samza-core/src/main/java/org/apache/samza/table/caching/SupplierGauge.java

/*
 * 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.samza.table.caching;

import java.util.function.Supplier;

import org.apache.samza.metrics.Gauge;

import com.google.common.base.Preconditions;


/**
 * Simple Gauge backed by an external supplier expression.
 * @param <T> data type of the gauge
 */
public class SupplierGauge<T> extends Gauge<T> {
  private Supplier<T> supplier;

  public SupplierGauge(String name, Supplier<T> supplier) {
    super(name, null);
    Preconditions.checkNotNull(supplier);
    this.supplier = supplier;
  }

  @Override
  public T getValue() {
    return supplier.get();
  }
}