/usr/include/Wt/Dbo/Transaction is in libwtdbo-dev 3.3.6+dfsg-1.1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 | // This may look like C code, but it's really -*- C++ -*-
/*
* Copyright (C) 2008 Emweb bvba, Kessel-Lo, Belgium.
*
* See the LICENSE file for terms of use.
*/
#ifndef WT_DBO_TRANSACTION_H_
#define WT_DBO_TRANSACTION_H_
#include <vector>
#include <Wt/Dbo/WDboDllDefs.h>
namespace Wt {
namespace Dbo {
class Session;
class SqlConnection;
class ptr_base;
/*! \class Transaction Wt/Dbo/Transaction Wt/Dbo/Transaction
* \brief A database transaction.
*
* This class implements a RAII transaction. Most dbo manipulations
* require that a transaction is active, and database changes will not
* be committed to the database until the active transaction is
* committed. A transaction can be committed using commit(), but also
* commits automatically when it is deleted while no exception is
* being thrown (using std::uncaught_exception()). This means that it
* is possible that the transaction destructor throws an exception in
* case the transaction still needs to be committed, and the commit
* fails. If the transaction is deleted because of stack unwinding while
* an exception is thrown, then the transaction rolls back.
*
* A transaction is active until it is either committed or rolled
* back. When a transaction is rolled back or fails, the modified
* database objects are not successfully synchronized with the
* database. A roll-back does not affect the value of the in memory
* database objects, so they may possibly be synchronized later in a
* new transaction or discarded using Session::rereadAll().
*
* In most occasions you will want to guard any method that touches
* the database using a transaction object on the stack.
*
* But you may create multiple (nested) transaction objects at the
* same time: in this way you can guard a method with a transaction
* object even if it is called from another method which also defines
* a transaction at a wider scope. Nested transactions act in
* concert and reference the same logical transaction: the logical
* transaction will fail if at least one transaction fails, and will
* be committed only if all transactions are committed.
*
* Usage example:
* \code
* void doSomething(Wt::Dbo::Session& session)
* {
* Wt::Dbo::Transaction transaction(session);
*
* Wt::Dbo::ptr<Account> a = session.load<Account>(42);
* ...
*
* // the transaction will roll back if an exception is thrown, or
* // commit otherwise
* }
* \endcode
*
* \ingroup dbo
*/
class WTDBO_API Transaction
{
public:
/*! \brief Constructor.
*
* Opens a transaction for the given \p session. If a transaction is
* already open for the session, this transaction is added. All open
* transactions must commit successfully for the entire transaction to
* succeed.
*/
explicit Transaction(Session& session);
/*! \brief Destructor.
*
* If the transaction is still active, it is rolled back.
*/
~Transaction() WT_CXX11ONLY(noexcept(false));
/*! \brief Returns whether the transaction is still active.
*
* A transaction is active unless it has been committed or rolled
* back.
*
* While a transaction is active, new transactions for the same
* session are treated as nested transactions.
*/
bool isActive() const;
/*! \brief Commits the transaction.
*
* If this is the last open transaction for the session, the session
* is flushed and pending changes are committed to the database.
*
* Returns whether the transaction was flushed to the database
* (i.e. whether this was indeed the last open transaction).
*
* \sa rollback()
*/
bool commit();
/*! \brief Rolls back the transaction.
*
* The transaction is rolled back (if it was still active), and is no
* longer active.
*
* \sa commit()
*/
void rollback();
/*! \brief Returns the session associated with this transaction.
*
* \sa Transaction()
*/
Session& session() const;
/*! \brief Returns the connection used by this transaction
*/
SqlConnection *connection() const;
private:
struct Impl {
Session& session_;
bool active_;
bool needsRollback_;
bool open_;
int transactionCount_;
std::vector<ptr_base *> objects_;
SqlConnection *connection_;
void open();
void commit();
void rollback();
Impl(Session& session_);
~Impl();
};
bool committed_;
Session& session_;
Impl *impl_;
friend class Session;
void release();
};
}
}
#endif // WT_DBO_TRANSACTION_H_
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