MapGauge.java

/**
 * Copyright 2017 StreamSets Inc.
 *
 * Licensed under 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 com.streamsets.datacollector.metrics;

import com.codahale.metrics.Gauge;

import java.util.Comparator;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentSkipListMap;

/**
 * Thread safe Gauge that holds map (Concurrent one).
 *
 * Optional it can also support sorted concurrent map.
 */
public class MapGauge implements Gauge<Map<String, Object>> {

  private final Map<String, Object> stateMap;

  public MapGauge(Comparator<String> comparator) {
    if(comparator == null) {
      stateMap = new ConcurrentHashMap<>();
    } else {
      stateMap = new ConcurrentSkipListMap<>(comparator);
    }
  }

  @Override
  public Map<String, Object> getValue() {
    return stateMap;
  }
}