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.net;
  
  import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
  import java.util.function.BiPredicate;
  
  import org.apache.cassandra.locator.InetAddressAndPort;
  
  /**
   * A message sink that all outbound messages go through.
   *
   * Default sink {@link Sink} used by {@link MessagingService} is {@link MessagingService#doSend(Message, InetAddressAndPort, ConnectionType)}, which proceeds to
   * send messages over the network, but it can be overridden to filter out certain messages, record the fact
   * of attempted delivery, or delay they delivery.
   *
   * This facility is most useful for test code.
   */
  public class OutboundSink
  {
      public interface Sink
      {
          void accept(Message<?> message, InetAddressAndPort to, ConnectionType connectionType);
      }
  
      private static class Filtered implements Sink
      {
          final BiPredicate<Message<?>, InetAddressAndPort> condition;
          final Sink next;
  
          private Filtered(BiPredicate<Message<?>, InetAddressAndPort> condition, Sink next)
          {
              this.condition = condition;
              this.next = next;
          }
  
          public void accept(Message<?> message, InetAddressAndPort to, ConnectionType connectionType)
          {
              if (condition.test(message, to))
                  next.accept(message, to, connectionType);
          }
      }
  
      private volatile Sink sink;
      private static final AtomicReferenceFieldUpdater<OutboundSink, Sink> sinkUpdater
          = AtomicReferenceFieldUpdater.newUpdater(OutboundSink.class, Sink.class, "sink");
  
      OutboundSink(Sink sink)
      {
          this.sink = sink;
      }
  
      public void accept(Message<?> message, InetAddressAndPort to, ConnectionType connectionType)
      {
          sink.accept(message, to, connectionType);
      }
  
      public void add(BiPredicate<Message<?>, InetAddressAndPort> allow)
      {
          sinkUpdater.updateAndGet(this, sink -> new Filtered(allow, sink));
      }
  
      public void remove(BiPredicate<Message<?>, InetAddressAndPort> allow)
      {
          sinkUpdater.updateAndGet(this, sink -> without(sink, allow));
      }
  
      public void clear()
      {
          sinkUpdater.updateAndGet(this, OutboundSink::clear);
      }
  
      private static Sink clear(Sink sink)
      {
          while (sink instanceof OutboundSink.Filtered)
              sink = ((OutboundSink.Filtered) sink).next;
          return sink;
      }
  
      private static Sink without(Sink sink, BiPredicate<Message<?>, InetAddressAndPort> condition)
      {
          if (!(sink instanceof Filtered))
              return sink;
  
          Filtered filtered = (Filtered) sink;
          Sink next = without(filtered.next, condition);
          return condition.equals(filtered.condition) ? next
                                                      : next == filtered.next
                                                        ? sink
                                                        : new Filtered(filtered.condition, next);
      }
  
  }
  