content: /*
      Android Asynchronous Http Client
      Copyright (c) 2011 James Smith <james@loopj.com>
      https://github.com/android-async-http/android-async-http
  
      Licensed 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
  
          https://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.
  */
  
  /*
      Some of the retry logic in this class is heavily borrowed from the
      fantastic droid-fu project: https://github.com/donnfelker/droid-fu
  */
  
  package com.loopj.android.http;
  
  import android.os.SystemClock;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.net.SocketException;
  import java.net.UnknownHostException;
  import java.util.HashSet;
  
  import javax.net.ssl.SSLException;
  
  import cz.msebera.android.httpclient.NoHttpResponseException;
  import cz.msebera.android.httpclient.client.HttpRequestRetryHandler;
  import cz.msebera.android.httpclient.client.methods.HttpUriRequest;
  import cz.msebera.android.httpclient.protocol.ExecutionContext;
  import cz.msebera.android.httpclient.protocol.HttpContext;
  
  class RetryHandler implements HttpRequestRetryHandler {
      private final static HashSet<Class<?>> exceptionWhitelist = new HashSet<Class<?>>();
      private final static HashSet<Class<?>> exceptionBlacklist = new HashSet<Class<?>>();
  
      static {
          // Retry if the server dropped connection on us
          exceptionWhitelist.add(NoHttpResponseException.class);
          // retry-this, since it may happens as part of a Wi-Fi to 3G failover
          exceptionWhitelist.add(UnknownHostException.class);
          // retry-this, since it may happens as part of a Wi-Fi to 3G failover
          exceptionWhitelist.add(SocketException.class);
  
          // never retry timeouts
          exceptionBlacklist.add(InterruptedIOException.class);
          // never retry SSL handshake failures
          exceptionBlacklist.add(SSLException.class);
      }
  
      private final int maxRetries;
      private final int retrySleepTimeMS;
  
      public RetryHandler(int maxRetries, int retrySleepTimeMS) {
          this.maxRetries = maxRetries;
          this.retrySleepTimeMS = retrySleepTimeMS;
      }
  
      static void addClassToWhitelist(Class<?> cls) {
          exceptionWhitelist.add(cls);
      }
  
      static void addClassToBlacklist(Class<?> cls) {
          exceptionBlacklist.add(cls);
      }
  
      @Override
      public boolean retryRequest(IOException exception, int executionCount, HttpContext context) {
          boolean retry = true;
  
          Boolean b = (Boolean) context.getAttribute(ExecutionContext.HTTP_REQ_SENT);
          boolean sent = (b != null && b);
  
          if (executionCount > maxRetries) {
              // Do not retry if over max retry count
              retry = false;
          } else if (isInList(exceptionWhitelist, exception)) {
              // immediately retry if error is whitelisted
              retry = true;
          } else if (isInList(exceptionBlacklist, exception)) {
              // immediately cancel retry if the error is blacklisted
              retry = false;
          } else if (!sent) {
              // for most other errors, retry only if request hasn't been fully sent yet
              retry = true;
          }
  
          if (retry) {
              // resend all idempotent requests
              HttpUriRequest currentReq = (HttpUriRequest) context.getAttribute(ExecutionContext.HTTP_REQUEST);
              if (currentReq == null) {
                  return false;
              }
          }
  
          if (retry) {
              SystemClock.sleep(retrySleepTimeMS);
          } else {
              exception.printStackTrace();
          }
  
          return retry;
      }
  
      protected boolean isInList(HashSet<Class<?>> list, Throwable error) {
          for (Class<?> aList : list) {
              if (aList.isInstance(error)) {
                  return true;
              }
          }
          return false;
      }
  }
  