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;
  
  import io.netty.buffer.ByteBuf;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  import org.apache.bookkeeper.bookie.storage.EntryLogScanner;
  import org.apache.bookkeeper.bookie.storage.EntryLogger;
  import org.apache.bookkeeper.conf.ServerConfiguration;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * This is the basic entry log compactor to compact entry logs.
   * The compaction is done by scanning the old entry log file, copy the active ledgers to the
   * current entry logger and remove the old entry log when the scan is over.
   */
  public class EntryLogCompactor extends AbstractLogCompactor {
      private static final Logger LOG = LoggerFactory.getLogger(EntryLogCompactor.class);
  
      final CompactionScannerFactory scannerFactory = new CompactionScannerFactory();
      final EntryLogger entryLogger;
      final CompactableLedgerStorage ledgerStorage;
      private final int maxOutstandingRequests;
  
      public EntryLogCompactor(
              ServerConfiguration conf,
              EntryLogger entryLogger,
              CompactableLedgerStorage ledgerStorage,
              LogRemovalListener logRemover) {
          super(conf, logRemover);
          this.maxOutstandingRequests = conf.getCompactionMaxOutstandingRequests();
          this.entryLogger = entryLogger;
          this.ledgerStorage = ledgerStorage;
      }
  
      @Override
      public boolean compact(EntryLogMetadata entryLogMeta) {
          try {
              entryLogger.scanEntryLog(entryLogMeta.getEntryLogId(),
                  scannerFactory.newScanner(entryLogMeta));
              scannerFactory.flush();
              LOG.info("Removing entry log {} after compaction", entryLogMeta.getEntryLogId());
              logRemovalListener.removeEntryLog(entryLogMeta.getEntryLogId());
          } catch (LedgerDirsManager.NoWritableLedgerDirException nwlde) {
              LOG.warn("No writable ledger directory available, aborting compaction", nwlde);
              return false;
          } catch (IOException ioe) {
              // if compact entry log throws IOException, we don't want to remove that
              // entry log. however, if some entries from that log have been re-added
              // to the entry log, and the offset updated, it's ok to flush that
              LOG.error("Error compacting entry log. Log won't be deleted", ioe);
              return false;
          }
          return true;
      }
  
      /**
       * A scanner wrapper to check whether a ledger is alive in an entry log file.
       */
      class CompactionScannerFactory {
          List<EntryLocation> offsets = new ArrayList<EntryLocation>();
  
          EntryLogScanner newScanner(final EntryLogMetadata meta) {
  
              return new EntryLogScanner() {
                  @Override
                  public boolean accept(long ledgerId) {
                      return meta.containsLedger(ledgerId);
                  }
  
                  @Override
                  public void process(final long ledgerId, long offset, ByteBuf entry) throws IOException {
                      throttler.acquire(entry.readableBytes());
  
                      if (offsets.size() > maxOutstandingRequests) {
                          flush();
                      }
                      long entryId = entry.getLong(entry.readerIndex() + 8);
  
                      long newoffset = entryLogger.addEntry(ledgerId, entry);
                      offsets.add(new EntryLocation(ledgerId, entryId, newoffset));
  
                  }
              };
          }
  
          void flush() throws IOException {
              if (offsets.isEmpty()) {
                  if (LOG.isDebugEnabled()) {
                      LOG.debug("Skipping entry log flushing, as there are no offset!");
                  }
                  return;
              }
  
              // Before updating the index, we want to wait until all the compacted entries are flushed into the
              // entryLog
              try {
                  entryLogger.flush();
                  ledgerStorage.updateEntriesLocations(offsets);
                  ledgerStorage.flushEntriesLocationsIndex();
              } finally {
                  offsets.clear();
              }
          }
      }
  }
  