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

chrome/service/cloud_print/cloud_print_url_fetcher.h

Index: chrome/service/cloud_print/cloud_print_url_fetcher.h
===================================================================
--- chrome/service/cloud_print/cloud_print_url_fetcher.h	(revision 66188)
+++ chrome/service/cloud_print/cloud_print_url_fetcher.h	(working copy)
@@ -12,16 +12,14 @@
 
 class DictionaryValue;
 class GURL;
-class URLFetcherProtectEntry;
+class RequestThrottlerManager;
 class URLRequestStatus;
 
 // A wrapper around URLFetcher for CloudPrint. URLFetcher applies retry logic
 // only on HTTP response codes >= 500. In the cloud print case, we want to
 // retry on all network errors. In addition, we want to treat non-JSON responses
 // (for all CloudPrint APIs that expect JSON responses) as errors and they
-// must also be retried. Also URLFetcher uses the host name of the URL as the
-// key for applying the retry policy. In our case, we want to apply one global
-// policy for many requests (not necessarily scoped by hostname).
+// must also be retried.
 class CloudPrintURLFetcher
     : public base::RefCountedThreadSafe<CloudPrintURLFetcher>,
       public URLFetcher::Delegate {
@@ -79,11 +77,11 @@
   void StartGetRequest(const GURL& url,
                        Delegate* delegate,
                        const std::string& auth_token,
-                       const std::string& retry_policy);
+                       int max_retries);
   void StartPostRequest(const GURL& url,
                         Delegate* delegate,
                         const std::string& auth_token,
-                        const std::string& retry_policy,
+                        int max_retries,
                         const std::string& post_data_mime_type,
                         const std::string& post_data);
 
@@ -102,14 +100,14 @@
                           URLFetcher::RequestType request_type,
                           Delegate* delegate,
                           const std::string& auth_token,
-                          const std::string& retry_policy,
+                          int max_retries,
                           const std::string& post_data_mime_type,
                           const std::string& post_data);
   void StartRequestNow();
 
   scoped_ptr<URLFetcher> request_;
   Delegate* delegate_;
-  URLFetcherProtectEntry* protect_entry_;
+  RequestThrottlerManager* request_throttler_manager_;

[willchan no longer on Chromium, 2010/11/17 20:32:34]

Why are we caching the singleton into a pointer?

[yzshen, 2010/11/19 23:51:36]

I thought it was right since I read this in singleton.h: "Every call to get(),
operator->() and operator*() incurs some overhead... You may wish to cache the
result of get(); it will not change."

I've changed it.

   int num_retries_;
 };