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.CompactionEntryLog;
  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 class is used for compaction. Compaction is done in several transactional phases.
   * Phase 1: Scan old entry log and compact entries to a new .compacting log file.
   * Phase 2: Flush .compacting log to disk and it becomes .compacted log file when this completes.
   * Phase 3: Flush ledger cache and .compacted file becomes .log file when this completes. Remove old
   * entry log file afterwards.
   */
  public class TransactionalEntryLogCompactor extends AbstractLogCompactor {
  
      private static final Logger LOG = LoggerFactory.getLogger(TransactionalEntryLogCompactor.class);
  
      final EntryLogger entryLogger;
      final CompactableLedgerStorage ledgerStorage;
      final List<EntryLocation> offsets = new ArrayList<>();
  
      // compaction log file suffix
      public static final String COMPACTING_SUFFIX = ".log.compacting";
      // flushed compaction log file suffix
      public static final String COMPACTED_SUFFIX = ".compacted";
  
      public TransactionalEntryLogCompactor(
              ServerConfiguration conf,
              EntryLogger entryLogger,
              CompactableLedgerStorage ledgerStorage,
              LogRemovalListener logRemover) {
          super(conf, logRemover);
          this.entryLogger = entryLogger;
          this.ledgerStorage = ledgerStorage;
      }
  
      /**
       * Delete all previously incomplete compacting logs and recover the index for compacted logs.
       */
      @Override
      public void cleanUpAndRecover() {
          // clean up compacting logs and recover index for already compacted logs
          for (CompactionEntryLog log : entryLogger.incompleteCompactionLogs()) {
              LOG.info("Found compacted log file {} has partially flushed index, recovering index.", log);
              CompactionPhase updateIndex = new UpdateIndexPhase(log, true);
              updateIndex.run();
          }
      }
  
      @Override
      public boolean compact(EntryLogMetadata metadata) {
          if (metadata != null) {
              LOG.info("Compacting entry log {} with usage {}.",
                  metadata.getEntryLogId(), metadata.getUsage());
              CompactionEntryLog compactionLog;
              try {
                  compactionLog = entryLogger.newCompactionLog(metadata.getEntryLogId());
              } catch (IOException ioe) {
                  LOG.error("Exception creating new compaction entry log", ioe);
                  return false;
              }
              CompactionPhase scanEntryLog = new ScanEntryLogPhase(metadata, compactionLog);
              if (!scanEntryLog.run()) {
                  LOG.info("Compaction for entry log {} end in ScanEntryLogPhase.", metadata.getEntryLogId());
                  return false;
              }
  
              CompactionPhase flushCompactionLog = new FlushCompactionLogPhase(compactionLog);
              if (!flushCompactionLog.run()) {
                  LOG.info("Compaction for entry log {} end in FlushCompactionLogPhase.", metadata.getEntryLogId());
                  return false;
              }
  
              CompactionPhase updateIndex = new UpdateIndexPhase(compactionLog);
              if (!updateIndex.run()) {
                  LOG.info("Compaction for entry log {} end in UpdateIndexPhase.", metadata.getEntryLogId());
                  return false;
              }
              LOG.info("Compacted entry log : {}.", metadata.getEntryLogId());
              return true;
          }
          return false;
      }
  
      /**
       * An abstract class that would be extended to be the actual transactional phases for compaction.
       */
      abstract static class CompactionPhase {
          private String phaseName = "";
  
          CompactionPhase(String phaseName) {
              this.phaseName = phaseName;
          }
  
          boolean run() {
              try {
                  start();
                  return complete();
              } catch (IOException e) {
                  LOG.error("Encounter exception in compaction phase {}. Abort current compaction.", phaseName, e);
                  abort();
              }
              return false;
          }
  
          abstract void start() throws IOException;
  
          abstract boolean complete() throws IOException;
  
          abstract void abort();
  
      }
  
      /**
       * Assume we're compacting entry log 1 to entry log 3.
       * The first phase is to scan entries in 1.log and copy them to compaction log file "3.log.compacting".
       * We'll try to allocate a new compaction log before scanning to make sure we have a log file to write.
       * If after scanning, there's no data written, it means there's no valid entries to be compacted,
       * so we can remove 1.log directly, clear the offsets and end the compaction.
       * Otherwise, we should move on to the next phase.
       *
       * <p>If anything failed in this phase, we should delete the compaction log and clean the offsets.
       */
      class ScanEntryLogPhase extends CompactionPhase {
          private final EntryLogMetadata metadata;
          private final CompactionEntryLog compactionLog;
  
          ScanEntryLogPhase(EntryLogMetadata metadata, CompactionEntryLog compactionLog) {
              super("ScanEntryLogPhase");
              this.metadata = metadata;
              this.compactionLog = compactionLog;
          }
  
          @Override
          void start() throws IOException {
              // scan entry log into compaction log and offset list
              entryLogger.scanEntryLog(metadata.getEntryLogId(), new EntryLogScanner() {
                  @Override
                  public boolean accept(long ledgerId) {
                      return metadata.containsLedger(ledgerId);
                  }
  
                  @Override
                  public void process(long ledgerId, long offset, ByteBuf entry) throws IOException {
                      throttler.acquire(entry.readableBytes());
                      synchronized (TransactionalEntryLogCompactor.this) {
                          long lid = entry.getLong(entry.readerIndex());
                          long entryId = entry.getLong(entry.readerIndex() + 8);
                          if (lid != ledgerId || entryId < -1) {
                              LOG.warn("Scanning expected ledgerId {}, but found invalid entry "
                                      + "with ledgerId {} entryId {} at offset {}",
                                      ledgerId, lid, entryId, offset);
                              throw new IOException("Invalid entry found @ offset " + offset);
                          }
                          long newOffset = compactionLog.addEntry(ledgerId, entry);
                          offsets.add(new EntryLocation(ledgerId, entryId, newOffset));
  
