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/*
 * Copyright 2016 LINE Corporation
 *
 * LINE Corporation 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 com.linecorp.armeria.common;

import com.linecorp.armeria.common.stream.DeferredStreamMessage;

/**
 * An {@link HttpResponse} whose stream is published later by another {@link HttpResponse}. It is useful when
 * your {@link HttpResponse} will not be instantiated early. For example:
 * {@code
 * public class DelayService extends DecoratingService {
 *     public DelayService(Service delegate) {
 *         super(delegate);
 *     }
 *
 *     public HttpResponse serve(ServiceRequestContext ctx, HttpRequest req) {
 *         // Delay all requests by 3 seconds.
 *         DeferredHttpResponse res = new DeferredHttpResponse();
 *         ctx.eventLoop().schedule(() -> {
 *             res.delegate(delegate().serve(ctx, req));
 *         }, 3, TimeUnit.SECONDS);
 *         return res;
 *     }
 * }
 * }
 */
public class DeferredHttpResponse extends DeferredStreamMessage implements HttpResponse {
    /**
     * Sets the delegate {@link HttpResponse} which will publish the stream actually.
     *
     * @throws IllegalStateException if the delegate has been set already or
     *                               if {@link #close()} or {@link #close(Throwable)} was called already.
     */
    public void delegate(HttpResponse delegate) {
        super.delegate(delegate);
    }
}