#max ? this.#evict(false) : this.#size); this.#keyList[index] = k; this.#valList[index] = v; this.#keyMap.set(k, index); this.#next[this.#tail] = index; this.#prev[index] = this.#tail; this.#tail = index; this.#size++; this.#addItemSize(index, size, status); if (status) status.set = 'add'; noUpdateTTL = false; } else { // update this.#moveToTail(index); const oldVal = this.#valList[index]; if (v !== oldVal) { if (this.#hasFetchMethod && this.#isBackgroundFetch(oldVal)) { oldVal.__abortController.abort(new Error('replaced')); const { __staleWhileFetching: s } = oldVal; if (s !== undefined && !noDisposeOnSet) { if (this.#hasDispose) { this.#dispose?.(s, k, 'set'); } if (this.#hasDisposeAfter) { this.#disposed?.push([s, k, 'set']); } } } else if (!noDisposeOnSet) { if (this.#hasDispose) { this.#dispose?.(oldVal, k, 'set'); } if (this.#hasDisposeAfter) { this.#disposed?.push([oldVal, k, 'set']); } } this.#removeItemSize(index); this.#addItemSize(index, size, status); this.#valList[index] = v; if (status) { status.set = 'replace'; const oldValue = oldVal && this.#isBackgroundFetch(oldVal) ? oldVal.__staleWhileFetching : oldVal; if (oldValue !== undefined) status.oldValue = oldValue; } } else if (status) { status.set = 'update'; } } if (ttl !== 0 && !this.#ttls) { this.#initializeTTLTracking(); } if (this.#ttls) { if (!noUpdateTTL) { this.#setItemTTL(index, ttl, start); } if (status) this.#statusTTL(status, index); } if (!noDisposeOnSet && this.#hasDisposeAfter && this.#disposed) { const dt = this.#disposed; let task; while ((task = dt?.shift())) { this.#disposeAfter?.(...task); } } return this; } /** * Evict the least recently used item, returning its value or * `undefined` if cache is empty. */ pop() { try { while (this.#size) { const val = this.#valList[this.#head]; this.#evict(true); if (this.#isBackgroundFetch(val)) { if (val.__staleWhileFetching) { return val.__staleWhileFetching; } } else if (val !== undefined) { return val; } } } finally { if (this.#hasDisposeAfter && this.#disposed) { const dt = this.#disposed; let task; while ((task = dt?.shift())) { this.#disposeAfter?.(...task); } } } } #evict(free) { const head = this.#head; const k = this.#keyList[head]; const v = this.#valList[head]; if (this.#hasFetchMethod && this.#isBackgroundFetch(v)) { v.__abortController.abort(new Error('evicted')); } else if (this.#hasDispose || this.#hasDisposeAfter) { if (this.#hasDispose) { this.#dispose?.(v, k, 'evict'); } if (this.#hasDisposeAfter) { this.#disposed?.push([v, k, 'evict']); } } this.#removeItemSize(head); // if we aren't about to use the index, then null these out if (free) { this.#keyList[head] = undefined; this.#valList[head] = undefined; this.#free.push(head); } if (this.#size === 1) { this.#head = this.#tail = 0; this.#free.length = 0; } else { this.#head = this.#next[head]; } this.#keyMap.delete(k); this.#size--; return head; } /** * Check if a key is in the cache, without updating the recency of use. * Will return false if the item is stale, even though it is technically * in the cache. * * Will not update item age unless * {@link LRUCache.OptionsBase.updateAgeOnHas} is set. */ has(k, hasOptions = {}) { const { updateAgeOnHas = this.updateAgeOnHas, status } = hasOptions; const index = this.#keyMap.get(k); if (index !== undefined) { const v = this.#valList[index]; if (this.#isBackgroundFetch(v) && v.__staleWhileFetching === undefined) { return false; } if (!this.#isStale(index)) { if (updateAgeOnHas) { this.#updateItemAge(index); } if (status) { status.has = 'hit'; this.#statusTTL(status, index); } return true; } else if (status) { status.has = 'stale'; this.#statusTTL(status, index); } } else if (status) { status.has = 'miss'; } return false; } /** * Like {@link LRUCache#get} but doesn't update recency or delete stale * items. * * Returns `undefined` if the item is stale, unless * {@link LRUCache.OptionsBase.allowStale} is set. */ peek(k, peekOptions = {}) { const { allowStale = this.allowStale } = peekOptions; const index = this.#keyMap.get(k); if (index === undefined || (!allowStale && this.#isStale(index))) { return; } const v = this.#valList[index]; // either stale and allowed, or forcing a refresh of non-stale value return this.#isBackgroundFetch(v) ? v.__staleWhileFetching : v; } #backgroundFetch(k, index, options, context) { const v = index === undefined ? undefined : this.#valList[index]; if (this.#isBackgroundFetch(v)) { return v; } const ac = new AC(); const { signal } = options; // when/if our AC signals, then stop listening to theirs. signal?.addEventListener('abort', () => ac.abort(signal.reason), { signal: ac.signal, }); const fetchOpts = { signal: ac.signal, options, context, }; const cb = (v, updateCache = false) => { const { aborted } = ac.signal; const ignoreAbort = options.ignoreFetchAbort && v !