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 <string>
  11 #include <vector>
  12
  13 #include "base/atomic_sequence_num.h"
  14 #include "base/basictypes.h"
  15 #include "base/files/file_path.h"
  16 #include "base/gtest_prod_util.h"
  17 #include "base/memory/ref_counted.h"
  18 #include "base/observer_list.h"
  19 #include "base/time/time.h"
  20 #include "content/common/content_export.h"
  21 #include "url/gurl.h"
  22
  23 namespace base {
  24 class FilePath;
  25 class NullableString16;
  26 class Time;
  27 }
  28
  29 namespace storage {
  30 class SpecialStoragePolicy;
  31 }
  32
  33 namespace content {
  34
  35 class DOMStorageArea;
  36 class DOMStorageNamespace;
  37 class DOMStorageSession;
  38 class DOMStorageTaskRunner;
  39 class SessionStorageDatabase;
  40 struct LocalStorageUsageInfo;
  41 struct SessionStorageUsageInfo;
  42
  43 // The Context is the root of an object containment hierarchy for
  44 // Namespaces and Areas related to the owning profile.
  45 // One instance is allocated in the main process for each profile,
  46 // instance methods should be called serially in the background as
  47 // determined by the task_runner. Specifically not on chrome's non-blocking
  48 // IO thread since these methods can result in blocking file io.
  49 //
  50 // In general terms, the DOMStorage object relationships are...
  51 //   Contexts (per-profile) own Namespaces which own Areas which share Maps.
  52 //   Hosts(per-renderer) refer to Namespaces and Areas open in its renderer.
  53 //   Sessions (per-tab) cause the creation and deletion of session Namespaces.
  54 //
  55 // Session Namespaces are cloned by initially making a shallow copy of
  56 // all contained Areas, the shallow copies refer to the same refcounted Map,
  57 // and does a deep copy-on-write if needed.
  58 //
  59 // Classes intended to be used by an embedder are DOMStorageContextImpl,
  60 // DOMStorageHost, and DOMStorageSession. The other classes are for
  61 // internal consumption.
  62 class CONTENT_EXPORT DOMStorageContextImpl
  63     : public base::RefCountedThreadSafe<DOMStorageContextImpl> {
  64  public:
  65   // An interface for observing Local and Session Storage events on the
  66   // background thread.
  67   class EventObserver {
  68    public:
  69     // |old_value| may be null on initial insert.
  70     virtual void OnDOMStorageItemSet(
  71         const DOMStorageArea* area,
  72         const base::string16& key,
  73         const base::string16& new_value,
  74         const base::NullableString16& old_value,
  75         const GURL& page_url) = 0;
  76     virtual void OnDOMStorageItemRemoved(
  77         const DOMStorageArea* area,
  78         const base::string16& key,
  79         const base::string16& old_value,
  80         const GURL& page_url) = 0;
  81     virtual void OnDOMStorageAreaCleared(
  82         const DOMStorageArea* area,
  83         const GURL& page_url) = 0;
  84
  85    protected:
  86     virtual ~EventObserver() {}
  87   };
  88
  89   // |localstorage_directory| and |sessionstorage_directory| may be empty
  90   // for incognito browser contexts.
  91   DOMStorageContextImpl(const base::FilePath& localstorage_directory,
  92                         const base::FilePath& sessionstorage_directory,
  93                         storage::SpecialStoragePolicy* special_storage_policy,
  94                         DOMStorageTaskRunner* task_runner);
  95
  96   // Returns the directory path for localStorage, or an empty directory, if
  97   // there is no backing on disk.
  98   const base::FilePath& localstorage_directory() {
  99     return localstorage_directory_;
 100   }
 101
 102   // Returns the directory path for sessionStorage, or an empty directory, if
 103   // there is no backing on disk.
 104   const base::FilePath& sessionstorage_directory() {
 105     return sessionstorage_directory_;
 106   }
 107
 108   DOMStorageTaskRunner* task_runner() const { return task_runner_.get(); }
 109   DOMStorageNamespace* GetStorageNamespace(int64 namespace_id);
 110
 111   void GetLocalStorageUsage(std::vector<LocalStorageUsageInfo>* infos,
 112                             bool include_file_info);
 113   void GetSessionStorageUsage(std::vector<SessionStorageUsageInfo>* infos);
 114   void DeleteLocalStorage(const GURL& origin);
 115   void DeleteSessionStorage(const SessionStorageUsageInfo& usage_info);
 116
 117   // Used by content settings to alter the behavior around
 118   // what data to keep and what data to discard at shutdown.
 119   // The policy is not so straight forward to describe, see
 120   // the implementation for details.
 121   void SetForceKeepSessionState() {
 122     force_keep_session_state_ = true;
 123   }
 124
 125   // Called when the owning BrowserContext is ending.
