content/browser/dom_storage/session_storage_database.h

   1 // Copyright 2013 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_SESSION_STORAGE_DATABASE_H_
   6 #define CONTENT_BROWSER_DOM_STORAGE_SESSION_STORAGE_DATABASE_H_
   7
   8 #include <map>
   9 #include <string>
  10
  11 #include "base/files/file_path.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/synchronization/lock.h"
  15 #include "content/common/content_export.h"
  16 #include "content/common/dom_storage/dom_storage_types.h"
  17 #include "third_party/leveldatabase/src/include/leveldb/status.h"
  18
  19 class GURL;
  20
  21 namespace leveldb {
  22 class DB;
  23 struct ReadOptions;
  24 class WriteBatch;
  25 }  // namespace leveldb
  26
  27 namespace content {
  28
  29 // SessionStorageDatabase holds the data from multiple namespaces and multiple
  30 // origins. All DOMStorageAreas for session storage share the same
  31 // SessionStorageDatabase.
  32
  33 // Only one thread is allowed to call the public functions other than
  34 // ReadAreaValues and ReadNamespacesAndOrigins. Other threads are allowed to
  35 // call ReadAreaValues and ReadNamespacesAndOrigins.
  36 class CONTENT_EXPORT SessionStorageDatabase :
  37     public base::RefCountedThreadSafe<SessionStorageDatabase> {
  38  public:
  39   explicit SessionStorageDatabase(const base::FilePath& file_path);
  40
  41   // Reads the (key, value) pairs for |namespace_id| and |origin|. |result| is
  42   // assumed to be empty and any duplicate keys will be overwritten. If the
  43   // database exists on disk then it will be opened. If it does not exist then
  44   // it will not be created and |result| will be unmodified.
  45   void ReadAreaValues(const std::string& namespace_id,
  46                       const GURL& origin,
  47                       DOMStorageValuesMap* result);
  48
  49   // Updates the data for |namespace_id| and |origin|. Will remove all keys
  50   // before updating the database if |clear_all_first| is set. Then all entries
  51   // in |changes| will be examined - keys mapped to a null NullableString16 will
  52   // be removed and all others will be inserted/updated as appropriate. It is
  53   // allowed to write data into a shallow copy created by CloneNamespace, and in
  54   // that case the copy will be made deep before writing the values.
  55   bool CommitAreaChanges(const std::string& namespace_id,
  56                          const GURL& origin,
  57                          bool clear_all_first,
  58                          const DOMStorageValuesMap& changes);
  59
  60   // Creates shallow copies of the areas for |namespace_id| and associates them
  61   // with |new_namespace_id|.
  62   bool CloneNamespace(const std::string& namespace_id,
  63                       const std::string& new_namespace_id);
  64
  65   // Deletes the data for |namespace_id| and |origin|.
  66   bool DeleteArea(const std::string& namespace_id, const GURL& origin);
  67
  68   // Deletes the data for |namespace_id|.
  69   bool DeleteNamespace(const std::string& namespace_id);
  70
  71   // Reads the namespace IDs and origins present in the database.
  72   bool ReadNamespacesAndOrigins(
  73       std::map<std::string, std::vector<GURL> >* namespaces_and_origins);
  74
  75  private:
  76   friend class base::RefCountedThreadSafe<SessionStorageDatabase>;
  77   class DBOperation;
  78   friend class SessionStorageDatabase::DBOperation;
  79   friend class SessionStorageDatabaseTest;
  80
  81   ~SessionStorageDatabase();
  82
  83   // Opens the database at file_path_ if it exists already and creates it if
  84   // |create_if_needed| is true. Returns true if the database was opened, false
  85   // if the opening failed or was not necessary (the database doesn't exist and
  86   // |create_if_needed| is false). The possible failures are:
  87   // - leveldb cannot open the database.
  88   // - The database is in an inconsistent or errored state.
  89   bool LazyOpen(bool create_if_needed);
  90
  91   // Tries to open the database at file_path_, assigns |db| to point to the
  92   // opened leveldb::DB instance.
  93   leveldb::Status TryToOpen(leveldb::DB** db);
  94
  95   // Returns true if the database is already open, false otherwise.
  96   bool IsOpen() const;
  97
  98   // Helpers for checking caller erros, invariants and database errors. All
  99   // these return |ok|, for chaining.
 100   bool CallerErrorCheck(bool ok) const;
 101   bool ConsistencyCheck(bool ok);
 102   bool DatabaseErrorCheck(bool ok);
 103
 104   // Helper functions. All return true if the operation succeeded, and false if
 105   // it failed (a database error or a consistency error). If the return type is
 106   // void, the operation cannot fail. If they return false, ConsistencyCheck or
 107   // DatabaseErrorCheck have already been called.
