470 lines
11 KiB
JavaScript
470 lines
11 KiB
JavaScript
module.exports = LRUCache
|
|
|
|
// This will be a proper iterable 'Map' in engines that support it,
|
|
// or a fakey-fake PseudoMap in older versions.
|
|
var Map = require('pseudomap')
|
|
var util = require('util')
|
|
|
|
// A linked list to keep track of recently-used-ness
|
|
var Yallist = require('yallist')
|
|
|
|
// use symbols if possible, otherwise just _props
|
|
var symbols = {}
|
|
var hasSymbol = typeof Symbol === 'function'
|
|
var makeSymbol
|
|
/* istanbul ignore if */
|
|
if (hasSymbol) {
|
|
makeSymbol = function (key) {
|
|
return Symbol.for(key)
|
|
}
|
|
} else {
|
|
makeSymbol = function (key) {
|
|
return '_' + key
|
|
}
|
|
}
|
|
|
|
function priv (obj, key, val) {
|
|
var sym
|
|
if (symbols[key]) {
|
|
sym = symbols[key]
|
|
} else {
|
|
sym = makeSymbol(key)
|
|
symbols[key] = sym
|
|
}
|
|
if (arguments.length === 2) {
|
|
return obj[sym]
|
|
} else {
|
|
obj[sym] = val
|
|
return val
|
|
}
|
|
}
|
|
|
|
function naiveLength () { return 1 }
|
|
|
|
// lruList is a yallist where the head is the youngest
|
|
// item, and the tail is the oldest. the list contains the Hit
|
|
// objects as the entries.
|
|
// Each Hit object has a reference to its Yallist.Node. This
|
|
// never changes.
|
|
//
|
|
// cache is a Map (or PseudoMap) that matches the keys to
|
|
// the Yallist.Node object.
|
|
function LRUCache (options) {
|
|
if (!(this instanceof LRUCache)) {
|
|
return new LRUCache(options)
|
|
}
|
|
|
|
if (typeof options === 'number') {
|
|
options = { max: options }
|
|
}
|
|
|
|
if (!options) {
|
|
options = {}
|
|
}
|
|
|
|
var max = priv(this, 'max', options.max)
|
|
// Kind of weird to have a default max of Infinity, but oh well.
|
|
if (!max ||
|
|
!(typeof max === 'number') ||
|
|
max <= 0) {
|
|
priv(this, 'max', Infinity)
|
|
}
|
|
|
|
var lc = options.length || naiveLength
|
|
if (typeof lc !== 'function') {
|
|
lc = naiveLength
|
|
}
|
|
priv(this, 'lengthCalculator', lc)
|
|
|
|
priv(this, 'allowStale', options.stale || false)
|
|
priv(this, 'maxAge', options.maxAge || 0)
|
|
priv(this, 'dispose', options.dispose)
|
|
this.reset()
|
|
}
|
|
|
|
// resize the cache when the max changes.
|
|
Object.defineProperty(LRUCache.prototype, 'max', {
|
|
set: function (mL) {
|
|
if (!mL || !(typeof mL === 'number') || mL <= 0) {
|
|
mL = Infinity
|
|
}
|
|
priv(this, 'max', mL)
|
|
trim(this)
|
|
},
|
|
get: function () {
|
|
return priv(this, 'max')
|
|
},
|
|
enumerable: true
|
|
})
|
|
|
|
Object.defineProperty(LRUCache.prototype, 'allowStale', {
|
|
set: function (allowStale) {
|
|
priv(this, 'allowStale', !!allowStale)
|
|
},
|
|
get: function () {
|
|
return priv(this, 'allowStale')
|
|
},
|
|
enumerable: true
|
|
})
|
|
|
|
Object.defineProperty(LRUCache.prototype, 'maxAge', {
|
|
set: function (mA) {
|
|
if (!mA || !(typeof mA === 'number') || mA < 0) {
|
|
mA = 0
|
|
}
|
|
priv(this, 'maxAge', mA)
|
|
trim(this)
|
|
},
|
|
get: function () {
|
|
return priv(this, 'maxAge')
|
|
},
|
|
enumerable: true
|
|
})
|
|
|
|
// resize the cache when the lengthCalculator changes.
