log4j-core/src/main/java/org/apache/logging/log4j/core/config/ReliabilityStrategyFactory.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache license, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the license for the specific language governing permissions and
 * limitations under the license.
 */

package org.apache.logging.log4j.core.config;

import org.apache.logging.log4j.core.util.Loader;
import org.apache.logging.log4j.status.StatusLogger;
import org.apache.logging.log4j.util.PropertiesUtil;

/**
 * Factory for ReliabilityStrategies.
 */
public final class ReliabilityStrategyFactory {
    private ReliabilityStrategyFactory() {
    }

    /**
     * Returns a new {@code ReliabilityStrategy} instance based on the value of system property
     * {@code log4j.ReliabilityStrategy}. If not value was specified this method returns a new
     * {@code AwaitUnconditionallyReliabilityStrategy}.
     * <p>
     * Valid values for this system property are {@code "AwaitUnconditionally"} (use
     * {@code AwaitUnconditionallyReliabilityStrategy}), {@code "Locking"} (use {@code LockingReliabilityStrategy}) and
     * {@code "AwaitCompletion"} (use the default {@code AwaitCompletionReliabilityStrategy}).
     * <p>
     * Users may also use this system property to specify the fully qualified class name of a class that implements the
     * {@code ReliabilityStrategy} and has a constructor that accepts a single {@code LoggerConfig} argument.
     *
     * @param loggerConfig the LoggerConfig the resulting {@code ReliabilityStrategy} is associated with
     * @return a ReliabilityStrategy that helps the specified LoggerConfig to log events reliably during or after a
     *         configuration change
     */
    public static ReliabilityStrategy getReliabilityStrategy(final LoggerConfig loggerConfig) {

        final String strategy = PropertiesUtil.getProperties().getStringProperty("log4j.ReliabilityStrategy",
                "AwaitCompletion");
        if ("AwaitCompletion".equals(strategy)) {
            return new AwaitCompletionReliabilityStrategy(loggerConfig);
        }
        if ("AwaitUnconditionally".equals(strategy)) {
            return new AwaitUnconditionallyReliabilityStrategy(loggerConfig);
        }
        if ("Locking".equals(strategy)) {
            return new LockingReliabilityStrategy(loggerConfig);
        }
        try {
            final Class<? extends ReliabilityStrategy> cls = Loader.loadClass(strategy).asSubclass(
                ReliabilityStrategy.class);
            return cls.getConstructor(LoggerConfig.class).newInstance(loggerConfig);
        } catch (final Exception dynamicFailed) {
            StatusLogger.getLogger().warn(
                    "Could not create ReliabilityStrategy for '{}', using default AwaitCompletionReliabilityStrategy: {}", strategy, dynamicFailed);
            return new AwaitCompletionReliabilityStrategy(loggerConfig);
        }
    }
}