components/web_resource/web_resource_service.h

   1 // Copyright 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 COMPONENTS_WEB_RESOURCE_WEB_RESOURCE_SERVICE_H_
   6 #define COMPONENTS_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 "components/web_resource/resource_request_allowed_notifier.h"
  14 #include "net/url_request/url_fetcher_delegate.h"
  15 #include "url/gurl.h"
  16
  17 class PrefService;
  18
  19 namespace base {
  20 class DictionaryValue;
  21 class Value;
  22 }
  23
  24 namespace net {
  25 class URLFetcher;
  26 class URLRequestContextGetter;
  27 }
  28
  29 namespace web_resource {
  30
  31 // A WebResourceService fetches JSON data from a web server and periodically
  32 // refreshes it.
  33 class WebResourceService
  34     : public net::URLFetcherDelegate,
  35       public ResourceRequestAllowedNotifier::Observer {
  36  public:
  37   // Creates a new WebResourceService.
  38   // If |application_locale| is not empty, it will be appended as a locale
  39   // parameter to the resource URL.
  40   WebResourceService(PrefService* prefs,
  41                      const GURL& web_resource_server,
  42                      const std::string& application_locale,  // May be empty
  43                      const char* last_update_time_pref_name,
  44                      int start_fetch_delay_ms,
  45                      int cache_update_delay_ms,
  46                      net::URLRequestContextGetter* request_context,
  47                      const char* disable_network_switch);
  48
  49   ~WebResourceService() override;
  50
  51   // Sleep until cache needs to be updated, but always for at least
  52   // |start_fetch_delay_ms| so we don't interfere with startup.
  53   // Then begin updating resources.
  54   void StartAfterDelay();
  55
  56  protected:
  57   // Callbacks for JSON parsing.
  58   using SuccessCallback = base::Callback<void(scoped_ptr<base::Value>)>;
  59   using ErrorCallback = base::Callback<void(const std::string&)>;
  60
  61   PrefService* prefs_;
  62
  63  private:
  64   // For the subclasses to process the result of a fetch.
  65   virtual void Unpack(const base::DictionaryValue& parsed_json) = 0;
  66
  67   // Parses a JSON string |data| and invokes |success_callback| or
  68   // |error_callback|.
  69   virtual void ParseJSON(const std::string& data,
  70                          const SuccessCallback& success_callback,
  71                          const ErrorCallback& error_callback) = 0;
  72
  73   // net::URLFetcherDelegate implementation:
  74   void OnURLFetchComplete(const net::URLFetcher* source) override;
  75
  76   // Schedules a fetch after |delay_ms| milliseconds.
  77   void ScheduleFetch(int64 delay_ms);
  78
  79   // Starts fetching data from the server.
  80   void StartFetch();
  81
  82   // Set |in_fetch_| to false, clean up temp directories (in the future).
  83   void EndFetch();
  84
  85   // Callbacks from the JSON parser.
  86   void OnUnpackFinished(scoped_ptr<base::Value> value);
  87   void OnUnpackError(const std::string& error_message);
  88
  89   // Implements ResourceRequestAllowedNotifier::Observer.
  90   void OnResourceRequestsAllowed() override;
  91
  92   // Helper class used to tell this service if it's allowed to make network
  93   // resource requests.
  94   ResourceRequestAllowedNotifier resource_request_allowed_notifier_;
  95
  96   // The tool that fetches the url data from the server.
  97   scoped_ptr<net::URLFetcher> url_fetcher_;
  98
  99   // True if we are currently fetching or unpacking data. If we are asked to
 100   // start a fetch when we are still fetching resource data, schedule another
 101   // one in |cache_update_delay_ms_| time, and silently exit.
 102   bool in_fetch_;
 103
 104   // URL that hosts the web resource.
 105   GURL web_resource_server_;
 106
 107   // Application locale, appended to the URL if not empty.
 108   std::string application_locale_;
 109
 110   // Pref name to store the last update's time.
 111   const char* last_update_time_pref_name_;
 112
 113   // Delay on first fetch so we don't interfere with startup.
 114   int start_fetch_delay_ms_;
 115
 116   // Delay between calls to update the web resource cache. This delay may be
 117   // different for different builds of Chrome.
 118   int cache_update_delay_ms_;
 119
 120   // The request context for the resource fetch.
 121   scoped_refptr<net::URLRequestContextGetter> request_context_;
 122
 123   // So that we can delay our start so as not to affect start-up time; also,
 124   // so that we can schedule future cache updates.
 125   base::WeakPtrFactory<WebResourceService> weak_ptr_factory_;
 126
 127   DISALLOW_COPY_AND_ASSIGN(WebResourceService);
 128 };
 129
 130 }  // namespace web_resource
 131
 132 #endif  // COMPONENTS_WEB_RESOURCE_WEB_RESOURCE_SERVICE_H_