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 static org.apache.asterix.common.replication.IPartitionReplica.PartitionReplicaStatus.CATCHING_UP;
  import static org.apache.asterix.common.replication.IPartitionReplica.PartitionReplicaStatus.DISCONNECTED;
  import static org.apache.asterix.common.replication.IPartitionReplica.PartitionReplicaStatus.IN_SYNC;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Future;
  
  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.storage.ReplicaIdentifier;
  import org.apache.asterix.replication.management.NetworkingUtil;
  import org.apache.asterix.replication.messaging.ReplicationProtocol;
  import org.apache.asterix.replication.sync.ReplicaSynchronizer;
  import org.apache.hyracks.api.network.ISocketChannel;
  import org.apache.hyracks.util.NetworkUtil;
  import org.apache.hyracks.util.StorageUtil;
  import org.apache.hyracks.util.annotations.ThreadSafe;
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
  import com.fasterxml.jackson.core.JsonProcessingException;
  import com.fasterxml.jackson.databind.JsonNode;
  import com.fasterxml.jackson.databind.ObjectMapper;
  import com.fasterxml.jackson.databind.node.ObjectNode;
  
  @ThreadSafe
  public class PartitionReplica implements IPartitionReplica {
  
      private static final Logger LOGGER = LogManager.getLogger();
      private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
      private static final int INITIAL_BUFFER_SIZE = StorageUtil.getIntSizeInBytes(4, StorageUtil.StorageUnit.KILOBYTE);
      private final INcApplicationContext appCtx;
      private final ReplicaIdentifier id;
      private double syncProgress = -1;
      private long lastProgressTime = -1;
      private ByteBuffer reusbaleBuf;
      private PartitionReplicaStatus status = DISCONNECTED;
      private ISocketChannel sc;
      private Future<?> syncFuture;
  
      public PartitionReplica(ReplicaIdentifier id, INcApplicationContext appCtx) {
          this.id = id;
          this.appCtx = appCtx;
      }
  
      @Override
      public synchronized PartitionReplicaStatus getStatus() {
          return status;
      }
  
      @Override
      public ReplicaIdentifier getIdentifier() {
          return id;
      }
  
      @Override
      public synchronized void notifyFailure(Exception failure) {
          setStatus(DISCONNECTED);
      }
  
      public synchronized void sync() {
          sync(true, true);
      }
  
      public synchronized void sync(boolean register, boolean deltaRecovery) {
          if (status == IN_SYNC || status == CATCHING_UP) {
              return;
          }
          setStatus(CATCHING_UP);
          ExecutorService threadExecutor = (ExecutorService) appCtx.getThreadExecutor();
          syncFuture = threadExecutor.submit(() -> {
              try {
                  Thread.currentThread().setName("Replica " + id.toString() + " Synchronizer");
                  new ReplicaSynchronizer(appCtx, this).sync(register, deltaRecovery);
                  setStatus(IN_SYNC);
              } catch (Exception e) {
                  LOGGER.error(() -> "Failed to sync replica " + this, e);
                  notifyFailure(e);
              } finally {
                  close();
              }
          });
      }
  
      public synchronized void abort() {
          if (syncFuture != null) {
              syncFuture.cancel(true);
          }
          syncFuture = null;
      }
  
      public synchronized ISocketChannel getChannel() {
          try {
              if (!NetworkingUtil.isHealthy(sc)) {
                  establishReplicaConnection();
              }
              return sc;
          } catch (IOException e) {
              throw new ReplicationException(e);
          }
      }
  
      private void establishReplicaConnection() 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...
          sc = ReplicationProtocol.establishReplicaConnection(appCtx, id.refreshLocation());
      }
  
      public synchronized void close() {
          try {
              if (NetworkingUtil.isHealthy(sc)) {
                  sendGoodBye();
              }
              NetworkUtil.closeQuietly(sc);
          } finally {
              sc = null;
          }
      }
  
      public synchronized ByteBuffer getReusableBuffer() {
          if (reusbaleBuf == null) {
              reusbaleBuf = ByteBuffer.allocate(INITIAL_BUFFER_SIZE);
          }
          return reusbaleBuf;
      }
  
      public synchronized void setSyncProgress(double syncProgress) {
          this.syncProgress = syncProgress;
          lastProgressTime = System.nanoTime();
      }
  
      @Override
      public synchronized double getSyncProgress() {
          return syncProgress;
      }
  
      private JsonNode asJson() {
          ObjectNode json = OBJECT_MAPPER.createObjectNode();
          json.put("id", id.toString());
          json.put("status", status.name());
          json.put("syncProgress", syncProgress);
          return json;
      }
  
      @Override
      public boolean equals(Object o) {
          if (this == o) {
              return true;
          }
          if (o == null || getClass() != o.getClass()) {
              return false;
          }
          PartitionReplica that = (PartitionReplica) o;
          return id.equals(that.id);
      }
  
      @Override
      public synchronized long getLastProgressTime() {
          switch (status) {
              case IN_SYNC:
                  return System.nanoTime();
              case CATCHING_UP:
                  return lastProgressTime;
              case DISCONNECTED:
                  return -1;
          }
          return -1;
      }
  
      @Override
      public int hashCode() {
          return id.hashCode();
      }
  
      @Override
      public String toString() {
          try {
              return OBJECT_MAPPER.writeValueAsString(asJson());
          } catch (JsonProcessingException e) {
              throw new ReplicationException(e);
          }
      }
  
      private synchronized void setStatus(PartitionReplicaStatus status) {
          if (this.status == status) {
              return;
          }
          LOGGER.info(() -> "Replica " + this + " status changing: " + this.status + " -> " + status);
          this.status = status;
          switch (status) {
              case IN_SYNC:
                  syncProgress = 1;
                  break;
              case CATCHING_UP:
                  lastProgressTime = System.nanoTime();
                  break;
              case DISCONNECTED:
                  syncProgress = -1;
                  break;
          }
      }
  
      private void sendGoodBye() {
          try {
              ReplicationProtocol.sendGoodbye(sc);
          } catch (Exception e) {
              LOGGER.warn("Failed to send good bye to {}", this, e);
          }
      }
  }
  