dynatrace-cordova-outsystems-plugin/node_modules/combined-stream/lib/combined_stream.js

This plugin gives you the ability to use the Dynatrace instrumentation in your hybrid application (Cordova, Ionic, ..). It uses the Mobile Agent, the JavaScript Agent and the Javascript Bridge. The Mobile Agent will give you all device specific values con

var util = require('util');
var Stream = require('stream').Stream;
var DelayedStream = require('delayed-stream');

module.exports = CombinedStream;
function CombinedStream() {
  this.writable = false;
  this.readable = true;
  this.dataSize = 0;
  this.maxDataSize = 2 * 1024 * 1024;
  this.pauseStreams = true;

  this._released = false;
  this._streams = [];
  this._currentStream = null;
  this._insideLoop = false;
  this._pendingNext = false;
}
util.inherits(CombinedStream, Stream);

CombinedStream.create = function(options) {
  var combinedStream = new this();

  options = options || {};
  for (var option in options) {
    combinedStream[option] = options[option];
  }

  return combinedStream;
};

CombinedStream.isStreamLike = function(stream) {
  return (typeof stream !== 'function')
    && (typeof stream !== 'string')
    && (typeof stream !== 'boolean')
    && (typeof stream !== 'number')
    && (!Buffer.isBuffer(stream));
};

CombinedStream.prototype.append = function(stream) {
  var isStreamLike = CombinedStream.isStreamLike(stream);

  if (isStreamLike) {
    if (!(stream instanceof DelayedStream)) {
      var newStream = DelayedStream.create(stream, {
        maxDataSize: Infinity,
        pauseStream: this.pauseStreams,
      });
      stream.on('data', this._checkDataSize.bind(this));
      stream = newStream;
    }

    this._handleErrors(stream);

    if (this.pauseStreams) {
      stream.pause();
    }
  }

  this._streams.push(stream);
  return this;
};

CombinedStream.prototype.pipe = function(dest, options) {
  Stream.prototype.pipe.call(this, dest, options);
  this.resume();
  return dest;
};

CombinedStream.prototype._getNext = function() {
  this._currentStream = null;

  if (this._insideLoop) {
    this._pendingNext = true;
    return; // defer call
  }

  this._insideLoop = true;
  try {
    do {
      this._pendingNext = false;
      this._realGetNext();
    } while (this._pendingNext);
  } finally {
    this._insideLoop = false;
  }
};

CombinedStream.prototype._realGetNext = function() {
  var stream = this._streams.shift();


  if (typeof stream == 'undefined') {
    this.end();
    return;
  }

  if (typeof stream !== 'function') {
    this._pipeNext(stream);
    return;
  }

  var getStream = stream;
  getStream(function(stream) {
    var isStreamLike = CombinedStream.isStreamLike(stream);
    if (isStreamLike) {
      stream.on('data', this._checkDataSize.bind(this));
      this._handleErrors(stream);
    }

    this._pipeNext(stream);
  }.bind(this));
};

CombinedStream.prototype._pipeNext = function(stream) {
  this._currentStream = stream;

  var isStreamLike = CombinedStream.isStreamLike(stream);
  if (isStreamLike) {
    stream.on('end', this._getNext.bind(this));
    stream.pipe(this, {end: false});
    return;
  }

  var value = stream;
  this.write(value);
  this._getNext();
};

CombinedStream.prototype._handleErrors = function(stream) {
  var self = this;
  stream.on('error', function(err) {
    self._emitError(err);
  });
};

CombinedStream.prototype.write = function(data) {
  this.emit('data', data);
};

CombinedStream.prototype.pause = function() {
  if (!this.pauseStreams) {
    return;
  }

  if(this.pauseStreams && this._currentStream && typeof(this._currentStream.pause) == 'function') this._currentStream.pause();
  this.emit('pause');
};

CombinedStream.prototype.resume = function() {
  if (!this._released) {
    this._released = true;
    this.writable = true;
    this._getNext();
  }

  if(this.pauseStreams && this._currentStream && typeof(this._currentStream.resume) == 'function') this._currentStream.resume();
  this.emit('resume');
};

CombinedStream.prototype.end = function() {
  this._reset();
  this.emit('end');
};

CombinedStream.prototype.destroy = function() {
  this._reset();
  this.emit('close');
};

CombinedStream.prototype._reset = function() {
  this.writable = false;
  this._streams = [];
  this._currentStream = null;
};

CombinedStream.prototype._checkDataSize = function() {
  this._updateDataSize();
  if (this.dataSize <= this.maxDataSize) {
    return;
  }

  var message =
    'DelayedStream#maxDataSize of ' + this.maxDataSize + ' bytes exceeded.';
  this._emitError(new Error(message));
};

CombinedStream.prototype._updateDataSize = function() {
  this.dataSize = 0;

  var self = this;
  this._streams.forEach(function(stream) {
    if (!stream.dataSize) {
      return;
    }

    self.dataSize += stream.dataSize;
  });

  if (this._currentStream && this._currentStream.dataSize) {
    this.dataSize += this._currentStream.dataSize;
  }
};

CombinedStream.prototype._emitError = function(err) {
  this._reset();
  this.emit('error', err);
};