libpqxx  7.3.0
transaction_base.hxx
1 /* Common code and definitions for the transaction classes.
2  *
3  * pqxx::transaction_base defines the interface for any abstract class that
4  * represents a database transaction.
5  *
6  * DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/transaction_base instead.
7  *
8  * Copyright (c) 2000-2020, Jeroen T. Vermeulen.
9  *
10  * See COPYING for copyright license. If you did not receive a file called
11  * COPYING with this source code, please notify the distributor of this
12  * mistake, or contact the author.
13  */
14 #ifndef PQXX_H_TRANSACTION_BASE
15 #define PQXX_H_TRANSACTION_BASE
16 
17 #include "pqxx/compiler-public.hxx"
18 #include "pqxx/internal/compiler-internal-pre.hxx"
19 
20 #include <string_view>
21 
22 /* End-user programs need not include this file, unless they define their own
23  * transaction classes. This is not something the typical program should want
24  * to do.
25  *
26  * However, reading this file is worthwhile because it defines the public
27  * interface for the available transaction classes such as transaction and
28  * nontransaction.
29  */
30 
31 #include "pqxx/connection.hxx"
32 #include "pqxx/internal/concat.hxx"
33 #include "pqxx/internal/encoding_group.hxx"
34 #include "pqxx/isolation.hxx"
35 #include "pqxx/result.hxx"
36 #include "pqxx/row.hxx"
37 #include "pqxx/stream_from.hxx"
38 
39 namespace pqxx::internal::gate
40 {
41 class transaction_subtransaction;
42 class transaction_sql_cursor;
43 class transaction_stream_to;
44 class transaction_transactionfocus;
45 } // namespace pqxx::internal::gate
46 
47 
48 namespace pqxx
49 {
50 using namespace std::literals;
51 
52 
65 
71 class PQXX_LIBEXPORT PQXX_NOVTABLE transaction_base
72 {
73 public:
74  transaction_base() = delete;
79 
80  virtual ~transaction_base() = 0;
81 
83 
95  void commit();
96 
98 
101  void abort();
102 
107  [[nodiscard]] std::string esc(char const text[]) const
109  {
110  return conn().esc(text);
111  }
113  [[nodiscard]] std::string esc(char const text[], std::size_t maxlen) const
114  {
115  return conn().esc(text, maxlen);
116  }
118  [[nodiscard]] std::string esc(std::string_view text) const
119  {
120  return conn().esc(text);
121  }
122 
124 
135  [[nodiscard]] std::string
136  esc_raw(unsigned char const data[], std::size_t len) const
137  {
138  return conn().esc_raw(data, len);
139  }
141  [[nodiscard]] std::string esc_raw(zview) const;
142 
144 
147  [[nodiscard]] std::string unesc_raw(zview text) const
148  {
149  return conn().unesc_raw(text);
150  }
151 
153 
156  [[nodiscard]] std::string unesc_raw(char const *text) const
157  {
158  return conn().unesc_raw(text);
159  }
160 
162 
163  template<typename T> [[nodiscard]] std::string quote(T const &t) const
164  {
165  return conn().quote(t);
166  }
167 
169  [[nodiscard]] std::string
170  quote_raw(unsigned char const bin[], std::size_t len) const
171  {
172  return conn().quote_raw(bin, len);
173  }
174 
175  [[nodiscard]] std::string quote_raw(zview bin) const;
176 
178  [[nodiscard]] std::string quote_name(std::string_view identifier) const
179  {
180  return conn().quote_name(identifier);
181  }
182 
184  [[nodiscard]] std::string
185  esc_like(std::string_view bin, char escape_char = '\\') const
186  {
187  return conn().esc_like(bin, escape_char);
188  }
190 
192 
206  result
207  exec(std::string_view query, std::string_view desc = std::string_view{});
208 
210  std::stringstream const &query, std::string_view desc = std::string_view{})
211  {
212  return exec(query.str(), desc);
213  }
214 
216 
221  result exec0(zview query, std::string_view desc = std::string_view{})
222  {
223  return exec_n(0, query, desc);
224  }
225 
227 
233  row exec1(zview query, std::string_view desc = std::string_view{})
234  {
235  return exec_n(1, query, desc).front();
236  }
237 
239 
244  result exec_n(
245  result::size_type rows, zview query,
246  std::string_view desc = std::string_view{});
247 
249  template<typename TYPE>
250  TYPE query_value(zview query, std::string_view desc = std::string_view{})
251  {
252  row const r{exec1(query, desc)};
253  if (std::size(r) != 1)
254  throw usage_error{internal::concat(
255  "Queried single value from result with ", std::size(r), " columns.")};
256  return r[0].as<TYPE>();
257  }
258 
260 
300  template<typename... TYPE> [[nodiscard]] auto stream(std::string_view query)
301  {
302  return pqxx::internal::owning_stream_input_iteration<TYPE...>{
303  std::make_unique<pqxx::stream_from>(*this, from_query_t{}, query)};
304  }
305 
335  template<typename... Args> result exec_params(zview query, Args &&...args)
337  {
338  return internal_exec_params(
339  query, internal::params(std::forward<Args>(args)...));
340  }
341 
342  // Execute parameterised statement, expect a single-row result.
