001/*
002 * ====================================================================
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *   http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing,
014 * software distributed under the License is distributed on an
015 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
016 * KIND, either express or implied.  See the License for the
017 * specific language governing permissions and limitations
018 * under the License.
019 * ====================================================================
020 *
021 * This software consists of voluntary contributions made by many
022 * individuals on behalf of the Apache Software Foundation.  For more
023 * information on the Apache Software Foundation, please see
024 * <http://www.apache.org/>.
025 *
026 */
027package org.apache.http.client;
028
029import org.apache.http.HttpResponse;
030
031/**
032 * When managing a dynamic number of connections for a given route, this
033 * strategy assesses whether a given request execution outcome should
034 * result in a backoff signal or not, based on either examining the
035 * {@code Throwable} that resulted or by examining the resulting
036 * response (e.g. for its status code).
037 *
038 * @since 4.2
039 *
040 */
041public interface ConnectionBackoffStrategy {
042
043    /**
044     * Determines whether seeing the given {@code Throwable} as
045     * a result of request execution should result in a backoff
046     * signal.
047     * @param t the {@code Throwable} that happened
048     * @return {@code true} if a backoff signal should be
049     *   given
050     */
051    boolean shouldBackoff(Throwable t);
052
053    /**
054     * Determines whether receiving the given {@link HttpResponse} as
055     * a result of request execution should result in a backoff
056     * signal. Implementations MUST restrict themselves to examining
057     * the response header and MUST NOT consume any of the response
058     * body, if any.
059     * @param resp the {@code HttpResponse} that was received
060     * @return {@code true} if a backoff signal should be
061     *   given
062     */
063    boolean shouldBackoff(HttpResponse resp);
064}