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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.config;
19  
20  import org.apache.logging.log4j.core.util.Loader;
21  import org.apache.logging.log4j.status.StatusLogger;
22  import org.apache.logging.log4j.util.PropertiesUtil;
23  
24  /**
25   * Factory for ReliabilityStrategies.
26   */
27  public final class ReliabilityStrategyFactory {
28      private ReliabilityStrategyFactory() {
29      }
30  
31      /**
32       * Returns a new {@code ReliabilityStrategy} instance based on the value of system property
33       * {@code log4j.ReliabilityStrategy}. If not value was specified this method returns a new
34       * {@code AwaitUnconditionallyReliabilityStrategy}.
35       * <p>
36       * Valid values for this system property are {@code "AwaitUnconditionally"} (use
37       * {@code AwaitUnconditionallyReliabilityStrategy}), {@code "Locking"} (use {@code LockingReliabilityStrategy}) and
38       * {@code "AwaitCompletion"} (use the default {@code AwaitCompletionReliabilityStrategy}).
39       * <p>
40       * Users may also use this system property to specify the fully qualified class name of a class that implements the
41       * {@code ReliabilityStrategy} and has a constructor that accepts a single {@code LoggerConfig} argument.
42       *
43       * @param loggerConfig the LoggerConfig the resulting {@code ReliabilityStrategy} is associated with
44       * @return a ReliabilityStrategy that helps the specified LoggerConfig to log events reliably during or after a
45       *         configuration change
46       */
47      public static ReliabilityStrategy getReliabilityStrategy(final LoggerConfig loggerConfig) {
48  
49          final String strategy = PropertiesUtil.getProperties().getStringProperty("log4j.ReliabilityStrategy",
50                  "AwaitCompletion");
51          if ("AwaitCompletion".equals(strategy)) {
52              return new AwaitCompletionReliabilityStrategy(loggerConfig);
53          }
54          if ("AwaitUnconditionally".equals(strategy)) {
55              return new AwaitUnconditionallyReliabilityStrategy(loggerConfig);
56          }
57          if ("Locking".equals(strategy)) {
58              return new LockingReliabilityStrategy(loggerConfig);
59          }
60          try {
61              final Class<? extends ReliabilityStrategy> cls = Loader.loadClass(strategy).asSubclass(
62                  ReliabilityStrategy.class);
63              return cls.getConstructor(LoggerConfig.class).newInstance(loggerConfig);
64          } catch (final Exception dynamicFailed) {
65              StatusLogger.getLogger().warn(
66                      "Could not create ReliabilityStrategy for '{}', using default AwaitCompletionReliabilityStrategy: {}", strategy, dynamicFailed);
67              return new AwaitCompletionReliabilityStrategy(loggerConfig);
68          }
69      }
70  }