| /* |
| * 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.net; |
| |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.atomic.AtomicReferenceFieldUpdater; |
| |
| import org.apache.cassandra.locator.InetAddressAndPort; |
| |
| /** |
| * Callback that {@link org.apache.cassandra.locator.DynamicEndpointSnitch} listens to in order |
| * to update host scores. |
| * |
| * FIXME: rename/specialise, since only used by DES? |
| */ |
| public class LatencySubscribers |
| { |
| public interface Subscriber |
| { |
| void receiveTiming(InetAddressAndPort address, long latency, TimeUnit unit); |
| } |
| |
| private volatile Subscriber subscribers; |
| private static final AtomicReferenceFieldUpdater<LatencySubscribers, Subscriber> subscribersUpdater |
| = AtomicReferenceFieldUpdater.newUpdater(LatencySubscribers.class, Subscriber.class, "subscribers"); |
| |
| private static Subscriber merge(Subscriber a, Subscriber b) |
| { |
| if (a == null) return b; |
| if (b == null) return a; |
| return (address, latency, unit) -> { |
| a.receiveTiming(address, latency, unit); |
| b.receiveTiming(address, latency, unit); |
| }; |
| } |
| |
| public void subscribe(Subscriber subscriber) |
| { |
| subscribersUpdater.accumulateAndGet(this, subscriber, LatencySubscribers::merge); |
| } |
| |
| public void add(InetAddressAndPort address, long latency, TimeUnit unit) |
| { |
| Subscriber subscribers = this.subscribers; |
| if (subscribers != null) |
| subscribers.receiveTiming(address, latency, unit); |
| } |
| |
| /** |
| * Track latency information for the dynamic snitch |
| * |
| * @param cb the callback associated with this message -- this lets us know if it's a message type we're interested in |
| * @param address the host that replied to the message |
| */ |
| public void maybeAdd(RequestCallback cb, InetAddressAndPort address, long latency, TimeUnit unit) |
| { |
| if (cb.trackLatencyForSnitch()) |
| add(address, latency, unit); |
| } |
| } |