| /* |
| * 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.Collection; |
| import java.util.concurrent.atomic.AtomicIntegerFieldUpdater; |
| import java.util.concurrent.atomic.AtomicReferenceFieldUpdater; |
| |
| import io.netty.util.concurrent.Future; |
| import io.netty.util.concurrent.GenericFutureListener; |
| import io.netty.util.concurrent.GlobalEventExecutor; |
| import io.netty.util.concurrent.Promise; |
| |
| /** |
| * Netty's PromiseCombiner is not threadsafe, and we combine futures from multiple event executors. |
| * |
| * This class groups a number of Future into a single logical Future, by registering a listener to each that |
| * decrements a shared counter; if any of them fail, the FutureCombiner is completed with the first cause, |
| * but in all scenario only completes when all underlying future have completed (exceptionally or otherwise) |
| * |
| * This Future is always uncancellable. |
| * |
| * We extend FutureDelegate, and simply provide it an uncancellable Promise that will be completed by the listeners |
| * registered to the input futures. |
| */ |
| class FutureCombiner extends FutureDelegate<Void> |
| { |
| private volatile boolean failed; |
| |
| private volatile Throwable firstCause; |
| private static final AtomicReferenceFieldUpdater<FutureCombiner, Throwable> firstCauseUpdater = |
| AtomicReferenceFieldUpdater.newUpdater(FutureCombiner.class, Throwable.class, "firstCause"); |
| |
| private volatile int waitingOn; |
| private static final AtomicIntegerFieldUpdater<FutureCombiner> waitingOnUpdater = |
| AtomicIntegerFieldUpdater.newUpdater(FutureCombiner.class, "waitingOn"); |
| |
| FutureCombiner(Collection<? extends Future<?>> combine) |
| { |
| this(AsyncPromise.uncancellable(GlobalEventExecutor.INSTANCE), combine); |
| } |
| |
| private FutureCombiner(Promise<Void> combined, Collection<? extends Future<?>> combine) |
| { |
| super(combined); |
| |
| if (0 == (waitingOn = combine.size())) |
| combined.trySuccess(null); |
| |
| GenericFutureListener<? extends Future<Object>> listener = result -> |
| { |
| if (!result.isSuccess()) |
| { |
| firstCauseUpdater.compareAndSet(this, null, result.cause()); |
| failed = true; |
| } |
| |
| if (0 == waitingOnUpdater.decrementAndGet(this)) |
| { |
| if (failed) |
| combined.tryFailure(firstCause); |
| else |
| combined.trySuccess(null); |
| } |
| }; |
| |
| for (Future<?> future : combine) |
| future.addListener(listener); |
| } |
| } |