| var util = require('util') |
| |
| var EventEmitter = require('eventemitter3').EventEmitter |
| |
| function TtlItem(value) { |
| this.next = null |
| this.prev = null |
| this.time = null |
| this.value = value |
| } |
| |
| function TtlSet(ttl) { |
| EventEmitter.call(this) |
| this.head = null |
| this.tail = null |
| this.mapping = Object.create(null) |
| this.ttl = ttl |
| this.timer = null |
| } |
| |
| util.inherits(TtlSet, EventEmitter) |
| |
| TtlSet.SILENT = 1 |
| |
| TtlSet.prototype.bump = function(value, time, flags) { |
| var item = this._remove(this.mapping[value]) || this._create(value, flags) |
| |
| item.time = time || Date.now() |
| item.prev = this.tail |
| |
| this.tail = item |
| |
| if (item.prev) { |
| item.prev.next = item |
| } |
| else { |
| this.head = item |
| this._scheduleCheck() |
| } |
| } |
| |
| TtlSet.prototype.drop = function(value, flags) { |
| this._drop(this.mapping[value], flags) |
| } |
| |
| TtlSet.prototype.stop = function() { |
| clearTimeout(this.timer) |
| } |
| |
| TtlSet.prototype._scheduleCheck = function() { |
| clearTimeout(this.timer) |
| if (this.head) { |
| var delay = Math.max(0, this.ttl - (Date.now() - this.head.time)) |
| this.timer = setTimeout(this._check.bind(this), delay) |
| } |
| } |
| |
| TtlSet.prototype._check = function() { |
| var now = Date.now() |
| |
| var item |
| while ((item = this.head)) { |
| if (now - item.time > this.ttl) { |
| this._drop(item, 0) |
| } |
| else { |
| break |
| } |
| } |
| |
| this._scheduleCheck() |
| } |
| |
| TtlSet.prototype._create = function(value, flags) { |
| var item = new TtlItem(value) |
| |
| this.mapping[value] = item |
| |
| if ((flags & TtlSet.SILENT) !== TtlSet.SILENT) { |
| this.emit('insert', value) |
| } |
| |
| return item |
| } |
| |
| TtlSet.prototype._drop = function(item, flags) { |
| if (item) { |
| this._remove(item) |
| |
| delete this.mapping[item.value] |
| |
| if ((flags & TtlSet.SILENT) !== TtlSet.SILENT) { |
| this.emit('drop', item.value) |
| } |
| } |
| } |
| |
| TtlSet.prototype._remove = function(item) { |
| if (!item) { |
| return null |
| } |
| |
| if (item.prev) { |
| item.prev.next = item.next |
| } |
| |
| if (item.next) { |
| item.next.prev = item.prev |
| } |
| |
| if (item === this.head) { |
| this.head = item.next |
| } |
| |
| if (item === this.tail) { |
| this.tail = item.prev |
| } |
| |
| item.next = item.prev = null |
| |
| return item |
| } |
| |
| module.exports = TtlSet |