httpclient5/src/main/java/org/apache/hc/client5/http/impl/sync/RetryExec.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.
 * ====================================================================
 *
 * 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
 * <http://www.apache.org/>.
 *
 */

package org.apache.hc.client5.http.impl.sync;

import java.io.IOException;

import org.apache.hc.client5.http.HttpRoute;
import org.apache.hc.client5.http.impl.ExecSupport;
import org.apache.hc.client5.http.protocol.HttpClientContext;
import org.apache.hc.client5.http.protocol.NonRepeatableRequestException;
import org.apache.hc.client5.http.sync.ExecChain;
import org.apache.hc.client5.http.sync.ExecChainHandler;
import org.apache.hc.client5.http.sync.HttpRequestRetryHandler;
import org.apache.hc.core5.annotation.Contract;
import org.apache.hc.core5.annotation.ThreadingBehavior;
import org.apache.hc.core5.http.ClassicHttpRequest;
import org.apache.hc.core5.http.ClassicHttpResponse;
import org.apache.hc.core5.http.HttpEntity;
import org.apache.hc.core5.http.HttpException;
import org.apache.hc.core5.http.NoHttpResponseException;
import org.apache.hc.core5.util.Args;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

/**
 * Request executor in the request execution chain that is responsible
 * for making a decision whether a request failed due to an I/O error
 * should be re-executed.
 * <p>
 * Further responsibilities such as communication with the opposite
 * endpoint is delegated to the next executor in the request execution
 * chain.
 * </p>
 *
 * @since 4.3
 */
@Contract(threading = ThreadingBehavior.IMMUTABLE_CONDITIONAL)
final class RetryExec implements ExecChainHandler {

    private final Logger log = LogManager.getLogger(getClass());

    private final HttpRequestRetryHandler retryHandler;

    public RetryExec(
            final HttpRequestRetryHandler retryHandler) {
        Args.notNull(retryHandler, "HTTP request retry handler");
        this.retryHandler = retryHandler;
    }

    @Override
    public ClassicHttpResponse execute(
            final ClassicHttpRequest request,
            final ExecChain.Scope scope,
            final ExecChain chain) throws IOException, HttpException {
        Args.notNull(request, "HTTP request");
        Args.notNull(scope, "Scope");
        final HttpRoute route = scope.route;
        final HttpClientContext context = scope.clientContext;
        ClassicHttpRequest currentRequest = request;
        for (int execCount = 1;; execCount++) {
            try {
                return chain.proceed(currentRequest, scope);
            } catch (final IOException ex) {
                if (scope.execRuntime.isExecutionAborted()) {
                    throw new RequestFailedException("Request aborted");
                }
                if (retryHandler.retryRequest(request, ex, execCount, context)) {
                    if (this.log.isInfoEnabled()) {
                        this.log.info("I/O exception ("+ ex.getClass().getName() +
                                ") caught when processing request to "
                                + route +
                                ": "
                                + ex.getMessage());
                    }
                    if (this.log.isDebugEnabled()) {
                        this.log.debug(ex.getMessage(), ex);
                    }
                    final HttpEntity entity = request.getEntity();
                    if (entity != null && !entity.isRepeatable()) {
                        this.log.debug("Cannot retry non-repeatable request");
                        throw new NonRepeatableRequestException("Cannot retry request " +
                                "with a non-repeatable request entity", ex);
                    }
                    currentRequest = ExecSupport.copy(scope.originalRequest);
                    if (this.log.isInfoEnabled()) {
                        this.log.info("Retrying request to " + route);
                    }
                } else {
                    if (ex instanceof NoHttpResponseException) {
                        final NoHttpResponseException updatedex = new NoHttpResponseException(
                                route.getTargetHost().toHostString() + " failed to respond");
                        updatedex.setStackTrace(ex.getStackTrace());
                        throw updatedex;
                    } else {
                        throw ex;
                    }
                }
            }
        }
    }

}