1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache license, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the license for the specific language governing permissions and
15 * limitations under the license.
16 */
17
18 package org.apache.logging.log4j.core;
19
20 /**
21 * All proper Java frameworks implement some sort of object life cycle. In Log4j, the main interface for handling
22 * the life cycle context of an object is this one. An object first starts in the {@link State#INITIALIZED} state
23 * by default to indicate the class has been loaded. From here, calling the {@link #start()} method will change this
24 * state to {@link State#STARTING}. After successfully being started, this state is changed to {@link State#STARTED}.
25 * When the {@link #stop()} is called, this goes into the {@link State#STOPPING} state. After successfully being
26 * stopped, this goes into the {@link State#STOPPED} state. In most circumstances, implementation classes should
27 * store their {@link State} in a {@code volatile} field or inside an
28 * {@link java.util.concurrent.atomic.AtomicReference} dependent on synchronization and concurrency requirements.
29 */
30 public interface LifeCycle {
31
32 /**
33 * Status of a life cycle like a {@link LoggerContext}.
34 */
35 public enum State {
36 /** Object is in its initial state and not yet initialized. */
37 INITIALIZING,
38 /** Initialized but not yet started. */
39 INITIALIZED,
40 /** In the process of starting. */
41 STARTING,
42 /** Has started. */
43 STARTED,
44 /** Stopping is in progress. */
45 STOPPING,
46 /** Has stopped. */
47 STOPPED
48 }
49
50 /**
51 * Gets the life-cycle state.
52 *
53 * @return the life-cycle state
54 */
55 State getState();
56
57 void initialize();
58
59 void start();
60
61 void stop();
62
63 boolean isStarted();
64
65 boolean isStopped();
66 }