com.spotify.apollo.concurrent.Util.java Source code

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Here is the source code for com.spotify.apollo.concurrent.Util.java

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/*
 * -\-\-
 * Spotify Apollo Extra
 * --
 * Copyright (C) 2013 - 2015 Spotify AB
 * --
 * Licensed 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 com.spotify.apollo.concurrent;

import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.SettableFuture;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionStage;

/**
 * Contains some utilities for working with futures and completion stages.
 */
public final class Util {
    private Util() {
        // prevent instantiation
    }

    public static <T> CompletionStage<T> asStage(ListenableFuture<T> future) {
        CompletableFuture<T> completableFuture = new CompletableFuture<>();

        Futures.addCallback(future, new FutureCallback<T>() {
            @Override
            public void onSuccess(T result) {
                completableFuture.complete(result);
            }

            @Override
            public void onFailure(Throwable t) {
                completableFuture.completeExceptionally(t);
            }
        });

        return completableFuture;
    }

    public static <T> ListenableFuture<T> asFuture(CompletionStage<T> stage) {
        SettableFuture<T> future = SettableFuture.create();

        stage.whenComplete((result, throwable) -> {
            if (throwable != null) {
                future.setException(throwable);
            } else {
                future.set(result);
            }
        });

        return future;
    }
}