/**
    *
    * 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.client.example;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configured;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.client.BufferedMutator;
  import org.apache.hadoop.hbase.client.BufferedMutatorParams;
  import org.apache.hadoop.hbase.client.Connection;
  import org.apache.hadoop.hbase.client.ConnectionFactory;
  import org.apache.hadoop.hbase.client.Put;
  import org.apache.hadoop.hbase.client.RetriesExhaustedWithDetailsException;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.util.Tool;
  import org.apache.hadoop.util.ToolRunner;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.concurrent.Callable;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.Future;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.TimeoutException;
  
  /**
   * An example of using the {@link BufferedMutator} interface.
   */
  public class BufferedMutatorExample extends Configured implements Tool {
  
    private static final Log LOG = LogFactory.getLog(BufferedMutatorExample.class);
  
    private static final int POOL_SIZE = 10;
    private static final int TASK_COUNT = 100;
    private static final TableName TABLE = TableName.valueOf("foo");
    private static final byte[] FAMILY = Bytes.toBytes("f");
  
    @Override
    public int run(String[] args) throws InterruptedException, ExecutionException, TimeoutException {
  
      /** a callback invoked when an asynchronous write fails. */
      final BufferedMutator.ExceptionListener listener = new BufferedMutator.ExceptionListener() {
        @Override
        public void onException(RetriesExhaustedWithDetailsException e, BufferedMutator mutator) {
          for (int i = 0; i < e.getNumExceptions(); i++) {
            LOG.info("Failed to sent put " + e.getRow(i) + ".");
          }
        }
      };
      BufferedMutatorParams params = new BufferedMutatorParams(TABLE)
          .listener(listener);
  
      //
      // step 1: create a single Connection and a BufferedMutator, shared by all worker threads.
      //
      try (final Connection conn = ConnectionFactory.createConnection(getConf());
           final BufferedMutator mutator = conn.getBufferedMutator(params)) {
  
        /** worker pool that operates on BufferedTable instances */
        final ExecutorService workerPool = Executors.newFixedThreadPool(POOL_SIZE);
        List<Future<Void>> futures = new ArrayList<>(TASK_COUNT);
  
        for (int i = 0; i < TASK_COUNT; i++) {
          futures.add(workerPool.submit(new Callable<Void>() {
            @Override
            public Void call() throws Exception {
              //
              // step 2: each worker sends edits to the shared BufferedMutator instance. They all use
              // the same backing buffer, call-back "listener", and RPC executor pool.
              //
              Put p = new Put(Bytes.toBytes("someRow"));
              p.addColumn(FAMILY, Bytes.toBytes("someQualifier"), Bytes.toBytes("some value"));
              mutator.mutate(p);
              // do work... maybe you want to call mutator.flush() after many edits to ensure any of
              // this worker's edits are sent before exiting the Callable
              return null;
            }
          }));
        }
 
       //
       // step 3: clean up the worker pool, shut down.
       //
       for (Future<Void> f : futures) {
         f.get(5, TimeUnit.MINUTES);
       }
       workerPool.shutdown();
     } catch (IOException e) {
       // exception while creating/destroying Connection or BufferedMutator
       LOG.info("exception while creating/destroying Connection or BufferedMutator", e);
     } // BufferedMutator.close() ensures all work is flushed. Could be the custom listener is
       // invoked from here.
     return 0;
   }
 
   public static void main(String[] args) throws Exception {
     ToolRunner.run(new BufferedMutatorExample(), args);
   }
 }