Move webkit/{browser,common}/dom_storage into content/

content/browser/dom_storage/dom_storage_context_impl.h

 // 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_DOM_STORAGE_DOM_STORAGE_CONTEXT_IMPL_H_
 #define CONTENT_BROWSER_DOM_STORAGE_DOM_STORAGE_CONTEXT_IMPL_H_
 
+#include <map>
+#include <set>
+#include <vector>
+
+#include "base/atomic_sequence_num.h"
+#include "base/basictypes.h"
+#include "base/files/file_path.h"
+#include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
-#include "content/public/browser/dom_storage_context.h"
+#include "base/observer_list.h"
+#include "base/time/time.h"
+#include "content/common/content_export.h"
+#include "url/gurl.h"
 
 namespace base {
 class FilePath;
-}
-
-namespace dom_storage {
-class DomStorageContext;
+class NullableString16;
+class Time;
 }
 
 namespace quota {
 class SpecialStoragePolicy;
 }
 
 namespace content {
 
-// This is owned by BrowserContext (aka Profile) and encapsulates all
-// per-profile dom storage state.
-class CONTENT_EXPORT DOMStorageContextImpl :
-    NON_EXPORTED_BASE(public DOMStorageContext),
-    public base::RefCountedThreadSafe<DOMStorageContextImpl> {
+class DOMStorageArea;
+class DOMStorageNamespace;
+class DOMStorageSession;
+class DOMStorageTaskRunner;
+class SessionStorageDatabase;
+struct LocalStorageUsageInfo;
+struct SessionStorageUsageInfo;
+
+// The Context is the root of an object containment hierachy for
+// Namespaces and Areas related to the owning profile.
+// One instance is allocated in the main process for each profile,
+// instance methods should be called serially in the background as
+// determined by the task_runner. Specifcally not on chrome's non-blocking
+// IO thread since these methods can result in blocking file io.
+//
+// In general terms, the DOMStorage object relationships are...
+//   Contexts (per-profile) own Namespaces which own Areas which share Maps.
+//   Hosts(per-renderer) refer to Namespaces and Areas open in its renderer.
+//   Sessions (per-tab) cause the creation and deletion of session Namespaces.
+//
+// Session Namespaces are cloned by initially making a shallow copy of
+// all contained Areas, the shallow copies refer to the same refcounted Map,
+// and does a deep copy-on-write if needed.
+//
+// Classes intended to be used by an embedder are DOMStorageContextImpl,
+// DOMStorageHost, and DOMStorageSession. The other classes are for
+// internal consumption.
+class CONTENT_EXPORT DOMStorageContextImpl
+    : public base::RefCountedThreadSafe<DOMStorageContextImpl> {
  public:
-  // If |data_path| is empty, nothing will be saved to disk.
-  DOMStorageContextImpl(const base::FilePath& data_path,
-                        quota::SpecialStoragePolicy* special_storage_policy);
-
-  // DOMStorageContext implementation.
-  virtual void GetLocalStorageUsage(
-      const GetLocalStorageUsageCallback& callback) OVERRIDE;
-  virtual void GetSessionStorageUsage(
-      const GetSessionStorageUsageCallback& callback) OVERRIDE;
-  virtual void DeleteLocalStorage(const GURL& origin) OVERRIDE;
-  virtual void DeleteSessionStorage(
-      const dom_storage::SessionStorageUsageInfo& usage_info) OVERRIDE;
-  virtual void SetSaveSessionStorageOnDisk() OVERRIDE;
-  virtual scoped_refptr<SessionStorageNamespace>
-      RecreateSessionStorage(const std::string& persistent_id) OVERRIDE;
-  virtual void StartScavengingUnusedSessionStorage() OVERRIDE;
-
-  // Called to free up memory that's not strictly needed.
+  // An interface for observing Local and Session Storage events on the
+  // background thread.
+  class EventObserver {
+   public:
+    // |old_value| may be null on initial insert.
+    virtual void OnDOMStorageItemSet(
+        const DOMStorageArea* area,
+        const base::string16& key,
+        const base::string16& new_value,
+        const base::NullableString16& old_value,
+        const GURL& page_url) = 0;
+    virtual void OnDOMStorageItemRemoved(
+        const DOMStorageArea* area,
+        const base::string16& key,
+        const base::string16& old_value,
+        const GURL& page_url) = 0;
+    virtual void OnDOMStorageAreaCleared(
+        const DOMStorageArea* area,
+        const GURL& page_url) = 0;
+
+   protected:
+    virtual ~EventObserver() {}
+  };
+
+  // |localstorage_directory| and |sessionstorage_directory| may be empty
+  // for incognito browser contexts.
+  DOMStorageContextImpl(
+      const base::FilePath& localstorage_directory,
+      const base::FilePath& sessionstorage_directory,
+      quota::SpecialStoragePolicy* special_storage_policy,
+      DOMStorageTaskRunner* task_runner);
+
+  // Returns the directory path for localStorage, or an empty directory, if
+  // there is no backing on disk.
+  const base::FilePath& localstorage_directory() {
+    return localstorage_directory_;
+  }
+
+  // Returns the directory path for sessionStorage, or an empty directory, if
+  // there is no backing on disk.
+  const base::FilePath& sessionstorage_directory() {
+    return sessionstorage_directory_;
+  }
+
+  DOMStorageTaskRunner* task_runner() const { return task_runner_.get(); }
+  DOMStorageNamespace* GetStorageNamespace(int64 namespace_id);
+
+  void GetLocalStorageUsage(std::vector<LocalStorageUsageInfo>* infos,
+                            bool include_file_info);
+  void GetSessionStorageUsage(std::vector<SessionStorageUsageInfo>* infos);
+  void DeleteLocalStorage(const GURL& origin);
+  void DeleteSessionStorage(const SessionStorageUsageInfo& usage_info);
   void PurgeMemory();
 