|
|
Object.defineProperty(LRUCache.prototype, 'lengthCalculator', {
|
|
set: function (lC) {
|
|
if (typeof lC !== 'function') {
|
|
lC = naiveLength
|
|
}
|
|
if (lC !== priv(this, 'lengthCalculator')) {
|
|
priv(this, 'lengthCalculator', lC)
|
|
priv(this, 'length', 0)
|
|
priv(this, 'lruList').forEach(function (hit) {
|
|
hit.length = priv(this, 'lengthCalculator').call(this, hit.value, hit.key)
|
|
priv(this, 'length', priv(this, 'length') + hit.length)
|
|
}, this)
|
|
}
|
|
trim(this)
|
|
},
|
|
get: function () { return priv(this, 'lengthCalculator') },
|
|
enumerable: true
|
|
})
|
|
|
|
Object.defineProperty(LRUCache.prototype, 'length', {
|
|
get: function () { return priv(this, 'length') },
|
|
enumerable: true
|
|
})
|
|
|
|
Object.defineProperty(LRUCache.prototype, 'itemCount', {
|
|
get: function () { return priv(this, 'lruList').length },
|
|
enumerable: true
|
|
})
|
|
|
|
LRUCache.prototype.rforEach = function (fn, thisp) {
|
|
thisp = thisp || this
|
|
for (var walker = priv(this, 'lruList').tail; walker !== null;) {
|
|
var prev = walker.prev
|
|
forEachStep(this, fn, walker, thisp)
|
|
walker = prev
|
|
}
|
|
}
|
|
|
|
function forEachStep (self, fn, node, thisp) {
|
|
var hit = node.value
|
|
if (isStale(self, hit)) {
|
|
del(self, node)
|
|
if (!priv(self, 'allowStale')) {
|
|
hit = undefined
|
|
}
|
|
}
|
|
if (hit) {
|
|
fn.call(thisp, hit.value, hit.key, self)
|
|
}
|
|
}
|
|
|
|
LRUCache.prototype.forEach = function (fn, thisp) {
|
|
thisp = thisp || this
|
|
for (var walker = priv(this, 'lruList').head; walker !== null;) {
|
|
var next = walker.next
|
|
forEachStep(this, fn, walker, thisp)
|
|
walker = next
|
|
}
|
|
}
|
|
|
|
LRUCache.prototype.keys = function () {
|
|
return priv(this, 'lruList').toArray().map(function (k) {
|
|
return k.key
|
|
}, this)
|
|
}
|
|
|
|
LRUCache.prototype.values = function () {
|
|
return priv(this, 'lruList').toArray().map(function (k) {
|
|
return k.value
|
|
}, this)
|
|
}
|
|
|
|
LRUCache.prototype.reset = function () {
|
|
if (priv(this, 'dispose') &&
|
|
priv(this, 'lruList') &&
|
|
priv(this, 'lruList').length) {
|
|
priv(this, 'lruList').forEach(function (hit) {
|
|
priv(this, 'dispose').call(this, hit.key, hit.value)
|
|
}, this)
|
|
}
|
|
|
|
priv(this, 'cache', new Map()) // hash of items by key
|
|
priv(this, 'lruList', new Yallist()) // list of items in order of use recency
|
|
priv(this, 'length', 0) // length of items in the list
|
|
}
|
|
|
|
LRUCache.prototype.dump = function () {
|
|
return priv(this, 'lruList').map(function (hit) {
|
|
if (!isStale(this, hit)) {
|
|
return {
|
|
k: hit.key,
|
|
v: hit.value,