345  template<typename... Args> row exec_params1(zview query, Args &&...args)
346  {
347  return exec_params_n(1, query, std::forward<Args>(args)...).front();
348  }
349 
350  // Execute parameterised statement, expect a result with zero rows.
353  template<typename... Args> result exec_params0(zview query, Args &&...args)
354  {
355  return exec_params_n(0, query, std::forward<Args>(args)...);
356  }
357 
358  // Execute parameterised statement, expect exactly a given number of rows.
361  template<typename... Args>
362  result exec_params_n(std::size_t rows, zview query, Args &&...args)
363  {
364  auto const r{exec_params(query, std::forward<Args>(args)...)};
365  check_rowcount_params(rows, std::size(r));
366  return r;
367  }
369 
398 
400  template<typename... Args>
401  result exec_prepared(zview statement, Args &&...args)
402  {
403  return internal_exec_prepared(
404  statement, internal::params(std::forward<Args>(args)...));
405  }
406 
408 
410  template<typename... Args>
411  row exec_prepared1(zview statement, Args &&...args)
412  {
413  return exec_prepared_n(1, statement, std::forward<Args>(args)...).front();
414  }
415 
417 
419  template<typename... Args>
420  result exec_prepared0(zview statement, Args &&...args)
421  {
422  return exec_prepared_n(0, statement, std::forward<Args>(args)...);
423  }
424 
426 
429  template<typename... Args>
430  result
431  exec_prepared_n(result::size_type rows, zview statement, Args &&...args)
432  {
433  auto const r{exec_prepared(statement, std::forward<Args>(args)...)};
434  check_rowcount_prepared(statement, rows, std::size(r));
435  return r;
436  }
437 
439 
444  void process_notice(char const msg[]) const { m_conn.process_notice(msg); }
447  void process_notice(zview msg) const { m_conn.process_notice(msg); }
449 
451  [[nodiscard]] connection &conn() const { return m_conn; }
452 
454 
464  void set_variable(std::string_view var, std::string_view value);
465 
467 
470  std::string get_variable(std::string_view);
471 
473  [[nodiscard]] std::string_view name() const noexcept { return m_name; }
474 
475 protected:
477 
481  connection &c, std::string_view tname,
482  std::shared_ptr<std::string> rollback_cmd) :
483  m_conn{c}, m_name{tname}, m_rollback_cmd{rollback_cmd}
484  {}
485 
487 
492  transaction_base(connection &c, std::string_view tname);
493 
495  explicit transaction_base(connection &c);
496 
498  void register_transaction();
499 
501  void close() noexcept;
502 
504  virtual void do_commit() = 0;
505 
507 
510  virtual void do_abort();
511 
513  void set_rollback_cmd(std::shared_ptr<std::string> cmd)
514  {
515  m_rollback_cmd = cmd;
516  }
517 
519  result direct_exec(std::string_view);
520  result direct_exec(std::shared_ptr<std::string>);
521 
522 private:
523  enum class status
524  {
525  active,
526  aborted,
527  committed,
528  in_doubt
529  };
530 
531  PQXX_PRIVATE void check_pending_error();
532 
533  template<typename T> bool parm_is_null(T *p) const noexcept
534  {
535  return p == nullptr;
536  }
537  template<typename T> bool parm_is_null(T) const noexcept { return false; }
538 
539  result internal_exec_prepared(zview statement, internal::params const &args);
540 
541  result internal_exec_params(zview query, internal::params const &args);
542 
544  void check_rowcount_prepared(
545  zview statement, result::size_type expected_rows,