   // Used by content settings to alter the behavior around
   // what data to keep and what data to discard at shutdown.
   // The policy is not so straight forward to describe, see
   // the implementation for details.
-  void SetForceKeepSessionState();
-
-  // Called when the BrowserContext/Profile is going away.
+  void SetForceKeepSessionState() {
+    force_keep_session_state_ = true;
+  }
+
+  // Called when the owning BrowserContext is ending.
+  // Schedules the commit of any unsaved changes and will delete
+  // and keep data on disk per the content settings and special storage
+  // policies. Contained areas and namespaces will stop functioning after
+  // this method has been called.
   void Shutdown();
 
+  // Methods to add, remove, and notify EventObservers.
+  void AddEventObserver(EventObserver* observer);
+  void RemoveEventObserver(EventObserver* observer);
+  void NotifyItemSet(
+      const DOMStorageArea* area,
+      const base::string16& key,
+      const base::string16& new_value,
+      const base::NullableString16& old_value,
+      const GURL& page_url);
+  void NotifyItemRemoved(
+      const DOMStorageArea* area,
+      const base::string16& key,
+      const base::string16& old_value,
+      const GURL& page_url);
+  void NotifyAreaCleared(
+      const DOMStorageArea* area,
+      const GURL& page_url);
+
+  // May be called on any thread.
+  int64 AllocateSessionId() {
+    return session_id_sequence_.GetNext();
+  }
+
+  std::string AllocatePersistentSessionId();
+
+  // Must be called on the background thread.
+  void CreateSessionNamespace(int64 namespace_id,
+                              const std::string& persistent_namespace_id);
+  void DeleteSessionNamespace(int64 namespace_id, bool should_persist_data);
+  void CloneSessionNamespace(int64 existing_id, int64 new_id,
+                             const std::string& new_persistent_id);
+
+  // Starts backing sessionStorage on disk. This function must be called right
+  // after DOMStorageContextImpl is created, before it's used.
+  void SetSaveSessionStorageOnDisk();
+
+  // Deletes all namespaces which don't have an associated DOMStorageNamespace
+  // alive. This function is used for deleting possible leftover data after an
+  // unclean exit.
+  void StartScavengingUnusedSessionStorage();
+
  private:
-  friend class DOMStorageMessageFilter;  // for access to context()
-  friend class SessionStorageNamespaceImpl;  // ditto
+  friend class DOMStorageContextImplTest;
+  FRIEND_TEST_ALL_PREFIXES(DOMStorageContextImplTest, Basics);
   friend class base::RefCountedThreadSafe<DOMStorageContextImpl>;
-
-  virtual ~DOMStorageContextImpl();
-  dom_storage::DomStorageContext* context() const { return context_.get(); }
-
-  scoped_refptr<dom_storage::DomStorageContext> context_;
-
-  DISALLOW_IMPLICIT_CONSTRUCTORS(DOMStorageContextImpl);
+  typedef std::map<int64, scoped_refptr<DOMStorageNamespace> >
+      StorageNamespaceMap;
+
+  ~DOMStorageContextImpl();
+
+  void ClearSessionOnlyOrigins();
+
+  // For scavenging unused sessionStorages.
+  void FindUnusedNamespaces();
+  void FindUnusedNamespacesInCommitSequence(
+      const std::set<std::string>& namespace_ids_in_use,
+      const std::set<std::string>& protected_persistent_session_ids);
+  void DeleteNextUnusedNamespace();
+  void DeleteNextUnusedNamespaceInCommitSequence();
+
+  // Collection of namespaces keyed by id.
+  StorageNamespaceMap namespaces_;
+
+  // Where localstorage data is stored, maybe empty for the incognito use case.
+  base::FilePath localstorage_directory_;
+
+  // Where sessionstorage data is stored, maybe empty for the incognito use
+  // case. Always empty until the file-backed session storage feature is
+  // implemented.
+  base::FilePath sessionstorage_directory_;
+
+  // Used to schedule sequenced background tasks.
+  scoped_refptr<DOMStorageTaskRunner> task_runner_;
+
+  // List of objects observing local storage events.
+  ObserverList<EventObserver> event_observers_;
+
+  // We use a 32 bit identifier for per tab storage sessions.
+  // At a tab per second, this range is large enough for 68 years.
+  base::AtomicSequenceNumber session_id_sequence_;
+
+  bool is_shutdown_;
+  bool force_keep_session_state_;
+  scoped_refptr<quota::SpecialStoragePolicy> special_storage_policy_;
+  scoped_refptr<SessionStorageDatabase> session_storage_database_;
+
+  // For cleaning up unused namespaces gradually.
+  bool scavenging_started_;
+  std::vector<std::string> deletable_persistent_namespace_ids_;
+
+  // Persistent namespace IDs to protect from gradual deletion (they will
+  // be needed for session restore).
+  std::set<std::string> protected_persistent_session_ids_;
+
+  // Mapping between persistent namespace IDs and namespace IDs for
+  // sessionStorage.
+  std::map<std::string, int64> persistent_namespace_id_to_namespace_id_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOM_STORAGE_DOM_STORAGE_CONTEXT_IMPL_H_