tephra-hbase-compat-2.4/src/main/java/org/apache/tephra/hbase/coprocessor/FilteredInternalScanner.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.tephra.hbase.coprocessor;

import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.Filter.ReturnCode;
import org.apache.hadoop.hbase.regionserver.InternalScanner;
import org.apache.hadoop.hbase.regionserver.ScannerContext;
import org.apache.tephra.hbase.coprocessor.TransactionProcessor.IncludeInProgressFilter;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * Wrapper of InternalScanner to apply Transaction visibility filter for flush and compact
 */
public class FilteredInternalScanner implements InternalScanner {

  private final InternalScanner delegate;
  private final Filter filter;
  private List<Cell> outResult = new ArrayList<Cell>();

  public FilteredInternalScanner(InternalScanner internalScanner, IncludeInProgressFilter filter) {
    this.delegate = internalScanner;
    this.filter = filter;
  }

  @Override
  public void close() throws IOException {
    this.delegate.close();
  }

  @Override
  public boolean next(List<Cell> result, ScannerContext scannerContext) throws IOException {
    outResult.clear();
    if (filter.filterAllRemaining()) { return false; }
    while (true) {
      boolean next = delegate.next(outResult, scannerContext);
      for (Cell cell : outResult) {
        ReturnCode code = filter.filterKeyValue(cell);
        switch (code) {
        // included, so we are done
        case INCLUDE:
        case INCLUDE_AND_NEXT_COL:
          result.add(cell);
          break;
        case SKIP:
        case NEXT_COL:
        case NEXT_ROW:
        default:
          break;
        }
      }
      if (!next) {
        return next;
      }
      if (!result.isEmpty()) {
        return true;
      }

    }
  }

}