|
|
e: hit.now + (hit.maxAge || 0)
|
|
}
|
|
}
|
|
}, this).toArray().filter(function (h) {
|
|
return h
|
|
})
|
|
}
|
|
|
|
LRUCache.prototype.dumpLru = function () {
|
|
return priv(this, 'lruList')
|
|
}
|
|
|
|
LRUCache.prototype.inspect = function (n, opts) {
|
|
var str = 'LRUCache {'
|
|
var extras = false
|
|
|
|
var as = priv(this, 'allowStale')
|
|
if (as) {
|
|
str += '\n allowStale: true'
|
|
extras = true
|
|
}
|
|
|
|
var max = priv(this, 'max')
|
|
if (max && max !== Infinity) {
|
|
if (extras) {
|
|
str += ','
|
|
}
|
|
str += '\n max: ' + util.inspect(max, opts)
|
|
extras = true
|
|
}
|
|
|
|
var maxAge = priv(this, 'maxAge')
|
|
if (maxAge) {
|
|
if (extras) {
|
|
str += ','
|
|
}
|
|
str += '\n maxAge: ' + util.inspect(maxAge, opts)
|
|
extras = true
|
|
}
|
|
|
|
var lc = priv(this, 'lengthCalculator')
|
|
if (lc && lc !== naiveLength) {
|
|
if (extras) {
|
|
str += ','
|
|
}
|
|
str += '\n length: ' + util.inspect(priv(this, 'length'), opts)
|
|
extras = true
|
|
}
|
|
|
|
var didFirst = false
|
|
priv(this, 'lruList').forEach(function (item) {
|
|
if (didFirst) {
|
|
str += ',\n '
|
|
} else {
|
|
if (extras) {
|
|
str += ',\n'
|
|
}
|
|
didFirst = true
|
|
str += '\n '
|
|
}
|
|
var key = util.inspect(item.key).split('\n').join('\n ')
|
|
var val = { value: item.value }
|
|
if (item.maxAge !== maxAge) {
|
|
val.maxAge = item.maxAge
|
|
}
|
|
if (lc !== naiveLength) {
|
|
val.length = item.length
|
|
}
|
|
if (isStale(this, item)) {
|
|
val.stale = true
|
|
}
|
|
|
|
val = util.inspect(val, opts).split('\n').join('\n ')
|
|
str += key + ' => ' + val
|
|
})
|
|
|
|
if (didFirst || extras) {
|
|
str += '\n'
|
|
}
|
|
str += '}'
|
|
|
|
return str
|
|
}
|
|
|
|
LRUCache.prototype.set = function (key, value, maxAge) {
|
|
maxAge = maxAge || priv(this, 'maxAge')
|
|
|
|
var now = maxAge ? Date.now() : 0
|
|
var len = priv(this, 'lengthCalculator').call(this, value, key)
|
|
|
|
if (priv(this, 'cache').has(key)) {
|
|
if (len > priv(this, 'max')) {
|
|
del(this, priv(this, 'cache').get(key))
|
|
return false
|
|
}
|
|
|
|
var node = priv(this, 'cache').get(key)
|
|
var item = node.value
|
|
|
|
// dispose of the old one before overwriting
|
|
if (priv(this, 'dispose')) {
|
|
priv(this, 'dispose').call(this, key, item.value)
|
|
}
|
|
|
|
item.now = now
|
|
item.maxAge = maxAge
|
|
item.value = value
|
|
priv(this, 'length', priv(this, 'length') + (len - item.length))
|
|
item.length = len
|
|
this.get(key)
|
|
trim(this)
|
|
return true
|
|
}
|
|
|
|
var hit = new Entry(key, value, len, now, maxAge)
|
|
|
|
// oversized objects fall out of cache automatically.
