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 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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,
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package org.apache.logging.log4j.core;

All proper Java frameworks implement some sort of object life cycle. In Log4j, the main interface for handling the life cycle context of an object is this one. An object first starts in the State.INITIALIZED state by default to indicate the class has been loaded. From here, calling the start() method will change this state to State.STARTING. After successfully being started, this state is changed to State.STARTED. When the stop() is called, this goes into the State.STOPPING state. After successfully being stopped, this goes into the State.STOPPED state. In most circumstances, implementation classes should store their State in a volatile field or inside an AtomicReference dependent on synchronization and concurrency requirements. 
See Also:
AbstractLifeCycle/**
 * All proper Java frameworks implement some sort of object life cycle. In Log4j, the main interface for handling
 * the life cycle context of an object is this one. An object first starts in the {@link State#INITIALIZED} state
 * by default to indicate the class has been loaded. From here, calling the {@link #start()} method will change this
 * state to {@link State#STARTING}. After successfully being started, this state is changed to {@link State#STARTED}.
 * When the {@link #stop()} is called, this goes into the {@link State#STOPPING} state. After successfully being
 * stopped, this goes into the {@link State#STOPPED} state. In most circumstances, implementation classes should
 * store their {@link State} in a {@code volatile} field or inside an
 * {@link java.util.concurrent.atomic.AtomicReference} dependent on synchronization and concurrency requirements.
 *
 * @see AbstractLifeCycle
 */
public interface LifeCycle {

    
Status of a life cycle like a LoggerContext. /**
     * Status of a life cycle like a {@link LoggerContext}.
     */
    enum State {
        
Object is in its initial state and not yet initialized. /** Object is in its initial state and not yet initialized. */
        INITIALIZING,
        
Initialized but not yet started. /** Initialized but not yet started. */
        INITIALIZED,
        
In the process of starting. /** In the process of starting. */
        STARTING,
        
Has started. /** Has started. */
        STARTED,
        
Stopping is in progress. /** Stopping is in progress. */
        STOPPING,
        
Has stopped. /** Has stopped. */
        STOPPED
    }

    
Gets the life-cycle state.
Returns:
the life-cycle state/**
     * Gets the life-cycle state.
     *
     * @return the life-cycle state
     */
    State getState();

    void initialize();

    void start();

    void stop();

    boolean isStarted();

    boolean isStopped();

}