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.stats;
  
  /**
   * A simple interface that exposes just 2 useful methods. One to get the logger for an Op stat
   * and another to get the logger for a simple stat
   */
  public interface StatsLogger {
      /**
       * @param name
       *          Stats Name
       * @return Get the logger for an OpStat described by the <i>name</i>.
       */
      OpStatsLogger getOpStatsLogger(String name);
  
      /**
       * @param name
       *          Stats Name
       * @return Get the logger for an OpStat described by the <i>name</i> with extra
       * labels for the threadpool/threadname and thread no. Lone threads always
       * have 0 as their thread no.
       */
      OpStatsLogger getThreadScopedOpStatsLogger(String name);
  
      /**
       * @param name
       *          Stats Name
       * @return Get the logger for a simple stat described by the <i>name</i>
       */
      Counter getCounter(String name);
  
      /**
       * @param name
       *          Stats Name
       * @return Get the logger for a simple stat described by the <i>name</i> with extra
       * labels for the threadpool/threadname and thread no. Lone threads always
       * have 0 as their thread no.
       */
      Counter getThreadScopedCounter(String name);
  
      /**
       * Register given <i>gauge</i> as name <i>name</i>.
       *
       * @param name
       *          gauge name
       * @param gauge
       *          gauge function
       */
      <T extends Number> void registerGauge(String name, Gauge<T> gauge);
  
      /**
       * Unregister given <i>gauge</i> from name <i>name</i>.
       *
       * @param name
       *          name of the gauge
       * @param gauge
       *          gauge function
       */
      <T extends Number> void unregisterGauge(String name, Gauge<T> gauge);
  
      /**
       * Provide the stats logger under scope <i>name</i>.
       *
       * @param name
       *          scope name.
       * @return stats logger under scope <i>name</i>.
       */
      StatsLogger scope(String name);
  
      /**
       * Provide the stats logger with an attached label.
       *
       * @param labelName
       *          the name of the label.
       * @param labelValue
       *          the value of the label.
       *
       * @return stats logger under scope <i>name</i>.
       */
      default StatsLogger scopeLabel(String labelName, String labelValue) {
          // Provide default implementation for backward compatibility
          return scope(new StringBuilder()
                  .append(labelName)
                  .append('_')
                  .append(labelValue.replace('.', '_')
                          .replace('-', '_')
                          .replace(':', '_'))
                  .toString());
      }
  
      /**
       * Remove the given <i>statsLogger</i> for scope <i>name</i>.
       * It can be no-op if the underlying stats provider doesn't have the ability to remove scope.
       *
       * @param name name of the scope
       * @param statsLogger the stats logger of this scope.
       */
      void removeScope(String name, StatsLogger statsLogger);
  
  }
  