package client;

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;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
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 util.HBaseHelper;


// cc BufferedMutatorExample Shows the use of the client side write buffer
public class BufferedMutatorExample {

  private static final Log LOG = LogFactory.getLog(
    BufferedMutatorExample.class);

  // vv BufferedMutatorExample
  private static final int POOL_SIZE = 10;
  private static final int TASK_COUNT = 100;
  private static final TableName TABLE = TableName.valueOf("testtable");
  private static final byte[] FAMILY = Bytes.toBytes("colfam1");

  public static void main(String[] args) throws Exception {
    Configuration configuration = HBaseConfiguration.create();
    // ^^ BufferedMutatorExample
    HBaseHelper helper = HBaseHelper.getHelper(configuration);
    helper.dropTable("testtable");
    helper.createTable("testtable", "colfam1");
    // vv BufferedMutatorExample
    BufferedMutator.ExceptionListener listener =
      new BufferedMutator.ExceptionListener() { // co BufferedMutatorExample-01-Listener Create a custom listener instance.
      @Override
      public void onException(RetriesExhaustedWithDetailsException e,
        BufferedMutator mutator) {
        for (int i = 0; i < e.getNumExceptions(); i++) { // co BufferedMutatorExample-02-OnException Handle callback in case of an exception.
          LOG.info("Failed to sent put: " + e.getRow(i)); // co BufferedMutatorExample-03-PrintRow Generically retrieve the mutation that failed, using the common superclass.
        }
      }
    };
    BufferedMutatorParams params =
      new BufferedMutatorParams(TABLE).listener(listener); // co BufferedMutatorExample-04-Params Create a parameter instance, set the table name and custom listener reference.

    try (
      Connection conn = ConnectionFactory.createConnection(configuration); // co BufferedMutatorExample-05-Allocate Allocate the shared resources using the Java 7 try-with-resource pattern.
      BufferedMutator mutator = conn.getBufferedMutator(params)
    ) {
      ExecutorService workerPool = Executors.newFixedThreadPool(POOL_SIZE); // co BufferedMutatorExample-06-Pool Create a worker pool to update the shared mutator in parallel.
      List<Future<Void>> futures = new ArrayList<>(TASK_COUNT);

      for (int i = 0; i < TASK_COUNT; i++) { // co BufferedMutatorExample-07-Threads Start all the workers up.
        futures.add(workerPool.submit(new Callable<Void>() {
          @Override
          public Void call() throws Exception {
            Put p = new Put(Bytes.toBytes("row1"));
            p.addColumn(FAMILY, Bytes.toBytes("qual1"), Bytes.toBytes("val1"));
            mutator.mutate(p); // co BufferedMutatorExample-08-Put Each worker uses the shared mutator instance, sharing the same backing buffer, callback listener, and RPC execuor pool.
            // [...]
            // Do work... Maybe call mutator.flush() after many edits to ensure
            // any of this worker's edits are sent before exiting the Callable
            return null;
          }
        }));
      }

      for (Future<Void> f : futures) {
        f.get(5, TimeUnit.MINUTES); // co BufferedMutatorExample-09-Shutdown Wait for workers and shut down the pool.
      }
      workerPool.shutdown();
    } catch (IOException e) { // co BufferedMutatorExample-10-ImplicitClose The try-with-resource construct ensures that first the mutator, and then the connection are closed. This could trigger exceptions and call the custom listener.
      LOG.info("Exception while creating or freeing resources", e);
    }
  }
}