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.arrow.driver.jdbc;
  
  import java.sql.SQLException;
  import java.util.Map;
  import java.util.Properties;
  import java.util.Queue;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import javax.sql.ConnectionEvent;
  import javax.sql.ConnectionEventListener;
  import javax.sql.ConnectionPoolDataSource;
  import javax.sql.PooledConnection;
  import org.apache.arrow.driver.jdbc.utils.ArrowFlightConnectionConfigImpl;
  
  /** {@link ConnectionPoolDataSource} implementation for Arrow Flight JDBC Driver. */
  public class ArrowFlightJdbcConnectionPoolDataSource extends ArrowFlightJdbcDataSource
      implements ConnectionPoolDataSource, ConnectionEventListener, AutoCloseable {
    private final Map<Properties, Queue<ArrowFlightJdbcPooledConnection>> pool =
        new ConcurrentHashMap<>();
  
    /**
     * Instantiates a new DataSource.
     *
     * @param properties the properties
     * @param config the config.
     */
    protected ArrowFlightJdbcConnectionPoolDataSource(
        final Properties properties, final ArrowFlightConnectionConfigImpl config) {
      super(properties, config);
    }
  
    /**
     * Creates a new {@link ArrowFlightJdbcConnectionPoolDataSource}.
     *
     * @param properties the properties.
     * @return a new data source.
     */
    public static ArrowFlightJdbcConnectionPoolDataSource createNewDataSource(
        final Properties properties) {
      return new ArrowFlightJdbcConnectionPoolDataSource(
          properties, new ArrowFlightConnectionConfigImpl(properties));
    }
  
    @Override
    public PooledConnection getPooledConnection() throws SQLException {
      final ArrowFlightConnectionConfigImpl config = getConfig();
      return this.getPooledConnection(config.getUser(), config.getPassword());
    }
  
    @Override
    public PooledConnection getPooledConnection(final String username, final String password)
        throws SQLException {
      final Properties properties = getProperties(username, password);
      Queue<ArrowFlightJdbcPooledConnection> objectPool =
          pool.computeIfAbsent(properties, s -> new ConcurrentLinkedQueue<>());
      ArrowFlightJdbcPooledConnection pooledConnection = objectPool.poll();
      if (pooledConnection == null) {
        pooledConnection = createPooledConnection(new ArrowFlightConnectionConfigImpl(properties));
      } else {
        pooledConnection.reset();
      }
      return pooledConnection;
    }
  
    private ArrowFlightJdbcPooledConnection createPooledConnection(
        final ArrowFlightConnectionConfigImpl config) throws SQLException {
      ArrowFlightJdbcPooledConnection pooledConnection =
          new ArrowFlightJdbcPooledConnection(getConnection(config.getUser(), config.getPassword()));
      pooledConnection.addConnectionEventListener(this);
      return pooledConnection;
    }
  
    @Override
    public void connectionClosed(ConnectionEvent connectionEvent) {
      final ArrowFlightJdbcPooledConnection pooledConnection =
          (ArrowFlightJdbcPooledConnection) connectionEvent.getSource();
      Queue<ArrowFlightJdbcPooledConnection> connectionQueue =
          pool.get(pooledConnection.getProperties());
      connectionQueue.add(pooledConnection);
    }
  
    @Override
    public void connectionErrorOccurred(ConnectionEvent connectionEvent) {}
  
    @Override
    public void close() throws Exception {
      SQLException lastException = null;
      for (Queue<ArrowFlightJdbcPooledConnection> connections : this.pool.values()) {
        while (!connections.isEmpty()) {
          PooledConnection pooledConnection = connections.poll();
          try {
            pooledConnection.close();
          } catch (SQLException e) {
            lastException = e;
          }
        }
      }
  
      if (lastException != null) {
        throw lastException;
      }
    }
  }
  