instrument.js

/**
* @license Apache-2.0
*
* Copyright (c) 2018 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

'use strict';

// MODULES //

// MAIN //

/**
* Creates a high-resolution timer to measure async operations.
*
* @returns {Function} function to stop the timer and return the duration in milliseconds
*/
function createTimer() {
	var start = process.hrtime();

	return stop;

	/**
	* Stops the timer and returns the elapsed time.
	*
	* @private
	* @returns {number} elapsed time in milliseconds
	*/
	function stop() {
		var diff = process.hrtime( start );

		// Convert to milliseconds:
		return ( diff[ 0 ] * 1e3 ) + ( diff[ 1 ] / 1e6 );
	}
}


// EXPORTS //

module.exports = createTimer;