001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017
018package org.apache.logging.log4j.core.config;
019
020import org.apache.logging.log4j.core.util.Loader;
021import org.apache.logging.log4j.status.StatusLogger;
022import org.apache.logging.log4j.util.PropertiesUtil;
023
024/**
025 * Factory for ReliabilityStrategies.
026 */
027public final class ReliabilityStrategyFactory {
028    private ReliabilityStrategyFactory() {
029    }
030
031    /**
032     * Returns a new {@code ReliabilityStrategy} instance based on the value of system property
033     * {@code log4j.ReliabilityStrategy}. If not value was specified this method returns a new
034     * {@code AwaitUnconditionallyReliabilityStrategy}.
035     * <p>
036     * Valid values for this system property are {@code "AwaitUnconditionally"} (use
037     * {@code AwaitUnconditionallyReliabilityStrategy}), {@code "Locking"} (use {@code LockingReliabilityStrategy}) and
038     * {@code "AwaitCompletion"} (use the default {@code AwaitCompletionReliabilityStrategy}).
039     * <p>
040     * Users may also use this system property to specify the fully qualified class name of a class that implements the
041     * {@code ReliabilityStrategy} and has a constructor that accepts a single {@code LoggerConfig} argument.
042     *
043     * @param loggerConfig the LoggerConfig the resulting {@code ReliabilityStrategy} is associated with
044     * @return a ReliabilityStrategy that helps the specified LoggerConfig to log events reliably during or after a
045     *         configuration change
046     */
047    public static ReliabilityStrategy getReliabilityStrategy(final LoggerConfig loggerConfig) {
048
049        final String strategy = PropertiesUtil.getProperties().getStringProperty("log4j.ReliabilityStrategy",
050                "AwaitCompletion");
051        if ("AwaitCompletion".equals(strategy)) {
052            return new AwaitCompletionReliabilityStrategy(loggerConfig);
053        }
054        if ("AwaitUnconditionally".equals(strategy)) {
055            return new AwaitUnconditionallyReliabilityStrategy(loggerConfig);
056        }
057        if ("Locking".equals(strategy)) {
058            return new LockingReliabilityStrategy(loggerConfig);
059        }
060        try {
061            final Class<? extends ReliabilityStrategy> cls = Loader.loadClass(strategy).asSubclass(
062                ReliabilityStrategy.class);
063            return cls.getConstructor(LoggerConfig.class).newInstance(loggerConfig);
064        } catch (final Exception dynamicFailed) {
065            StatusLogger.getLogger().warn(
066                    "Could not create ReliabilityStrategy for '{}', using default AwaitCompletionReliabilityStrategy: {}", strategy, dynamicFailed);
067            return new AwaitCompletionReliabilityStrategy(loggerConfig);
068        }
069    }
070}