com.google.common.util.concurrent.CollectionFuture Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of wildfly-client-all

This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

There is a newer version: 34.0.0.Final

Show newest version

/*
 * Copyright (C) 2006 The Guava Authors
 *
 * 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.google.common.util.concurrent;

import static com.google.common.collect.Lists.newArrayListWithCapacity;
import static java.util.Collections.unmodifiableList;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.Lists;
import java.util.Collections;
import java.util.List;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/** Aggregate future that collects (stores) results of each future. */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
abstract class CollectionFuture
    extends AggregateFuture {
  /*
   * We access this field racily but safely. For discussion of a similar situation, see the comments
   * on the fields of TimeoutFuture. This field is slightly different from the fields discussed
   * there: cancel() never reads this field, only writes to it. That makes the race here completely
   * harmless, rather than just 99.99% harmless.
   */
  @CheckForNull private List<@Nullable Present> values;

  CollectionFuture(
      ImmutableCollection> futures,
      boolean allMustSucceed) {
    super(futures, allMustSucceed, true);

    List<@Nullable Present> values =
        futures.isEmpty()
            ? Collections.<@Nullable Present>emptyList()
            : Lists.<@Nullable Present>newArrayListWithCapacity(futures.size());

    // Populate the results list with null initially.
    for (int i = 0; i < futures.size(); ++i) {
      values.add(null);
    }

    this.values = values;
  }

  @Override
  final void collectOneValue(int index, @ParametricNullness V returnValue) {
    List<@Nullable Present> localValues = values;
    if (localValues != null) {
      localValues.set(index, new Present<>(returnValue));
    }
  }

  @Override
  final void handleAllCompleted() {
    List<@Nullable Present> localValues = values;
    if (localValues != null) {
      set(combine(localValues));
    }
  }

  @Override
  void releaseResources(ReleaseResourcesReason reason) {
    super.releaseResources(reason);
    this.values = null;
  }

  abstract C combine(List<@Nullable Present> values);

  /** Used for {@link Futures#allAsList} and {@link Futures#successfulAsList}. */
  static final class ListFuture
      extends CollectionFuture> {
    ListFuture(
        ImmutableCollection> futures,
        boolean allMustSucceed) {
      super(futures, allMustSucceed);
      init();
    }

    @Override
    public List<@Nullable V> combine(List<@Nullable Present> values) {
      List<@Nullable V> result = newArrayListWithCapacity(values.size());
      for (Present element : values) {
        result.add(element != null ? element.value : null);
      }
      return unmodifiableList(result);
    }
  }

  /** The result of a successful {@code Future}. */
  private static final class Present {
    @ParametricNullness final V value;

    Present(@ParametricNullness V value) {
      this.value = value;
    }
  }
}