/*
    * 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.appender.rolling;
  
  import java.lang.reflect.Method;
  
  import org.apache.logging.log4j.core.Core;
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.config.plugins.Plugin;
  import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
  import org.apache.logging.log4j.core.config.plugins.PluginFactory;
  import org.apache.logging.log4j.core.util.Loader;
  import org.apache.logging.log4j.status.StatusLogger;
  
  /**
   * Triggers a rollover on every restart, but only if the file size is greater than zero.
   */
  @Plugin(name = "OnStartupTriggeringPolicy", category = Core.CATEGORY_NAME, printObject = true)
  public class OnStartupTriggeringPolicy extends AbstractTriggeringPolicy {
  
      private static final long JVM_START_TIME = initStartTime();
  
      private final long minSize;
  
      private OnStartupTriggeringPolicy(final long minSize) {
          this.minSize = minSize;
      }
  
      /**
       * Returns the result of {@code ManagementFactory.getRuntimeMXBean().getStartTime()},
       * or the current system time if JMX is not available.
       */
      private static long initStartTime() {
          // LOG4J2-379:
          // We'd like to call ManagementFactory.getRuntimeMXBean().getStartTime(),
          // but Google App Engine throws a java.lang.NoClassDefFoundError
          // "java.lang.management.ManagementFactory is a restricted class".
          // The reflection is necessary because without it, Google App Engine
          // will refuse to initialize this class.
          try {
              final Class<?> factoryClass = Loader.loadSystemClass("java.lang.management.ManagementFactory");
              final Method getRuntimeMXBean = factoryClass.getMethod("getRuntimeMXBean");
              final Object runtimeMXBean = getRuntimeMXBean.invoke(null);
  
              final Class<?> runtimeMXBeanClass = Loader.loadSystemClass("java.lang.management.RuntimeMXBean");
              final Method getStartTime = runtimeMXBeanClass.getMethod("getStartTime");
              final Long result = (Long) getStartTime.invoke(runtimeMXBean);
  
              return result;
          } catch (final Throwable t) {
              StatusLogger.getLogger().error("Unable to call ManagementFactory.getRuntimeMXBean().getStartTime(), "
                      + "using system time for OnStartupTriggeringPolicy", t);
              // We have little option but to declare "now" as the beginning of time.
              return System.currentTimeMillis();
          }
      }
  
      /**
       * Provide the RollingFileManager to the policy.
       * @param manager The RollingFileManager.
       */
      @Override
      public void initialize(final RollingFileManager manager) {
          if (manager.getFileTime() < JVM_START_TIME && manager.getFileSize() >= minSize) {
              StatusLogger.getLogger().debug("Initiating rollover at startup");
              if (minSize == 0) {
                  manager.setRenameEmptyFiles(true);
              }
              manager.skipFooter(true);
              manager.rollover();
              manager.skipFooter(false);
          }
      }
  
      /**
       * Determine if a rollover should be triggered.
       * @param event   A reference to the current event.
       * @return true if the target file's timestamp is older than the JVM start time.
       */
      @Override
      public boolean isTriggeringEvent(final LogEvent event) {
          return false;
      }
  
      @Override
     public String toString() {
         return "OnStartupTriggeringPolicy";
     }
 
     @PluginFactory
     public static OnStartupTriggeringPolicy createPolicy(
             @PluginAttribute(value = "minSize", defaultLong = 1) final long minSize) {
         return new OnStartupTriggeringPolicy(minSize);
     }
 }