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.asterix.replication.api;
  
  import java.io.IOException;
  import java.net.InetSocketAddress;
  import java.util.ArrayDeque;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Optional;
  import java.util.Set;
  
  import org.apache.asterix.common.api.INcApplicationContext;
  import org.apache.asterix.common.exceptions.ReplicationException;
  import org.apache.asterix.common.replication.IPartitionReplica;
  import org.apache.asterix.common.replication.IReplicationDestination;
  import org.apache.asterix.common.storage.ReplicaIdentifier;
  import org.apache.asterix.replication.management.NetworkingUtil;
  import org.apache.asterix.replication.messaging.ReplicationProtocol;
  import org.apache.hyracks.api.network.ISocketChannel;
  import org.apache.hyracks.util.NetworkUtil;
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
  public class ReplicationDestination implements IReplicationDestination {
  
      private static final Logger LOGGER = LogManager.getLogger();
      private final Set<IPartitionReplica> replicas = new HashSet<>();
      private final InetSocketAddress inputLocation;
      private final Map<ReplicaIdentifier, ArrayDeque<PartitionReplica>> replicasConnPool = new HashMap<>();
      private InetSocketAddress resolvedLocation;
      private ISocketChannel logRepChannel;
  
      private ReplicationDestination(InetSocketAddress location) {
          this.inputLocation = location;
          this.resolvedLocation = NetworkUtil.ensureResolved(location);
      }
  
      public static ReplicationDestination at(InetSocketAddress location) {
          if (!location.isUnresolved()) {
              throw new IllegalArgumentException("only unresolved addresses are allowed!");
          }
          return new ReplicationDestination(new InetSocketAddress(location.getHostString(), location.getPort()));
      }
  
      @Override
      public synchronized void add(IPartitionReplica replica) {
          replicas.add(replica);
      }
  
      @Override
      public synchronized void remove(IPartitionReplica replica) {
          replicas.remove(replica);
          ArrayDeque<PartitionReplica> partitionConnections = replicasConnPool.remove(replica.getIdentifier());
          if (partitionConnections != null) {
              partitionConnections.forEach(PartitionReplica::close);
              partitionConnections.clear();
          }
      }
  
      @Override
      public synchronized void notifyFailure(Exception failure) {
          replicas.forEach(replica -> replica.notifyFailure(failure));
          closeLogReplicationChannel();
      }
  
      @Override
      public Set<IPartitionReplica> getReplicas() {
          return new HashSet<>(replicas);
      }
  
      public synchronized Optional<IPartitionReplica> getPartitionReplica(int partition) {
          return replicas.stream().filter(replica -> replica.getIdentifier().getPartition() == partition
                  && replica.getStatus() == IPartitionReplica.PartitionReplicaStatus.IN_SYNC).findAny();
      }
  
      public synchronized ISocketChannel getLogReplicationChannel(INcApplicationContext appCtx) {
          try {
              if (!NetworkingUtil.isHealthy(logRepChannel)) {
                  establishReplicaConnection(appCtx);
              }
              return logRepChannel;
          } catch (IOException e) {
              throw new ReplicationException(e);
          }
      }
  
      protected void establishReplicaConnection(INcApplicationContext appCtx) throws IOException {
          // try to re-resolve the address, in case our replica has had his IP address updated, and that is why
          // the connection is unhealthy...
          resolvedLocation = NetworkUtil.refresh(resolvedLocation);
          logRepChannel = ReplicationProtocol.establishReplicaConnection(appCtx, resolvedLocation);
      }
  
      private synchronized void closeLogReplicationChannel() {
          try {
              if (logRepChannel != null && logRepChannel.getSocketChannel().isOpen()) {
                  ReplicationProtocol.sendGoodbye(logRepChannel);
                  logRepChannel.close();
                  logRepChannel = null;
              }
          } catch (IOException e) {
              LOGGER.warn("Exception while closing socket", e);
          }
      }
  
      @Override
      public InetSocketAddress getLocation() {
          return resolvedLocation;
      }
  
      @Override
      public boolean equals(Object o) {
          if (this == o) {
              return true;
          }
          if (o == null || getClass() != o.getClass()) {
              return false;
          }
          ReplicationDestination that = (ReplicationDestination) o;
          return Objects.equals(inputLocation, that.inputLocation);
      }
  
      @Override
      public String toString() {
          return resolvedLocation.toString();
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(inputLocation);
      }
  
      public synchronized PartitionReplica getPartitionReplicaConnection(ReplicaIdentifier identifier,
              INcApplicationContext appCtx) {
          ArrayDeque<PartitionReplica> partitionReplicas =
                  replicasConnPool.computeIfAbsent(identifier, k -> new ArrayDeque<>());
          if (!partitionReplicas.isEmpty()) {
              return partitionReplicas.remove();
          }
          return new PartitionReplica(identifier, appCtx);
      }
  
      public synchronized void recycleConnection(PartitionReplica partitionReplica) {
          ArrayDeque<PartitionReplica> partitionReplicas = replicasConnPool.get(partitionReplica.getIdentifier());
          if (partitionReplicas != null) {
              partitionReplicas.add(partitionReplica);
          }
      }
  
      public synchronized void closeConnections() {
          replicasConnPool
                  .forEach(((identifier, partitionReplicas) -> partitionReplicas.forEach(PartitionReplica::close)));
      }
  }
  