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.kafka.common.utils;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.lang.reflect.Constructor;
  import java.lang.reflect.InvocationHandler;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.lang.reflect.Proxy;
  import java.util.Arrays;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  
  public class LoggingSignalHandler {
  
      private static final Logger log = LoggerFactory.getLogger(LoggingSignalHandler.class);
  
      private static final List<String> SIGNALS = Arrays.asList("TERM", "INT", "HUP");
  
      private final Constructor<?> signalConstructor;
      private final Class<?> signalHandlerClass;
      private final Method signalHandleMethod;
      private final Method signalGetNameMethod;
      private final Method signalHandlerHandleMethod;
  
      /**
       * Create an instance of this class.
       *
       * @throws ReflectiveOperationException if the underlying API has changed in an incompatible manner.
       */
      public LoggingSignalHandler() throws ReflectiveOperationException {
          Class<?> signalClass = Class.forName("sun.misc.Signal");
          signalConstructor = signalClass.getConstructor(String.class);
          signalHandlerClass = Class.forName("sun.misc.SignalHandler");
          signalHandlerHandleMethod = signalHandlerClass.getMethod("handle", signalClass);
          signalHandleMethod = signalClass.getMethod("handle", signalClass, signalHandlerClass);
          signalGetNameMethod = signalClass.getMethod("getName");
      }
  
      /**
       * Register signal handler to log termination due to SIGTERM, SIGHUP and SIGINT (control-c). This method
       * does not currently work on Windows.
       *
       * @implNote sun.misc.Signal and sun.misc.SignalHandler are described as "not encapsulated" in
       * http://openjdk.java.net/jeps/260. However, they are not available in the compile classpath if the `--release`
       * flag is used. As a workaround, we rely on reflection.
       */
      public void register() throws ReflectiveOperationException {
          Map<String, Object> jvmSignalHandlers = new ConcurrentHashMap<>();
  
          for (String signal : SIGNALS) {
              register(signal, jvmSignalHandlers);
          }
          log.info("Registered signal handlers for " + String.join(", ", SIGNALS));
      }
  
      private Object createSignalHandler(final Map<String, Object> jvmSignalHandlers) {
          InvocationHandler invocationHandler = new InvocationHandler() {
  
              private String getName(Object signal) throws Throwable {
                  try {
                      return (String) signalGetNameMethod.invoke(signal);
                  } catch (InvocationTargetException e) {
                      throw e.getCause();
                  }
              }
  
              private void handle(Object signalHandler, Object signal) throws ReflectiveOperationException {
                  signalHandlerHandleMethod.invoke(signalHandler, signal);
              }
  
              @Override
              public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                  Object signal = args[0];
                  log.info("Terminating process due to signal {}", signal);
                  Object handler = jvmSignalHandlers.get(getName(signal));
                  if (handler != null)
                      handle(handler, signal);
                  return null;
              }
          };
          return Proxy.newProxyInstance(Utils.getContextOrKafkaClassLoader(), new Class<?>[] {signalHandlerClass},
                  invocationHandler);
      }
  
      private void register(String signalName, final Map<String, Object> jvmSignalHandlers) throws ReflectiveOperationException {
          Object signal = signalConstructor.newInstance(signalName);
          Object signalHandler = createSignalHandler(jvmSignalHandlers);
          Object oldHandler = signalHandleMethod.invoke(null, signal, signalHandler);
          if (oldHandler != null)
              jvmSignalHandlers.put(signalName, oldHandler);
      }
  }
  