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Apache HttpComponents Client
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/*
 * ====================================================================
 * 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 *
 */

package org.apache.http.impl.execchain;

import java.io.IOException;
import java.io.InterruptedIOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.Header;
import org.apache.http.HttpException;
import org.apache.http.annotation.Contract;
import org.apache.http.annotation.ThreadingBehavior;
import org.apache.http.client.ServiceUnavailableRetryStrategy;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpExecutionAware;
import org.apache.http.client.methods.HttpRequestWrapper;
import org.apache.http.client.protocol.HttpClientContext;
import org.apache.http.conn.routing.HttpRoute;
import org.apache.http.util.Args;

/**
 * Request executor in the request execution chain that is responsible
 * for making a decision whether a request that received a non-2xx response
 * from the target server should be re-executed.
 * 
 * Further responsibilities such as communication with the opposite
 * endpoint is delegated to the next executor in the request execution
 * chain.
 * 
 *
 * @since 4.3
 */
@Contract(threading = ThreadingBehavior.IMMUTABLE_CONDITIONAL)
public class ServiceUnavailableRetryExec implements ClientExecChain {

    private final Log log = LogFactory.getLog(getClass());

    private final ClientExecChain requestExecutor;
    private final ServiceUnavailableRetryStrategy retryStrategy;

    public ServiceUnavailableRetryExec(
            final ClientExecChain requestExecutor,
            final ServiceUnavailableRetryStrategy retryStrategy) {
        super();
        Args.notNull(requestExecutor, "HTTP request executor");
        Args.notNull(retryStrategy, "Retry strategy");
        this.requestExecutor = requestExecutor;
        this.retryStrategy = retryStrategy;
    }

    @Override
    public CloseableHttpResponse execute(
            final HttpRoute route,
            final HttpRequestWrapper request,
            final HttpClientContext context,
            final HttpExecutionAware execAware) throws IOException, HttpException {
        final Header[] origheaders = request.getAllHeaders();
        for (int c = 1;; c++) {
            final CloseableHttpResponse response = this.requestExecutor.execute(
                    route, request, context, execAware);
            try {
                if (this.retryStrategy.retryRequest(response, c, context)
                        && RequestEntityProxy.isRepeatable(request)) {
                    response.close();
                    final long nextInterval = this.retryStrategy.getRetryInterval();
                    if (nextInterval > 0) {
                        try {
                            this.log.trace("Wait for " + nextInterval);
                            Thread.sleep(nextInterval);
                        } catch (final InterruptedException e) {
                            Thread.currentThread().interrupt();
                            throw new InterruptedIOException();
                        }
                    }
                    request.setHeaders(origheaders);
                } else {
                    return response;
                }
            } catch (final RuntimeException ex) {
                response.close();
                throw ex;
            }
        }
    }

}