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.async;
18
19 import org.apache.logging.log4j.status.StatusLogger;
20
21 /**
22 * Factory for {@code Clock} objects.
23 */
24 public final class ClockFactory {
25
26 /**
27 * Name of the system property that can be used to specify a {@code Clock}
28 * implementation class.
29 */
30 public static final String PROPERTY_NAME = "AsyncLogger.Clock";
31 private static final StatusLogger LOGGER = StatusLogger.getLogger();
32
33 // private static final Clock clock = createClock();
34
35 private ClockFactory() {
36 }
37
38 /**
39 * Returns a {@code Clock} instance depending on the value of system
40 * property {@code "AsyncLogger.Clock"}.
41 * <p>
42 * If system property {@code AsyncLogger.Clock=CachedClock} is specified,
43 * this method returns an instance of {@link CachedClock}. If system
44 * property {@code AsyncLogger.Clock=CoarseCachedClock} is specified, this
45 * method returns an instance of {@link CoarseCachedClock}.
46 * <p>
47 * If another value is specified, this value is taken as the fully qualified
48 * class name of a class that implements the {@code Clock} interface. An
49 * object of this class is instantiated and returned.
50 * <p>
51 * If no value is specified, or if the specified value could not correctly
52 * be instantiated or did not implement the {@code Clock} interface, then an
53 * instance of {@link SystemClock} is returned.
54 *
55 * @return a {@code Clock} instance
56 */
57 public static Clock getClock() {
58 return createClock();
59 }
60
61 private static Clock createClock() {
62 String userRequest = System.getProperty(PROPERTY_NAME);
63 if (userRequest == null || "SystemClock".equals(userRequest)) {
64 LOGGER.debug("Using default SystemClock for timestamps");
65 return new SystemClock();
66 }
67 if (CachedClock.class.getName().equals(userRequest) //
68 || "CachedClock".equals(userRequest)) {
69 LOGGER.debug("Using specified CachedClock for timestamps");
70 return CachedClock.instance();
71 }
72 if (CoarseCachedClock.class.getName().equals(userRequest) //
73 || "CoarseCachedClock".equals(userRequest)) {
74 LOGGER.debug("Using specified CoarseCachedClock for timestamps");
75 return CoarseCachedClock.instance();
76 }
77 try {
78 Clock result = (Clock) Class.forName(userRequest).newInstance();
79 LOGGER.debug("Using {} for timestamps", userRequest);
80 return result;
81 } catch (Exception e) {
82 String fmt = "Could not create {}: {}, using default SystemClock for timestamps";
83 LOGGER.error(fmt, userRequest, e);
84 return new SystemClock();
85 }
86 }
87 }