File size: 2,565 Bytes
08aee07 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 | 'use strict';
const Assert = require('@hapi/hoek/lib/assert');
const Clone = require('@hapi/hoek/lib/clone');
const Common = require('./common');
const internals = {
max: 1000,
supported: new Set(['undefined', 'boolean', 'number', 'string'])
};
exports.provider = {
provision(options) {
return new internals.Cache(options);
}
};
// Least Recently Used (LRU) Cache
internals.Cache = class {
constructor(options = {}) {
Common.assertOptions(options, ['max']);
Assert(options.max === undefined || options.max && options.max > 0 && isFinite(options.max), 'Invalid max cache size');
this._max = options.max || internals.max;
this._map = new Map(); // Map of nodes by key
this._list = new internals.List(); // List of nodes (most recently used in head)
}
get length() {
return this._map.size;
}
set(key, value) {
if (key !== null &&
!internals.supported.has(typeof key)) {
return;
}
let node = this._map.get(key);
if (node) {
node.value = value;
this._list.first(node);
return;
}
node = this._list.unshift({ key, value });
this._map.set(key, node);
this._compact();
}
get(key) {
const node = this._map.get(key);
if (node) {
this._list.first(node);
return Clone(node.value);
}
}
_compact() {
if (this._map.size > this._max) {
const node = this._list.pop();
this._map.delete(node.key);
}
}
};
internals.List = class {
constructor() {
this.tail = null;
this.head = null;
}
unshift(node) {
node.next = null;
node.prev = this.head;
if (this.head) {
this.head.next = node;
}
this.head = node;
if (!this.tail) {
this.tail = node;
}
return node;
}
first(node) {
if (node === this.head) {
return;
}
this._remove(node);
this.unshift(node);
}
pop() {
return this._remove(this.tail);
}
_remove(node) {
const { next, prev } = node;
next.prev = prev;
if (prev) {
prev.next = next;
}
if (node === this.tail) {
this.tail = next;
}
node.prev = null;
node.next = null;
return node;
}
};
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