Asynchronous initialization in Simple Index.

net/disk_cache/simple/simple_index.h

 // Copyright (c) 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 NET_DISK_CACHE_SIMPLE_SIMPLE_INDEX_H_
 #define NET_DISK_CACHE_SIMPLE_SIMPLE_INDEX_H_
 
 #include <map>
 #include <string>
 
@@ skipping 11 matching lines @@
 }
 
 namespace disk_cache {
 
 // This class is not Thread-safe.
 class SimpleIndex
     : public base::SupportsWeakPtr<SimpleIndex> {
  public:
   SimpleIndex(
       const scoped_refptr<base::TaskRunner>& cache_thread,
+      const scoped_refptr<base::TaskRunner>& io_thread,
       const base::FilePath& path);
 
   virtual ~SimpleIndex();
 
-  // Should be called on CacheThread.
-  bool Initialize();
+  void Initialize();
 
   void Insert(const std::string& key);
   void Remove(const std::string& key);
 
   bool Has(const std::string& key) const;
 
   // Update the last used time of the entry with the given key and return true
   // iff the entry exist in the index.
   bool UseIfExists(const std::string& key);
 
-  void Cleanup();
+  void WriteToDisk();
 
   // Update the size (in bytes) of an entry, in the metadata stored in the
   // index. This should be the total disk-file size including all streams of the
   // entry.
   bool UpdateEntrySize(const std::string& key, uint64 entry_size);
 
  private:
   // TODO(felipeg): This way we are storing the hash_key string twice (as the
   // hash_map::key and as a member of EntryMetadata. We could save space if we
   // redefine the hash_map::operators and make the hash_map::key be part of the
   // EntryMetadata itself.
   typedef base::hash_map<std::string, SimpleIndexFile::EntryMetadata> EntrySet;
 
-  void InsertInternal(const SimpleIndexFile::EntryMetadata& entry_metadata);
+  typedef base::Callback<void(scoped_ptr<EntrySet>)> MergeCallback;
+
+  static void InsertInternal(
+      EntrySet* entry_set,
+      const SimpleIndexFile::EntryMetadata& entry_metadata);
+
+  // Load index from disk. If it is corrupted, call RestoreFromDisk().
+  static void LoadFromDisk(
+      const base::FilePath& index_filename,
+      const scoped_refptr<base::TaskRunner>& io_thread,
+      const MergeCallback& merge_callback);
 
   // Enumerates all entries' files on disk and regenerates the index.
-  bool RestoreFromDisk();
+  static void RestoreFromDisk(
+      const base::FilePath& index_filename,
+      const scoped_refptr<base::TaskRunner>& io_thread,
+      const MergeCallback& merge_callback);
+
+  // Must run on IO Thread.
+  void MergeInitializingSet(scoped_ptr<EntrySet> initializing_set);
 
   // |out_buffer| needs to be pre-allocated. The serialized index is stored in
   // |out_buffer|.
   void Serialize(std::string* out_buffer);
 
   bool OpenIndexFile();
   bool CloseIndexFile();
 
   static void UpdateFile(const base::FilePath& index_filename,
                          const base::FilePath& temp_filename,
                          scoped_ptr<std::string> buffer);
 
-  const base::FilePath path_;
-
   EntrySet entries_set_;
   uint64 cache_size_;  // Total cache storage size in bytes.
 
+  // This stores all the hash_key of entries that are removed during
+  // initialization.
+  base::hash_set<std::string> removals_set_;

[gavinp, 2013/04/11 09:56:32]

I like: removed_entries_ better for a name.

[felipeg, 2013/04/11 11:25:45]

Done.

+  bool initialized_;
+
   base::FilePath index_filename_;
-  base::PlatformFile index_file_;
 
-  // We keep the thread from where Initialize() method has been called so that
-  // we run the Cleanup method in the same thread. Usually that should be the
-  // CacheThread.
   scoped_refptr<base::TaskRunner> cache_thread_;
+  scoped_refptr<base::TaskRunner> io_thread_;
+
+  // All nonstatic SimpleEntryImpl methods should always be called on the IO
+  // thread, in all cases. |io_thread_checker_| documents and enforces this.
+  base::ThreadChecker io_thread_checker_;
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_INDEX_H_