sql/transaction.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 SQL_TRANSACTION_H_
   6 #define SQL_TRANSACTION_H_
   7
   8 #include "base/macros.h"
   9 #include "sql/sql_export.h"
  10
  11 namespace sql {
  12
  13 class Connection;
  14
  15 class SQL_EXPORT Transaction {
  16  public:
  17   // Creates the scoped transaction object. You MUST call Begin() to begin the
  18   // transaction. If you have begun a transaction and not committed it, the
  19   // constructor will roll back the transaction. If you want to commit, you
  20   // need to manually call Commit before this goes out of scope.
  21   //
  22   // Nested transactions are supported. See sql::Connection::BeginTransaction
  23   // for details.
  24   explicit Transaction(Connection* connection);
  25   ~Transaction();
  26
  27   // Returns true when there is a transaction that has been successfully begun.
  28   bool is_open() const { return is_open_; }
  29
  30   // Begins the transaction. This uses the default sqlite "deferred" transaction
  31   // type, which means that the DB lock is lazily acquired the next time the
  32   // database is accessed, not in the begin transaction command.
  33   //
  34   // Returns false on failure. Note that if this fails, you shouldn't do
  35   // anything you expect to be actually transactional, because it won't be!
  36   bool Begin();
  37
  38   // Rolls back the transaction. This will happen automatically if you do
  39   // nothing when the transaction goes out of scope.
  40   void Rollback();
  41
  42   // Commits the transaction, returning true on success. This will return
  43   // false if sqlite could not commit it, or if another transaction in the
  44   // same outermost transaction has been rolled back (which necessitates a
  45   // rollback of all transactions in that outermost one).
  46   bool Commit();
  47
  48  private:
  49   Connection* connection_;
  50
  51   // True when the transaction is open, false when it's already been committed
  52   // or rolled back.
  53   bool is_open_;
  54
  55   DISALLOW_COPY_AND_ASSIGN(Transaction);
  56 };
  57
  58 }  // namespace sql
  59
  60 #endif  // SQL_TRANSACTION_H_