chrome/browser/ui/app_list/search/common/webservice_cache.h

   1 // Copyright 2013 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_UI_APP_LIST_SEARCH_COMMON_WEBSERVICE_CACHE_H_
   6 #define CHROME_BROWSER_UI_APP_LIST_SEARCH_COMMON_WEBSERVICE_CACHE_H_
   7
   8 #include <utility>
   9
  10 #include "base/basictypes.h"
  11 #include "base/containers/mru_cache.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/time/time.h"
  15 #include "components/keyed_service/core/keyed_service.h"
  16 #include "ui/app_list/search/dictionary_data_store.h"
  17
  18 namespace base {
  19 class DictionaryValue;
  20 }
  21
  22 namespace content {
  23 class BrowserContext;
  24 }
  25
  26 namespace app_list {
  27
  28 enum ResultStatus {
  29   FRESH = 0,
  30   STALE = 1
  31 };
  32
  33 // Pair of values, first indicating whether this is a fresh result or stale,
  34 // the second holding the actual value.
  35 typedef std::pair<ResultStatus, const base::DictionaryValue*> CacheResult;
  36
  37 // WebserviceCache manages a cache of search results which should be valid
  38 // during an input session. This will reduce unnecessary queries for typing
  39 // backspace or so on. This is not meant to hold cache entries across multiple
  40 // search sessions.
  41 class WebserviceCache : public KeyedService,
  42                         public base::SupportsWeakPtr<WebserviceCache> {
  43  public:
  44   enum QueryType {
  45     WEBSTORE = 0,
  46     PEOPLE = 1
  47   };
  48
  49   explicit WebserviceCache(content::BrowserContext* context);
  50   ~WebserviceCache() override;
  51
  52   // Checks the current cache and returns the value for the |query| if it's
  53   // valid. Otherwise an CacheResult object with the result field set to NULL.
  54   // A query consists of a query 'type' and the query itself. The two current
  55   // types of queries supported are webstore queries and people search queries.
  56   // The type silos the query into it's own separate domain, preventing any
  57   // mixing of the queries.
  58   const CacheResult Get(QueryType type, const std::string& query);
  59
  60   // Puts the new result to the query.
  61   void Put(QueryType type,
  62            const std::string& query,
  63            scoped_ptr<base::DictionaryValue> result);
  64
  65  private:
  66   struct Payload {
  67     Payload(const base::Time& time,
  68             const base::DictionaryValue* result)
  69         : time(time), result(result) {}
  70     Payload() {}
  71
  72     base::Time time;
  73     const base::DictionaryValue* result;
  74   };
  75
  76   class CacheDeletor {
  77    public:
  78     void operator()(const Payload& payload);
  79   };
  80   typedef base::MRUCacheBase<std::string, Payload, CacheDeletor> Cache;
  81
  82   // Callback for when the cache is loaded from the dictionary data store.
  83   void OnCacheLoaded(scoped_ptr<base::DictionaryValue>);
  84
  85   // Populates the payload parameter with the corresponding payload stored
  86   // in the given dictionary. If the dictionary is invalid for any reason,
  87   // this method will return false.
  88   bool PayloadFromDict(const base::DictionaryValue* dict,
  89                        Payload* payload);
  90
  91   // Returns a dictionary value for a given payload. The returned dictionary
  92   // will be owned by the data_store_ cached_dict, and freed on the destruction
  93   // of our dictionary datastore.
  94   base::DictionaryValue* DictFromPayload(const Payload& payload);
  95
  96   // Trims our MRU cache, making sure that any element that is removed is also
  97   // removed from the dictionary data store.
  98   void TrimCache();
  99
 100   // Prepends a type string to the given query and returns a new query string.
 101   std::string PrependType(QueryType type, const std::string& query);
 102
 103   Cache cache_;
 104   scoped_refptr<DictionaryDataStore> data_store_;
 105
 106   bool cache_loaded_;
 107
 108   DISALLOW_COPY_AND_ASSIGN(WebserviceCache);
 109 };
 110
 111 }  // namespace app_list
 112
 113 #endif  // CHROME_BROWSER_UI_APP_LIST_SEARCH_COMMON_WEBSERVICE_CACHE_H_