/*
    *
    * 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.regionserver;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.TreeMap;
  import java.util.UUID;
  import java.util.concurrent.atomic.AtomicLong;
  
  import org.apache.commons.lang.StringUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.CellScanner;
  import org.apache.hadoop.hbase.CellUtil;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.HBaseConfiguration;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.Stoppable;
  import org.apache.hadoop.hbase.client.Connection;
  import org.apache.hadoop.hbase.client.ConnectionFactory;
  import org.apache.hadoop.hbase.client.Delete;
  import org.apache.hadoop.hbase.client.Mutation;
  import org.apache.hadoop.hbase.client.Put;
  import org.apache.hadoop.hbase.client.Row;
  import org.apache.hadoop.hbase.client.Table;
  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.WALEntry;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
  
  /**
   * <p>
   * This class is responsible for replicating the edits coming
   * from another cluster.
   * </p><p>
   * This replication process is currently waiting for the edits to be applied
   * before the method can return. This means that the replication of edits
   * is synchronized (after reading from WALs in ReplicationSource) and that a
   * single region server cannot receive edits from two sources at the same time
   * </p><p>
   * This class uses the native HBase client in order to replicate entries.
   * </p>
   *
   * TODO make this class more like ReplicationSource wrt log handling
   */
  @InterfaceAudience.Private
  public class ReplicationSink {
  
    private static final Log LOG = LogFactory.getLog(ReplicationSink.class);
    private final Configuration conf;
    // Volatile because of note in here -- look for double-checked locking:
    // http://www.oracle.com/technetwork/articles/javase/bloch-effective-08-qa-140880.html
    private volatile Connection sharedHtableCon;
    private final MetricsSink metrics;
    private final AtomicLong totalReplicatedEdits = new AtomicLong();
    private final Object sharedHtableConLock = new Object();
  
    /**
     * Create a sink for replication
     *
     * @param conf                conf object
     * @param stopper             boolean to tell this thread to stop
     * @throws IOException thrown when HDFS goes bad or bad file name
     */
    public ReplicationSink(Configuration conf, Stoppable stopper)
        throws IOException {
      this.conf = HBaseConfiguration.create(conf);
      decorateConf();
      this.metrics = new MetricsSink();
    }
  
    /**
     * decorate the Configuration object to make replication more receptive to delays:
     * lessen the timeout and numTries.
     */
   private void decorateConf() {
     this.conf.setInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER,
         this.conf.getInt("replication.sink.client.retries.number", 4));
     this.conf.setInt(HConstants.HBASE_CLIENT_OPERATION_TIMEOUT,
         this.conf.getInt("replication.sink.client.ops.timeout", 10000));
     String replicationCodec = this.conf.get(HConstants.REPLICATION_CODEC_CONF_KEY);
     if (StringUtils.isNotEmpty(replicationCodec)) {
       this.conf.set(HConstants.RPC_CODEC_CONF_KEY, replicationCodec);
     }
    }
 
   /**
    * Replicate this array of entries directly into the local cluster using the native client. Only
    * operates against raw protobuf type saving on a conversion from pb to pojo.
    * @param entries
    * @param cells
    * @throws IOException
    */
   public void replicateEntries(List<WALEntry> entries, final CellScanner cells) throws IOException {
     if (entries.isEmpty()) return;
     if (cells == null) throw new NullPointerException("TODO: Add handling of null CellScanner");
     // Very simple optimization where we batch sequences of rows going
     // to the same table.
     try {
       long totalReplicated = 0;
       // Map of table => list of Rows, grouped by cluster id, we only want to flushCommits once per
       // invocation of this method per table and cluster id.
       Map<TableName, Map<List<UUID>, List<Row>>> rowMap =
           new TreeMap<TableName, Map<List<UUID>, List<Row>>>();
       for (WALEntry entry : entries) {
         TableName table =
             TableName.valueOf(entry.getKey().getTableName().toByteArray());
         Cell previousCell = null;
         Mutation m = null;
         int count = entry.getAssociatedCellCount();
         for (int i = 0; i < count; i++) {
           // Throw index out of bounds if our cell count is off
           if (!cells.advance()) {
             throw new ArrayIndexOutOfBoundsException("Expected=" + count + ", index=" + i);
           }
           Cell cell = cells.current();
           if (isNewRowOrType(previousCell, cell)) {
             // Create new mutation
             m = CellUtil.isDelete(cell)?
               new Delete(cell.getRowArray(), cell.getRowOffset(), cell.getRowLength()):
               new Put(cell.getRowArray(), cell.getRowOffset(), cell.getRowLength());
             List<UUID> clusterIds = new ArrayList<UUID>();
             for(HBaseProtos.UUID clusterId : entry.getKey().getClusterIdsList()){
               clusterIds.add(toUUID(clusterId));
             }
             m.setClusterIds(clusterIds);
             addToHashMultiMap(rowMap, table, clusterIds, m);
           }
           if (CellUtil.isDelete(cell)) {
             ((Delete)m).addDeleteMarker(cell);
           } else {
             ((Put)m).add(cell);
           }
           previousCell = cell;
         }
         totalReplicated++;
       }
       for (Entry<TableName, Map<List<UUID>,List<Row>>> entry : rowMap.entrySet()) {
         batch(entry.getKey(), entry.getValue().values());
       }
       int size = entries.size();
       this.metrics.setAgeOfLastAppliedOp(entries.get(size - 1).getKey().getWriteTime());
       this.metrics.applyBatch(size);
       this.totalReplicatedEdits.addAndGet(totalReplicated);
     } catch (IOException ex) {
       LOG.error("Unable to accept edit because:", ex);
       throw ex;
     }
   }
 
