/**
    * 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.hadoop.hbase.replication;
  
  import java.io.IOException;
  import java.util.List;
  import java.util.UUID;
  
  import org.apache.hadoop.hbase.Abortable;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.TableDescriptors;
  import org.apache.hadoop.hbase.wal.WAL.Entry;
  import org.apache.hadoop.hbase.replication.regionserver.MetricsSource;
  
  import com.google.common.util.concurrent.Service;
  
  /**
   * ReplicationEndpoint is a plugin which implements replication
   * to other HBase clusters, or other systems. ReplicationEndpoint implementation
   * can be specified at the peer creation time by specifying it
   * in the {@link ReplicationPeerConfig}. A ReplicationEndpoint is run in a thread
   * in each region server in the same process.
   * <p>
   * ReplicationEndpoint is closely tied to ReplicationSource in a producer-consumer
   * relation. ReplicationSource is an HBase-private class which tails the logs and manages
   * the queue of logs plus management and persistence of all the state for replication.
   * ReplicationEndpoint on the other hand is responsible for doing the actual shipping
   * and persisting of the WAL entries in the other cluster.
   */
  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.REPLICATION)
  public interface ReplicationEndpoint extends Service, ReplicationPeerConfigListener {
  
    @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.REPLICATION)
    class Context {
      private final Configuration localConf;
      private final Configuration conf;
      private final FileSystem fs;
      private final TableDescriptors tableDescriptors;
      private final ReplicationPeer replicationPeer;
      private final String peerId;
      private final UUID clusterId;
      private final MetricsSource metrics;
      private final Abortable abortable;
  
      @InterfaceAudience.Private
      public Context(
          final Configuration localConf,
          final Configuration conf,
          final FileSystem fs,
          final String peerId,
          final UUID clusterId,
          final ReplicationPeer replicationPeer,
          final MetricsSource metrics,
          final TableDescriptors tableDescriptors,
          final Abortable abortable) {
        this.localConf = localConf;
        this.conf = conf;
        this.fs = fs;
        this.clusterId = clusterId;
        this.peerId = peerId;
        this.replicationPeer = replicationPeer;
        this.metrics = metrics;
        this.tableDescriptors = tableDescriptors;
        this.abortable = abortable;
      }
      public Configuration getConfiguration() {
        return conf;
      }
      public Configuration getLocalConfiguration() {
        return localConf;
      }
      public FileSystem getFilesystem() {
        return fs;
      }
      public UUID getClusterId() {
        return clusterId;
      }
      public String getPeerId() {
        return peerId;
      }
     public ReplicationPeerConfig getPeerConfig() {
       return replicationPeer.getPeerConfig();
     }
     public ReplicationPeer getReplicationPeer() {
       return replicationPeer;
     }
     public MetricsSource getMetrics() {
       return metrics;
     }
     public TableDescriptors getTableDescriptors() {
       return tableDescriptors;
     }
     public Abortable getAbortable() { return abortable; }
   }
 
   /**
    * Initialize the replication endpoint with the given context.
    * @param context replication context
    * @throws IOException
    */
   void init(Context context) throws IOException;
 
   /** Whether or not, the replication endpoint can replicate to it's source cluster with the same
    * UUID */
   boolean canReplicateToSameCluster();
 
   /**
    * Returns a UUID of the provided peer id. Every HBase cluster instance has a persisted
    * associated UUID. If the replication is not performed to an actual HBase cluster (but
    * some other system), the UUID returned has to uniquely identify the connected target system.
    * @return a UUID or null if the peer cluster does not exist or is not connected.
    */
   UUID getPeerUUID();
 
   /**
    * Returns a WALEntryFilter to use for filtering out WALEntries from the log. Replication
    * infrastructure will call this filter before sending the edits to shipEdits().
    * @return a {@link WALEntryFilter} or null.
    */
   WALEntryFilter getWALEntryfilter();
 
   /**
    * A context for {@link ReplicationEndpoint#replicate(ReplicateContext)} method.
    */
   @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.REPLICATION)
   static class ReplicateContext {
     List<Entry> entries;
     int size;
     String walGroupId;
     @InterfaceAudience.Private
     public ReplicateContext() {
     }
 
     public ReplicateContext setEntries(List<Entry> entries) {
       this.entries = entries;
       return this;
     }
     public ReplicateContext setSize(int size) {
       this.size = size;
       return this;
     }
     public ReplicateContext setWalGroupId(String walGroupId) {
       this.walGroupId = walGroupId;
       return this;
     }
     public List<Entry> getEntries() {
       return entries;
     }
     public int getSize() {
       return size;
     }
     public String getWalGroupId(){
       return walGroupId;
     }
   }
 
   /**
    * Replicate the given set of entries (in the context) to the other cluster.
    * Can block until all the given entries are replicated. Upon this method is returned,
    * all entries that were passed in the context are assumed to be persisted in the
    * target cluster.
    * @param replicateContext a context where WAL entries and other
    * parameters can be obtained.
    */
   boolean replicate(ReplicateContext replicateContext);
 
 }