Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/sqlalchemy/engine/util.py: 60%

1# engine/util.py 

2# Copyright (C) 2005-2024 the SQLAlchemy authors and contributors 

3# <see AUTHORS file> 

4# 

5# This module is part of SQLAlchemy and is released under 

6# the MIT License: https://www.opensource.org/licenses/mit-license.php 

7 

8from __future__ import annotations 

9 

10from typing import Any 

11from typing import Callable 

12from typing import Optional 

13from typing import Protocol 

14from typing import TypeVar 

15 

16from ._util_cy import _distill_params_20 as _distill_params_20 # noqa: F401 

17from ._util_cy import _distill_raw_params as _distill_raw_params # noqa: F401 

18from .. import exc 

19from .. import util 

20from ..util.typing import Self 

21 

22_C = TypeVar("_C", bound=Callable[[], Any]) 

23 

24 

25def connection_memoize(key: str) -> Callable[[_C], _C]: 

26 """Decorator, memoize a function in a connection.info stash. 

27 

28 Only applicable to functions which take no arguments other than a 

29 connection. The memo will be stored in ``connection.info[key]``. 

30 """ 

31 

32 @util.decorator 

33 def decorated(fn, self, connection): # type: ignore 

34 connection = connection.connect() 

35 try: 

36 return connection.info[key] 

37 except KeyError: 

38 connection.info[key] = val = fn(self, connection) 

39 return val 

40 

41 return decorated 

42 

43 

44class _TConsSubject(Protocol): 

45 _trans_context_manager: Optional[TransactionalContext] 

46 

47 

48class TransactionalContext: 

49 """Apply Python context manager behavior to transaction objects. 

50 

51 Performs validation to ensure the subject of the transaction is not 

52 used if the transaction were ended prematurely. 

53 

54 """ 

55 

56 __slots__ = ("_outer_trans_ctx", "_trans_subject", "__weakref__") 

57 

58 _trans_subject: Optional[_TConsSubject] 

59 

60 def _transaction_is_active(self) -> bool: 

61 raise NotImplementedError() 

62 

63 def _transaction_is_closed(self) -> bool: 

64 raise NotImplementedError() 

65 

66 def _rollback_can_be_called(self) -> bool: 

67 """indicates the object is in a state that is known to be acceptable 

68 for rollback() to be called. 

69 

70 This does not necessarily mean rollback() will succeed or not raise 

71 an error, just that there is currently no state detected that indicates 

72 rollback() would fail or emit warnings. 

73 

74 It also does not mean that there's a transaction in progress, as 

75 it is usually safe to call rollback() even if no transaction is 

76 present. 

77 

78 .. versionadded:: 1.4.28 

79 

80 """ 

81 raise NotImplementedError() 

82 

83 def _get_subject(self) -> _TConsSubject: 

84 raise NotImplementedError() 

85 

86 def commit(self) -> None: 

87 raise NotImplementedError() 

88 

89 def rollback(self) -> None: 

90 raise NotImplementedError() 

91 

92 def close(self) -> None: 

93 raise NotImplementedError() 

94 

95 @classmethod 

96 def _trans_ctx_check(cls, subject: _TConsSubject) -> None: 

97 trans_context = subject._trans_context_manager 

98 if trans_context: 

99 if not trans_context._transaction_is_active(): 

100 raise exc.InvalidRequestError( 

101 "Can't operate on closed transaction inside context " 

102 "manager. Please complete the context manager " 

103 "before emitting further commands." 

104 ) 

105 

106 def __enter__(self) -> Self: 

107 subject = self._get_subject() 

108 

109 # none for outer transaction, may be non-None for nested 

110 # savepoint, legacy nesting cases 

111 trans_context = subject._trans_context_manager 

112 self._outer_trans_ctx = trans_context 

113 

114 self._trans_subject = subject 

115 subject._trans_context_manager = self 

116 return self 

117 

118 def __exit__(self, type_: Any, value: Any, traceback: Any) -> None: 

119 subject = getattr(self, "_trans_subject", None) 

120 

121 # simplistically we could assume that 

122 # "subject._trans_context_manager is self". However, any calling 

123 # code that is manipulating __exit__ directly would break this 

124 # assumption. alembic context manager 

125 # is an example of partial use that just calls __exit__ and 

126 # not __enter__ at the moment. it's safe to assume this is being done 

127 # in the wild also 

128 out_of_band_exit = ( 

129 subject is None or subject._trans_context_manager is not self 

130 ) 

131 

132 if type_ is None and self._transaction_is_active(): 

133 try: 

134 self.commit() 

135 except: 

136 with util.safe_reraise(): 

137 if self._rollback_can_be_called(): 

138 self.rollback() 

139 finally: 

140 if not out_of_band_exit: 

141 assert subject is not None 

142 subject._trans_context_manager = self._outer_trans_ctx 

143 self._trans_subject = self._outer_trans_ctx = None 

144 else: 

145 try: 

146 if not self._transaction_is_active(): 

147 if not self._transaction_is_closed(): 

148 self.close() 

149 else: 

150 if self._rollback_can_be_called(): 

151 self.rollback() 

152 finally: 

153 if not out_of_band_exit: 

154 assert subject is not None 

155 subject._trans_context_manager = self._outer_trans_ctx 

156 self._trans_subject = self._outer_trans_ctx = None