%PDF-
%PDF-
Mini Shell
Mini Shell
const perf = typeof performance === 'object' && performance &&
typeof performance.now === 'function' ? performance : Date
const hasAbortController = typeof AbortController === 'function'
// minimal backwards-compatibility polyfill
// this doesn't have nearly all the checks and whatnot that
// actual AbortController/Signal has, but it's enough for
// our purposes, and if used properly, behaves the same.
const AC = hasAbortController ? AbortController : Object.assign(
class AbortController {
constructor () { this.signal = new AC.AbortSignal }
abort () {
this.signal.dispatchEvent('abort')
}
},
{
AbortSignal: class AbortSignal {
constructor () {
this.aborted = false
this._listeners = []
}
dispatchEvent (type) {
if (type === 'abort') {
this.aborted = true
const e = { type, target: this }
this.onabort(e)
this._listeners.forEach(f => f(e), this)
}
}
onabort () {}
addEventListener (ev, fn) {
if (ev === 'abort') {
this._listeners.push(fn)
}
}
removeEventListener (ev, fn) {
if (ev === 'abort') {
this._listeners = this._listeners.filter(f => f !== fn)
}
}
}
}
)
const warned = new Set()
const deprecatedOption = (opt, instead) => {
const code = `LRU_CACHE_OPTION_${opt}`
if (shouldWarn(code)) {
warn(code, `${opt} option`, `options.${instead}`, LRUCache)
}
}
const deprecatedMethod = (method, instead) => {
const code = `LRU_CACHE_METHOD_${method}`
if (shouldWarn(code)) {
const { prototype } = LRUCache
const { get } = Object.getOwnPropertyDescriptor(prototype, method)
warn(code, `${method} method`, `cache.${instead}()`, get)
}
}
const deprecatedProperty = (field, instead) => {
const code = `LRU_CACHE_PROPERTY_${field}`
if (shouldWarn(code)) {
const { prototype } = LRUCache
const { get } = Object.getOwnPropertyDescriptor(prototype, field)
warn(code, `${field} property`, `cache.${instead}`, get)
}
}
const emitWarning = (...a) => {
typeof process === 'object' &&
process &&
typeof process.emitWarning === 'function'
? process.emitWarning(...a)
: console.error(...a)
}
const shouldWarn = code => !warned.has(code)
const warn = (code, what, instead, fn) => {
warned.add(code)
const msg = `The ${what} is deprecated. Please use ${instead} instead.`
emitWarning(msg, 'DeprecationWarning', code, fn)
}
const isPosInt = n => n && n === Math.floor(n) && n > 0 && isFinite(n)
/* istanbul ignore next - 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
class ZeroArray extends Array {
constructor (size) {
super(size)
this.fill(0)
}
}
class Stack {
constructor (max) {
if (max === 0) {
return []
}
const UintArray = getUintArray(max)
this.heap = new UintArray(max)
this.length = 0
}
push (n) {
this.heap[this.length++] = n
}
pop () {
return this.heap[--this.length]
}
}
class LRUCache {
constructor (options = {}) {
const {
max = 0,
ttl,
ttlResolution = 1,
ttlAutopurge,
updateAgeOnGet,
updateAgeOnHas,
allowStale,
dispose,
disposeAfter,
noDisposeOnSet,
noUpdateTTL,
maxSize = 0,
sizeCalculation,
fetchMethod,
} = options
// deprecated options, don't trigger a warning for getting them if
// the thing being passed in is another LRUCache we're copying.
