components/dom_distiller/core/distilled_content_store.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 COMPONENTS_DOM_DISTILLER_CORE_DOM_DISTILLER_CONTENT_STORE_H_
   6 #define COMPONENTS_DOM_DISTILLER_CORE_DOM_DISTILLER_CONTENT_STORE_H_
   7
   8 #include <string>
   9
  10 #include "base/bind.h"
  11 #include "base/containers/hash_tables.h"
  12 #include "base/containers/mru_cache.h"
  13 #include "components/dom_distiller/core/article_entry.h"
  14 #include "components/dom_distiller/core/proto/distilled_article.pb.h"
  15
  16 namespace dom_distiller {
  17
  18 // The maximum number of items to keep in the cache before deleting some.
  19 const int kDefaultMaxNumCachedEntries = 32;
  20
  21 // This is a simple interface for saving and loading of distilled content for an
  22 // ArticleEntry.
  23 class DistilledContentStore {
  24  public:
  25   typedef base::Callback<
  26       void(bool /* success */, scoped_ptr<DistilledArticleProto>)> LoadCallback;
  27   typedef base::Callback<void(bool /* success */)> SaveCallback;
  28
  29   virtual void SaveContent(const ArticleEntry& entry,
  30                            const DistilledArticleProto& proto,
  31                            SaveCallback callback) = 0;
  32   virtual void LoadContent(const ArticleEntry& entry,
  33                            LoadCallback callback) = 0;
  34
  35   DistilledContentStore() {};
  36   virtual ~DistilledContentStore() {};
  37
  38  private:
  39   DISALLOW_COPY_AND_ASSIGN(DistilledContentStore);
  40 };
  41
  42 // This content store keeps up to |max_num_entries| of the last accessed items
  43 // in its cache. Both loading and saving content is counted as access.
  44 // Lookup can be done based on entry ID or URL.
  45 class InMemoryContentStore : public DistilledContentStore {
  46  public:
  47   explicit InMemoryContentStore(const int max_num_entries);
  48   virtual ~InMemoryContentStore();
  49
  50   // DistilledContentStore implementation
  51   virtual void SaveContent(const ArticleEntry& entry,
  52                            const DistilledArticleProto& proto,
  53                            SaveCallback callback) OVERRIDE;
  54   virtual void LoadContent(const ArticleEntry& entry,
  55                            LoadCallback callback) OVERRIDE;
  56
  57   // Synchronously saves the content.
  58   void InjectContent(const ArticleEntry& entry,
  59                      const DistilledArticleProto& proto);
  60
  61  private:
  62   // The CacheDeletor gets called when anything is removed from the ContentMap.
  63   class CacheDeletor {
  64    public:
  65     explicit CacheDeletor(InMemoryContentStore* store);
  66     ~CacheDeletor();
  67     void operator()(const DistilledArticleProto& proto);
  68
  69    private:
  70     InMemoryContentStore* store_;
  71   };
  72
  73   void AddUrlToIdMapping(const ArticleEntry& entry,
  74                          const DistilledArticleProto& proto);
  75
  76   void EraseUrlToIdMapping(const DistilledArticleProto& proto);
  77
  78   typedef base::MRUCacheBase<std::string,
  79                              DistilledArticleProto,
  80                              InMemoryContentStore::CacheDeletor> ContentMap;
  81   typedef base::hash_map<std::string, std::string> UrlMap;
  82
  83   ContentMap cache_;
  84   UrlMap url_to_id_;
  85 };
  86
  87 }  // dom_distiller
  88
  89 #endif  // COMPONENTS_DOM_DISTILLER_CORE_DOM_DISTILLER_CONTENT_CACHE_H_