546  result::size_type actual_rows);
547 
549  void
550  check_rowcount_params(std::size_t expected_rows, std::size_t actual_rows);
551 
553  [[nodiscard]] std::string description() const;
554 
555  friend class pqxx::internal::gate::transaction_transactionfocus;
556  PQXX_PRIVATE void register_focus(internal::transactionfocus *);
557  PQXX_PRIVATE void unregister_focus(internal::transactionfocus *) noexcept;
558  PQXX_PRIVATE void register_pending_error(zview) noexcept;
559  PQXX_PRIVATE void register_pending_error(std::string &&) noexcept;
560 
561  connection &m_conn;
562 
564 
567  internal::transactionfocus const *m_focus = nullptr;
568 
569  status m_status = status::active;
570  bool m_registered = false;
571  std::string m_name;
572  std::string m_pending_error;
573 
575  std::shared_ptr<std::string> m_rollback_cmd;
576 
577  constexpr static std::string_view s_type_name{"transaction"sv};
578 };
579 
580 
581 // TODO: C++20 "Conversion remains valid after underlying result dies" concept?
583 template<>
584 std::string_view transaction_base::query_value<std::string_view>(
585  zview query, std::string_view desc) = delete;
587 template<>
588 zview transaction_base::query_value<zview>(
589  zview query, std::string_view desc) = delete;
590 
591 } // namespace pqxx
592 
593 
594 namespace pqxx::internal
595 {
597 template<pqxx::isolation_level isolation, pqxx::write_policy rw>
598 extern const zview begin_cmd;
599 
600 // These are not static members, so "constexpr" does not imply "inline".
601 template<>
602 inline constexpr zview begin_cmd<read_committed, write_policy::read_write>{
603  "BEGIN"_zv};
604 template<>
605 inline constexpr zview begin_cmd<read_committed, write_policy::read_only>{
606  "BEGIN READ ONLY"_zv};
607 template<>
608 inline constexpr zview begin_cmd<repeatable_read, write_policy::read_write>{
609  "BEGIN ISOLATION LEVEL REPEATABLE READ"_zv};
610 template<>
611 inline constexpr zview begin_cmd<repeatable_read, write_policy::read_only>{
612  "BEGIN ISOLATION LEVEL REPEATABLE READ READ ONLY"_zv};
613 template<>
614 inline constexpr zview begin_cmd<serializable, write_policy::read_write>{
615  "BEGIN ISOLATION LEVEL SERIALIZABLE"_zv};
616 template<>
617 inline constexpr zview begin_cmd<serializable, write_policy::read_only>{
618  "BEGIN ISOLATION LEVEL SERIALIZABLE READ ONLY"_zv};
619 } // namespace pqxx::internal
620 
621 #include "pqxx/internal/compiler-internal-post.hxx"
622 #endif
pqxx::transaction_base::exec_prepared_n
result exec_prepared_n(result::size_type rows, zview statement, Args &&...args)
Execute a prepared statement, expect a result with given number of rows.
Definition: transaction_base.hxx:431
pqxx::transaction_base::quote_raw
std::string quote_raw(unsigned char const bin[], std::size_t len) const
Binary-escape and quote a binary string for use as an SQL constant.
Definition: transaction_base.hxx:170
pqxx::transaction_base::exec_prepared1
row exec_prepared1(zview statement, Args &&...args)
Execute a prepared statement, and expect a single-row result.
Definition: transaction_base.hxx:411
pqxx::transaction_base::esc_raw
std::string esc_raw(unsigned char const data[], std::size_t len) const
Escape binary data for use as SQL string literal in this transaction.
Definition: transaction_base.hxx:136
pqxx
The home of all libpqxx classes, functions, templates, etc.
