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;
  
  import java.lang.management.ManagementFactory;
  import java.util.Collections;
  import java.util.Set;
  import java.util.UUID;
  import java.util.function.Consumer;
  import javax.management.MBeanServer;
  import javax.management.MBeanServerFactory;
  import javax.management.MalformedObjectNameException;
  import javax.management.ObjectName;
  import javax.management.QueryExp;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static org.apache.cassandra.config.CassandraRelevantProperties.ORG_APACHE_CASSANDRA_DISABLE_MBEAN_REGISTRATION;
  import static org.apache.cassandra.config.CassandraRelevantProperties.DTEST_IS_IN_JVM_DTEST;
  import static org.apache.cassandra.config.CassandraRelevantProperties.MBEAN_REGISTRATION_CLASS;
  
  /**
   * Helper class to avoid catching and rethrowing checked exceptions on MBean and
   * allow turning of MBean registration for test purposes.
   */
  public interface MBeanWrapper
  {
      Logger logger = LoggerFactory.getLogger(MBeanWrapper.class);
  
      MBeanWrapper instance = create();
  
      static MBeanWrapper create()
      {
          // If we're running in the in-jvm dtest environment, always use the delegating
          // mbean wrapper even if we start off with no-op, so it can be switched later
          if (DTEST_IS_IN_JVM_DTEST.getBoolean())
          {
              return new DelegatingMbeanWrapper(getMBeanWrapper());
          }
  
          return getMBeanWrapper();
      }
  
      static MBeanWrapper getMBeanWrapper()
      {
          if (ORG_APACHE_CASSANDRA_DISABLE_MBEAN_REGISTRATION.getBoolean())
          {
              return new NoOpMBeanWrapper();
          }
  
          String klass = MBEAN_REGISTRATION_CLASS.getString();
          if (klass == null)
          {
              if (DTEST_IS_IN_JVM_DTEST.getBoolean())
              {
                  return new NoOpMBeanWrapper();
              }
              else
              {
                  return new PlatformMBeanWrapper();
              }
          }
          return FBUtilities.construct(klass, "mbean");
      }
  
      // Passing true for graceful will log exceptions instead of rethrowing them
      void registerMBean(Object obj, ObjectName mbeanName, OnException onException);
      default void registerMBean(Object obj, ObjectName mbeanName)
      {
          registerMBean(obj, mbeanName, OnException.THROW);
      }
  
      default void registerMBean(Object obj, String mbeanName, OnException onException)
      {
          ObjectName name = create(mbeanName, onException);
          if (name == null)
          {
              return;
          }
          registerMBean(obj, name, onException);
      }
      default void registerMBean(Object obj, String mbeanName)
      {
          registerMBean(obj, mbeanName, OnException.THROW);
      }
  
      boolean isRegistered(ObjectName mbeanName, OnException onException);
      default boolean isRegistered(ObjectName mbeanName)
      {
          return isRegistered(mbeanName, OnException.THROW);
      }
  
      default boolean isRegistered(String mbeanName, OnException onException)
      {
          ObjectName name = create(mbeanName, onException);
          if (name == null)
          {
              return false;
          }
          return isRegistered(name, onException);
      }
      default boolean isRegistered(String mbeanName)
      {
          return isRegistered(mbeanName, OnException.THROW);
      }
  
      void unregisterMBean(ObjectName mbeanName, OnException onException);
      default void unregisterMBean(ObjectName mbeanName)
      {
          unregisterMBean(mbeanName, OnException.THROW);
      }
  
      default void unregisterMBean(String mbeanName, OnException onException)
      {
          ObjectName name = create(mbeanName, onException);
          if (name == null)
          {
              return;
          }
          unregisterMBean(name, onException);
      }
      default void unregisterMBean(String mbeanName)
      {
          unregisterMBean(mbeanName, OnException.THROW);
      }
  
      static ObjectName create(String mbeanName, OnException onException)
      {
          try
          {
              return new ObjectName(mbeanName);
          }
          catch (MalformedObjectNameException e)
          {
              onException.handler.accept(e);
              return null;
          }
      }
  
      Set<ObjectName> queryNames(ObjectName name, QueryExp query);
  
