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// 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 SQL_TRANSACTION_H_
#define SQL_TRANSACTION_H_
#include "base/component_export.h"
#include "base/sequence_checker.h"
#include "base/thread_annotations.h"
namespace sql {
class Database;
// Automatically rolls back uncommitted transactions when going out of scope.
//
// This class is not thread-safe. Each instance must be used from a single
// sequence.
class COMPONENT_EXPORT(SQL) Transaction {
public:
// Creates the scoped transaction object. You MUST call Begin() to begin the
// transaction. If you have begun a transaction and not committed it, the
// constructor will roll back the transaction. If you want to commit, you
// need to manually call Commit before this goes out of scope.
//
// Nested transactions are supported. See sql::Database::BeginTransaction
// for details.
explicit Transaction(Database* connection);
Transaction(const Transaction&) = delete;
Transaction& operator=(const Transaction&) = delete;
~Transaction();
// Returns true when there is a transaction that has been successfully begun.
bool is_open() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
return is_open_;
}
// Begins the transaction. This uses the default sqlite "deferred" transaction
// type, which means that the DB lock is lazily acquired the next time the
// database is accessed, not in the begin transaction command.
//
// Returns false on failure. Note that if this fails, you shouldn't do
// anything you expect to be actually transactional, because it won't be!
bool Begin();
// Rolls back the transaction. This will happen automatically if you do
// nothing when the transaction goes out of scope.
void Rollback();
// Commits the transaction, returning true on success. This will return
// false if sqlite could not commit it, or if another transaction in the
// same outermost transaction has been rolled back (which necessitates a
// rollback of all transactions in that outermost one).
bool Commit();
private:
SEQUENCE_CHECKER(sequence_checker_);
Database* const database_;
// True when the transaction is open, false when it's already been committed
// or rolled back.
bool is_open_ GUARDED_BY_CONTEXT(sequence_checker_) = false;
};
} // namespace sql
#endif // SQL_TRANSACTION_H_
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