Definition: array.hxx:26
pqxx::transaction_base::unesc_raw
std::string unesc_raw(zview text) const
Unescape binary data, e.g. from a table field or notification payload.
Definition: transaction_base.hxx:147
pqxx::transaction_base::abort
void abort()
Abort the transaction.
Definition: transaction_base.cxx:172
pqxx::transaction_base::exec
result exec(std::stringstream const &query, std::string_view desc=std::string_view{})
Definition: transaction_base.hxx:209
pqxx::transaction_base::exec_params1
row exec_params1(zview query, Args &&...args)
Definition: transaction_base.hxx:345
pqxx::internal::gate
Definition: connection.hxx:95
pqxx::transaction_base::exec_prepared0
result exec_prepared0(zview statement, Args &&...args)
Execute a prepared statement, and expect a result with zero rows.
Definition: transaction_base.hxx:420
pqxx::transaction_base::esc_like
std::string esc_like(std::string_view bin, char escape_char='\\') const
Escape string for literal LIKE match.
Definition: transaction_base.hxx:185
pqxx::transaction_base::do_abort
virtual void do_abort()
Transaction type-specific way of aborting a transaction.
Definition: transaction_base.cxx:165
pqxx::transaction_base::set_variable
void set_variable(std::string_view var, std::string_view value)
Set session variable using SQL "SET" command.
Definition: transaction_base.cxx:315
pqxx::internal::check_unique_register
void check_unique_register(void const *old_guest, std::string_view old_class, std::string_view old_name, void const *new_guest, std::string_view new_class, std::string_view new_name)
Check validity of registering a new "guest" in a "host.".
Definition: util.cxx:58
pqxx::internal
Internal items for libpqxx' own use. Do not use these yourself.
Definition: composite.hxx:74
pqxx::transaction_base::transaction_base
transaction_base(connection &c, std::string_view tname, std::shared_ptr< std::string > rollback_cmd)
Create a transaction (to be called by implementation classes only).
Definition: transaction_base.hxx:480
pqxx::connection
Connection to a database.
Definition: connection.hxx:164
pqxx::transaction_base::direct_exec
result direct_exec(std::string_view)
Execute query on connection directly.
Definition: transaction_base.cxx:437
pqxx::unexpected_rows
Query returned an unexpected number of rows.
Definition: except.hxx:200
pqxx::row
Reference to one row in a result.
Definition: row.hxx:46
pqxx::internal_error
Internal error in libpqxx library.
Definition: except.hxx:158
pqxx::transaction_base::get_variable
std::string get_variable(std::string_view)
Read session variable using SQL "SHOW" command.
Definition: transaction_base.cxx:322
pqxx::transaction_base::stream
auto stream(std::string_view query)
Execute a query, and loop over the results row by row.
Definition: transaction_base.hxx:300
pqxx::transaction_base::name
std::string_view name() const noexcept
Transaction name, if you passed one to the constructor; or empty string.
Definition: transaction_base.hxx:473
pqxx::transaction_base::operator=
transaction_base & operator=(transaction_base &&)=delete
pqxx::transaction_base::quote
std::string quote(T const &t) const
Represent object as SQL string, including quoting & escaping.
Definition: transaction_base.hxx:163
pqxx::transaction_base::esc
std::string esc(std::string_view text) const
Escape string for use as SQL string literal in this transaction.
Definition: transaction_base.hxx:118
pqxx::usage_error
Error in usage of libpqxx library, similar to std::logic_error.
Definition: except.hxx:165
pqxx::transaction_base::exec_n
result exec_n(result::size_type rows, zview query, std::string_view desc=std::string_view{})
Execute query, expect given number of rows.
Definition: transaction_base.cxx:258
pqxx::broken_connection
Exception class for lost or failed backend connection.
Definition: except.hxx:68
pqxx::transaction_base::query_value
TYPE query_value(zview query, std::string_view desc=std::string_view{})
Execute query, expecting exactly 1 row with 1 field.
Definition: transaction_base.hxx:250
pqxx::transaction_base::exec_prepared
result exec_prepared(zview statement, Args &&...args)
Execute a prepared statement, with optional arguments.
