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.service.reads;
  
  import org.apache.cassandra.db.ConsistencyLevel;
  import org.apache.cassandra.db.Mutation;
  import org.apache.cassandra.db.ReadCommand;
  import org.apache.cassandra.db.ReadCommand.PotentialTxnConflicts;
  import org.apache.cassandra.db.ReadResponse;
  import org.apache.cassandra.dht.Token;
  import org.apache.cassandra.locator.EndpointsForToken;
  import org.apache.cassandra.locator.InetAddressAndPort;
  import org.apache.cassandra.locator.ReplicaLayout;
  import org.apache.cassandra.net.Message;
  import org.apache.cassandra.net.MessagingService;
  import org.apache.cassandra.net.RequestCallback;
  import org.apache.cassandra.schema.KeyspaceMetadata;
  import org.apache.cassandra.schema.TableId;
  import org.apache.cassandra.tcm.ClusterMetadata;
  
  public interface ReadCoordinator
  {
      ReadCoordinator DEFAULT = new ReadCoordinator()
      {
          public boolean localReadSupported()
          {
              return true;
          }
  
          public EndpointsForToken forNonLocalStrategyTokenRead(ClusterMetadata metadata, KeyspaceMetadata keyspace, TableId tableId, Token token)
          {
              return ReplicaLayout.forNonLocalStrategyTokenRead(metadata, keyspace, token);
          }
  
          public void sendReadCommand(Message<ReadCommand> message, InetAddressAndPort to, RequestCallback<ReadResponse> callback)
          {
              MessagingService.instance().sendWithCallback(message, to, callback);
          }
  
          public void sendReadRepairMutation(Message<Mutation> message, InetAddressAndPort to, RequestCallback<Object> callback)
          {
              MessagingService.instance().sendWithCallback(message, to, callback);
          }
  
          public boolean isEventuallyConsistent()
          {
              return true;
          }
      };
  
      boolean localReadSupported();
      EndpointsForToken forNonLocalStrategyTokenRead(ClusterMetadata metadata, KeyspaceMetadata keyspace, TableId tableId, Token token);
      default ReadCommand maybeAllowOutOfRangeReads(ReadCommand command, ConsistencyLevel cl)
      {
          return command;
      }
      void sendReadCommand(Message<ReadCommand> message, InetAddressAndPort to, RequestCallback<ReadResponse> callback);
      default void notifyOfInitialContacts(EndpointsForToken fullDataRequests, EndpointsForToken transientRequests, EndpointsForToken digestRequests) {}
      void sendReadRepairMutation(Message<Mutation> message, InetAddressAndPort to, RequestCallback<Object> callback);
      default PotentialTxnConflicts potentialTxnConflicts()
      {
          return isEventuallyConsistent() ? PotentialTxnConflicts.DISALLOW : PotentialTxnConflicts.ALLOW;
      }
      boolean isEventuallyConsistent();
  }
  