processing/src/main/java/org/apache/druid/segment/AbstractIndex.java

/*
 * 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.druid.segment;

import org.apache.druid.java.util.common.Intervals;
import org.apache.druid.java.util.common.granularity.Granularities;
import org.apache.druid.segment.column.ColumnHolder;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

public abstract class AbstractIndex
{
  public abstract List<String> getColumnNames();

  public abstract StorageAdapter toStorageAdapter();

  @Override
  public String toString()
  {
    List<String> columnNames = new ArrayList<>();
    columnNames.add(ColumnHolder.TIME_COLUMN_NAME);
    columnNames.addAll(getColumnNames());

    return toStorageAdapter()
        .makeCursors(
            null,
            Intervals.ETERNITY,
            VirtualColumns.EMPTY,
            Granularities.ALL,
            false,
            null
        )
        .accumulate(new StringBuilder(), (sb, cursor) -> {
          ColumnSelectorFactory columnSelectorFactory = cursor.getColumnSelectorFactory();
          List<ColumnValueSelector> selectors =
              columnNames.stream().map(columnSelectorFactory::makeColumnValueSelector).collect(Collectors.toList());
          while (!cursor.isDone()) {
            sb.append('[');
            for (int i = 0; i < selectors.size(); i++) {
              sb.append(columnNames.get(i)).append('=');
              ColumnValueSelector selector = selectors.get(i);
              Object columnValue = selector.getObject();
              sb.append(columnValue);
              sb.append(", ");
            }
            sb.setLength(sb.length() - 2);
            sb.append("]\n");
            cursor.advance();
          }
          sb.append("\n");
          return sb;
        }).toString();
  }
}