|
|
if (hit.length > priv(this, 'max')) {
|
|
if (priv(this, 'dispose')) {
|
|
priv(this, 'dispose').call(this, key, value)
|
|
}
|
|
return false
|
|
}
|
|
|
|
priv(this, 'length', priv(this, 'length') + hit.length)
|
|
priv(this, 'lruList').unshift(hit)
|
|
priv(this, 'cache').set(key, priv(this, 'lruList').head)
|
|
trim(this)
|
|
return true
|
|
}
|
|
|
|
LRUCache.prototype.has = function (key) {
|
|
if (!priv(this, 'cache').has(key)) return false
|
|
var hit = priv(this, 'cache').get(key).value
|
|
if (isStale(this, hit)) {
|
|
return false
|
|
}
|
|
return true
|
|
}
|
|
|
|
LRUCache.prototype.get = function (key) {
|
|
return get(this, key, true)
|
|
}
|
|
|
|
LRUCache.prototype.peek = function (key) {
|
|
return get(this, key, false)
|
|
}
|
|
|
|
LRUCache.prototype.pop = function () {
|
|
var node = priv(this, 'lruList').tail
|
|
if (!node) return null
|
|
del(this, node)
|
|
return node.value
|
|
}
|
|
|
|
LRUCache.prototype.del = function (key) {
|
|
del(this, priv(this, 'cache').get(key))
|
|
}
|
|
|
|
LRUCache.prototype.load = function (arr) {
|
|
// reset the cache
|
|
this.reset()
|
|
|
|
var now = Date.now()
|
|
// A previous serialized cache has the most recent items first
|
|
for (var l = arr.length - 1; l >= 0; l--) {
|
|
var hit = arr[l]
|
|
var expiresAt = hit.e || 0
|
|
if (expiresAt === 0) {
|
|
// the item was created without expiration in a non aged cache
|
|
this.set(hit.k, hit.v)
|
|
} else {
|
|
var maxAge = expiresAt - now
|
|
// dont add already expired items
|
|
if (maxAge > 0) {
|
|
this.set(hit.k, hit.v, maxAge)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
LRUCache.prototype.prune = function () {
|
|
var self = this
|
|
priv(this, 'cache').forEach(function (value, key) {
|
|
get(self, key, false)
|
|
})
|
|
}
|
|
|
|
function get (self, key, doUse) {
|
|
var node = priv(self, 'cache').get(key)
|
|
if (node) {
|
|
var hit = node.value
|
|
if (isStale(self, hit)) {
|
|
del(self, node)
|
|
if (!priv(self, 'allowStale')) hit = undefined
|
|
} else {
|
|
if (doUse) {
|
|
priv(self, 'lruList').unshiftNode(node)
|
|
}
|
|
}
|
|
if (hit) hit = hit.value
|
|
}
|
|
return hit
|
|
}
|
|
|
|
function isStale (self, hit) {
|
|
if (!hit || (!hit.maxAge && !priv(self, 'maxAge'))) {
|
|
return false
|
|
}
|
|
var stale = false
|
|
var diff = Date.now() - hit.now
|
|
if (hit.maxAge) {
|
|
stale = diff > hit.maxAge
|
|
} else {
|
|
stale = priv(self, 'maxAge') && (diff > priv(self, 'maxAge'))
|
|
}
|
|
return stale
|
|
}
|
|
|
|
function trim (self) {
|
|
if (priv(self, 'length') > priv(self, 'max')) {
|
|
for (var walker = priv(self, 'lruList').tail;
|
|
priv(self, 'length') > priv(self, 'max') && walker !== null;) {
|
|
// We know that we're about to delete this one, and also
|
|
// what the next least recently used key will be, so just
|
|
// go ahead and set it now.
|
|
var prev = walker.prev
|
|
del(self, walker)
|
|
walker = prev
|
|
}
|
|
}
|
|
}
|
|
|
|
function del (self, node) {
|
|
if (node) {
|
|
var hit = node.value
|
|
if (priv(self, 'dispose')) {
|
|
priv(self, 'dispose').call(this, hit.key, hit.value)
|
|
}
|
|
priv(self, 'length', priv(self, 'length') - hit.length)
|
|
priv(self, 'cache').delete(hit.key)
|
|
priv(self, 'lruList').removeNode(node)
|
|
}
|
|
}
|
|
|
|
// classy, since V8 prefers predictable objects.
|
|
function Entry (key, value, length, now, maxAge) {
|
|
this.key = key
|
|
this.value = value
|
|
this.length = length
|
|
this.now = now
|
|
this.maxAge = maxAge || 0
|
|
}
|