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/*
* Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package com.sun.enterprise.admin.monitor.stats;
import org.glassfish.j2ee.statistics.Statistic;
import java.io.Serializable;
/**
* An interface that gives a flexibility to set various values for a particular Statistic.
* This provision is basically to have the same data structure to collect and
* return the (read-only copy of) statistical data. This extends the
* java.io.Serializable, so that its subclasses can be serialized to facilitate
* working with other management clients.
* Refer to the package description
* to understand the intent of this interface.
*
* Methods of this class should be called judiciously by the component that is
* gathering the statistics.
*
* @author Kedar Mhaswade
* @since S1AS8.0
* @version 1.0
*/
public interface MutableStatistic extends Serializable {
/**
* Returns a read-only view of this Statistic. An implementing class has
* to return the instances of Statistic interfaces defined in
* {@link javax.management.j2ee.statistic}
* and {@link com.sun.enterprise.admin.monitor.stats} packages.
*
* @return an instance of a specific Statistic interface
*/
Statistic unmodifiableView();
/**
* Returns an instance of Statistic whose state can be changed by the caller. It is important
* to know that caller should not cache the return value from this method. In general, there
* is a problem in this contract in that, a client would not know from a Stats.getCreateCount()
* method whether the return value is something that is being modified or is invariant. Hence
* the caller should not cache the returned value in a collection and then collectively
* process it. The main idea behind providing this method is to control the
* number of instances created (per Mahesh's Suggestion).
* @return an instance of Statistic interface that should not be cached.
*/
Statistic modifiableView();
/**
* Resets the encapsulated Statistic interface to its initial value. The idea being, if (after
* creation of the instance) the state changes, the initial state can be easily regained by
* calling this method. Note that the time of last sampling changes to the instant
* when this method is invoked.
*/
void reset();
}