Blob support for IDB [Chromium]

content/browser/indexed_db/indexed_db_active_blob_registry.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 CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_ACTIVE_BLOB_REGISTRY_H_
+#define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_ACTIVE_BLOB_REGISTRY_H_
+
+#include <map>
+#include <set>
+#include <utility>
+#include "base/basictypes.h"
+#include "base/files/file_path.h"
+#include "base/memory/weak_ptr.h"
+#include "webkit/common/blob/shareable_file_reference.h"
+
+namespace content {
+
+class IndexedDBBackingStore;
+
+class IndexedDBActiveBlobRegistry {
+public:
+  IndexedDBActiveBlobRegistry(IndexedDBBackingStore* backing_store);
+  ~IndexedDBActiveBlobRegistry();
+
+  // Most methods of this class, and the closure returned by
+  // GetAddBlobRefCallback, should only be called on the backing_store's task
+  // runner.  The exception is the closure returned by GetFinalReleaseCallback,
+  // which just calls ReleaseBlobRefThreadSafe.
+
+  // Use DatabaseMetaDataKey::AllBlobsKey for "the whole database".
+  bool MarkDeletedCheckIfUsed(int64 database_id, int64 blob_key);
+
+  webkit_blob::ShareableFileReference::FinalReleaseCallback
+      GetFinalReleaseCallback(int64 database_id, int64 blob_key);
+  // This closure holds a raw pointer to the IndexedDBActiveBlobRegistry,
+  // and may not be called after it is deleted.
+  base::Closure GetAddBlobRefCallback(int64 database_id, int64 blob_key);
+  // Call this to force the registry to drop its reference to the backing store.
+  // This will also turn any outstanding callbacks into no-ops.
+  void ForceShutdown();
+
+private:
+  void AddBlobRef(int64 database_id, int64 blob_key);
+  void ReleaseBlobRef(int64 database_id, int64 blob_key);
+  static void ReleaseBlobRefThreadSafe(
+    scoped_refptr<base::TaskRunner> task_runner,
+    base::WeakPtr<IndexedDBActiveBlobRegistry> weak_ptr, int64 database_id,
+    int64 blob_key, const base::FilePath& unused);
+
+  // Maps blob_key -> IsDeleted; if the record's absent, it's not in active use
+  // and we don't care if it's deleted.
+  typedef std::map<int64, bool> SingleDBMap;
+  // Maps DB ID -> SingleDBMap
+  typedef std::map<int64, SingleDBMap> AllDBsMap;
+  typedef std::set<int64> DeletedDBSet;
+
+  AllDBsMap use_tracker_;
+  DeletedDBSet deleted_dbs_;
+  // Think of backing_store_ as a scoped_refptr, but it's manually managed.
+  // We'll hold a reference as long as there's a blob registered in use_counts_,

[jsbell, 2013/12/18 23:04:40]

use_counts_ => use_tracker_ ?

[ericu, 2013/12/19 05:19:11]

Updated comment.

+  // but not otherwise.  Ideally the blobs would hold the references themselves,
+  // but they live on the wrong thread.
+  IndexedDBBackingStore* backing_store_;
+  base::WeakPtrFactory<IndexedDBActiveBlobRegistry> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(IndexedDBActiveBlobRegistry);
+};
+
+} // namespace content
+
+#endif // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_ACTIVE_BLOB_REGISTRY_H_