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