== undefined; if (options.status) { if (aborted && !updateCache) { options.status.fetchAborted = true; options.status.fetchError = ac.signal.reason; if (ignoreAbort) options.status.fetchAbortIgnored = true; } else { options.status.fetchResolved = true; } } if (aborted && !ignoreAbort && !updateCache) { return fetchFail(ac.signal.reason); } // either we didn't abort, and are still here, or we did, and ignored const bf = p; if (this.#valList[index] === p) { if (v === undefined) { if (bf.__staleWhileFetching) { this.#valList[index] = bf.__staleWhileFetching; } else { this.delete(k); } } else { if (options.status) options.status.fetchUpdated = true; this.set(k, v, fetchOpts.options); } } return v; }; const eb = (er) => { if (options.status) { options.status.fetchRejected = true; options.status.fetchError = er; } return fetchFail(er); }; const fetchFail = (er) => { const { aborted } = ac.signal; const allowStaleAborted = aborted && options.allowStaleOnFetchAbort; const allowStale = allowStaleAborted || options.allowStaleOnFetchRejection; const noDelete = allowStale || options.noDeleteOnFetchRejection; const bf = p; if (this.#valList[index] === p) { // if we allow stale on fetch rejections, then we need to ensure that // the stale value is not removed from the cache when the fetch fails. const del = !noDelete || bf.__staleWhileFetching === undefined; if (del) { this.delete(k); } else if (!allowStaleAborted) { // still replace the *promise* with the stale value, // since we are done with the promise at this point. // leave it untouched if we're still waiting for an // aborted background fetch that hasn't yet returned. this.#valList[index] = bf.__staleWhileFetching; } } if (allowStale) { if (options.status && bf.__staleWhileFetching !== undefined) { options.status.returnedStale = true; } return bf.__staleWhileFetching; } else if (bf.__returned === bf) { throw er; } }; const pcall = (res, rej) => { const fmp = this.#fetchMethod?.(k, v, fetchOpts); if (fmp && fmp instanceof Promise) { fmp.then(v => res(v === undefined ? undefined : v), rej); } // ignored, we go until we finish, regardless. // defer check until we are actually aborting, // so fetchMethod can override. ac.signal.addEventListener('abort', () => { if (!options.ignoreFetchAbort || options.allowStaleOnFetchAbort) { res(undefined); // when it eventually resolves, update the cache. if (options.allowStaleOnFetchAbort) { res = v => cb(v, true); } } }); }; if (options.status) options.status.fetchDispatched = true; const p = new Promise(pcall).then(cb, eb); const bf = Object.assign(p, { __abortController: ac, __staleWhileFetching: v, __returned: undefined, }); if (index === undefined) { // internal, don't expose status. this.set(k, bf, { ...fetchOpts.options, status: undefined }); index = this.#keyMap.get(k); } else { this.#valList[index] = bf; } return bf; } #isBackgroundFetch(p) { if (!this.#hasFetchMethod) return false; const b = p; return (!!b && b instanceof Promise && b.hasOwnProperty('__staleWhileFetching') && b.__abortController instanceof AC); } async fetch(k, fetchOptions = {}) { const { // get options allowStale = this.allowStale, updateAgeOnGet = this.updateAgeOnGet, noDeleteOnStaleGet = this.noDeleteOnStaleGet, // set options ttl = this.ttl, noDisposeOnSet = this.noDisposeOnSet, size = 0, sizeCalculation = this.sizeCalculation, noUpdateTTL = this.noUpdateTTL, // fetch exclusive options noDeleteOnFetchRejection = this.noDeleteOnFetchRejection, allowStaleOnFetchRejection = this.allowStaleOnFetchRejection, ignoreFetchAbort = this.ignoreFetchAbort, allowStaleOnFetchAbort = this.allowStaleOnFetchAbort, context, forceRefresh = false, status, signal, } = fetchOptions; if (!this.#hasFetchMethod) { if (status) status.fetch = 'get'; return this.get(k, { allowStale, updateAgeOnGet, noDeleteOnStaleGet, status, }); } const options = { allowStale, updateAgeOnGet, noDeleteOnStaleGet, ttl, noDisposeOnSet, size, sizeCalculation, noUpdateTTL, noDeleteOnFetchRejection, allowStaleOnFetchRejection, allowStaleOnFetchAbort, ignoreFetchAbort, status, signal, }; let index = this.#keyMap.get(k); if (index === undefined) { if (status) status.fetch = 'miss'; const p = this.#backgroundFetch(k, index, options, context); return (p.__returned = p); } else { // in cache, maybe already fetching const v = this.#valList[index]; if (this.#isBackgroundFetch(v)) { const stale = allowStale && v.__staleWhileFetching !== undefined; if (status) { status.fetch = 'inflight'; if (stale) status.returnedStale = true; } return stale ? v.__staleWhileFetching : (v.__returned = v); } // if we force a refresh, that means do NOT serve the cached value, // unless we are already in the process of refreshing the cache. const isStale = this.