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 package org.apache.logging.log4j.core.appender.db;
18
19 import java.util.concurrent.TimeUnit;
20 import java.util.concurrent.locks.Lock;
21 import java.util.concurrent.locks.ReadWriteLock;
22 import java.util.concurrent.locks.ReentrantReadWriteLock;
23
24 import org.apache.logging.log4j.LoggingException;
25 import org.apache.logging.log4j.core.Filter;
26 import org.apache.logging.log4j.core.Layout;
27 import org.apache.logging.log4j.core.LogEvent;
28 import org.apache.logging.log4j.core.appender.AbstractAppender;
29 import org.apache.logging.log4j.core.appender.AppenderLoggingException;
30
31 /**
32 * An abstract Appender for writing events to a database of some type, be it relational or NoSQL. All database appenders
33 * should inherit from this base appender. Three implementations are currently provided:
34 * {@link org.apache.logging.log4j.core.appender.db.jdbc JDBC}, {@link org.apache.logging.log4j.core.appender.db.jpa
35 * JPA}, and <a href="/log4j/2.x/log4j-nosql/apidocs/">NoSQL</a>.
36 *
37 * @param <T> Specifies which type of {@link AbstractDatabaseManager} this Appender requires.
38 */
39 public abstract class AbstractDatabaseAppender<T extends AbstractDatabaseManager> extends AbstractAppender {
40
41 private final ReadWriteLock lock = new ReentrantReadWriteLock();
42 private final Lock readLock = lock.readLock();
43 private final Lock writeLock = lock.writeLock();
44
45 private T manager;
46
47 /**
48 * Instantiates the base appender.
49 *
50 * @param name The appender name.
51 * @param filter The filter, if any, to use.
52 * @param ignoreExceptions If {@code true} exceptions encountered when appending events are logged; otherwise
53 * they are propagated to the caller.
54 * @param manager The matching {@link AbstractDatabaseManager} implementation.
55 */
56 protected AbstractDatabaseAppender(final String name, final Filter filter, final boolean ignoreExceptions,
57 final T manager) {
58 super(name, filter, null, ignoreExceptions);
59 this.manager = manager;
60 }
61
62 /**
63 * This always returns {@code null}, as database appenders do not use a single layout. The JPA and NoSQL appenders
64 * do not use a layout at all. The JDBC appender has a layout-per-column pattern.
65 *
66 * @return {@code null}.
67 */
68 @Override
69 public final Layout<LogEvent> getLayout() {
70 return null;
71 }
72
73 /**
74 * Returns the underlying manager in use within this appender.
75 *
76 * @return the manager.
77 */
78 public final T getManager() {
79 return this.manager;
80 }
81
82 @Override
83 public final void start() {
84 if (this.getManager() == null) {
85 LOGGER.error("No AbstractDatabaseManager set for the appender named [{}].", this.getName());
86 }
87 super.start();
88 if (this.getManager() != null) {
89 this.getManager().startup();
90 }
91 }
92
93 @Override
94 public boolean stop(final long timeout, final TimeUnit timeUnit) {
95 setStopping();
96 boolean stopped = super.stop(timeout, timeUnit, false);
97 if (this.getManager() != null) {
98 stopped &= this.getManager().stop(timeout, timeUnit);
99 }
100 setStopped();
101 return stopped;
102 }
103
104 @Override
105 public final void append(final LogEvent event) {
106 this.readLock.lock();
107 try {
108 this.getManager().write(event);
109 } catch (final LoggingException e) {
110 LOGGER.error("Unable to write to database [{}] for appender [{}].", this.getManager().getName(),
111 this.getName(), e);
112 throw e;
113 } catch (final Exception e) {
114 LOGGER.error("Unable to write to database [{}] for appender [{}].", this.getManager().getName(),
115 this.getName(), e);
116 throw new AppenderLoggingException("Unable to write to database in appender: " + e.getMessage(), e);
117 } finally {
118 this.readLock.unlock();
119 }
120 }
121
122 /**
123 * Replaces the underlying manager in use within this appender. This can be useful for manually changing the way log
124 * events are written to the database without losing buffered or in-progress events. The existing manager is
125 * released only after the new manager has been installed. This method is thread-safe.
126 *
127 * @param manager The new manager to install.
128 */
129 protected final void replaceManager(final T manager) {
130 this.writeLock.lock();
131 try {
132 final T old = this.getManager();
133 if (!manager.isRunning()) {
134 manager.startup();
135 }
136 this.manager = manager;
137 old.close();
138 } finally {
139 this.writeLock.unlock();
140 }
141 }
142 }