# all files / lib/spdy-transport/ window.js

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96.15% Branches 25/26
92.31% Functions 12/13
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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]

        Iif (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
        }
      })
    }