content/browser/dom_storage/dom_storage_context_impl.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_BROWSER_DOM_STORAGE_DOM_STORAGE_CONTEXT_IMPL_H_
   6 #define CONTENT_BROWSER_DOM_STORAGE_DOM_STORAGE_CONTEXT_IMPL_H_
   7
   8 #include <map>
   9 #include <set>
  10 #include <vector>
  11
  12 #include "base/atomic_sequence_num.h"
  13 #include "base/basictypes.h"
  14 #include "base/files/file_path.h"
  15 #include "base/gtest_prod_util.h"
  16 #include "base/memory/ref_counted.h"
  17 #include "base/observer_list.h"
  18 #include "base/time/time.h"
  19 #include "content/common/content_export.h"
  20 #include "url/gurl.h"
  21
  22 namespace base {
  23 class FilePath;
  24 class NullableString16;
  25 class Time;
  26 }
  27
  28 namespace storage {
  29 class SpecialStoragePolicy;
  30 }
  31
  32 namespace content {
  33
  34 class DOMStorageArea;
  35 class DOMStorageNamespace;
  36 class DOMStorageSession;
  37 class DOMStorageTaskRunner;
  38 class SessionStorageDatabase;
  39 struct LocalStorageUsageInfo;
  40 struct SessionStorageUsageInfo;
  41
  42 // The Context is the root of an object containment hierachy for
  43 // Namespaces and Areas related to the owning profile.
  44 // One instance is allocated in the main process for each profile,
  45 // instance methods should be called serially in the background as
  46 // determined by the task_runner. Specifcally not on chrome's non-blocking
  47 // IO thread since these methods can result in blocking file io.
  48 //
  49 // In general terms, the DOMStorage object relationships are...
  50 //   Contexts (per-profile) own Namespaces which own Areas which share Maps.
  51 //   Hosts(per-renderer) refer to Namespaces and Areas open in its renderer.
  52 //   Sessions (per-tab) cause the creation and deletion of session Namespaces.
  53 //
  54 // Session Namespaces are cloned by initially making a shallow copy of
  55 // all contained Areas, the shallow copies refer to the same refcounted Map,
  56 // and does a deep copy-on-write if needed.
  57 //
  58 // Classes intended to be used by an embedder are DOMStorageContextImpl,
  59 // DOMStorageHost, and DOMStorageSession. The other classes are for
  60 // internal consumption.
  61 class CONTENT_EXPORT DOMStorageContextImpl
  62     : public base::RefCountedThreadSafe<DOMStorageContextImpl> {
  63  public:
  64   // An interface for observing Local and Session Storage events on the
  65   // background thread.
  66   class EventObserver {
  67    public:
  68     // |old_value| may be null on initial insert.
  69     virtual void OnDOMStorageItemSet(
  70         const DOMStorageArea* area,
  71         const base::string16& key,
  72         const base::string16& new_value,
  73         const base::NullableString16& old_value,
  74         const GURL& page_url) = 0;
  75     virtual void OnDOMStorageItemRemoved(
  76         const DOMStorageArea* area,
  77         const base::string16& key,
  78         const base::string16& old_value,
  79         const GURL& page_url) = 0;
  80     virtual void OnDOMStorageAreaCleared(
  81         const DOMStorageArea* area,
  82         const GURL& page_url) = 0;
  83
  84    protected:
  85     virtual ~EventObserver() {}
  86   };
  87
  88   // |localstorage_directory| and |sessionstorage_directory| may be empty
  89   // for incognito browser contexts.
  90   DOMStorageContextImpl(const base::FilePath& localstorage_directory,
  91                         const base::FilePath& sessionstorage_directory,
  92                         storage::SpecialStoragePolicy* special_storage_policy,
  93                         DOMStorageTaskRunner* task_runner);
  94
  95   // Returns the directory path for localStorage, or an empty directory, if
  96   // there is no backing on disk.
  97   const base::FilePath& localstorage_directory() {
  98     return localstorage_directory_;
  99   }
 100
 101   // Returns the directory path for sessionStorage, or an empty directory, if
 102   // there is no backing on disk.
 103   const base::FilePath& sessionstorage_directory() {
 104     return sessionstorage_directory_;
 105   }
 106
 107   DOMStorageTaskRunner* task_runner() const { return task_runner_.get(); }
 108   DOMStorageNamespace* GetStorageNamespace(int64 namespace_id);
 109
 110   void GetLocalStorageUsage(std::vector<LocalStorageUsageInfo>* infos,
 111                             bool include_file_info);
 112   void GetSessionStorageUsage(std::vector<SessionStorageUsageInfo>* infos);
 113   void DeleteLocalStorage(const GURL& origin);
 114   void DeleteSessionStorage(const SessionStorageUsageInfo& usage_info);
 115
 116   // Used by content settings to alter the behavior around
 117   // what data to keep and what data to discard at shutdown.
 118   // The policy is not so straight forward to describe, see
 119   // the implementation for details.