 126   // Schedules the commit of any unsaved changes and will delete
 127   // and keep data on disk per the content settings and special storage
 128   // policies. Contained areas and namespaces will stop functioning after
 129   // this method has been called.
 130   void Shutdown();
 131
 132   // Initiate the process of flushing (writing - not sync'ing) any unwritten
 133   // data managed by this instance. Flushing will start "soon".
 134   void Flush();
 135
 136   // Methods to add, remove, and notify EventObservers.
 137   void AddEventObserver(EventObserver* observer);
 138   void RemoveEventObserver(EventObserver* observer);
 139   void NotifyItemSet(
 140       const DOMStorageArea* area,
 141       const base::string16& key,
 142       const base::string16& new_value,
 143       const base::NullableString16& old_value,
 144       const GURL& page_url);
 145   void NotifyItemRemoved(
 146       const DOMStorageArea* area,
 147       const base::string16& key,
 148       const base::string16& old_value,
 149       const GURL& page_url);
 150   void NotifyAreaCleared(
 151       const DOMStorageArea* area,
 152       const GURL& page_url);
 153
 154   // May be called on any thread.
 155   int64 AllocateSessionId();
 156   std::string AllocatePersistentSessionId();
 157
 158   // Must be called on the background thread.
 159   void CreateSessionNamespace(int64 namespace_id,
 160                               const std::string& persistent_namespace_id);
 161   void DeleteSessionNamespace(int64 namespace_id, bool should_persist_data);
 162   void CloneSessionNamespace(int64 existing_id, int64 new_id,
 163                              const std::string& new_persistent_id);
 164
 165   // Starts backing sessionStorage on disk. This function must be called right
 166   // after DOMStorageContextImpl is created, before it's used.
 167   void SetSaveSessionStorageOnDisk();
 168
 169   // Deletes all namespaces which don't have an associated DOMStorageNamespace
 170   // alive. This function is used for deleting possible leftover data after an
 171   // unclean exit.
 172   void StartScavengingUnusedSessionStorage();
 173
 174  private:
 175   friend class DOMStorageContextImplTest;
 176   FRIEND_TEST_ALL_PREFIXES(DOMStorageContextImplTest, Basics);
 177   friend class base::RefCountedThreadSafe<DOMStorageContextImpl>;
 178   typedef std::map<int64, scoped_refptr<DOMStorageNamespace> >
 179       StorageNamespaceMap;
 180
 181   ~DOMStorageContextImpl();
 182
 183   void ClearSessionOnlyOrigins();
 184
 185   // For scavenging unused sessionStorages.
 186   void FindUnusedNamespaces();
 187   void FindUnusedNamespacesInCommitSequence(
 188       const std::set<std::string>& namespace_ids_in_use,
 189       const std::set<std::string>& protected_persistent_session_ids);
 190   void DeleteNextUnusedNamespace();
 191   void DeleteNextUnusedNamespaceInCommitSequence();
 192
 193   // Collection of namespaces keyed by id.
 194   StorageNamespaceMap namespaces_;
 195
 196   // Where localstorage data is stored, maybe empty for the incognito use case.
 197   base::FilePath localstorage_directory_;
 198
 199   // Where sessionstorage data is stored, maybe empty for the incognito use
 200   // case. Always empty until the file-backed session storage feature is
 201   // implemented.
 202   base::FilePath sessionstorage_directory_;
 203
 204   // Used to schedule sequenced background tasks.
 205   scoped_refptr<DOMStorageTaskRunner> task_runner_;
 206
 207   // List of objects observing local storage events.
 208   base::ObserverList<EventObserver> event_observers_;
 209
 210   // We use a 32 bit identifier for per tab storage sessions.
 211   // At a tab per second, this range is large enough for 68 years.
 212   // The offset is to more quickly detect the error condition where
 213   // an id related to one context is mistakenly used in another.
 214   base::AtomicSequenceNumber session_id_sequence_;
 215   const int session_id_offset_;
 216
 217   bool is_shutdown_;
 218   bool force_keep_session_state_;
 219   scoped_refptr<storage::SpecialStoragePolicy> special_storage_policy_;
 220   scoped_refptr<SessionStorageDatabase> session_storage_database_;
 221
 222   // For cleaning up unused namespaces gradually.
 223   bool scavenging_started_;
 224   std::vector<std::string> deletable_persistent_namespace_ids_;
 225
 226   // Persistent namespace IDs to protect from gradual deletion (they will
 227   // be needed for session restore).
 228   std::set<std::string> protected_persistent_session_ids_;
 229
 230   // Mapping between persistent namespace IDs and namespace IDs for
 231   // sessionStorage.
 232   std::map<std::string, int64> persistent_namespace_id_to_namespace_id_;
 233 };
 234
 235 }  // namespace content
 236
 237 #endif  // CONTENT_BROWSER_DOM_STORAGE_DOM_STORAGE_CONTEXT_IMPL_H_