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.db;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.cassandra.config.DatabaseDescriptor;
  import org.apache.cassandra.locator.InetAddressAndPort;
  import org.apache.cassandra.net.Message;
  import org.apache.cassandra.net.MessagingService;
  import org.apache.cassandra.service.StorageProxy;
  import org.apache.cassandra.transport.Dispatcher;
  
  public class CounterMutationVerbHandler extends AbstractMutationVerbHandler<CounterMutation>
  {
      public static final CounterMutationVerbHandler instance = new CounterMutationVerbHandler();
  
      private static final Logger logger = LoggerFactory.getLogger(CounterMutationVerbHandler.class);
  
      protected void applyMutation(final Message<CounterMutation> message, InetAddressAndPort respondToAddress)
      {
          final CounterMutation cm = message.payload;
          logger.trace("Applying forwarded {}", cm);
  
          String localDataCenter = DatabaseDescriptor.getLocator().local().datacenter;
          // We should not wait for the result of the write in this thread,
          // otherwise we could have a distributed deadlock between replicas
          // running this VerbHandler (see #4578).
          // Instead, we use a callback to send the response. Note that the callback
          // will not be called if the request timeout, but this is ok
          // because the coordinator of the counter mutation will timeout on
          // it's own in that case.
          StorageProxy.applyCounterMutationOnLeader(cm,
                                                    localDataCenter,
                                                    () -> MessagingService.instance().send(message.emptyResponse(), respondToAddress),
                                                    Dispatcher.RequestTime.forImmediateExecution());
      }
  }
  