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.directentrylogger;
  
  import java.io.File;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.concurrent.TimeUnit;
  import org.apache.bookkeeper.bookie.LedgerDirsManager;
  import org.apache.bookkeeper.bookie.storage.EntryLogIds;
  import org.apache.bookkeeper.slogger.Slogger;
  import org.apache.bookkeeper.util.LedgerDirUtil;
  import org.apache.commons.lang3.tuple.Pair;
  /**
   * EntryLogIdsImpl.
   */
  public class EntryLogIdsImpl implements EntryLogIds {
  
  
      private final LedgerDirsManager ledgerDirsManager;
      private final Slogger slog;
      private int nextId;
      private int maxId;
  
      public EntryLogIdsImpl(LedgerDirsManager ledgerDirsManager,
                             Slogger slog) throws IOException {
          this.ledgerDirsManager = ledgerDirsManager;
          this.slog = slog.ctx(EntryLogIdsImpl.class);
          findLargestGap();
      }
  
      @Override
      public int nextId() throws IOException {
          while (true) {
              synchronized (this) {
                  int current = nextId;
                  nextId++;
                  if (nextId == maxId) {
                      findLargestGap();
                  } else {
                      return current;
                  }
              }
          }
      }
  
      private void findLargestGap() throws IOException {
          long start = System.nanoTime();
          List<Integer> currentIds = new ArrayList<Integer>();
  
          for (File ledgerDir : ledgerDirsManager.getAllLedgerDirs()) {
              currentIds.addAll(LedgerDirUtil.logIdsInDirectory(ledgerDir));
              currentIds.addAll(LedgerDirUtil.compactedLogIdsInDirectory(ledgerDir));
          }
          Pair<Integer, Integer> gap = LedgerDirUtil.findLargestGap(currentIds);
          nextId = gap.getLeft();
          maxId = gap.getRight();
          slog.kv("dirs", ledgerDirsManager.getAllLedgerDirs())
              .kv("nextId", nextId)
              .kv("maxId", maxId)
              .kv("durationMs", TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start))
              .info(Events.ENTRYLOG_IDS_CANDIDATES_SELECTED);
      }
  }
  