cassandra-trunk/src/java/org/apache/cassandra/utils/concurrent/Future.java
/*
 * 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.cassandra.utils.concurrent;

import java.util.concurrent.Executor;
import java.util.function.BiConsumer;
import java.util.function.Consumer;
import java.util.function.Function;

import com.google.common.util.concurrent.AsyncFunction;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.ListenableFuture; // checkstyle: permit this import

import io.netty.util.concurrent.GenericFutureListener;

import io.netty.util.internal.PlatformDependent;
import org.apache.cassandra.utils.Shared;

import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static org.apache.cassandra.utils.Shared.Recursive.INTERFACES;
import static org.apache.cassandra.utils.Shared.Scope.SIMULATION;

/**
 * A Future that integrates several different (but equivalent) APIs used within Cassandra into a single concept,
 * integrating also with our {@link Awaitable} abstraction, to overall improve coherency and clarity in the codebase.
 */
@Shared(scope = SIMULATION, ancestors = INTERFACES)
public interface Future<V> extends io.netty.util.concurrent.Future<V>, ListenableFuture<V>, Awaitable
{
    /**
     * Wait indefinitely for this future to complete, throwing any interrupt
     * @throws InterruptedException if interrupted
     */
    @Override
    Future<V> await() throws InterruptedException;

    /**
     * Wait indefinitely for this future to complete
     */
    @Override
    Future<V> awaitUninterruptibly();

    /**
     * Wait indefinitely for this promise to complete, throwing any interrupt as an UncheckedInterruptedException
     * @throws UncheckedInterruptedException if interrupted
     */
    @Override
    Future<V> awaitThrowUncheckedOnInterrupt();

    default void rethrowIfFailed()
    {
        Throwable cause = this.cause();
        if (cause != null)
        {
            PlatformDependent.throwException(cause);
        }
    }

    /**
     * waits for completion; in case of failure rethrows the original exception without a new wrapping exception
     * so may cause problems for reporting stack traces
     */
    @Override
    default Future<V> sync() throws InterruptedException
    {
        await();
        rethrowIfFailed();
        return this;
    }

    /**
     * waits for completion; in case of failure rethrows the original exception without a new wrapping exception
     * so may cause problems for reporting stack traces
     */
    @Override
    default Future<V> syncUninterruptibly()
    {
        awaitUninterruptibly();
        rethrowIfFailed();
        return this;
    }

    /**
     * waits for completion; in case of failure rethrows the original exception without a new wrapping exception
     * so may cause problems for reporting stack traces
     */
    default Future<V> syncThrowUncheckedOnInterrupt()
    {
        awaitThrowUncheckedOnInterrupt();
        rethrowIfFailed();
        return this;
    }

    @Deprecated
    @Override
    default boolean await(long l) throws InterruptedException
    {
        return await(l, MILLISECONDS);
    }

    @Deprecated
    @Override
    default boolean awaitUninterruptibly(long l)
    {
        return awaitUninterruptibly(l, MILLISECONDS);
    }

    /**
     * Support {@link com.google.common.util.concurrent.Futures#addCallback} natively
     */
    Future<V> addCallback(BiConsumer<? super V, Throwable> callback);

    /**
     * Support {@link com.google.common.util.concurrent.Futures#addCallback} natively
     */
    Future<V> addCallback(BiConsumer<? super V, Throwable> callback, Executor executor);

    /**
     * Support {@link com.google.common.util.concurrent.Futures#addCallback} natively
     */
    Future<V> addCallback(FutureCallback<? super V> callback);

    /**
     * Support {@link com.google.common.util.concurrent.Futures#addCallback} natively
     */
    Future<V> addCallback(FutureCallback<? super V> callback, Executor executor);

    /**
     * Support {@link com.google.common.util.concurrent.Futures#addCallback} natively
     */
    Future<V> addCallback(Consumer<? super V> onSuccess, Consumer<? super Throwable> onFailure);

    /**
     * Support {@link com.google.common.util.concurrent.Futures#addCallback} natively
     */
    Future<V> addCallback(Consumer<? super V> onSuccess, Consumer<? super Throwable> onFailure, Executor executor);

    /**
     * Support {@link com.google.common.util.concurrent.Futures#transform(ListenableFuture, com.google.common.base.Function, Executor)} natively
     */
    default <T> Future<T> map(Function<? super V, ? extends T> mapper)
    {
        return map(mapper, null);
    }

    /**
     * Support {@link com.google.common.util.concurrent.Futures#transform(ListenableFuture, com.google.common.base.Function, Executor)} natively
     */
    <T> Future<T> map(Function<? super V, ? extends T> mapper, Executor executor);

    /**
     * Support {@link com.google.common.util.concurrent.Futures#transformAsync(ListenableFuture, AsyncFunction, Executor)} natively
     */
    default <T> Future<T> flatMap(Function<? super V, ? extends Future<T>> flatMapper)
    {
        return flatMap(flatMapper, null);
    }

    /**
     * Support {@link com.google.common.util.concurrent.Futures#transformAsync(ListenableFuture, AsyncFunction, Executor)} natively
     */
    <T> Future<T> flatMap(Function<? super V, ? extends Future<T>> flatMapper, Executor executor);

    /**
     * Invoke {@code runnable} on completion, using {@code executor}.
     *
     * Tasks are submitted to their executors in the order they were added to this Future.
     */
    @Override
    void addListener(Runnable runnable, Executor executor);

    /**
     * Invoke {@code runnable} on completion. Depending on the implementation and its configuration, this
     * may be executed immediately by the notifying/completing thread, or asynchronously by an executor.
     * Tasks are executed, or submitted to the executor, in the order they were added to this Future.
     */
    void addListener(Runnable runnable);

    Executor notifyExecutor();

    @Override Future<V> addListener(GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>> genericFutureListener);
    @Override Future<V> addListeners(GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>>... genericFutureListeners);
    @Override Future<V> removeListener(GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>> genericFutureListener);
    @Override Future<V> removeListeners(GenericFutureListener<? extends io.netty.util.concurrent.Future<? super V>>... genericFutureListeners);
}

