Add caching for apps list search results.

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

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_UI_APP_LIST_SEARCH_COMMON_WEBSERVICE_CACHE_H_
 #define CHROME_BROWSER_UI_APP_LIST_SEARCH_COMMON_WEBSERVICE_CACHE_H_
 
 #include <utility>
 
 #include "base/basictypes.h"
 #include "base/containers/mru_cache.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
+#include "chrome/browser/ui/app_list/search/common/dictionary_data_store.h"
+#include "components/browser_context_keyed_service/browser_context_keyed_service.h"
 
 namespace base {
 class DictionaryValue;
 }
 
+namespace content {
+class BrowserContext;
+}
+
 namespace app_list {
 
+enum ResultStatus {
+  FRESH = 0,
+  STALE = 1
+};
+
+// Pair of values, first indicating whether this is a fresh result or stale,
+// the second holding the actual value.
+typedef std::pair<ResultStatus, const base::DictionaryValue*> CacheResult;
+
 // WebserviceCache manages a cache of search results which should be valid
 // during an input session. This will reduce unnecessary queries for typing
 // backspace or so on. This is not meant to hold cache entries across multiple
 // search sessions.
-class WebserviceCache {
+class WebserviceCache : public BrowserContextKeyedService,
+                        public base::SupportsWeakPtr<WebserviceCache> {
  public:
-  WebserviceCache();
-  ~WebserviceCache();
+  enum QueryType {
+    WEBSTORE = 0,
+    PEOPLE = 1
+  };
+
+  explicit WebserviceCache(content::BrowserContext* context);
+  virtual ~WebserviceCache();
 
   // Checks the current cache and returns the value for the |query| if it's
-  // valid. Otherwise returns NULL.
-  const base::DictionaryValue* Get(const std::string& query);
+  // valid. Otherwise an CacheResult object with the result field set to NULL.
+  // A query consists of a query 'type' and the query itself. The two current
+  // types of queries supported are webstore queries and people search queries.
+  // The type silos the query into it's own separate domain, preventing any
+  // mixing of the queries.
+  const CacheResult Get(QueryType type, const std::string& query);
 
   // Puts the new result to the query.
-  void Put(const std::string& query, scoped_ptr<base::DictionaryValue> result);
+  void Put(QueryType type,
+           const std::string& query,
+           scoped_ptr<base::DictionaryValue> result);
 
  private:
-  typedef std::pair<base::Time, base::DictionaryValue*> Payload;
+  struct Payload {
+    Payload(const base::Time& time,
+            const base::DictionaryValue* result)
+        : time(time), result(result) {}
+    Payload() {}
+
+    base::Time time;
+    const base::DictionaryValue* result;
+  };
+
   class CacheDeletor {
    public:
     void operator()(Payload& payload);
   };
   typedef base::MRUCacheBase<std::string, Payload, CacheDeletor> Cache;
 
+  // Callback for when the cache is loaded from the dictionary data store.
+  void OnCacheLoaded(scoped_ptr<base::DictionaryValue>);
+
+  // Populates the payload parameter with the corresponding payload stored
+  // in the given dictionary. If the dictionary is invalid for any reason,
+  // this method will return false.
+  bool PayloadFromDict(const base::DictionaryValue* dict,
+                       Payload* payload);
+
+  // Returns a dictionary value for a given payload. The returned dictionary
+  // will be owned by the data_store_ cached_dict, and freed on the destruction
+  // of our dictionary datastore.
+  base::DictionaryValue* DictFromPayload(const Payload& payload);
+
+  // Trims our MRU cache, making sure that any element that is removed is also
+  // removed from the dictionary data store.
+  void TrimCache();
+
+  // Prepends a type string to the given query and returns a new query string.
+  std::string PrependType(QueryType type, const std::string& query);
+
   Cache cache_;
+  scoped_refptr<DictionaryDataStore> data_store_;
+
+  bool cache_loaded_;
 
   DISALLOW_COPY_AND_ASSIGN(WebserviceCache);
 };
 
 }  // namespace app_list
 
 #endif  // CHROME_BROWSER_UI_APP_LIST_SEARCH_COMMON_WEBSERVICE_CACHE_H_