      MBeanServer getMBeanServer();
  
      class NoOpMBeanWrapper implements MBeanWrapper
      {
          public void registerMBean(Object obj, ObjectName mbeanName, OnException onException) {}
          public void registerMBean(Object obj, String mbeanName, OnException onException) {}
          public boolean isRegistered(ObjectName mbeanName, OnException onException) { return false; }
          public boolean isRegistered(String mbeanName, OnException onException) { return false; }
          public void unregisterMBean(ObjectName mbeanName, OnException onException) {}
          public void unregisterMBean(String mbeanName, OnException onException) {}
          public Set<ObjectName> queryNames(ObjectName name, QueryExp query) {return Collections.emptySet(); }
          public MBeanServer getMBeanServer() { return null; }
      }
  
      class PlatformMBeanWrapper implements MBeanWrapper
      {
          private final MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
          public void registerMBean(Object obj, ObjectName mbeanName, OnException onException)
          {
              try
              {
                  mbs.registerMBean(obj, mbeanName);
              }
              catch (Exception e)
              {
                  onException.handler.accept(e);
              }
          }
  
          public boolean isRegistered(ObjectName mbeanName, OnException onException)
          {
              try
              {
                  return mbs.isRegistered(mbeanName);
              }
              catch (Exception e)
              {
                  onException.handler.accept(e);
              }
              return false;
          }
  
          public void unregisterMBean(ObjectName mbeanName, OnException onException)
          {
              try
              {
                  mbs.unregisterMBean(mbeanName);
              }
              catch (Exception e)
              {
                  onException.handler.accept(e);
              }
          }
  
          public Set<ObjectName> queryNames(ObjectName name, QueryExp query)
          {
              return mbs.queryNames(name, query);
          }
  
          public MBeanServer getMBeanServer()
          {
              return mbs;
          }
      }
  
      class InstanceMBeanWrapper implements MBeanWrapper
      {
          private MBeanServer mbs;
          public final UUID id = UUID.randomUUID();
  
          public InstanceMBeanWrapper(String hostname)
          {
              mbs = MBeanServerFactory.createMBeanServer(hostname + "-" + id);
          }
  
          public void registerMBean(Object obj, ObjectName mbeanName, OnException onException)
          {
              try
              {
                  mbs.registerMBean(obj, mbeanName);
              }
              catch (Exception e)
              {
                  onException.handler.accept(e);
              }
          }
  
          public boolean isRegistered(ObjectName mbeanName, OnException onException)
          {
              try
              {
                  return mbs.isRegistered(mbeanName);
              }
              catch (Exception e)
              {
                  onException.handler.accept(e);
              }
              return false;
          }
  
          public void unregisterMBean(ObjectName mbeanName, OnException onException)
          {
              try
              {
                  mbs.unregisterMBean(mbeanName);
              }
              catch (Exception e)
              {
                  onException.handler.accept(e);
              }
          }
  
          public Set<ObjectName> queryNames(ObjectName name, QueryExp query)
          {
              return mbs.queryNames(name, query);
          }
  
          public MBeanServer getMBeanServer()
          {
              return mbs;
          }
  
          public void close() {
              mbs.queryNames(null, null).forEach(name -> {
                  try {
                      if (!name.getCanonicalName().contains("MBeanServerDelegate"))
                      {
                          mbs.unregisterMBean(name);
                      }
                  } catch (Throwable e) {
                      logger.debug("Could not unregister mbean {}", name.getCanonicalName());
                  }
              });
              MBeanServerFactory.releaseMBeanServer(mbs);
              mbs = null;
          }
      }
  
      class DelegatingMbeanWrapper implements MBeanWrapper
      {
          MBeanWrapper delegate;
  
          public DelegatingMbeanWrapper(MBeanWrapper mBeanWrapper)
          {
              delegate = mBeanWrapper;
          }
  
          public void setDelegate(MBeanWrapper wrapper) {
              delegate = wrapper;
          }
  
          public MBeanWrapper getDelegate()
          {
              return delegate;
          }
          
          public void registerMBean(Object obj, ObjectName mbeanName, OnException onException)
          {
              try
              {
                  delegate.registerMBean(obj, mbeanName);
              }
              catch (Exception e)
              {
                  onException.handler.accept(e);
              }
          }
  
          public boolean isRegistered(ObjectName mbeanName, OnException onException)
          {
              try
              {
                  return delegate.isRegistered(mbeanName);
              }
              catch (Exception e)
              {
                  onException.handler.accept(e);
              }
              return false;
          }
  
          public void unregisterMBean(ObjectName mbeanName, OnException onException)
          {
              try
              {
                  delegate.unregisterMBean(mbeanName);
              }
              catch (Exception e)
              {
                  onException.handler.accept(e);
              }
          }
  
          public Set<ObjectName> queryNames(ObjectName name, QueryExp query)
          {
              return delegate.queryNames(name, query);
          }
  
          public MBeanServer getMBeanServer()
          {
              return delegate.getMBeanServer();
          }
      }
  
      enum OnException
      {
          THROW(e -> { throw new RuntimeException(e); }),
          LOG(e -> { logger.error("Error in MBean wrapper: ", e); }),
          IGNORE(e -> {});
  
          public final Consumer<Exception> handler;
          OnException(Consumer<Exception> handler)
          {
              this.handler = handler;
          }
      }
  }
  