/*
* Copyright (c) 1998-2011 Caucho Technology -- all rights reserved
*
* This file is part of Resin(R) Open Source
*
* Each copy or derived work must preserve the copyright notice and this
* notice unmodified.
*
* Resin Open Source is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* Resin Open Source is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
* of NON-INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with Resin Open Source; if not, write to the
*
* Free Software Foundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* @author Scott Ferguson
*/
package com.caucho.env.meter;
/**
* Meters gather information from Sensors in a ResinSystem. Some sampled
* meters like the CPU and JMX don't have an associated Sensor, but gather
* the data as they are polled.
*
* Meters typically gather information when polled and then reset any internal
* accumulated counters. For example, a request counter meter will clear the
* request count after being sampled.
*
* Meter values can typically be peeked which will return the current value
* without resetting internal counters.
*/
public interface Meter {
/**
* Returns the meter's name.
*/
public String getName();
/**
* Gather the meter's next sample.
*/
public double sample();
/**
* Returns the current meter value without updating the sample.
*/
public double peek();
}