org.apache.hadoop.util.LambdaUtils Maven / Gradle / Ivy
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* 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.hadoop.util;
import java.util.concurrent.Callable;
import java.util.concurrent.CompletableFuture;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
/**
* Lambda-expression utilities be they generic or specific to
* Hadoop datatypes.
*/
@InterfaceAudience.Private
@InterfaceStability.Unstable
public final class LambdaUtils {
private LambdaUtils() {
}
/**
* Utility method to evaluate a callable and fill in the future
* with the result or the exception raised.
* Once this method returns, the future will have been evaluated to
* either a return value or an exception.
* @param type of future
* @param result future for the result.
* @param call callable to invoke.
* @return the future passed in
*/
public static CompletableFuture eval(
final CompletableFuture result,
final Callable call) {
try {
result.complete(call.call());
} catch (Throwable tx) {
result.completeExceptionally(tx);
}
return result;
}
}