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.ldb;
  
  import static org.apache.bookkeeper.bookie.BookKeeperServerStats.BOOKIE_SCOPE;
  import static org.apache.bookkeeper.bookie.BookKeeperServerStats.CATEGORY_SERVER;
  
  import java.util.function.Supplier;
  import lombok.Getter;
  import org.apache.bookkeeper.stats.Gauge;
  import org.apache.bookkeeper.stats.StatsLogger;
  import org.apache.bookkeeper.stats.annotations.StatsDoc;
  
  /**
   * A umbrella class for ledger metadata index stats.
   */
  @StatsDoc(
      name = BOOKIE_SCOPE,
      category = CATEGORY_SERVER,
      help = "Ledger metadata index stats"
  )
  @Getter
  class LedgerMetadataIndexStats {
  
      private static final String LEDGERS_COUNT = "ledgers-count";
  
      @StatsDoc(
          name = LEDGERS_COUNT,
          help = "Current number of ledgers"
      )
      private final Gauge<Long> ledgersCountGauge;
  
      LedgerMetadataIndexStats(StatsLogger statsLogger,
                               Supplier<Long> ledgersCountSupplier) {
          ledgersCountGauge = new Gauge<Long>() {
              @Override
              public Long getDefaultValue() {
                  return 0L;
              }
  
              @Override
              public Long getSample() {
                  return ledgersCountSupplier.get();
              }
          };
          statsLogger.registerGauge(LEDGERS_COUNT, ledgersCountGauge);
      }
  
  }
  