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node_modules/on-finished/index.js 3.6 KB
aaac7fed   liuqimichale   add
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  /*!
   * on-finished
   * Copyright(c) 2013 Jonathan Ong
   * Copyright(c) 2014 Douglas Christopher Wilson
   * MIT Licensed
   */
  
  'use strict'
  
  /**
   * Module exports.
   * @public
   */
  
  module.exports = onFinished
  module.exports.isFinished = isFinished
  
  /**
   * Module dependencies.
   * @private
   */
  
  var first = require('ee-first')
  
  /**
   * Variables.
   * @private
   */
  
  /* istanbul ignore next */
  var defer = typeof setImmediate === 'function'
    ? setImmediate
    : function(fn){ process.nextTick(fn.bind.apply(fn, arguments)) }
  
  /**
   * Invoke callback when the response has finished, useful for
   * cleaning up resources afterwards.
   *
   * @param {object} msg
   * @param {function} listener
   * @return {object}
   * @public
   */
  
  function onFinished(msg, listener) {
    if (isFinished(msg) !== false) {
      defer(listener, null, msg)
      return msg
    }
  
    // attach the listener to the message
    attachListener(msg, listener)
  
    return msg
  }
  
  /**
   * Determine if message is already finished.
   *
   * @param {object} msg
   * @return {boolean}
   * @public
   */
  
  function isFinished(msg) {
    var socket = msg.socket
  
    if (typeof msg.finished === 'boolean') {
      // OutgoingMessage
      return Boolean(msg.finished || (socket && !socket.writable))
    }
  
    if (typeof msg.complete === 'boolean') {
      // IncomingMessage
      return Boolean(msg.upgrade || !socket || !socket.readable || (msg.complete && !msg.readable))
    }
  
    // don't know
    return undefined
  }
  
  /**
   * Attach a finished listener to the message.
   *
   * @param {object} msg
   * @param {function} callback
   * @private
   */
  
  function attachFinishedListener(msg, callback) {
    var eeMsg
    var eeSocket
    var finished = false
  
    function onFinish(error) {
      eeMsg.cancel()
      eeSocket.cancel()
  
      finished = true
      callback(error)
    }
  
    // finished on first message event
    eeMsg = eeSocket = first([[msg, 'end', 'finish']], onFinish)
  
    function onSocket(socket) {
      // remove listener
      msg.removeListener('socket', onSocket)
  
      if (finished) return
      if (eeMsg !== eeSocket) return
  
      // finished on first socket event
      eeSocket = first([[socket, 'error', 'close']], onFinish)
    }
  
    if (msg.socket) {
      // socket already assigned
      onSocket(msg.socket)
      return
    }
  
    // wait for socket to be assigned
    msg.on('socket', onSocket)
  
    if (msg.socket === undefined) {
      // node.js 0.8 patch
      patchAssignSocket(msg, onSocket)
    }
  }
  
  /**
   * Attach the listener to the message.
   *
   * @param {object} msg
   * @return {function}
   * @private
   */
  
  function attachListener(msg, listener) {
    var attached = msg.__onFinished
  
    // create a private single listener with queue
    if (!attached || !attached.queue) {
      attached = msg.__onFinished = createListener(msg)
      attachFinishedListener(msg, attached)
    }
  
    attached.queue.push(listener)
  }
  
  /**
   * Create listener on message.
   *
   * @param {object} msg
   * @return {function}
   * @private
   */
  
  function createListener(msg) {
    function listener(err) {
      if (msg.__onFinished === listener) msg.__onFinished = null
      if (!listener.queue) return
  
      var queue = listener.queue
      listener.queue = null
  
      for (var i = 0; i < queue.length; i++) {
        queue[i](err, msg)
      }
    }
  
    listener.queue = []
  
    return listener
  }
  
  /**
   * Patch ServerResponse.prototype.assignSocket for node.js 0.8.
   *
   * @param {ServerResponse} res
   * @param {function} callback
   * @private
   */
  
  function patchAssignSocket(res, callback) {
    var assignSocket = res.assignSocket
  
    if (typeof assignSocket !== 'function') return
  
    // res.on('socket', callback) is broken in 0.8
    res.assignSocket = function _assignSocket(socket) {
      assignSocket.call(this, socket)
      callback(socket)
    }
  }