chrome/browser/web_resource/web_resource_service.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_WEB_RESOURCE_WEB_RESOURCE_SERVICE_H_
   6 #define CHROME_BROWSER_WEB_RESOURCE_WEB_RESOURCE_SERVICE_H_
   7
   8 #include <string>
   9
  10 #include "base/memory/ref_counted.h"
  11 #include "base/memory/scoped_ptr.h"
  12 #include "base/memory/weak_ptr.h"
  13 #include "chrome/browser/web_resource/json_asynchronous_unpacker.h"
  14 #include "chrome/browser/web_resource/resource_request_allowed_notifier.h"
  15 #include "net/url_request/url_fetcher_delegate.h"
  16 #include "url/gurl.h"
  17
  18 class PrefService;
  19
  20 namespace base {
  21 class DictionaryValue;
  22 }
  23
  24 namespace net {
  25 class URLFetcher;
  26 }
  27
  28 // A WebResourceService fetches JSON data from a web server and periodically
  29 // refreshes it.
  30 class WebResourceService
  31     : public net::URLFetcherDelegate,
  32       public JSONAsynchronousUnpackerDelegate,
  33       public base::RefCountedThreadSafe<WebResourceService>,
  34       public ResourceRequestAllowedNotifier::Observer {
  35  public:
  36   WebResourceService(PrefService* prefs,
  37                      const GURL& web_resource_server,
  38                      bool apply_locale_to_url_,
  39                      const char* last_update_time_pref_name,
  40                      int start_fetch_delay_ms,
  41                      int cache_update_delay_ms);
  42
  43   // Sleep until cache needs to be updated, but always for at least
  44   // |start_fetch_delay_ms| so we don't interfere with startup.
  45   // Then begin updating resources.
  46   void StartAfterDelay();
  47
  48   // JSONAsynchronousUnpackerDelegate methods.
  49   virtual void OnUnpackFinished(
  50       const base::DictionaryValue& parsed_json) OVERRIDE;
  51   virtual void OnUnpackError(const std::string& error_message) OVERRIDE;
  52
  53  protected:
  54   virtual ~WebResourceService();
  55
  56   // For the subclasses to process the result of a fetch.
  57   virtual void Unpack(const base::DictionaryValue& parsed_json) = 0;
  58
  59   PrefService* prefs_;
  60
  61  private:
  62   class UnpackerClient;
  63   friend class base::RefCountedThreadSafe<WebResourceService>;
  64
  65   // net::URLFetcherDelegate implementation:
  66   virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
  67
  68   // Schedules a fetch after |delay_ms| milliseconds.
  69   void ScheduleFetch(int64 delay_ms);
  70
  71   // Starts fetching data from the server.
  72   void StartFetch();
  73
  74   // Set |in_fetch_| to false, clean up temp directories (in the future).
  75   void EndFetch();
  76
  77   // Implements ResourceRequestAllowedNotifier::Observer.
  78   virtual void OnResourceRequestsAllowed() OVERRIDE;
  79
  80   // Helper class used to tell this service if it's allowed to make network
  81   // resource requests.
  82   ResourceRequestAllowedNotifier resource_request_allowed_notifier_;
  83
  84   // The tool that fetches the url data from the server.
  85   scoped_ptr<net::URLFetcher> url_fetcher_;
  86
  87   // The tool that parses and transforms the json data. Weak reference as it
  88   // deletes itself once the unpack is done.
  89   JSONAsynchronousUnpacker* json_unpacker_;
  90
  91   // True if we are currently fetching or unpacking data. If we are asked to
  92   // start a fetch when we are still fetching resource data, schedule another
  93   // one in |cache_update_delay_ms_| time, and silently exit.
  94   bool in_fetch_;
  95
  96   // URL that hosts the web resource.
  97   GURL web_resource_server_;
  98
  99   // Indicates whether we should append locale to the web resource server URL.
 100   bool apply_locale_to_url_;
 101
 102   // Pref name to store the last update's time.
 103   const char* last_update_time_pref_name_;
 104
 105   // Delay on first fetch so we don't interfere with startup.
 106   int start_fetch_delay_ms_;
 107
 108   // Delay between calls to update the web resource cache. This delay may be
 109   // different for different builds of Chrome.
 110   int cache_update_delay_ms_;
 111
 112   // So that we can delay our start so as not to affect start-up time; also,
 113   // so that we can schedule future cache updates.
 114   base::WeakPtrFactory<WebResourceService> weak_ptr_factory_;
 115
 116   DISALLOW_COPY_AND_ASSIGN(WebResourceService);
 117 };
 118
 119 #endif  // CHROME_BROWSER_WEB_RESOURCE_WEB_RESOURCE_SERVICE_H_