const {
length,
maxAge,
stale,
} = options instanceof LRUCache ? {} : 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.sizeCalculation = sizeCalculation || length
if (this.sizeCalculation) {
if (!this.maxSize) {
throw new TypeError('cannot set sizeCalculation without setting maxSize')
}
if (typeof this.sizeCalculation !== 'function') {
throw new TypeError('sizeCalculation set to non-function')
}
}
this.fetchMethod = fetchMethod || null
if (this.fetchMethod && typeof this.fetchMethod !== 'function') {
throw new TypeError('fetchMethod must be a function if specified')
}
this.keyMap = new Map()
this.keyList = new Array(max).fill(null)
this.valList = new Array(max).fill(null)
this.next = new UintArray(max)
this.prev = new UintArray(max)
this.head = 0
this.tail = 0
this.free = new Stack(max)
this.initialFill = 1
this.size = 0
if (typeof dispose === 'function') {
this.dispose = dispose
}
if (typeof disposeAfter === 'function') {
this.disposeAfter = disposeAfter
this.disposed = []
} else {
this.disposeAfter = null
this.disposed = null
}
this.noDisposeOnSet = !!noDisposeOnSet
this.noUpdateTTL = !!noUpdateTTL
if (this.maxSize !== 0) {
if (!isPosInt(this.maxSize)) {
throw new TypeError('maxSize must be a positive integer if specified')
}
this.initializeSizeTracking()
}
this.allowStale = !!allowStale || !!stale
this.updateAgeOnGet = !!updateAgeOnGet
this.updateAgeOnHas = !!updateAgeOnHas
this.ttlResolution = isPosInt(ttlResolution) || ttlResolution === 0
? ttlResolution : 1
this.ttlAutopurge = !!ttlAutopurge
this.ttl = ttl || maxAge || 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)
}
}
if (stale) {
deprecatedOption('stale', 'allowStale')
}
if (maxAge) {
deprecatedOption('maxAge', 'ttl')
}
if (length) {
deprecatedOption('length', 'sizeCalculation')
}
}
getRemainingTTL (key) {
return this.has(key, { updateAgeOnHas: false }) ? Infinity : 0
}
initializeTTLTracking () {
this.ttls = new ZeroArray(this.max)
this.starts = new ZeroArray(this.max)
this.setItemTTL = (index, ttl) => {
this.starts[index] = ttl !== 0 ? perf.now() : 0
this.ttls[index] = ttl
if (ttl !== 0 && this.ttlAutopurge) {
const t = setTimeout(() => {
if (this.isStale(index)) {
this.delete(this.keyList[index])
}
}, ttl + 1)
/* istanbul ignore else - unref() not supported on all platforms */
if (t.unref) {
t.unref()
}
}
}
this.updateItemAge = (index) => {
this.starts[index] = this.ttls[index] !== 0 ? perf.now() : 0
}
// 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)
/* istanbul ignore else - not available on all platforms */
if (t.unref) {
t.unref()
}
}
return n
}
this.getRemainingTTL = (key) => {
const index = this.keyMap.get(key)
if (index === undefined) {
return 0
}
return this.ttls[index] === 0 || this.starts[index] === 0 ? Infinity
: ((this.starts[index] + this.ttls[index]) - (cachedNow || getNow()))
}
this.isStale = (index) => {
return this.ttls[index] !== 0 && this.starts[index] !== 0 &&
((cachedNow || getNow()) - this.starts[index] > this.ttls[index])
}
}
updateItemAge (index) {}
setItemTTL (index, ttl) {}
isStale (index) { return false }
initializeSizeTracking () {
this.calculatedSize = 0
this.sizes = new ZeroArray(this.max)
this.removeItemSize = index => this.calculatedSize -= this.sizes[index]
this.requireSize = (k, v, size, sizeCalculation) => {
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)')
}
}
return size
}
this.addItemSize = (index, v, k, size) => {
this.sizes[index] = size
const maxSize = this.maxSize - this.sizes[index]
while (this.calculatedSize > maxSize) {
this.evict(true)
}
this.calculatedSize += this.sizes[index]
}
}
removeItemSize (index) {}
addItemSize (index, v, k, size) {}
requireSize (k, v, size, sizeCalculation) {
if (size || sizeCalculation) {
throw new TypeError('cannot set size without setting maxSize on cache')
}
}
*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 this.keyMap.get(this.keyList[index]) === index
}
*entries () {
for (const i of this.indexes()) {
