Enter the transaction or savepoint block.
(self)
| 94 | |
| 95 | @connresource.guarded |
| 96 | async def start(self): |
| 97 | """Enter the transaction or savepoint block.""" |
| 98 | self.__check_state_base('start') |
| 99 | if self._state is TransactionState.STARTED: |
| 100 | raise apg_errors.InterfaceError( |
| 101 | 'cannot start; the transaction is already started') |
| 102 | |
| 103 | con = self._connection |
| 104 | |
| 105 | if con._top_xact is None: |
| 106 | if con._protocol.is_in_transaction(): |
| 107 | raise apg_errors.InterfaceError( |
| 108 | 'cannot use Connection.transaction() in ' |
| 109 | 'a manually started transaction') |
| 110 | con._top_xact = self |
| 111 | else: |
| 112 | # Nested transaction block |
| 113 | if self._isolation: |
| 114 | top_xact_isolation = con._top_xact._isolation |
| 115 | if top_xact_isolation is None: |
| 116 | top_xact_isolation = ISOLATION_LEVELS_BY_VALUE[ |
| 117 | await self._connection.fetchval( |
| 118 | 'SHOW transaction_isolation;')] |
| 119 | if self._isolation != top_xact_isolation: |
| 120 | raise apg_errors.InterfaceError( |
| 121 | 'nested transaction has a different isolation level: ' |
| 122 | 'current {!r} != outer {!r}'.format( |
| 123 | self._isolation, top_xact_isolation)) |
| 124 | self._nested = True |
| 125 | |
| 126 | if self._nested: |
| 127 | self._id = con._get_unique_id('savepoint') |
| 128 | query = 'SAVEPOINT {};'.format(self._id) |
| 129 | else: |
| 130 | query = 'BEGIN' |
| 131 | if self._isolation == 'read_committed': |
| 132 | query += ' ISOLATION LEVEL READ COMMITTED' |
| 133 | elif self._isolation == 'read_uncommitted': |
| 134 | query += ' ISOLATION LEVEL READ UNCOMMITTED' |
| 135 | elif self._isolation == 'repeatable_read': |
| 136 | query += ' ISOLATION LEVEL REPEATABLE READ' |
| 137 | elif self._isolation == 'serializable': |
| 138 | query += ' ISOLATION LEVEL SERIALIZABLE' |
| 139 | if self._readonly: |
| 140 | query += ' READ ONLY' |
| 141 | if self._deferrable: |
| 142 | query += ' DEFERRABLE' |
| 143 | query += ';' |
| 144 | |
| 145 | try: |
| 146 | await self._connection.execute(query) |
| 147 | except BaseException: |
| 148 | self._state = TransactionState.FAILED |
| 149 | raise |
| 150 | else: |
| 151 | self._state = TransactionState.STARTED |
| 152 | |
| 153 | def __check_state_base(self, opname): |
no test coverage detected