| /* |
| * 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.cassandra.io.sstable; |
| |
| import java.util.function.BiFunction; |
| import java.util.function.Function; |
| |
| import org.apache.cassandra.io.sstable.format.SSTableReader; |
| |
| public abstract class AbstractMetricsProviders<R extends SSTableReader> implements MetricsProviders |
| { |
| protected final <T extends Number> GaugeProvider<T> newGaugeProvider(String name, Function<Iterable<R>, T> combiner) |
| { |
| return new SimpleGaugeProvider<>(this::map, name, combiner); |
| } |
| |
| protected final <T extends Number> GaugeProvider<T> newGaugeProvider(String name, T neutralValue, Function<R, T> extractor, BiFunction<T, T, T> combiner) |
| { |
| return new SimpleGaugeProvider<>(this::map, name, readers -> { |
| T total = neutralValue; |
| for (R reader : readers) |
| total = combiner.apply(total, extractor.apply(reader)); |
| return total; |
| }); |
| } |
| |
| protected abstract R map(SSTableReader r); |
| } |