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   1 /**
   2  * Copyright (c) 2010-2024 Contributors to the openHAB project
   3  *
   4  * See the NOTICE file(s) distributed with this work for additional
   5  * information.
   6  *
   7  * This program and the accompanying materials are made available under the
   8  * terms of the Eclipse Public License 2.0 which is available at
   9  * http://www.eclipse.org/legal/epl-2.0
  10  *
  11  * SPDX-License-Identifier: EPL-2.0
  12  */
  13 package org.openhab.binding.fronius.internal.api;
  14
  15 import java.io.IOException;
  16
  17 import org.eclipse.jdt.annotation.NonNullByDefault;
  18 import org.eclipse.jetty.http.HttpMethod;
  19 import org.openhab.core.io.net.http.HttpUtil;
  20 import org.slf4j.Logger;
  21 import org.slf4j.LoggerFactory;
  22
  23 /**
  24  *
  25  * A version of HttpUtil implementation that retries on failure.
  26  *
  27  * @author Jimmy Tanagra - Initial contribution
  28  *
  29  */
  30 @NonNullByDefault
  31 public class FroniusHttpUtil {
  32     private static final Logger logger = LoggerFactory.getLogger(FroniusHttpUtil.class);
  33
  34     /**
  35      * Issue a HTTP request and retry on failure.
  36      *
  37      * @param httpMethod the HTTP method to use
  38      * @param url the url to execute
  39      * @param timeout the socket timeout in milliseconds to wait for data
  40      * @return the response body
  41      * @throws FroniusCommunicationException when the request execution failed or interrupted
  42      */
  43     public static synchronized String executeUrl(HttpMethod httpMethod, String url, int timeout)
  44             throws FroniusCommunicationException {
  45         int attemptCount = 1;
  46         try {
  47             while (true) {
  48                 Throwable lastException = null;
  49                 String result = null;
  50                 try {
  51                     result = HttpUtil.executeUrl(httpMethod.asString(), url, timeout);
  52                 } catch (IOException e) {
  53                     // HttpUtil::executeUrl wraps InterruptedException into IOException.
  54                     // Unwrap and rethrow it so that we don't retry on InterruptedException
  55                     Throwable cause = e.getCause();
  56                     if (cause instanceof InterruptedException interruptException) {
  57                         throw interruptException;
  58                     }
  59                     lastException = e;
  60                 }
  61
  62                 if (result != null) {
  63                     if (attemptCount > 1) {
  64                         logger.debug("Attempt #{} successful {}", attemptCount, url);
  65                     }
  66                     return result;
  67                 }
  68
  69                 if (attemptCount >= 3) {
  70                     logger.debug("Failed connecting to {} after {} attempts.", url, attemptCount, lastException);
  71                     throw new FroniusCommunicationException("Unable to connect", lastException);
  72                 }
  73
  74                 logger.debug("HTTP error on attempt #{} {}", attemptCount, url);
  75                 Thread.sleep(500 * attemptCount);
  76                 attemptCount++;
  77             }
  78         } catch (InterruptedException e) {
  79             Thread.currentThread().interrupt();
  80             throw new FroniusCommunicationException("Interrupted", e);
  81         }
  82     }
  83 }