Definition: transaction_base.hxx:401
pqxx::transaction_base::transaction_base
transaction_base(transaction_base const &)=delete
pqxx::transaction_base
Interface definition (and common code) for "transaction" classes.
Definition: transaction_base.hxx:72
pqxx::transaction_base::exec_params_n
result exec_params_n(std::size_t rows, zview query, Args &&...args)
Definition: transaction_base.hxx:362
pqxx::transaction_base::conn
connection & conn() const
The connection in which this transaction lives.
Definition: transaction_base.hxx:451
pqxx::transaction_base::operator=
transaction_base & operator=(transaction_base const &)=delete
pqxx::transaction_base::quote_name
std::string quote_name(std::string_view identifier) const
Escape an SQL identifier for use in a query.
Definition: transaction_base.hxx:178
pqxx::transaction_base::unesc_raw
std::string unesc_raw(char const *text) const
Unescape binary data, e.g. from a table field or notification payload.
Definition: transaction_base.hxx:156
pqxx::transaction_base::transaction_base
transaction_base(transaction_base &&)=delete
pqxx::transaction_base::~transaction_base
virtual ~transaction_base()=0
Definition: transaction_base.cxx:56
pqxx::row::as
std::tuple< TYPE... > as() const
Definition: row.hxx:184
pqxx::result::size_type
result_size_type size_type
Definition: result.hxx:73
pqxx::transaction_base::exec0
result exec0(zview query, std::string_view desc=std::string_view{})
Execute query, which should zero rows of data.
Definition: transaction_base.hxx:221
pqxx::transaction_base::process_notice
void process_notice(zview msg) const
Have connection process a warning message.
Definition: transaction_base.hxx:447
pqxx::internal::describe_object
std::string describe_object(std::string_view class_name, std::string_view name)
Describe an object for humans, based on class name and optional name.
Definition: util.cxx:48
pqxx::transaction_base::transaction_base
transaction_base()=delete
pqxx::transaction_base::commit
void commit()
Commit the transaction.
Definition: transaction_base.cxx:94
pqxx::in_doubt_error
"Help, I don't know whether transaction was committed successfully!"
Definition: except.hxx:107
pqxx::failure
Run-time failure encountered by libpqxx, similar to std::runtime_error.
Definition: except.hxx:43
pqxx::zview
Marker-type wrapper: zero-terminated std::string_view.
Definition: zview.hxx:38
pqxx::transaction_base::esc
std::string esc(char const text[], std::size_t maxlen) const
Escape string for use as SQL string literal in this transaction.
Definition: transaction_base.hxx:113
pqxx::transaction_base::exec1
row exec1(zview query, std::string_view desc=std::string_view{})
Execute query returning a single row of data.
Definition: transaction_base.hxx:233
pqxx::transaction_base::exec_params0
result exec_params0(zview query, Args &&...args)
Definition: transaction_base.hxx:353
pqxx::zview::c_str
constexpr char const * c_str() const noexcept
Either a null pointer, or a zero-terminated text buffer.
Definition: zview.hxx:76
pqxx::from_query_t
Marker for stream_from constructors: "stream from query.".
Definition: types.hxx:60
pqxx::internal::check_unique_unregister
void check_unique_unregister(void const *old_guest, std::string_view old_class, std::string_view old_name, void const *new_guest, std::string_view new_class, std::string_view new_name)
Like check_unique_register, but for un-registering a guest.
Definition: util.cxx:75
pqxx::transaction_base::close
void close() noexcept
End transaction. To be called by implementing class' destructor.
Definition: transaction_base.cxx:328
pqxx::transaction_base::exec
result exec(std::string_view query, std::string_view desc=std::string_view{})
Execute query.
Definition: transaction_base.cxx:227
pqxx::transaction_base::register_transaction
void register_transaction()
Register this transaction with the connection.
Definition: transaction_base.cxx:86
pqxx::internal::begin_cmd
const zview begin_cmd
The SQL command for starting a given type of transaction.
pqxx::result
Result set containing data returned by a query or command.
Definition: result.hxx:71
pqxx::row::front
reference front() const noexcept
Definition: row.cxx:54