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 org.apache.bookkeeper.bookie.storage;
  
  import io.netty.buffer.ByteBuf;
  import java.io.IOException;
  
  /**
   * An entrylog to received compacted entries.
   * <p/>
   * The expected lifecycle for a compaction entry log is:
   * 1. Creation
   * 2. Mark compacted
   * 3. Make available
   * 4. Cleanup
   * <p/>
   * Abort can happen at during any step.
   */
  public interface CompactionEntryLog {
      /**
       * Add an entry to the log.
       * @param ledgerId the ledger the entry belong to
       * @param entry the payload of the entry
       * @return the position to which the entry was written
       */
      long addEntry(long ledgerId, ByteBuf entry) throws IOException;
  
      /**
       * Scan the entry log, reading out all contained entries.
       */
      void scan(EntryLogScanner scanner) throws IOException;
  
      /**
       * Flush any unwritten entries to physical storage.
       */
      void flush() throws IOException;
  
      /**
       * Abort the compaction log. This should delete any resources held
       * by this log.
       */
      void abort();
  
      /**
       * Mark the compaction log as compacted.
       * From this point, the heavy work of copying entries from one log
       * to another should be done. We don't want to repeat that work,
       * so this method should take steps to ensure that if the bookie crashes
       * we can resume the compaction from this point.
       */
      void markCompacted() throws IOException;
  
      /**
       * Make the log written by the compaction process available for reads.
       */
      void makeAvailable() throws IOException;
  
      /**
       * Clean up any temporary resources that were used by the compaction process.
       */
      void finalizeAndCleanup();
  
      /**
       * Get the log ID of the entrylog to which compacted entries are being written.
       */
      long getDstLogId();
  
      /**
       * Get the log ID of the entrylog which is being compacted.
       */
      long getSrcLogId();
  }
  