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.repair;
  
  import java.util.Map;
  import java.util.function.Consumer;
  import javax.annotation.Nullable;
  
  import org.apache.cassandra.db.DecoratedKey;
  import org.apache.cassandra.db.Mutation;
  import org.apache.cassandra.db.ReadCommand;
  import org.apache.cassandra.db.ReadCommand.PotentialTxnConflicts;
  import org.apache.cassandra.db.partitions.PartitionIterator;
  import org.apache.cassandra.db.partitions.UnfilteredPartitionIterators;
  import org.apache.cassandra.exceptions.ReadTimeoutException;
  import org.apache.cassandra.locator.Endpoints;
  import org.apache.cassandra.locator.Replica;
  import org.apache.cassandra.locator.ReplicaPlan;
  import org.apache.cassandra.service.reads.DigestResolver;
  import org.apache.cassandra.service.reads.ReadCoordinator;
  import org.apache.cassandra.transport.Dispatcher;
  
  public interface ReadRepair<E extends Endpoints<E>, P extends ReplicaPlan.ForRead<E, P>>
  {
      public interface Factory
      {
          <E extends Endpoints<E>, P extends ReplicaPlan.ForRead<E, P>>
          ReadRepair<E, P> create(ReadCoordinator coordinator, ReadCommand command, ReplicaPlan.Shared<E, P> replicaPlan, Dispatcher.RequestTime requestTime);
      }
  
      static <E extends Endpoints<E>, P extends ReplicaPlan.ForRead<E, P>>
      ReadRepair<E, P> create(ReadCoordinator coordinator, ReadCommand command, ReplicaPlan.Shared<E, P> replicaPlan, Dispatcher.RequestTime requestTime)
      {
          return command.metadata().params.readRepair.create(coordinator, command, replicaPlan, requestTime);
      }
  
      /**
       * Used by DataResolver to generate corrections as the partition iterator is consumed
       */
      UnfilteredPartitionIterators.MergeListener getMergeListener(P replicaPlan);
  
      /**
       * Called when the digests from the initial read don't match. Reads may block on the
       * repair started by this method.
       * @param digestResolver supplied so we can get the original data response
       * @param resultConsumer hook for the repair to set it's result on completion
       */
      public void startRepair(DigestResolver<E, P> digestResolver, @Nullable Consumer<PartitionIterator> resultConsumer);
  
      /**
       * Block on the reads (or timeout) sent out in {@link ReadRepair#startRepair}
       */
      public void awaitReads() throws ReadTimeoutException;
  
      /**
       * if it looks like we might not receive data requests from everyone in time, send additional requests
       * to additional replicas not contacted in the initial full data read. If the collection of nodes that
       * end up responding in time end up agreeing on the data, and we don't consider the response from the
       * disagreeing replica that triggered the read repair, that's ok, since the disagreeing data would not
       * have been successfully written and won't be included in the response the the client, preserving the
       * expectation of monotonic quorum reads
       */
      public void maybeSendAdditionalReads();
  
      /**
       * If it looks like we might not receive acks for all the repair mutations we sent out, combine all
       * the unacked mutations and send them to the minority of nodes not involved in the read repair data
       * read / write cycle. We will accept acks from them in lieu of acks from the initial mutations sent
       * out, so long as we receive the same number of acks as repair mutations transmitted. This prevents
       * misbehaving nodes from killing a quorum read, while continuing to guarantee monotonic quorum reads
       */
      public void maybeSendAdditionalWrites();
  
      /**
       * Block on any mutations (or timeout) we sent out to repair replicas in {@link ReadRepair#repairPartition}
       */
      public void awaitWrites();
  
      // For metrics need to know the source of the repair
      enum ReadRepairSource
      {
          // Running a dedicated repair transacation to do RR for a non-transactional reads
          REPAIR_VIA_ACCORD,
          // Read repair from a regular Accord transaction or non-transactional read
          OTHER
      }
  
      /**
       * Repairs a partition _after_ receiving data responses. This method receives replica list, since
       * we will block repair only on the replicas that have responded.
       */
      void repairPartition(DecoratedKey partitionKey, Map<Replica, Mutation> mutations, ReplicaPlan.ForWrite writePlan, ReadRepairSource rrSource);
  
      /**
       * Repairs a partition using the provided read coordinator
       */
      void repairPartitionDirectly(ReadCoordinator coordinator, DecoratedKey partitionKey, Map<Replica, Mutation> mutations, ReplicaPlan.ForWrite writePlan);
  
      default PotentialTxnConflicts coordinatorPotentialTxnConflicts()
      {
          return PotentialTxnConflicts.DISALLOW;
      }
  }
  