'use strict'
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var util = require('util')
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var EventEmitter = require('events').EventEmitter
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var debug = {
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server: require('debug')('spdy:window:server'),
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client: require('debug')('spdy:window:client')
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}
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function Side (window, name, options) {
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EventEmitter.call(this)
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this.name = name
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this.window = window
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this.current = options.size
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this.max = options.size
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this.limit = options.max
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this.lowWaterMark = options.lowWaterMark === undefined
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? this.max / 2
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: options.lowWaterMark
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this._refilling = false
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this._refillQueue = []
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}
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util.inherits(Side, EventEmitter)
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Side.prototype.setMax = function setMax (max) {
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this.window.debug('id=%d side=%s setMax=%d',
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this.window.id,
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this.name,
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max)
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this.max = max
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this.lowWaterMark = this.max / 2
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}
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Side.prototype.updateMax = function updateMax (max) {
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var delta = max - this.max
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this.window.debug('id=%d side=%s updateMax=%d delta=%d',
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this.window.id,
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this.name,
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max,
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delta)
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this.max = max
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this.lowWaterMark = max / 2
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this.update(delta)
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}
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Side.prototype.setLowWaterMark = function setLowWaterMark (lwm) {
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this.lowWaterMark = lwm
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}
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Side.prototype.update = function update (size, callback) {
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// Not enough space for the update, wait for refill
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if (size <= 0 && callback && this.isEmpty()) {
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this.window.debug('id=%d side=%s wait for refill=%d [%d/%d]',
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this.window.id,
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this.name,
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-size,
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this.current,
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this.max)
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this._refillQueue.push({
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size: size,
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callback: callback
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})
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return
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}
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this.current += size
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if (this.current > this.limit) {
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this.emit('overflow')
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return
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}
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this.window.debug('id=%d side=%s update by=%d [%d/%d]',
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this.window.id,
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this.name,
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size,
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this.current,
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this.max)
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// Time to send WINDOW_UPDATE
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if (size < 0 && this.isDraining()) {
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this.window.debug('id=%d side=%s drained', this.window.id, this.name)
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this.emit('drain')
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}
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// Time to write
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if (size > 0 && this.current > 0 && this.current <= size) {
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this.window.debug('id=%d side=%s full', this.window.id, this.name)
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this.emit('full')
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}
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this._processRefillQueue()
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if (callback) { process.nextTick(callback) }
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}
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Side.prototype.getCurrent = function getCurrent () {
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return this.current
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}
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Side.prototype.getMax = function getMax () {
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return this.max
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}
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Side.prototype.getDelta = function getDelta () {
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return this.max - this.current
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}
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Side.prototype.isDraining = function isDraining () {
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return this.current <= this.lowWaterMark
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}
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Side.prototype.isEmpty = function isEmpty () {
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return this.current <= 0
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}
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// Private
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Side.prototype._processRefillQueue = function _processRefillQueue () {
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// Prevent recursion
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if (this._refilling) {
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return
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}
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this._refilling = true
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while (this._refillQueue.length > 0) {
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var item = this._refillQueue[0]
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if (this.isEmpty()) {
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break
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}
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this.window.debug('id=%d side=%s refilled for size=%d',
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this.window.id,
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this.name,
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-item.size)
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this._refillQueue.shift()
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this.update(item.size, item.callback)
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}
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this._refilling = false
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}
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function Window (options) {
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this.id = options.id
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this.isServer = options.isServer
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this.debug = this.isServer ? debug.server : debug.client
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this.recv = new Side(this, 'recv', options.recv)
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this.send = new Side(this, 'send', options.send)
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}
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module.exports = Window
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Window.prototype.clone = function clone (id) {
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return new Window({
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id: id,
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isServer: this.isServer,
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recv: {
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size: this.recv.max,
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max: this.recv.limit,
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lowWaterMark: this.recv.lowWaterMark
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},
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send: {
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size: this.send.max,
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max: this.send.limit,
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lowWaterMark: this.send.lowWaterMark
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}
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})
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}
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