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