org.apache.bookkeeper.mledger.util.Futures Maven / Gradle / Ivy
/**
* 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.bookkeeper.mledger.util;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.bookkeeper.mledger.AsyncCallbacks.CloseCallback;
import org.apache.bookkeeper.mledger.ManagedLedgerException;
/**
* Conveniences to use with {@link CompletableFuture}.
*/
public class Futures {
public static final CompletableFuture NULL_PROMISE = CompletableFuture.completedFuture(null);
/**
* Adapts a {@link CloseCallback} to a {@link CompletableFuture}.
*/
public static class CloseFuture extends CompletableFuture implements CloseCallback {
@Override
public void closeComplete(Object ctx) {
complete(null);
}
@Override
public void closeFailed(ManagedLedgerException exception, Object ctx) {
completeExceptionally(exception);
}
}
public static CompletableFuture waitForAll(List> futures) {
final CompletableFuture compositeFuture = new CompletableFuture<>();
final AtomicInteger count = new AtomicInteger(futures.size());
for (CompletableFuture future : futures) {
future.whenComplete((r, ex) -> {
if (ex != null) {
compositeFuture.completeExceptionally(ex);
} else if (count.decrementAndGet() == 0) {
// All the pending futures did complete
compositeFuture.complete(null);
}
});
}
if (futures.isEmpty()) {
compositeFuture.complete(null);
}
return compositeFuture;
}
}