                          if (LOG.isDebugEnabled()) {
                              LOG.debug("Compact add entry : lid = {}, eid = {}, offset = {}",
                                      ledgerId, entryId, newOffset);
                          }
                      }
                  }
              });
          }
  
          @Override
          boolean complete() {
              if (offsets.isEmpty()) {
                  // no valid entries is compacted, delete entry log file
                  LOG.info("No valid entry is found in entry log after scan, removing entry log now.");
                  logRemovalListener.removeEntryLog(metadata.getEntryLogId());
                  compactionLog.abort();
                  compactingLogWriteDone();
                  return false;
              }
              return true;
          }
  
          @Override
          void abort() {
              offsets.clear();
              // since we haven't flushed yet, we only need to delete the unflushed compaction file.
              compactionLog.abort();
              compactingLogWriteDone();
          }
      }
  
      private void compactingLogWriteDone() {
          if (entryLogger instanceof DefaultEntryLogger) {
              ((DefaultEntryLogger) entryLogger).clearCompactingLogId();
          }
      }
  
      /**
       * Assume we're compacting log 1 to log 3.
       * This phase is to flush the compaction log.
       * When this phase starts, there should be a compaction log file like "3.log.compacting"
       * When compaction log is flushed, in order to indicate this phase is completed,
       * a hardlink file "3.log.1.compacted" should be created, and "3.log.compacting" should be deleted.
       */
      class FlushCompactionLogPhase extends CompactionPhase {
          final CompactionEntryLog compactionLog;
  
          FlushCompactionLogPhase(CompactionEntryLog compactionLog) {
              super("FlushCompactionLogPhase");
              this.compactionLog = compactionLog;
          }
  
          @Override
          void start() throws IOException {
              // flush the current compaction log.
              compactionLog.flush();
          }
  
          @Override
          boolean complete() throws IOException {
              try {
                  compactionLog.markCompacted();
                  return true;
              } catch (IOException ioe) {
                  LOG.warn("Error marking compaction as done", ioe);
                  return false;
              } finally {
                  compactingLogWriteDone();
              }
          }
  
          @Override
          void abort() {
              offsets.clear();
              // remove compaction log file and its hardlink
              compactionLog.abort();
              compactingLogWriteDone();
          }
      }
  
      /**
       * Assume we're compacting log 1 to log 3.
       * This phase is to update the entry locations and flush the index.
       * When the phase start, there should be a compacted file like "3.log.1.compacted",
       * where 3 is the new compaction logId and 1 is the old entry logId.
       * After the index the flushed successfully, a hardlink "3.log" file should be created,
       * and 3.log.1.compacted file should be deleted to indicate the phase is succeed.
       *
       * <p>This phase can also used to recover partially flushed index when we pass isInRecovery=true
       */
      class UpdateIndexPhase extends CompactionPhase {
          final CompactionEntryLog compactionLog;
          private final boolean isInRecovery;
  
          public UpdateIndexPhase(CompactionEntryLog compactionLog) {
              this(compactionLog, false);
          }
  
          public UpdateIndexPhase(CompactionEntryLog compactionLog, boolean isInRecovery) {
              super("UpdateIndexPhase");
              this.compactionLog = compactionLog;
              this.isInRecovery = isInRecovery;
          }
  
          @Override
          void start() throws IOException {
              compactionLog.makeAvailable();
              if (isInRecovery) {
                  recoverEntryLocations(compactionLog);
              }
              if (!offsets.isEmpty()) {
                  // update entry locations and flush index
                  ledgerStorage.updateEntriesLocations(offsets);
                  ledgerStorage.flushEntriesLocationsIndex();
              }
          }
  
          @Override
          boolean complete() {
              // When index is flushed, and entry log is removed,
              // delete the ".compacted" file to indicate this phase is completed.
              offsets.clear();
              compactionLog.finalizeAndCleanup();
              logRemovalListener.removeEntryLog(compactionLog.getSrcLogId());
              return true;
          }
  
          @Override
          void abort() {
              offsets.clear();
          }
  
          /**
           * Scan entry log to recover entry locations.
           */
          private void recoverEntryLocations(CompactionEntryLog compactionLog) throws IOException {
              compactionLog.scan(new EntryLogScanner() {
                  @Override
                  public boolean accept(long ledgerId) {
                      return true;
                  }
  
                  @Override
                  public void process(long ledgerId, long offset, ByteBuf entry) throws IOException {
                      long lid = entry.getLong(entry.readerIndex());
                      long entryId = entry.getLong(entry.readerIndex() + 8);
                      if (lid != ledgerId || entryId < -1) {
                          LOG.warn("Scanning expected ledgerId {}, but found invalid entry "
                                  + "with ledgerId {} entryId {} at offset {}",
                                  ledgerId, lid, entryId, offset);
                          throw new IOException("Invalid entry found @ offset " + offset);
                      }
                      long location = (compactionLog.getDstLogId() << 32L) | (offset + 4);
                      offsets.add(new EntryLocation(lid, entryId, location));
                  }
              });
              LOG.info("Recovered {} entry locations from compacted log {}", offsets.size(), compactionLog.getDstLogId());
          }
      }
  }
  