#isStale(index); if (!forceRefresh && !isStale) { if (status) status.fetch = 'hit'; this.#moveToTail(index); if (updateAgeOnGet) { this.#updateItemAge(index); } if (status) this.#statusTTL(status, index); return v; } // ok, it is stale or a forced refresh, and not already fetching. // refresh the cache. const p = this.#backgroundFetch(k, index, options, context); const hasStale = p.__staleWhileFetching !== undefined; const staleVal = hasStale && allowStale; if (status) { status.fetch = isStale ? 'stale' : 'refresh'; if (staleVal && isStale) status.returnedStale = true; } return staleVal ? p.__staleWhileFetching : (p.__returned = p); } } /** * Return a value from the cache. Will update the recency of the cache * entry found. * * If the key is not found, get() will return `undefined`. */ get(k, getOptions = {}) { const { allowStale = this.allowStale, updateAgeOnGet = this.updateAgeOnGet, noDeleteOnStaleGet = this.noDeleteOnStaleGet, status, } = getOptions; const index = this.#keyMap.get(k); if (index !== undefined) { const value = this.#valList[index]; const fetching = this.#isBackgroundFetch(value); if (status) this.#statusTTL(status, index); if (this.#isStale(index)) { if (status) status.get = 'stale'; // delete only if not an in-flight background fetch if (!fetching) { if (!noDeleteOnStaleGet) { this.delete(k); } if (status && allowStale) status.returnedStale = true; return allowStale ? value : undefined; } else { if (status && allowStale && value.__staleWhileFetching !== undefined) { status.returnedStale = true; } return allowStale ? value.__staleWhileFetching : undefined; } } else { if (status) status.get = 'hit'; // if we're currently fetching it, we don't actually have it yet // it's not stale, which means this isn't a staleWhileRefetching. // If it's not stale, and fetching, AND has a __staleWhileFetching // value, then that means the user fetched with {forceRefresh:true}, // so it's safe to return that value. if (fetching) { return value.__staleWhileFetching; } this.#moveToTail(index); if (updateAgeOnGet) { this.#updateItemAge(index); } return value; } } else if (status) { status.get = 'miss'; } } #connect(p, n) { this.#prev[n] = p; this.#next[p] = n; } #moveToTail(index) { // if tail already, nothing to do // if head, move head to next[index] // else // move next[prev[index]] to next[index] (head has no prev) // move prev[next[index]] to prev[index] // prev[index] = tail // next[tail] = index // tail = index if (index !== this.#tail) { if (index === this.#head) { this.#head = this.#next[index]; } else { this.#connect(this.#prev[index], this.#next[index]); } this.#connect(this.#tail, index); this.#tail = index; } } /** * Deletes a key out of the cache. * Returns true if the key was deleted, false otherwise. */ delete(k) { let deleted = false; if (this.#size !== 0) { const index = this.#keyMap.get(k); if (index !== undefined) { deleted = true; if (this.#size === 1) { this.clear(); } else { this.#removeItemSize(index); const v = this.#valList[index]; if (this.#isBackgroundFetch(v)) { v.__abortController.abort(new Error('deleted')); } else if (this.#hasDispose || this.#hasDisposeAfter) { if (this.#hasDispose) { this.#dispose?.(v, k, 'delete'); } if (this.#hasDisposeAfter) { this.#disposed?.push([v, k, 'delete']); } } this.#keyMap.delete(k); this.#keyList[index] = undefined; this.#valList[index] = undefined; if (index === this.#tail) { this.#tail = this.#prev[index]; } else if (index === this.#head) { this.#head = this.#next[index]; } else { const pi = this.#prev[index]; this.#next[pi] = this.#next[index]; const ni = this.#next[index]; this.#prev[ni] = this.#prev[index]; } this.#size--; this.#free.push(index); } } } if (this.#hasDisposeAfter && this.#disposed?.length) { const dt = this.#disposed; let task; while ((task = dt?.shift())) { this.#disposeAfter?.(...task); } } return deleted; } /** * Clear the cache entirely, throwing away all values. */ clear() { for (const index of this.#rindexes({ allowStale: true })) { const v = this.#valList[index]; if (this.#isBackgroundFetch(v)) { v.__abortController.abort(new Error('deleted')); } else { const k = this.#keyList[index]; if (this.#hasDispose) { this.#dispose?.(v, k, 'delete'); } if (this.#hasDisposeAfter) { this.#disposed?.push([v, k, 'delete']); } } } this.#keyMap.clear(); this.#valList.fill(undefined); this.#keyList.fill(undefined); if (this.#ttls && this.#starts) { this.#ttls.fill(0); this.#starts.fill(0); } if (this.#sizes) { this.#sizes.fill(0); } this.#head = 0; this.#tail = 0; this.#free.length = 0; this.#calculatedSize = 0; this.#size = 0; if (this.#hasDisposeAfter && this.#disposed) { const dt = this.#disposed; let task; while ((task = dt?.shift())) { this.#disposeAfter?.(...task); } } } } //# sourceMappingURL=index.js.map