content: /*
   * 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.cassandra.utils.logging;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.cassandra.utils.FBUtilities;
  
  /**
   * Dynamically loads and instantiates an appropriate {@link LoggingSupport} implementation according to the used slf4j binding.
   * For production use, this should always be {@link LogbackLoggingSupport}.
   */
  public class LoggingSupportFactory
  {
      private static final Logger logger = LoggerFactory.getLogger(LoggingSupportFactory.class);
  
      private static volatile LoggingSupport loggingSupport;
  
      private LoggingSupportFactory() {}
  
      /**
       * @return An appropriate {@link LoggingSupport} implementation according to the used slf4j binding.
       */
      public static LoggingSupport getLoggingSupport()
      {
          if (loggingSupport == null)
          {
              // unfortunately, this is the best way to determine if logback is being used for logger
              String loggerFactoryClass = LoggerFactory.getILoggerFactory().getClass().getName();
              if (loggerFactoryClass.contains("logback"))
              {
                  loggingSupport = FBUtilities.instanceOrConstruct("org.apache.cassandra.utils.logging.LogbackLoggingSupport", "LogbackLoggingSupport");
              }
              else
              {
                  loggingSupport = new NoOpFallbackLoggingSupport();
                  logger.warn("You are using Cassandra with an unsupported deployment. The intended logging implementation library logback is not used by slf4j. Detected slf4j logger factory: {}. "
                              + "You will not be able to dynamically manage log levels via JMX and may have performance or other issues.", loggerFactoryClass);
              }
          }
          return loggingSupport;
      }
  }
  