 108
 109   // Creates a namespace for |namespace_id| and updates the next namespace id if
 110   // needed. If |ok_if_exists| is false, checks that the namespace didn't exist
 111   // before.
 112   bool CreateNamespace(const std::string& namespace_id,
 113                        bool ok_if_exists,
 114                        leveldb::WriteBatch* batch);
 115
 116   // Reads the areas assoiated with |namespace_id| and puts the (origin, map_id)
 117   // pairs into |areas|.
 118   bool GetAreasInNamespace(const std::string& namespace_id,
 119                            std::map<std::string, std::string>* areas);
 120
 121   // Adds an association between |origin| and |map_id| into the namespace
 122   // |namespace_id|.
 123   void AddAreaToNamespace(const std::string& namespace_id,
 124                           const std::string& origin,
 125                           const std::string& map_id,
 126                           leveldb::WriteBatch* batch);
 127
 128   // Helpers for deleting data for |namespace_id| and |origin|.
 129   bool DeleteAreaHelper(const std::string& namespace_id,
 130                         const std::string& origin,
 131                         leveldb::WriteBatch* batch);
 132
 133   // Retrieves the map id for |namespace_id| and |origin|. It's not an error if
 134   // the map doesn't exist.
 135   bool GetMapForArea(const std::string& namespace_id,
 136                      const std::string& origin,
 137                      const leveldb::ReadOptions& options,
 138                      bool* exists,
 139                      std::string* map_id);
 140
 141   // Creates a new map for |namespace_id| and |origin|. |map_id| will hold the
 142   // id of the created map. If there is a map for |namespace_id| and |origin|,
 143   // this just overwrites the map id. The caller is responsible for decreasing
 144   // the ref count.
 145   bool CreateMapForArea(const std::string& namespace_id,
 146                         const GURL& origin,
 147                         std::string* map_id,
 148                         leveldb::WriteBatch* batch);
 149   // Reads the contents of the map |map_id| into |result|. If |only_keys| is
 150   // true, only keys are aread from the database and the values in |result| will
 151   // be empty.
 152   bool ReadMap(const std::string& map_id,
 153                const leveldb::ReadOptions& options,
 154                DOMStorageValuesMap* result,
 155                bool only_keys);
 156   // Writes |values| into the map |map_id|.
 157   void WriteValuesToMap(const std::string& map_id,
 158                         const DOMStorageValuesMap& values,
 159                         leveldb::WriteBatch* batch);
 160
 161   bool GetMapRefCount(const std::string& map_id, int64* ref_count);
 162   bool IncreaseMapRefCount(const std::string& map_id,
 163                            leveldb::WriteBatch* batch);
 164   // Decreases the ref count of a map by |decrease|. If the ref count goes to 0,
 165   // deletes the map.
 166   bool DecreaseMapRefCount(const std::string& map_id,
 167                            int decrease,
 168                            leveldb::WriteBatch* batch);
 169
 170   // Deletes all values in |map_id|.
 171   bool ClearMap(const std::string& map_id, leveldb::WriteBatch* batch);
 172
 173   // Breaks the association between (|namespace_id|, |origin|) and |map_id| and
 174   // creates a new map for (|namespace_id|, |origin|). Copies the data from the
 175   // old map if |copy_data| is true.
 176   bool DeepCopyArea(const std::string& namespace_id,
 177                     const GURL& origin,
 178                     bool copy_data,
 179                     std::string* map_id,
 180                     leveldb::WriteBatch* batch);
 181
 182   // Helper functions for creating the keys needed for the schema.
 183   static std::string NamespaceStartKey(const std::string& namespace_id);
 184   static std::string NamespaceKey(const std::string& namespace_id,
 185                                   const std::string& origin);
 186   static const char* NamespacePrefix();
 187   static std::string MapRefCountKey(const std::string& map_id);
 188   static std::string MapKey(const std::string& map_id, const std::string& key);
 189   static const char* NextMapIdKey();
 190
 191   scoped_ptr<leveldb::DB> db_;
 192   base::FilePath file_path_;
 193
 194   // For protecting the database opening code. Also guards the variables below.
 195   base::Lock db_lock_;
 196
 197   // True if a database error has occurred (e.g., cannot read data).
 198   bool db_error_;
 199   // True if the database is in an inconsistent state.
 200   bool is_inconsistent_;
 201   // True if the database is in a failed or inconsistent state, and we have
 202   // already deleted it (as an attempt to recover later).
 203   bool invalid_db_deleted_;
 204
 205   // The number of database operations in progress. We need this so that we can
 206   // delete an inconsistent database at the right moment.
 207   int operation_count_;
 208
 209   DISALLOW_COPY_AND_ASSIGN(SessionStorageDatabase);
 210 };
 211
 212 }  // namespace content
 213
 214 #endif  // CONTENT_BROWSER_DOM_STORAGE_SESSION_STORAGE_DATABASE_H_