yield [this.keyList[i], this.valList[i]]
}
}
*rentries () {
for (const i of this.rindexes()) {
yield [this.keyList[i], this.valList[i]]
}
}
*keys () {
for (const i of this.indexes()) {
yield this.keyList[i]
}
}
*rkeys () {
for (const i of this.rindexes()) {
yield this.keyList[i]
}
}
*values () {
for (const i of this.indexes()) {
yield this.valList[i]
}
}
*rvalues () {
for (const i of this.rindexes()) {
yield this.valList[i]
}
}
[Symbol.iterator] () {
return this.entries()
}
find (fn, getOptions = {}) {
for (const i of this.indexes()) {
if (fn(this.valList[i], this.keyList[i], this)) {
return this.get(this.keyList[i], getOptions)
}
}
}
forEach (fn, thisp = this) {
for (const i of this.indexes()) {
fn.call(thisp, this.valList[i], this.keyList[i], this)
}
}
rforEach (fn, thisp = this) {
for (const i of this.rindexes()) {
fn.call(thisp, this.valList[i], this.keyList[i], this)
}
}
get prune () {
deprecatedMethod('prune', 'purgeStale')
return this.purgeStale
}
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
}
dump () {
const arr = []
for (const i of this.indexes()) {
const key = this.keyList[i]
const value = this.valList[i]
const entry = { value }
if (this.ttls) {
entry.ttl = this.ttls[i]
}
if (this.sizes) {
entry.size = this.sizes[i]
}
arr.unshift([key, entry])
}
return arr
}
load (arr) {
this.clear()
for (const [key, entry] of arr) {
this.set(key, entry.value, entry)
}
}
dispose (v, k, reason) {}
set (k, v, {
ttl = this.ttl,
noDisposeOnSet = this.noDisposeOnSet,
size = 0,
sizeCalculation = this.sizeCalculation,
noUpdateTTL = this.noUpdateTTL,
} = {}) {
size = this.requireSize(k, v, size, sizeCalculation)
let index = this.size === 0 ? undefined : this.keyMap.get(k)
if (index === undefined) {
// addition
index = this.newIndex()
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, v, k, size)
noUpdateTTL = false
} else {
// update
const oldVal = this.valList[index]
if (v !== oldVal) {
if (this.isBackgroundFetch(oldVal)) {
oldVal.__abortController.abort()
} else {
if (!noDisposeOnSet) {
this.dispose(oldVal, k, 'set')
if (this.disposeAfter) {
this.disposed.push([oldVal, k, 'set'])
}
}
}
this.removeItemSize(index)
this.valList[index] = v
this.addItemSize(index, v, k, size)
}
this.moveToTail(index)
}
if (ttl !== 0 && this.ttl === 0 && !this.ttls) {
this.initializeTTLTracking()
}
if (!noUpdateTTL) {
this.setItemTTL(index, ttl)
}
if (this.disposeAfter) {
while (this.disposed.length) {
this.disposeAfter(...this.disposed.shift())
}
}
return this
}
newIndex () {
if (this.size === 0) {
return this.tail
}
if (this.size === this.max && this.max !== 0) {
return this.evict(false)
}
if (this.free.length !== 0) {
return this.free.pop()
}
// initial fill, just keep writing down the list
return this.initialFill++
}
pop () {
if (this.size) {
const val = this.valList[this.head]
this.evict(true)
return val
}
}
evict (free) {
const head = this.head
const k = this.keyList[head]
const v = this.valList[head]
if (this.isBackgroundFetch(v)) {
v.__abortController.abort()
} else {
this.dispose(v, k, 'evict')
if (this.disposeAfter) {
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] = null
this.valList[head] = null
this.free.push(head)
}
this.head = this.next[head]
this.keyMap.delete(k)
this.size --
return head
}
has (k, { updateAgeOnHas = this.updateAgeOnHas } = {}) {
const index = this.keyMap.get(k)
if (index !== undefined) {
if (!this.isStale(index)) {
if (updateAgeOnHas) {
this.updateItemAge(index)
}
return true
}
}
return false
}
// like get(), but without any LRU updating or TTL expiration
peek (k, { allowStale = this.allowStale } = {}) {
const index = this.keyMap.get(k)
if (index !== undefined && (allowStale || !this.isStale(index))) {
return this.valList[index]
}
}
backgroundFetch (k, index, options) {
const v = index === undefined ? undefined : this.valList[index]
if (this.isBackgroundFetch(v)) {
return v
}
const ac = new AC()
const fetchOpts = {
signal: ac.signal,
options,
}
