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 com.aliyun.odps.jdbc;
  
  import java.io.IOException;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import java.util.Map;
  
  import com.aliyun.odps.data.Record;
  import com.aliyun.odps.tunnel.InstanceTunnel.DownloadSession;
  import com.aliyun.odps.tunnel.TunnelException;
  import com.aliyun.odps.tunnel.io.TunnelRecordReader;
  
  public class OdpsForwardResultSet extends OdpsResultSet implements ResultSet {
  
    private DownloadSession sessionHandle;
    private TunnelRecordReader reader = null;
    private Record reuseRecord = null;
    private Object[] currentRow;
  
    private long fetchedRows = 0;
    private final long totalRows;
    private boolean isClosed = false;
  
    private long startTime;
  
    /**
     * For logging the time consumption for fetching 10000 rows
     */
    private static final long ACCUM_FETCHED_ROWS = 100000;
  
    /**
     * The maximum retry time we allow to tolerate the network problem
     */
    private static final int READER_REOPEN_TIME_MAX = 5;
  
    OdpsForwardResultSet(OdpsStatement stmt, OdpsResultSetMetaData meta, DownloadSession session)
        throws SQLException {
      this(stmt, meta, session, System.currentTimeMillis());
    }
  
  
    OdpsForwardResultSet(OdpsStatement stmt, OdpsResultSetMetaData meta, DownloadSession session,
                         long startTime)
        throws SQLException {
      super(stmt.getConnection(), stmt, meta);
      this.sessionHandle = session;
  
      int maxRows = stmt.resultSetMaxRows;
      long recordCount = sessionHandle.getRecordCount();
      // maxRows take effect only if it > 0
      if (maxRows > 0 && maxRows <= recordCount) {
        totalRows = maxRows;
      } else {
        totalRows = recordCount;
      }
      this.startTime = startTime;
    }
  
    protected void checkClosed() throws SQLException {
      if (isClosed) {
        throw new SQLException("The result set has been closed");
      }
    }
  
    @Override
    public int getRow() throws SQLException {
      checkClosed();
      return (int) fetchedRows;
    }
  
    @Override
    public int getType() throws SQLException {
      return ResultSet.TYPE_FORWARD_ONLY;
    }
  
    @Override
    public boolean isClosed() throws SQLException {
      return isClosed;
    }
  
    @Override
    public void close() throws SQLException {
      if (isClosed) {
        return;
      }
  
      isClosed = true;
      sessionHandle = null;
      try {
        if (reader != null) {
          reader.close();
        }
      } catch (IOException e) {
        throw new SQLException(e.getMessage(), e);
      }
      conn.log.info("the result set has been closed");
    }
  
    @Override
    public boolean next() throws SQLException {
      checkClosed();
  
      if (fetchedRows == totalRows) {
        return false;
      }
  
      // Tolerate the network problem by simply reopen the reader
      int retry = 0;
      while (true) {
        try {
          if (reader == null) {
            rebuildReader();
          }
          reuseRecord = reader.read(reuseRecord);
          if (reuseRecord == null) {
            // this means the end of stream
            long end = System.currentTimeMillis();
            conn.log.info(
                "It took me " + (end - startTime) + " ms to fetch all records, count:" + fetchedRows);
            return false;
          }
          int columns = reuseRecord.getColumnCount();
          currentRow = new Object[columns];
          for (int i = 0; i < columns; i++) {
            currentRow[i] = reuseRecord.get(i);
          }
  
          fetchedRows++;
          // Log the time consumption for fetching a bunch of rows
          if (fetchedRows % ACCUM_FETCHED_ROWS == 0 && fetchedRows != 0) {
            long current = System.currentTimeMillis();
            conn.log.info(
                String.format("fetched %d rows, %d KB, %.2f KB/s",
                              fetchedRows,
                              reader.getTotalBytes() / 1000,
                              (float) reader.getTotalBytes() / (current - startTime))
            );
          }
          return true;
        } catch (IOException e) {
          conn.log.info("read from a bad file, retry=" + retry);
          if (++retry == READER_REOPEN_TIME_MAX) {
            throw new SQLException("to much retries because: " + e.getMessage());
          }
          rebuildReader();
        }
      }
    }
  
    /**
     * Rebuild a reader to read the remainder of records from the cursor
     *
     * @throws SQLException
     */
    private void rebuildReader() throws SQLException {
      try {
        long count = totalRows - fetchedRows;
        reader = sessionHandle.openRecordReader(fetchedRows, count, true);
        conn.log.warn(String.format("open read record, start=%d, cnt=%d", fetchedRows, count));
      } catch (IOException e) {
        throw new SQLException(e.getMessage(), e);
      } catch (TunnelException e) {
        throw new SQLException(e.getMessage(), e);
      }
    }
  
    @Override
    protected Object[] rowAtCursor() throws SQLException {
      if (currentRow == null) {
        throw new SQLException("the row should be not-null, row=" + fetchedRows);
      }
  
      if (currentRow.length == 0) {
        throw new SQLException("the row should have more than 1 column , row=" + fetchedRows);
      }
  
      return currentRow;
    }
  }