org.apache.aurora.GuavaUtils.java Source code

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/**
 * 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 org.apache.aurora;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.function.Function;
import java.util.stream.Collector;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMultimap;
import com.google.common.collect.ImmutableSet;
import com.google.common.util.concurrent.Service;
import com.google.common.util.concurrent.Service.State;
import com.google.common.util.concurrent.ServiceManager;
import com.google.inject.Inject;

import org.apache.aurora.common.application.Lifecycle;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static java.util.stream.Collector.Characteristics.UNORDERED;

/**
 * Utilities for working with Guava.
 */
public final class GuavaUtils {
    private GuavaUtils() {
        // Utility class.
    }

    public static class LifecycleShutdownListener extends ServiceManager.Listener {
        private final Lifecycle lifecycle;
        private static final Logger LOG = LoggerFactory.getLogger(LifecycleShutdownListener.class);

        @Inject
        LifecycleShutdownListener(Lifecycle lifecycle) {
            this.lifecycle = lifecycle;
        }

        @Override
        public void failure(Service service) {
            LOG.error("Service: " + service + " failed unexpectedly. Triggering shutdown.");
            lifecycle.shutdown();
        }
    }

    /**
     * Collector to create a Guava ImmutableSet.
     */
    public static <T> Collector<T, ?, ImmutableSet<T>> toImmutableSet() {
        return Collector.of(ImmutableSet.Builder<T>::new, ImmutableSet.Builder::add, (l, r) -> l.addAll(r.build()),
                ImmutableSet.Builder::build, UNORDERED);
    }

    /**
     * Collector to create a Guava ImmutableList.
     */
    public static <T> Collector<T, ?, ImmutableList<T>> toImmutableList() {
        return Collector.of(ImmutableList.Builder<T>::new, ImmutableList.Builder::add,
                (l, r) -> l.addAll(r.build()), ImmutableList.Builder::build);
    }

    /**
     * Collector to create a Guava ImmutableMap.
     */
    public static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
            Function<? super T, ? extends K> keyMapper, Function<? super T, ? extends V> valueMapper) {
        return Collector.of(ImmutableMap.Builder<K, V>::new,
                (r, t) -> r.put(keyMapper.apply(t), valueMapper.apply(t)), (l, r) -> l.putAll(r.build()),
                ImmutableMap.Builder::build, UNORDERED);
    }

    /**
     * Interface for mocking. The Guava ServiceManager class is final.
     */
    public interface ServiceManagerIface {
        ServiceManagerIface startAsync();

        void awaitHealthy();

        ServiceManagerIface stopAsync();

        void awaitStopped(long timeout, TimeUnit unit) throws TimeoutException;

        ImmutableMultimap<State, Service> servicesByState();
    }

    /**
     * Create a new {@link ServiceManagerIface} that wraps a {@link ServiceManager}.
     *
     * @param delegate Service manager to delegate to.
     * @return A wrapper.
     */
    public static ServiceManagerIface serviceManager(final ServiceManager delegate) {
        return new ServiceManagerIface() {
            @Override
            public ServiceManagerIface startAsync() {
                delegate.startAsync();
                return this;
            }

            @Override
            public void awaitHealthy() {
                delegate.awaitHealthy();
            }

            @Override
            public ServiceManagerIface stopAsync() {
                delegate.stopAsync();
                return this;
            }

            @Override
            public void awaitStopped(long timeout, TimeUnit unit) throws TimeoutException {
                delegate.awaitStopped(timeout, unit);
            }

            @Override
            public ImmutableMultimap<State, Service> servicesByState() {
                return delegate.servicesByState();
            }
        };
    }
}