const p = Promise.resolve(this.fetchMethod(k, v, fetchOpts)).then(v => {
if (!ac.signal.aborted) {
this.set(k, v, fetchOpts.options)
}
return v
})
p.__abortController = ac
p.__staleWhileFetching = v
if (index === undefined) {
this.set(k, p, fetchOpts.options)
index = this.keyMap.get(k)
} else {
this.valList[index] = p
}
return p
}
isBackgroundFetch (p) {
return p && typeof p === 'object' && typeof p.then === 'function' &&
Object.prototype.hasOwnProperty.call(p, '__staleWhileFetching')
}
// this takes the union of get() and set() opts, because it does both
async fetch (k, {
allowStale = this.allowStale,
updateAgeOnGet = this.updateAgeOnGet,
ttl = this.ttl,
noDisposeOnSet = this.noDisposeOnSet,
size = 0,
sizeCalculation = this.sizeCalculation,
noUpdateTTL = this.noUpdateTTL,
} = {}) {
if (!this.fetchMethod) {
return this.get(k, {allowStale, updateAgeOnGet})
}
const options = {
allowStale,
updateAgeOnGet,
ttl,
noDisposeOnSet,
size,
sizeCalculation,
noUpdateTTL,
}
let index = this.keyMap.get(k)
if (index === undefined) {
return this.backgroundFetch(k, index, options)
} else {
// in cache, maybe already fetching
const v = this.valList[index]
if (this.isBackgroundFetch(v)) {
return allowStale && v.__staleWhileFetching !== undefined
? v.__staleWhileFetching : v
}
if (!this.isStale(index)) {
this.moveToTail(index)
if (updateAgeOnGet) {
this.updateItemAge(index)
}
return v
}
// ok, it is stale, and not already fetching
// refresh the cache.
const p = this.backgroundFetch(k, index, options)
return allowStale && p.__staleWhileFetching !== undefined
? p.__staleWhileFetching : p
}
}
get (k, {
allowStale = this.allowStale,
updateAgeOnGet = this.updateAgeOnGet,
} = {}) {
const index = this.keyMap.get(k)
if (index !== undefined) {
const value = this.valList[index]
const fetching = this.isBackgroundFetch(value)
if (this.isStale(index)) {
// delete only if not an in-flight background fetch
if (!fetching) {
this.delete(k)
return allowStale ? value : undefined
} else {
return allowStale ? value.__staleWhileFetching : undefined
}
} else {
// if we're currently fetching it, we don't actually have it yet
// it's not stale, which means this isn't a staleWhileRefetching,
// so we just return undefined
if (fetching) {
return undefined
}
this.moveToTail(index)
if (updateAgeOnGet) {
this.updateItemAge(index)
}
return value
}
}
}
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
}
}
get del () {
deprecatedMethod('del', 'delete')
return this.delete
}
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()
} else {
this.dispose(v, k, 'delete')
if (this.disposeAfter) {
this.disposed.push([v, k, 'delete'])
}
}
this.keyMap.delete(k)
this.keyList[index] = null
this.valList[index] = null
if (index === this.tail) {
this.tail = this.prev[index]
} else if (index === this.head) {
this.head = this.next[index]
} else {
this.next[this.prev[index]] = this.next[index]
this.prev[this.next[index]] = this.prev[index]
}
this.size --
this.free.push(index)
}
}
}
if (this.disposed) {
while (this.disposed.length) {
this.disposeAfter(...this.disposed.shift())
}
}
return deleted
}
clear () {
for (const index of this.rindexes({ allowStale: true })) {
const v = this.valList[index]
if (this.isBackgroundFetch(v)) {
v.__abortController.abort()
} else {
const k = this.keyList[index]
this.dispose(v, k, 'delete')
if (this.disposeAfter) {
this.disposed.push([v, k, 'delete'])
}
}
}
this.keyMap.clear()
this.valList.fill(null)
this.keyList.fill(null)
if (this.ttls) {
this.ttls.fill(0)
this.starts.fill(0)
}
if (this.sizes) {
this.sizes.fill(0)
}
this.head = 0
this.tail = 0
this.initialFill = 1
this.free.length = 0
this.calculatedSize = 0
this.size = 0
if (this.disposed) {
while (this.disposed.length) {
this.disposeAfter(...this.disposed.shift())
}
}
}
get reset () {
deprecatedMethod('reset', 'clear')
return this.clear
}
get length () {
deprecatedProperty('length', 'size')
return this.size
}
static get AbortController () {
return AC
}
}
module.exports = LRUCache
Zerion Mini Shell 1.0