   /**
    * @param previousCell
    * @param cell
    * @return True if we have crossed over onto a new row or type
    */
   private boolean isNewRowOrType(final Cell previousCell, final Cell cell) {
     return previousCell == null || previousCell.getTypeByte() != cell.getTypeByte() ||
         !CellUtil.matchingRow(previousCell, cell);
   }
 
   private java.util.UUID toUUID(final HBaseProtos.UUID uuid) {
     return new java.util.UUID(uuid.getMostSigBits(), uuid.getLeastSigBits());
   }
 
   /**
    * Simple helper to a map from key to (a list of) values
    * TODO: Make a general utility method
    * @param map
    * @param key1
    * @param key2
    * @param value
    * @return the list of values corresponding to key1 and key2
    */
   private <K1, K2, V> List<V> addToHashMultiMap(Map<K1, Map<K2,List<V>>> map, K1 key1, K2 key2, V value) {
     Map<K2,List<V>> innerMap = map.get(key1);
     if (innerMap == null) {
       innerMap = new HashMap<K2, List<V>>();
       map.put(key1, innerMap);
     }
     List<V> values = innerMap.get(key2);
     if (values == null) {
       values = new ArrayList<V>();
       innerMap.put(key2, values);
     }
     values.add(value);
     return values;
   }
 
   /**
    * stop the thread pool executor. It is called when the regionserver is stopped.
    */
   public void stopReplicationSinkServices() {
     try {
       if (this.sharedHtableCon != null) {
         synchronized (sharedHtableConLock) {
           if (this.sharedHtableCon != null) {
             this.sharedHtableCon.close();
             this.sharedHtableCon = null;
           }
         }
       }
     } catch (IOException e) {
       LOG.warn("IOException while closing the connection", e); // ignoring as we are closing.
     }
   }
 
 
   /**
    * Do the changes and handle the pool
    * @param tableName table to insert into
    * @param allRows list of actions
    * @throws IOException
    */
   protected void batch(TableName tableName, Collection<List<Row>> allRows) throws IOException {
     if (allRows.isEmpty()) {
       return;
     }
     Table table = null;
     try {
       // See https://en.wikipedia.org/wiki/Double-checked_locking
       Connection connection = this.sharedHtableCon;
       if (connection == null) {
         synchronized (sharedHtableConLock) {
           connection = this.sharedHtableCon;
           if (connection == null) {
             connection = this.sharedHtableCon = ConnectionFactory.createConnection(this.conf);
           }
         }
       }
       table = connection.getTable(tableName);
       for (List<Row> rows : allRows) {
         table.batch(rows);
       }
     } catch (InterruptedException ix) {
       throw (InterruptedIOException)new InterruptedIOException().initCause(ix);
     } finally {
       if (table != null) {
         table.close();
       }
     }
   }
 
   /**
    * Get a string representation of this sink's metrics
    * @return string with the total replicated edits count and the date
    * of the last edit that was applied
    */
   public String getStats() {
     return this.totalReplicatedEdits.get() == 0 ? "" : "Sink: " +
       "age in ms of last applied edit: " + this.metrics.refreshAgeOfLastAppliedOp() +
       ", total replicated edits: " + this.totalReplicatedEdits;
   }
 
   /**
    * Get replication Sink Metrics
    * @return MetricsSink
    */
   public MetricsSink getSinkMetrics() {
     return this.metrics;
   }
 }