transaction_base.hxx

#ifndef PQXX_H_TRANSACTION_BASE
#define PQXX_H_TRANSACTION_BASE

#include "pqxx/compiler-public.hxx"
#include "pqxx/compiler-internal-pre.hxx"

/* End-user programs need not include this file, unless they define their own
 * transaction classes.  This is not something the typical program should want
 * to do.
 *
 * However, reading this file is worthwhile because it defines the public
 * interface for the available transaction classes such as transaction and
 * nontransaction.
 */

#include "pqxx/connection_base.hxx"
#include "pqxx/isolation.hxx"
#include "pqxx/result.hxx"
#include "pqxx/row.hxx"

// Methods tested in eg. test module test01 are marked with "//[t01]".

namespace pqxx
{
namespace internal
{
class sql_cursor;

class PQXX_LIBEXPORT transactionfocus : public virtual namedclass
{
public:
  explicit transactionfocus(transaction_base &t) :
    namedclass("transactionfocus"),
    m_trans(t),
    m_registered(false)
  {
  }

  transactionfocus() =delete;
  transactionfocus(const transactionfocus &) =delete;
  transactionfocus &operator=(const transactionfocus &) =delete;

protected:
  void register_me();
  void unregister_me() noexcept;
  void reg_pending_error(const std::string &) noexcept;
  bool registered() const noexcept { return m_registered; }

  transaction_base &m_trans;

private:
  bool m_registered;
};



class PQXX_LIBEXPORT parameterized_invocation : statement_parameters
{
public:
  parameterized_invocation(connection_base &, const std::string &query);

  parameterized_invocation &operator()() { add_param(); return *this; }
  parameterized_invocation &operator()(const binarystring &v)
        { add_binary_param(v, true); return *this; }
  template<typename T> parameterized_invocation &operator()(const T &v)
        { add_param(v, true); return *this; }
  parameterized_invocation &operator()(const binarystring &v, bool nonnull)
        { add_binary_param(v, nonnull); return *this; }
  template<typename T>
        parameterized_invocation &operator()(const T &v, bool nonnull)
        { add_param(v, nonnull); return *this; }

  result exec();

private:
  parameterized_invocation &operator=(const parameterized_invocation &);

  connection_base &m_home;
  const std::string m_query;
};
} // namespace internal


namespace internal
{
namespace gate
{
class transaction_subtransaction;
class transaction_tablereader;
class transaction_tablewriter;
class transaction_transactionfocus;
} // namespace internal::gate
} // namespace internal



class PQXX_LIBEXPORT PQXX_NOVTABLE transaction_base :
  public virtual internal::namedclass
{
public:
  using isolation_tag = isolation_traits<read_committed>;

  transaction_base() =delete;
  transaction_base(const transaction_base &) =delete;
  transaction_base &operator=(const transaction_base &) =delete;

  virtual ~transaction_base() =0;                                       //[t01]


  void commit();                                                        //[t01]


  void abort();                                                         //[t10]

  std::string esc(const char str[]) const            { return conn().esc(str); }
  std::string esc(const char str[], size_t maxlen) const
                                             { return conn().esc(str, maxlen); }
  std::string esc(const std::string &str) const      { return conn().esc(str); }


  std::string esc_raw(const unsigned char data[], size_t len) const     //[t62]
                                           { return conn().esc_raw(data, len); }
  std::string esc_raw(const std::string &) const;                       //[t62]


  std::string unesc_raw(const std::string &text) const
                                              { return conn().unesc_raw(text); }


  std::string unesc_raw(const char *text) const
                                              { return conn().unesc_raw(text); }


  template<typename T> std::string quote(const T &t) const
                                                     { return conn().quote(t); }

  std::string quote_raw(const unsigned char str[], size_t len) const
                                          { return conn().quote_raw(str, len); }

  std::string quote_raw(const std::string &str) const;

  std::string quote_name(const std::string &identifier) const
                                       { return conn().quote_name(identifier); }


  result exec(
        const std::string &Query,
        const std::string &Desc=std::string());                         //[t01]

  result exec(
        const std::stringstream &Query,
        const std::string &Desc=std::string())
        { return exec(Query.str(), Desc); }


  result exec0(
        const std::string &Query,
        const std::string &Desc=std::string())
        { return exec_n(0, Query, Desc); }


  row exec1(const std::string &Query, const std::string &Desc=std::string())
        { return exec_n(1, Query, Desc).front(); }


  result exec_n(
        size_t rows,
        const std::string &Query,
        const std::string &Desc=std::string());

  template<typename ...Args>
  result exec_params(const std::string &query, Args ...args)
  {
    return internal_exec_params(query, internal::params(args...));
  }

  // Execute parameterised statement, expect a single-row result.
  template<typename ...Args>
  row exec_params1(const std::string &query, Args... args)
  {
    return exec_params_n(1, query, args...).front();
  }

  // Execute parameterised statement, expect a result with zero rows.
  template<typename ...Args>
  result exec_params0(const std::string &query, Args ...args)
  {
    return exec_params_n(0, query, args...);
  }

