
org.apache.cassandra.net.FutureCombiner Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of cassandra-all Show documentation
Show all versions of cassandra-all Show documentation
The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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
{
private volatile boolean failed;
private volatile Throwable firstCause;
private static final AtomicReferenceFieldUpdater firstCauseUpdater =
AtomicReferenceFieldUpdater.newUpdater(FutureCombiner.class, Throwable.class, "firstCause");
private volatile int waitingOn;
private static final AtomicIntegerFieldUpdater waitingOnUpdater =
AtomicIntegerFieldUpdater.newUpdater(FutureCombiner.class, "waitingOn");
FutureCombiner(Collection extends Future>> combine)
{
this(AsyncPromise.uncancellable(GlobalEventExecutor.INSTANCE), combine);
}
private FutureCombiner(Promise combined, Collection extends Future>> combine)
{
super(combined);
if (0 == (waitingOn = combine.size()))
combined.trySuccess(null);
GenericFutureListener extends Future
© 2015 - 2025 Weber Informatics LLC | Privacy Policy