/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* with the License.
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*
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* You can obtain a copy of the license at
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* trunk/opends/resource/legal-notices/OpenDS.LICENSE
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* or https://OpenDS.dev.java.net/OpenDS.LICENSE.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at
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* trunk/opends/resource/legal-notices/OpenDS.LICENSE. If applicable,
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* add the following below this CDDL HEADER, with the fields enclosed
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* by brackets "[]" replaced with your own identifying information:
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* Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*
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*
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* Copyright 2009 Sun Microsystems, Inc.
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*/
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package com.sun.opends.sdk.util;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.TimeoutException;
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import org.opends.sdk.ErrorResultException;
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import org.opends.sdk.FutureResult;
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import org.opends.sdk.ResultHandler;
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/**
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* An implementation of the {@code FutureResult} interface which can be
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* used to combine a sequence of two asynchronous operations into a
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* single future result. Implementations should override the methods
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* {@link #chainResult} and {@link #chainErrorResult} in order to define
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* the second asynchronous operation.
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*
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* @param <M>
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* The type of the inner result.
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* @param <N>
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* The type of the outer result.
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*/
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public abstract class RecursiveFutureResult<M, N> implements
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FutureResult<N>, ResultHandler<M>
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{
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private final class FutureResultImpl extends AbstractFutureResult<N>
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{
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private FutureResultImpl(ResultHandler<? super N> handler)
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{
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super(handler);
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}
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public int getRequestID()
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{
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return innerFuture.getRequestID();
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}
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/**
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* {@inheritDoc}
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*/
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protected ErrorResultException handleCancelRequest(
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boolean mayInterruptIfRunning)
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{
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innerFuture.cancel(mayInterruptIfRunning);
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if (outerFuture != null)
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{
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outerFuture.cancel(mayInterruptIfRunning);
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}
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return null;
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}
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}
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private final FutureResultImpl impl;
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private volatile FutureResult<M> innerFuture = null;
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// This does not need to be volatile since the inner future acts as a
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// memory barrier.
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private FutureResult<N> outerFuture = null;
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/**
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* Creates a new asynchronous result chain which will chain an outer
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* asynchronous request once the inner asynchronous request completes.
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*
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* @param handler
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* The outer result handler.
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*/
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protected RecursiveFutureResult(ResultHandler<? super N> handler)
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{
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this.impl = new FutureResultImpl(handler);
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}
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/**
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* {@inheritDoc}
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*/
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public final boolean cancel(boolean mayInterruptIfRunning)
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{
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return impl.cancel(mayInterruptIfRunning);
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}
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/**
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* {@inheritDoc}
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*/
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public final N get() throws ErrorResultException,
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InterruptedException
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{
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return impl.get();
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}
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/**
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* {@inheritDoc}
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*/
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public final N get(long timeout, TimeUnit unit)
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throws ErrorResultException, TimeoutException,
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InterruptedException
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{
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return impl.get(timeout, unit);
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}
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/**
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* {@inheritDoc}
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*/
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public final int getRequestID()
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{
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return impl.getRequestID();
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}
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/**
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* {@inheritDoc}
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*/
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public final void handleErrorResult(ErrorResultException error)
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{
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try
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{
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outerFuture = chainErrorResult(error, impl);
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}
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catch (final ErrorResultException e)
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{
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impl.handleErrorResult(e);
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}
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}
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/**
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* {@inheritDoc}
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*/
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public final void handleResult(M result)
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{
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try
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{
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outerFuture = chainResult(result, impl);
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}
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catch (final ErrorResultException e)
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{
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impl.handleErrorResult(e);
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}
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}
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/**
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* {@inheritDoc}
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*/
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public final boolean isCancelled()
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{
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return impl.isCancelled();
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}
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/**
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* {@inheritDoc}
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*/
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public final boolean isDone()
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{
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return impl.isDone();
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}
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/**
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* Sets the inner future for this result chain. This must be done
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* before this future is published.
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*
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* @param future
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* The inner future.
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*/
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public final void setFutureResult(FutureResult<M> future)
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{
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this.innerFuture = future;
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}
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/**
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* Invokes the outer request based on the error result of the inner
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* request and returns a future representing the result of the outer
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* request.
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* <p>
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* The default implementation is to terminate further processing by
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* re-throwing the inner error result.
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*
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* @param innerError
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* The error result of the inner request.
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* @param handler
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* The result handler to be used for the outer request.
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* @return A future representing the result of the outer request.
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* @throws ErrorResultException
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* If the outer request could not be invoked and processing
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* should terminate.
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*/
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protected FutureResult<N> chainErrorResult(
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ErrorResultException innerError, ResultHandler<? super N> handler)
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throws ErrorResultException
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{
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throw innerError;
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}
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/**
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* Invokes the outer request based on the result of the inner request
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* and returns a future representing the result of the outer request.
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*
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* @param innerResult
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* The result of the inner request.
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* @param handler
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* The result handler to be used for the outer request.
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* @return A future representing the result of the outer request.
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* @throws ErrorResultException
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* If the outer request could not be invoked and processing
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* should terminate.
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*/
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protected abstract FutureResult<N> chainResult(M innerResult,
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ResultHandler<? super N> handler) throws ErrorResultException;
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}
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