Framing for a DOMStorage backend that does not depend on in-process-webkit.

webkit/dom_storage/dom_storage_namespace.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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_IN_PROCESS_WEBKIT_DOM_STORAGE_NAMESPACE_H_
-#define CONTENT_BROWSER_IN_PROCESS_WEBKIT_DOM_STORAGE_NAMESPACE_H_
+#ifndef WEBKIT_DOM_STORAGE_DOM_STORAGE_NAMESPACE_H_
+#define WEBKIT_DOM_STORAGE_DOM_STORAGE_NAMESPACE_H_
 #pragma once
 
-#include "base/hash_tables.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/string16.h"
-#include "content/common/dom_storage_common.h"
-#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebString.h"
+#include <map>
 
-class DOMStorageArea;
-class DOMStorageContext;
-class FilePath;
+#include "base/basictypes.h"
+#include "base/file_path.h"
+#include "base/memory/ref_counted.h"
+#include "webkit/dom_storage/dom_storage_area.h"
 
-namespace WebKit {
-class WebStorageArea;
-class WebStorageNamespace;
-}
+class GURL;
 
-// Only to be used on the WebKit thread.
-class DOMStorageNamespace {
+namespace dom_storage {
+
+class DomStorageArea;
+class DomStorageTaskRunner;
+
+// Container for the set of per-origin Areas.
+// See class comments for DomStorageContext for a larger overview.
+class DomStorageNamespace
+    : public base::RefCountedThreadSafe<DomStorageNamespace> {
  public:
-  static DOMStorageNamespace* CreateLocalStorageNamespace(
-      DOMStorageContext* dom_storage_context, const FilePath& data_dir_path);
-  static DOMStorageNamespace* CreateSessionStorageNamespace(
-      DOMStorageContext* dom_storage_context, int64 namespace_id);
+  // Constructor for a LocalStorage namespace with id of 0
+  // and an optional backing directory on disk.
+  DomStorageNamespace(const FilePath& directory,  // may be empty
+                      DomStorageTaskRunner* task_runner);
 
-  ~DOMStorageNamespace();
+  // Constructor for a SessionStorage namespace with a non-zero id
+  // and no backing directory on disk.
+  DomStorageNamespace(int64 namespace_id,
+                      DomStorageTaskRunner* task_runner);
 
-  DOMStorageArea* GetStorageArea(const string16& origin);
-  DOMStorageNamespace* Copy(int64 clone_namespace_id);
+  int64 namespace_id() const { return namespace_id_; }
 
-  void PurgeMemory();
+  // Returns the storage area for the given origin,
+  // creating instance if needed. Each call to open
+  // must be balanced with a call to CloseStorageArea.
+  DomStorageArea* OpenStorageArea(const GURL& origin);
+  void CloseStorageArea(DomStorageArea* area);
 
-  const DOMStorageContext* dom_storage_context() const {
-    return dom_storage_context_;
-  }
-  int64 id() const { return id_; }
-  const WebKit::WebString& data_dir_path() const { return data_dir_path_; }
-  DOMStorageType dom_storage_type() const { return dom_storage_type_; }
-
-  // Creates a WebStorageArea for the given origin.  This should only be called
-  // by an owned DOMStorageArea.
-  WebKit::WebStorageArea* CreateWebStorageArea(const string16& origin);
+  // Creates a clone of |this| namespace including
+  // shallow copies of all contained areas.
+  // Should only be called for session storage namespaces.
+  DomStorageNamespace* Clone(int64 clone_namespace_id);
 
  private:
-  // Called by the static factory methods above.
-  DOMStorageNamespace(DOMStorageContext* dom_storage_context,
-                      int64 id,
-                      const WebKit::WebString& data_dir_path,
-                      DOMStorageType storage_type);
+  friend class base::RefCountedThreadSafe<DomStorageNamespace>;
 
-  // Creates the underlying WebStorageNamespace on demand.
-  void CreateWebStorageNamespaceIfNecessary();
+  // Struct to hold references to our contained areas and
+  // to keep track of how many tabs have a given area open.
+  struct AreaHolder {
+    scoped_refptr<DomStorageArea> area_;
+    int open_count_;
+    AreaHolder();
+    AreaHolder(DomStorageArea* area, int count);
+    ~AreaHolder();
+  };
+  typedef std::map<GURL, AreaHolder> AreaMap;
 
-  // All the storage areas we own.
-  typedef base::hash_map<string16, DOMStorageArea*> OriginToStorageAreaMap;
-  OriginToStorageAreaMap origin_to_storage_area_;
+  ~DomStorageNamespace();
 
-  // The DOMStorageContext that owns us.
-  DOMStorageContext* dom_storage_context_;
+  // Returns a pointer to the area holder in our map or NULL.
+  AreaHolder* GetAreaHolder(const GURL& origin);
 
-  // The WebKit storage namespace we manage.
-  scoped_ptr<WebKit::WebStorageNamespace> storage_namespace_;
-
-  // Our id.  Unique to our parent WebKitContext class.
-  int64 id_;
-
-  // The path used to create us, so we can recreate our WebStorageNamespace on
-  // demand.
-  WebKit::WebString data_dir_path_;
-
-  // SessionStorage vs. LocalStorage.
-  const DOMStorageType dom_storage_type_;
-
-  DISALLOW_IMPLICIT_CONSTRUCTORS(DOMStorageNamespace);
+  int64 namespace_id_;
+  FilePath directory_;
+  AreaMap areas_;
+  scoped_refptr<DomStorageTaskRunner> task_runner_;
 };
 
-#endif  // CONTENT_BROWSER_IN_PROCESS_WEBKIT_DOM_STORAGE_NAMESPACE_H_
+}  // namespace dom_storage
+
+
+#endif  // WEBKIT_DOM_STORAGE_DOM_STORAGE_NAMESPACE_H_