ca-apm-probe/lib/arf-parser.js

CA APM Node.js Agent monitors real-time health and performance of Node.js applications

 
/**
 * Copyright (c) 2015 CA. All rights reserved.
 *
 * This software and all information contained therein is confidential and proprietary and
 * shall not be duplicated, used, disclosed or disseminated in any way except as authorized
 * by the applicable license agreement, without the express written permission of CA. All
 * authorized reproductions must be marked with this language.
 *
 * EXCEPT AS SET FORTH IN THE APPLICABLE LICENSE AGREEMENT, TO THE EXTENT
 * PERMITTED BY APPLICABLE LAW, CA PROVIDES THIS SOFTWARE WITHOUT WARRANTY
 * OF ANY KIND, INCLUDING WITHOUT LIMITATION, ANY IMPLIED WARRANTIES OF
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT WILL CA BE
 * LIABLE TO THE END USER OR ANY THIRD PARTY FOR ANY LOSS OR DAMAGE, DIRECT OR
 * INDIRECT, FROM THE USE OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, LOST
 * PROFITS, BUSINESS INTERRUPTION, GOODWILL, OR LOST DATA, EVEN IF CA IS
 * EXPRESSLY ADVISED OF SUCH LOSS OR DAMAGE.
 */
 
// custom parser for arf messages sent by collector agent
'use strict';

var net = require('net');
var util = require('util');
var logger = require("./logger.js");

// raw data containing multiple json strings is separated by EOL character
var messageSeparator = '\n';
var Transform = require('stream').Transform;
util.inherits(ArfMessageParser, Transform);


function ArfMessageParser(options) {
	if (!(this instanceof ArfMessageParser))
		return new ArfMessageParser(options);

	Transform.call(this, options);
	this.maxAllowedBufferSize = 100;
	this.rawDataBuffer = [];
}

ArfMessageParser.prototype._transform = function(chunk, encoding, done) {
	try {
		var data = chunk.toString();
		logger.debug("raw data received from collector: %s", data);

		this.processData(data);
		done();
	} catch (e) {
		this.emit('error', new Error('invalid data chunk'));
		return;
	}
};

ArfMessageParser.prototype.processData = function(data) {

	// check if the data has a \n
	var split = -1;

	for (var i = 0; i < data.length; i++) {
		if (data[i] === messageSeparator) {
			split = i;
			break;
		}
	}

	if (split === -1) {
		// still waiting for the \n
		// stash the chunk, and try again.
		if (this.rawDataBuffer.length < this.maxAllowedBufferSize) {
			this.rawDataBuffer.push(data);
		}
	} else {
		var dataSegment = data.slice(0, split);
		this.rawDataBuffer.push(dataSegment);
		var message = this.rawDataBuffer.join('');

		logger.debug("emitting 'arf-message' event for message: %s", message);

		// and notify listeners that we are done parsing message
		this.emit('arf-message', message);

		// successfully sent event, clear buffer data now 
		this.rawDataBuffer = [];

		var remainingData = data.slice(split + messageSeparator.length);

		if (remainingData && remainingData.length > 0) {
			this.processData(remainingData);
		}
	}
}


module.exports = {
	ArfMessageParser: ArfMessageParser
};