/**
    *
    * 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.hadoop.hbase.regionserver;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.monitoring.MonitoredTask;
  import org.apache.hadoop.util.StringUtils;
  
  /**
   * Default implementation of StoreFlusher.
   */
  @InterfaceAudience.Private
  public class DefaultStoreFlusher extends StoreFlusher {
    private static final Log LOG = LogFactory.getLog(DefaultStoreFlusher.class);
    private final Object flushLock = new Object();
  
    public DefaultStoreFlusher(Configuration conf, Store store) {
      super(conf, store);
    }
  
    @Override
    public List<Path> flushSnapshot(MemStoreSnapshot snapshot, long cacheFlushId,
        MonitoredTask status) throws IOException {
      ArrayList<Path> result = new ArrayList<Path>();
      int cellsCount = snapshot.getCellsCount();
      if (cellsCount == 0) return result; // don't flush if there are no entries
  
      // Use a store scanner to find which rows to flush.
      long smallestReadPoint = store.getSmallestReadPoint();
      InternalScanner scanner = createScanner(snapshot.getScanner(), smallestReadPoint);
      if (scanner == null) {
        return result; // NULL scanner returned from coprocessor hooks means skip normal processing
      }
  
      StoreFile.Writer writer;
      try {
        // TODO:  We can fail in the below block before we complete adding this flush to
        //        list of store files.  Add cleanup of anything put on filesystem if we fail.
        synchronized (flushLock) {
          status.setStatus("Flushing " + store + ": creating writer");
          // Write the map out to the disk
          writer = store.createWriterInTmp(
              cellsCount, store.getFamily().getCompression(), false, true, true);
          writer.setTimeRangeTracker(snapshot.getTimeRangeTracker());
          IOException e = null;
          try {
            performFlush(scanner, writer, smallestReadPoint);
          } catch (IOException ioe) {
            e = ioe;
            // throw the exception out
            throw ioe;
          } finally {
            if (e != null) {
              writer.close();
            } else {
              finalizeWriter(writer, cacheFlushId, status);
            }
          }
        }
      } finally {
        scanner.close();
      }
      LOG.info("Flushed, sequenceid=" + cacheFlushId +", memsize="
          + StringUtils.humanReadableInt(snapshot.getSize()) +
          ", hasBloomFilter=" + writer.hasGeneralBloom() +
          ", into tmp file " + writer.getPath());
      result.add(writer.getPath());
      return result;
    }
  }