Implement exponential back-off mechanism and enforce it at the URLRequestHttpJob level.

chrome/common/net/url_fetcher.h

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // This file contains URLFetcher, a wrapper around URLRequest that handles
 // low-level details like thread safety, ref counting, and incremental buffer
 // reading.  This is useful for callers who simply want to get the data from a
 // URL and don't care about all the nitty-gritty details.
 //
 // NOTE(willchan): Only one "IO" thread is supported for URLFetcher.  This is a
 // temporary situation.  We will work on allowing support for multiple "io"
 // threads per process.
 
 #ifndef CHROME_COMMON_NET_URL_FETCHER_H_
 #define CHROME_COMMON_NET_URL_FETCHER_H_
 #pragma once
 
 #include <string>
+#include <vector>
 
 #include "base/message_loop.h"
 #include "base/ref_counted.h"
 #include "base/time.h"
 
 class GURL;
 typedef std::vector<std::string> ResponseCookies;
 class URLFetcher;
 class URLRequestContextGetter;
 class URLRequestStatus;
@@ skipping 116 matching lines @@
   // Set the URLRequestContext on the request.  Must be called before the
   // request is started.
   void set_request_context(
       URLRequestContextGetter* request_context_getter);
 
   // If |retry| is false, 5xx responses will be propagated to the observer,
   // if it is true URLFetcher will automatically re-execute the request,
   // after backoff_delay() elapses. URLFetcher has it set to true by default.
   void set_automatically_retry_on_5xx(bool retry);
 
+  int max_retries() const { return max_retries_; }
+
+  void set_max_retries(int max_retries) { max_retries_ = max_retries; }
+
   // Returns the back-off delay before the request will be retried,
   // when a 5xx response was received.
   base::TimeDelta backoff_delay() const { return backoff_delay_; }
 
   // Sets the back-off delay, allowing to mock 5xx requests in unit-tests.
 #if defined(UNIT_TEST)
   void set_backoff_delay(base::TimeDelta backoff_delay) {
     backoff_delay_ = backoff_delay;
   }
 #endif  // defined(UNIT_TEST)
 
   // Retrieve the response headers from the request.  Must only be called after
   // the OnURLFetchComplete callback has run.
   virtual net::HttpResponseHeaders* response_headers() const;
 
   // Start the request.  After this is called, you may not change any other
   // settings.
   virtual void Start();
 
   // Return the URL that this fetcher is processing.
   const GURL& url() const;
 
+  // Reports that the received content was malformed.
+  void ReceivedContentWasMalformed();
+
   // Cancels all existing URLRequests.  Will notify the URLFetcher::Delegates.
   // Note that any new URLFetchers created while this is running will not be
   // cancelled.  Typically, one would call this in the CleanUp() method of an IO
   // thread, so that no new URLRequests would be able to start on the IO thread
   // anyway.  This doesn't prevent new URLFetchers from trying to post to the IO
   // thread though, even though the task won't ever run.
   static void CancelAll();
 
  protected:
   // Returns the delegate.
   Delegate* delegate() const;
 
   // Used by tests.
   const std::string& upload_data() const;
 
  private:
   class Core;
 
   scoped_refptr<Core> core_;
 
   static Factory* factory_;
 
   // If |automatically_retry_on_5xx_| is false, 5xx responses will be
   // propagated to the observer, if it is true URLFetcher will automatically
   // re-execute the request, after the back-off delay has expired.
   // true by default.
   bool automatically_retry_on_5xx_;
   // Back-off time delay. 0 by default.
   base::TimeDelta backoff_delay_;
+  // Maximum retries allowed.
+  int max_retries_;
 
   static bool g_interception_enabled;
 
   DISALLOW_COPY_AND_ASSIGN(URLFetcher);
 };
 
 #endif  // CHROME_COMMON_NET_URL_FETCHER_H_