ZeroTierOne/ext/libpqxx-7.7.3/include/pqxx/transaction.hxx
2022-06-22 15:03:19 -07:00

109 lines
2.8 KiB
C++

/* Definition of the pqxx::transaction class.
* pqxx::transaction represents a standard database transaction.
*
* DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/transaction instead.
*
* Copyright (c) 2000-2022, Jeroen T. Vermeulen.
*
* See COPYING for copyright license. If you did not receive a file called
* COPYING with this source code, please notify the distributor of this
* mistake, or contact the author.
*/
#ifndef PQXX_H_TRANSACTION
#define PQXX_H_TRANSACTION
#if !defined(PQXX_HEADER_PRE)
# error "Include libpqxx headers as <pqxx/header>, not <pqxx/header.hxx>."
#endif
#include "pqxx/dbtransaction.hxx"
namespace pqxx::internal
{
/// Helper base class for the @ref transaction class template.
class PQXX_LIBEXPORT basic_transaction : public dbtransaction
{
protected:
basic_transaction(
connection &c, zview begin_command, std::string_view tname);
basic_transaction(connection &c, zview begin_command, std::string &&tname);
basic_transaction(connection &c, zview begin_command);
virtual ~basic_transaction() noexcept override = 0;
private:
virtual void do_commit() override;
};
} // namespace pqxx::internal
namespace pqxx
{
/**
* @ingroup transactions
*/
//@{
/// Standard back-end transaction, templatised on isolation level.
/** This is the type you'll normally want to use to represent a transaction on
* the database.
*
* Usage example: double all wages.
*
* ```cxx
* extern connection C;
* work T(C);
* try
* {
* T.exec0("UPDATE employees SET wage=wage*2");
* T.commit(); // NOTE: do this inside try block
* }
* catch (exception const &e)
* {
* cerr << e.what() << endl;
* T.abort(); // Usually not needed; same happens when T's life ends.
* }
* ```
*/
template<
isolation_level ISOLATION = isolation_level::read_committed,
write_policy READWRITE = write_policy::read_write>
class transaction final : public internal::basic_transaction
{
public:
/// Begin a transaction.
/**
* @param c Connection for this transaction to operate on.
* @param tname Optional name for transaction. Must begin with a letter and
* may contain letters and digits only.
*/
transaction(connection &c, std::string_view tname) :
internal::basic_transaction{
c, internal::begin_cmd<ISOLATION, READWRITE>, tname}
{}
/// Begin a transaction.
/**
* @param c Connection for this transaction to operate on.
* may contain letters and digits only.
*/
explicit transaction(connection &c) :
internal::basic_transaction{
c, internal::begin_cmd<ISOLATION, READWRITE>}
{}
virtual ~transaction() noexcept override { close(); }
};
/// The default transaction type.
using work = transaction<>;
/// Read-only transaction.
using read_transaction =
transaction<isolation_level::read_committed, write_policy::read_only>;
//@}
} // namespace pqxx
#endif