[Storage] Blob Storage Refactoring pt 1

storage/browser/blob/blob_storage_context.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 STORAGE_BROWSER_BLOB_BLOB_STORAGE_CONTEXT_H_
 #define STORAGE_BROWSER_BLOB_BLOB_STORAGE_CONTEXT_H_
 
 #include <map>
 #include <string>
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "storage/browser/blob/blob_data_handle.h"
+#include "storage/browser/blob/blob_data_snapshot.h"
 #include "storage/browser/storage_browser_export.h"
-#include "storage/common/blob/blob_data.h"
+#include "storage/common/data_element.h"
 
 class GURL;
 
 namespace base {
 class FilePath;
 class Time;
 }
 
 namespace content {
 class BlobStorageHost;
 }
 
 namespace storage {
 
 class BlobDataHandle;
+class BlobDataBuilder;
 
 // This class handles the logistics of blob Storage within the browser process,
 // and maintains a mapping from blob uuid to the data. The class is single
 // threaded and should only be used on the IO thread.
 // In chromium, there is one instance per profile.
 class STORAGE_EXPORT BlobStorageContext
     : public base::SupportsWeakPtr<BlobStorageContext> {
  public:
   BlobStorageContext();
   ~BlobStorageContext();
 
   scoped_ptr<BlobDataHandle> GetBlobDataFromUUID(const std::string& uuid);
   scoped_ptr<BlobDataHandle> GetBlobDataFromPublicURL(const GURL& url);
 
   // Useful for coining blobs from within the browser process. If the
   // blob cannot be added due to memory consumption, returns NULL.
-  scoped_ptr<BlobDataHandle> AddFinishedBlob(const BlobData* blob_data);
+  scoped_ptr<BlobDataHandle> AddFinishedBlob(const BlobDataBuilder& blob_data);
 
   // Useful for coining blob urls from within the browser process.
   bool RegisterPublicBlobURL(const GURL& url, const std::string& uuid);
   void RevokePublicBlobURL(const GURL& url);
 
  private:
   friend class content::BlobStorageHost;
   friend class BlobDataHandle::BlobDataHandleShared;
   friend class ViewBlobInternalsJob;
 
   enum EntryFlags {
-    BEING_BUILT = 1 << 0,
     EXCEEDED_MEMORY = 1 << 1,
   };
 
   struct BlobMapEntry {
     int refcount;
     int flags;
-    scoped_refptr<BlobData> data;
+    // data and data_builder are mutually exclusive.
+    scoped_ptr<BlobDataSnapshot> data;
+    scoped_ptr<BlobDataBuilder> data_builder;
 
     BlobMapEntry();
-    BlobMapEntry(int refcount, int flags, BlobData* data);
+    BlobMapEntry(int refcount, BlobDataBuilder* data);
     ~BlobMapEntry();
+
+    bool IsBeingBuilt();
   };
 
-  typedef std::map<std::string, BlobMapEntry>
-      BlobMap;
+  typedef std::map<std::string, BlobMapEntry*> BlobMap;
   typedef std::map<GURL, std::string> BlobURLMap;
 
+  // Called by BlobDataHandle.
+  scoped_ptr<BlobDataSnapshot> CreateSnapshot(const std::string& uuid);
+
   void StartBuildingBlob(const std::string& uuid);
   void AppendBlobDataItem(const std::string& uuid,
-                          const BlobData::Item& data_item);
+                          const DataElement& data_item);
   void FinishBuildingBlob(const std::string& uuid, const std::string& type);
   void CancelBuildingBlob(const std::string& uuid);
   void IncrementBlobRefCount(const std::string& uuid);
   void DecrementBlobRefCount(const std::string& uuid);
 
-  bool ExpandStorageItems(BlobData* target_blob_data,
-                          BlobData* src_blob_data,
+  bool ExpandStorageItems(BlobDataBuilder* target_blob_data,
+                          const BlobDataSnapshot& src_blob_data,
                           uint64 offset,
                           uint64 length);
-  bool AppendBytesItem(BlobData* target_blob_data,
-                       const char* data, int64 length);
-  void AppendFileItem(BlobData* target_blob_data,
+  bool AppendBytesItem(BlobDataBuilder* target_blob_data,
+                       const char* data,
+                       int64 length);
+  void AppendFileItem(BlobDataBuilder* target_blob_data,
                       const base::FilePath& file_path,
-                      uint64 offset, uint64 length,
+                      uint64 offset,
+                      uint64 length,
                       const base::Time& expected_modification_time);
-  void AppendFileSystemFileItem(
-      BlobData* target_blob_data,
-      const GURL& url, uint64 offset, uint64 length,
-      const base::Time& expected_modification_time);
+  void AppendFileSystemFileItem(BlobDataBuilder* target_blob_data,
+                                const GURL& url,
+                                uint64 offset,
+                                uint64 length,
+                                const base::Time& expected_modification_time);
 
   bool IsInUse(const std::string& uuid);
   bool IsBeingBuilt(const std::string& uuid);
   bool IsUrlRegistered(const GURL& blob_url);
 
   BlobMap blob_map_;
   BlobURLMap public_blob_urls_;
 
   // Used to keep track of how much memory is being utilized for blob data,
   // we count only the items of TYPE_DATA which are held in memory and not
   // items of TYPE_FILE.
   int64 memory_usage_;
 
   DISALLOW_COPY_AND_ASSIGN(BlobStorageContext);
 };
 
 }  // namespace storage
 
 #endif  // STORAGE_BROWSER_BLOB_BLOB_STORAGE_CONTEXT_H_