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.util;
18
19 import java.util.Objects;
20 import java.util.Properties;
21
22 /**
23 * PropertySource backed by the current system properties. Other than having a
24 * higher priority over normal properties, this follows the same rules as
25 * {@link PropertiesPropertySource}.
26 *
27 * @since 2.10.0
28 */
29 public class SystemPropertiesPropertySource implements PropertySource {
30
31 private static final int DEFAULT_PRIORITY = 100;
32 private static final String PREFIX = "log4j2.";
33
34 @Override
35 public int getPriority() {
36 return DEFAULT_PRIORITY;
37 }
38
39 @Override
40 public void forEach(final BiConsumer<String, String> action) {
41 Properties properties;
42 try {
43 properties = System.getProperties();
44 } catch (final SecurityException e) {
45 // (1) There is no status logger.
46 // (2) LowLevelLogUtil also consults system properties ("line.separator") to
47 // open a BufferedWriter, so this may fail as well. Just having a hard reference
48 // in this code to LowLevelLogUtil would cause a problem.
49 // (3) We could log to System.err (nah) or just be quiet as we do now.
50 return;
51 }
52 // Lock properties only long enough to get a thread-safe SAFE snapshot of its
53 // current keys, an array.
54 final Object[] keySet;
55 synchronized (properties) {
56 keySet = properties.keySet().toArray();
57 }
58 // Then traverse for an unknown amount of time.
59 // Some keys may now be absent, in which case, the value is null.
60 for (final Object key : keySet) {
61 final String keyStr = Objects.toString(key, null);
62 action.accept(keyStr, properties.getProperty(keyStr));
63 }
64 }
65
66 @Override
67 public CharSequence getNormalForm(final Iterable<? extends CharSequence> tokens) {
68 return PREFIX + Util.joinAsCamelCase(tokens);
69 }
70
71 }
72