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Fix performance regression on Node 4x #55

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Fix performance regression on Node 4x #55

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88 changes: 48 additions & 40 deletions lib/lru-cache.js
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Original file line number Diff line number Diff line change
Expand Up @@ -7,10 +7,6 @@ if (typeof module === 'object' && module.exports) {
this.LRUCache = LRUCache
}

function hOP (obj, key) {
return Object.prototype.hasOwnProperty.call(obj, key)
}

function naiveLength () { return 1 }

function LRUCache (options) {
Expand Down Expand Up @@ -55,15 +51,15 @@ Object.defineProperty(LRUCache.prototype, "lengthCalculator",
if (typeof lC !== "function") {
this._lengthCalculator = naiveLength
this._length = this._itemCount
for (var key in this._cache) {
this._cache[key].length = 1
for (var value of this._cache.values()) {
value.length = 1
}
} else {
this._lengthCalculator = lC
this._length = 0
for (var key in this._cache) {
this._cache[key].length = this._lengthCalculator(this._cache[key].value)
this._length += this._cache[key].length
for (var value of this._cache.values()) {
value.length = this._lengthCalculator(value.value)
this._length += value.length
}
}

Expand All @@ -89,9 +85,9 @@ LRUCache.prototype.forEach = function (fn, thisp) {
var i = 0
var itemCount = this._itemCount

for (var k = this._mru - 1; k >= 0 && i < itemCount; k--) if (this._lruList[k]) {
for (var k = this._mru - 1; k >= 0 && i < itemCount; k--) if (this._lruList.has(k)) {
i++
var hit = this._lruList[k]
var hit = this._lruList.get(k)
if (isStale(this, hit)) {
del(this, hit)
if (!this._allowStale) hit = undefined
Expand All @@ -105,8 +101,8 @@ LRUCache.prototype.forEach = function (fn, thisp) {
LRUCache.prototype.keys = function () {
var keys = new Array(this._itemCount)
var i = 0
for (var k = this._mru - 1; k >= 0 && i < this._itemCount; k--) if (this._lruList[k]) {
var hit = this._lruList[k]
for (var k = this._mru - 1; k >= 0 && i < this._itemCount; k--) if (this._lruList.has(k)) {
var hit = this._lruList.get(k)
keys[i++] = hit.key
}
return keys
Expand All @@ -115,22 +111,22 @@ LRUCache.prototype.keys = function () {
LRUCache.prototype.values = function () {
var values = new Array(this._itemCount)
var i = 0
for (var k = this._mru - 1; k >= 0 && i < this._itemCount; k--) if (this._lruList[k]) {
var hit = this._lruList[k]
for (var k = this._mru - 1; k >= 0 && i < this._itemCount; k--) if (this._lruList.has(k)) {
var hit = this._lruList.get(k)
values[i++] = hit.value
}
return values
}

LRUCache.prototype.reset = function () {
if (this._dispose && this._cache) {
for (var k in this._cache) {
this._dispose(k, this._cache[k].value)
for (var entry of this._cache) {
this._dispose(entry[0], entry[1].value)
}
}

this._cache = Object.create(null) // hash of items by key
this._lruList = Object.create(null) // list of items in order of use recency
this._cache = new Map() // hash of items by key
this._lruList = new Map() // list of items in order of use recency
this._mru = 0 // most recently used
this._lru = 0 // least recently used
this._length = 0 // number of items in the list
Expand All @@ -141,8 +137,8 @@ LRUCache.prototype.dump = function () {
var arr = []
var i = 0

for (var k = this._mru - 1; k >= 0 && i < this._itemCount; k--) if (this._lruList[k]) {
var hit = this._lruList[k]
for (var k = this._mru - 1; k >= 0 && i < this._itemCount; k--) if (this._lruList.has(k)) {
var hit = this._lruList.get(k)
if (!isStale(this, hit)) {
//Do not store staled hits
++i
Expand All @@ -162,24 +158,31 @@ LRUCache.prototype.dumpLru = function () {
}

LRUCache.prototype.set = function (key, value, maxAge) {
// Map allows any type of `key` (objects, number, etc). For backwards
// compatibility, coerce to a string.
key = String(key)

maxAge = maxAge || this._maxAge
var now = maxAge ? Date.now() : 0
var len = this._lengthCalculator(value)

if (hOP(this._cache, key)) {
if (this._cache.has(key)) {
if (len > this._max) {
del(this, this._cache[key])
del(this, this._cache.get(key))
return false
}

var item = this._cache.get(key)

// dispose of the old one before overwriting
if (this._dispose)
this._dispose(key, this._cache[key].value)
this._dispose(key, item.value)

this._cache[key].now = now
this._cache[key].maxAge = maxAge
this._cache[key].value = value
this._length += (len - this._cache[key].length)
this._cache[key].length = len
item.now = now
item.maxAge = maxAge
item.value = value
this._length += (len - item.length)
item.length = len
this.get(key)

if (this._length > this._max)
Expand All @@ -197,7 +200,8 @@ LRUCache.prototype.set = function (key, value, maxAge) {
}

this._length += hit.length
this._lruList[hit.lu] = this._cache[key] = hit
this._cache.set(key, hit)
this._lruList.set(hit.lu, hit)
this._itemCount ++

if (this._length > this._max)
Expand All @@ -207,8 +211,8 @@ LRUCache.prototype.set = function (key, value, maxAge) {
}

LRUCache.prototype.has = function (key) {
if (!hOP(this._cache, key)) return false
var hit = this._cache[key]
if (!this._cache.has(key)) return false
var hit = this._cache.get(key)
if (isStale(this, hit)) {
return false
}
Expand All @@ -224,13 +228,13 @@ LRUCache.prototype.peek = function (key) {
}

LRUCache.prototype.pop = function () {
var hit = this._lruList[this._lru]
var hit = this._lruList.get(this._lru)
del(this, hit)
return hit || null
}

LRUCache.prototype.del = function (key) {
del(this, this._cache[key])
del(this, this._cache.get(key))
}

LRUCache.prototype.load = function (arr) {
Expand All @@ -254,7 +258,11 @@ LRUCache.prototype.load = function (arr) {
}

function get (self, key, doUse) {
var hit = self._cache[key]
// Map allows any type of `key` (objects, number, etc). For backwards
// compatibility, coerce to a string.
key = String(key)

var hit = self._cache.get(key)
if (hit) {
if (isStale(self, hit)) {
del(self, hit)
Expand Down Expand Up @@ -282,25 +290,25 @@ function isStale(self, hit) {
function use (self, hit) {
shiftLU(self, hit)
hit.lu = self._mru ++
self._lruList[hit.lu] = hit
self._lruList.set(hit.lu, hit)
}

function trim (self) {
while (self._lru < self._mru && self._length > self._max)
del(self, self._lruList[self._lru])
del(self, self._lruList.get(self._lru))
}

function shiftLU (self, hit) {
delete self._lruList[ hit.lu ]
while (self._lru < self._mru && !self._lruList[self._lru]) self._lru ++
self._lruList.delete(hit.lu)
while (self._lru < self._mru && !self._lruList.has(self._lru)) self._lru ++
}

function del (self, hit) {
if (hit) {
if (self._dispose) self._dispose(hit.key, hit.value)
self._length -= hit.length
self._itemCount --
delete self._cache[ hit.key ]
self._cache.delete(hit.key)
shiftLU(self, hit)
}
}
Expand Down