 120   void SetForceKeepSessionState() {
 121     force_keep_session_state_ = true;
 122   }
 123
 124   // Called when the owning BrowserContext is ending.
 125   // Schedules the commit of any unsaved changes and will delete
 126   // and keep data on disk per the content settings and special storage
 127   // policies. Contained areas and namespaces will stop functioning after
 128   // this method has been called.
 129   void Shutdown();
 130
 131   // Methods to add, remove, and notify EventObservers.
 132   void AddEventObserver(EventObserver* observer);
 133   void RemoveEventObserver(EventObserver* observer);
 134   void NotifyItemSet(
 135       const DOMStorageArea* area,
 136       const base::string16& key,
 137       const base::string16& new_value,
 138       const base::NullableString16& old_value,
 139       const GURL& page_url);
 140   void NotifyItemRemoved(
 141       const DOMStorageArea* area,
 142       const base::string16& key,
 143       const base::string16& old_value,
 144       const GURL& page_url);
 145   void NotifyAreaCleared(
 146       const DOMStorageArea* area,
 147       const GURL& page_url);
 148
 149   // May be called on any thread.
 150   int64 AllocateSessionId();
 151   std::string AllocatePersistentSessionId();
 152
 153   // Must be called on the background thread.
 154   void CreateSessionNamespace(int64 namespace_id,
 155                               const std::string& persistent_namespace_id);
 156   void DeleteSessionNamespace(int64 namespace_id, bool should_persist_data);
 157   void CloneSessionNamespace(int64 existing_id, int64 new_id,
 158                              const std::string& new_persistent_id);
 159
 160   // Starts backing sessionStorage on disk. This function must be called right
 161   // after DOMStorageContextImpl is created, before it's used.
 162   void SetSaveSessionStorageOnDisk();
 163
 164   // Deletes all namespaces which don't have an associated DOMStorageNamespace
 165   // alive. This function is used for deleting possible leftover data after an
 166   // unclean exit.
 167   void StartScavengingUnusedSessionStorage();
 168
 169  private:
 170   friend class DOMStorageContextImplTest;
 171   FRIEND_TEST_ALL_PREFIXES(DOMStorageContextImplTest, Basics);
 172   friend class base::RefCountedThreadSafe<DOMStorageContextImpl>;
 173   typedef std::map<int64, scoped_refptr<DOMStorageNamespace> >
 174       StorageNamespaceMap;
 175
 176   ~DOMStorageContextImpl();
 177
 178   void ClearSessionOnlyOrigins();
 179
 180   // For scavenging unused sessionStorages.
 181   void FindUnusedNamespaces();
 182   void FindUnusedNamespacesInCommitSequence(
 183       const std::set<std::string>& namespace_ids_in_use,
 184       const std::set<std::string>& protected_persistent_session_ids);
 185   void DeleteNextUnusedNamespace();
 186   void DeleteNextUnusedNamespaceInCommitSequence();
 187
 188   // Collection of namespaces keyed by id.
 189   StorageNamespaceMap namespaces_;
 190
 191   // Where localstorage data is stored, maybe empty for the incognito use case.
 192   base::FilePath localstorage_directory_;
 193
 194   // Where sessionstorage data is stored, maybe empty for the incognito use
 195   // case. Always empty until the file-backed session storage feature is
 196   // implemented.
 197   base::FilePath sessionstorage_directory_;
 198
 199   // Used to schedule sequenced background tasks.
 200   scoped_refptr<DOMStorageTaskRunner> task_runner_;
 201
 202   // List of objects observing local storage events.
 203   ObserverList<EventObserver> event_observers_;
 204
 205   // We use a 32 bit identifier for per tab storage sessions.
 206   // At a tab per second, this range is large enough for 68 years.
 207   // The offset is to more quickly detect the error condition where
 208   // an id related to one context is mistakenly used in another.
 209   base::AtomicSequenceNumber session_id_sequence_;
 210   const int session_id_offset_;
 211
 212   bool is_shutdown_;
 213   bool force_keep_session_state_;
 214   scoped_refptr<storage::SpecialStoragePolicy> special_storage_policy_;
 215   scoped_refptr<SessionStorageDatabase> session_storage_database_;
 216
 217   // For cleaning up unused namespaces gradually.
 218   bool scavenging_started_;
 219   std::vector<std::string> deletable_persistent_namespace_ids_;
 220
 221   // Persistent namespace IDs to protect from gradual deletion (they will
 222   // be needed for session restore).
 223   std::set<std::string> protected_persistent_session_ids_;
 224
 225   // Mapping between persistent namespace IDs and namespace IDs for
 226   // sessionStorage.
 227   std::map<std::string, int64> persistent_namespace_id_to_namespace_id_;
 228 };
 229
 230 }  // namespace content
 231
 232 #endif  // CONTENT_BROWSER_DOM_STORAGE_DOM_STORAGE_CONTEXT_IMPL_H_