  // Execute parameterised statement, expect exactly a given number of rows.
  template<typename ...Args>
  result exec_params_n(size_t rows, const std::string &query, Args ...args)
  {
    const auto r = exec_params(query, args...);
    check_rowcount_params(rows, r.size());
    return r;
  }

  /* Use this to build up a parameterized statement invocation, then invoke it
   * using @c exec()
   *
   * Example: @c trans.parameterized("SELECT $1 + 1")(1).exec();
   *
   * This is the old, pre-C++11 way of handling parameterised statements.  As
   * of libpqxx 6.0, it's made much easier using variadic templates.
   */
  internal::parameterized_invocation parameterized(const std::string &query);


  template<typename ...Args>
  result exec_prepared(const std::string &statement, Args... args)
  {
    return internal_exec_prepared(statement, internal::params(args...));
  }


  template<typename ...Args>
  row exec_prepared1(const std::string &statement, Args... args)
  {
    return exec_prepared_n(1, statement, args...).front();
  }


  template<typename ...Args>
  result exec_prepared0(const std::string &statement, Args... args)
  {
    return exec_prepared_n(0, statement, args...);
  }


  template<typename ...Args>
  result exec_prepared_n(
        size_t rows,
        const std::string &statement,
        Args... args)
  {
    const auto r = exec_prepared(statement, args...);
    check_rowcount_prepared(statement, rows, r.size());
    return r;
  }


  prepare::invocation prepared(const std::string &statement=std::string());


  void process_notice(const char Msg[]) const                           //[t14]
        { m_conn.process_notice(Msg); }
  void process_notice(const std::string &Msg) const                     //[t14]
        { m_conn.process_notice(Msg); }

  connection_base &conn() const { return m_conn; }                      //[t04]


  void set_variable(const std::string &Var, const std::string &Val);    //[t61]


  std::string get_variable(const std::string &);                        //[t61]

protected:

  explicit transaction_base(connection_base &c, bool direct=true);


  void Begin();

  void End() noexcept;

  virtual void do_begin() =0;
  virtual result do_exec(const char Query[]) =0;
  virtual void do_commit() =0;
  virtual void do_abort() =0;

  // For use by implementing class:


  result direct_exec(const char C[], int Retries=0);

  void reactivation_avoidance_clear() noexcept
        {m_reactivation_avoidance.clear();}

protected:

  internal::reactivation_avoidance_counter m_reactivation_avoidance;

private:
  /* A transaction goes through the following stages in its lifecycle:
   * <ul>
   * <li> nascent: the transaction hasn't actually begun yet.  If our connection
   *    fails at this stage, it may recover and the transaction can attempt to
   *    establish itself again.
   * <li> active: the transaction has begun.  Since no commit command has been
   *    issued, abortion is implicit if the connection fails now.
   * <li> aborted: an abort has been issued; the transaction is terminated and
   *    its changes to the database rolled back.  It will accept no further
   *    commands.
   * <li> committed: the transaction has completed successfully, meaning that a
   *    commit has been issued.  No further commands are accepted.
   * <li> in_doubt: the connection was lost at the exact wrong time, and there
   *    is no way of telling whether the transaction was committed or aborted.
   * </ul>
   *
   * Checking and maintaining state machine logic is the responsibility of the
   * base class (ie., this one).
   */
  enum Status
  {
    st_nascent,
    st_active,
    st_aborted,
    st_committed,
    st_in_doubt
  };

  PQXX_PRIVATE void activate();

  PQXX_PRIVATE void CheckPendingError();

  template<typename T> bool parm_is_null(T *p) const noexcept
        { return !p; }
  template<typename T> bool parm_is_null(T) const noexcept
        { return false; }

  result internal_exec_prepared(
        const std::string &statement,
        const internal::params &args);

  result internal_exec_params(
        const std::string &query,
        const internal::params &args);

  void check_rowcount_prepared(
        const std::string &statement,
        size_t expected_rows,
        size_t actual_rows);

  void check_rowcount_params(
        size_t expected_rows, size_t actual_rows);

  friend class pqxx::internal::gate::transaction_transactionfocus;
  PQXX_PRIVATE void register_focus(internal::transactionfocus *);
  PQXX_PRIVATE void unregister_focus(internal::transactionfocus *) noexcept;
  PQXX_PRIVATE void register_pending_error(const std::string &) noexcept;

  friend class pqxx::internal::gate::transaction_tablereader;
  PQXX_PRIVATE void BeginCopyRead(const std::string &, const std::string &);
  bool read_copy_line(std::string &);

  friend class pqxx::internal::gate::transaction_tablewriter;
  PQXX_PRIVATE void BeginCopyWrite(
        const std::string &Table,
        const std::string &Columns);
  void write_copy_line(const std::string &);
  void end_copy_write();

  friend class pqxx::internal::gate::transaction_subtransaction;

  connection_base &m_conn;

  internal::unique<internal::transactionfocus> m_focus;
  Status m_status = st_nascent;
  bool m_registered = false;
  std::map<std::string, std::string> m_vars;
  std::string m_pending_error;
};

} // namespace pqxx

#include "pqxx/compiler-internal-post.hxx"

#endif