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   ~InMemoryContentStore() override;
  49
  50   // DistilledContentStore implementation
  51   void SaveContent(const ArticleEntry& entry,
  52                    const DistilledArticleProto& proto,
  53                    SaveCallback callback) override;
  54   void LoadContent(const ArticleEntry& entry, LoadCallback callback) override;
  55
  56   // Synchronously saves the content.
  57   void InjectContent(const ArticleEntry& entry,
  58                      const DistilledArticleProto& proto);
  59
  60  private:
  61   // The CacheDeletor gets called when anything is removed from the ContentMap.
  62   class CacheDeletor {
  63    public:
  64     explicit CacheDeletor(InMemoryContentStore* store);
  65     ~CacheDeletor();
  66     void operator()(const DistilledArticleProto& proto);
  67
  68    private:
  69     InMemoryContentStore* store_;
  70   };
  71
  72   void AddUrlToIdMapping(const ArticleEntry& entry,
  73                          const DistilledArticleProto& proto);
  74
  75   void EraseUrlToIdMapping(const DistilledArticleProto& proto);
  76
  77   typedef base::MRUCacheBase<std::string,
  78                              DistilledArticleProto,
  79                              InMemoryContentStore::CacheDeletor> ContentMap;
  80   typedef base::hash_map<std::string, std::string> UrlMap;
  81
  82   ContentMap cache_;
  83   UrlMap url_to_id_;
  84 };
  85
  86 }  // dom_distiller
  87
  88 #endif  // COMPONENTS_DOM_DISTILLER_CORE_DOM_DISTILLER_CONTENT_CACHE_H_