/*
 * 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.phoenix.iterate;

import java.sql.SQLException;
import java.util.List;
import org.apache.hadoop.hbase.HRegionLocation;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.phoenix.compile.QueryPlan;
import org.apache.phoenix.compile.StatementContext;

/**
 * Interface for a parallel scan grouper
 */
public interface ParallelScanGrouper {

  /**
   * Determines whether to create a new group of parallel scans.
   * @param plan                  current query plan
   * @param lastScan              the last scan processed
   * @param startKey              of the new scan
   * @param crossesRegionBoundary whether startKey in a different region than lastScan
   * @return true if we should create a new group of scans, starting with the scan whose start key
   *         we passed as startKey
   */
  boolean shouldStartNewScan(QueryPlan plan, Scan lastScan, byte[] startKey,
    boolean crossesRegionBoundary);

  List<HRegionLocation> getRegionBoundaries(StatementContext context, byte[] tableName)
    throws SQLException;

  /**
   * Retrieve table region locations that cover the startRegionBoundaryKey and
   * stopRegionBoundaryKey. The start key of the first region of the returned list must be less than
   * or equal to startRegionBoundaryKey. The end key of the last region of the returned list must be
   * greater than or equal to stopRegionBoundaryKey.
   * @param context                Statement Context.
   * @param tableName              Table name.
   * @param startRegionBoundaryKey Start region boundary key.
   * @param stopRegionBoundaryKey  Stop region boundary key.
   * @return The list of region locations that cover the startRegionBoundaryKey and
   *         stopRegionBoundaryKey key boundary.
   * @throws SQLException If fails to retrieve region locations.
   */
  List<HRegionLocation> getRegionBoundaries(StatementContext context, byte[] tableName,
    byte[] startRegionBoundaryKey, byte[] stopRegionBoundaryKey) throws SQLException;
}
