chrome/browser/search/suggestions/suggestions_service.h

   1 // Copyright 2014 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_SEARCH_SUGGESTIONS_SUGGESTIONS_SERVICE_H_
   6 #define CHROME_BROWSER_SEARCH_SUGGESTIONS_SUGGESTIONS_SERVICE_H_
   7
   8 #include <vector>
   9
  10 #include "base/basictypes.h"
  11 #include "base/callback.h"
  12 #include "base/gtest_prod_util.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/time/time.h"
  15 #include "chrome/browser/search/suggestions/proto/suggestions.pb.h"
  16 #include "components/keyed_service/core/keyed_service.h"
  17 #include "net/url_request/url_fetcher_delegate.h"
  18 #include "url/gurl.h"
  19
  20 class Profile;
  21
  22 namespace suggestions {
  23
  24 extern const char kSuggestionsFieldTrialName[];
  25 extern const char kSuggestionsFieldTrialURLParam[];
  26 extern const char kSuggestionsFieldTrialStateParam[];
  27 extern const char kSuggestionsFieldTrialStateEnabled[];
  28
  29 // An interface to fetch server suggestions asynchronously.
  30 class SuggestionsService : public KeyedService, public net::URLFetcherDelegate {
  31  public:
  32   typedef base::Callback<void(const SuggestionsProfile&)> ResponseCallback;
  33
  34   explicit SuggestionsService(Profile* profile);
  35   virtual ~SuggestionsService();
  36
  37   // Whether this service is enabled.
  38   static bool IsEnabled();
  39
  40   // Request suggestions data, which will be passed to |callback|. Initiates a
  41   // fetch request unless a pending one exists. To prevent multiple requests,
  42   // we place all |callback|s in a queue and update them simultaneously when
  43   // fetch request completes.
  44   void FetchSuggestionsData(ResponseCallback callback);
  45
  46  private:
  47   FRIEND_TEST_ALL_PREFIXES(SuggestionsServiceTest, FetchSuggestionsData);
  48
  49   // net::URLFetcherDelegate implementation.
  50   // Called when fetch request completes. Parses the received suggestions data,
  51   // and dispatches them to callbacks stored in queue.
  52   virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
  53
  54   // KeyedService implementation.
  55   virtual void Shutdown() OVERRIDE;
  56
  57   // Contains the current suggestions fetch request. Will only have a value
  58   // while a request is pending, and will be reset by |OnURLFetchComplete|.
  59   scoped_ptr<net::URLFetcher> pending_request_;
  60
  61   // The start time of the previous suggestions request. This is used to measure
  62   // the latency of requests. Initially zero.
  63   base::TimeTicks last_request_started_time_;
  64
  65   // The URL to fetch suggestions data from.
  66   GURL suggestions_url_;
  67
  68   // Queue of callbacks. These are flushed when fetch request completes.
  69   std::vector<ResponseCallback> waiting_requestors_;
  70
  71   Profile* profile_;
  72
  73   DISALLOW_COPY_AND_ASSIGN(SuggestionsService);
  74 };
  75
  76 }  // namespace suggestions
  77
  78 #endif  // CHROME_BROWSER_SEARCH_SUGGESTIONS_SUGGESTIONS_SERVICE_H_