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* #197 Add transaction model aiopg * add docs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,191 @@ | ||
| import asyncio | ||
| import enum | ||
| import uuid | ||
| import warnings | ||
| from abc import ABC, abstractmethod | ||
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| import psycopg2 | ||
| from aiopg.utils import PY_35, _TransactionPointContextManager | ||
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| __all__ = ('IsolationLevel', 'Transaction') | ||
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| class IsolationCompiler(ABC): | ||
| name = '' | ||
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| __slots__ = ('_readonly', '_deferrable') | ||
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| def __init__(self, readonly, deferrable): | ||
| self._readonly = readonly | ||
| self._deferrable = deferrable | ||
| self._check_readonly_deferrable() | ||
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| def _check_readonly_deferrable(self): | ||
| available = self._readonly or self._deferrable | ||
| if not isinstance(self, SerializableCompiler) and available: | ||
| raise ValueError('Is only available for serializable transactions') | ||
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| def savepoint(self, unique_id): | ||
| return 'SAVEPOINT {}'.format(unique_id) | ||
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| def release_savepoint(self, unique_id): | ||
| return 'RELEASE SAVEPOINT {}'.format(unique_id) | ||
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| def rollback_savepoint(self, unique_id): | ||
| return 'ROLLBACK TO SAVEPOINT {}'.format(unique_id) | ||
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| def commit(self): | ||
| return 'COMMIT' | ||
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| def rollback(self): | ||
| return 'ROLLBACK' | ||
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| @abstractmethod | ||
| def begin(self): | ||
| raise NotImplementedError("Please Implement this method") | ||
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| def __repr__(self): | ||
| return self.name | ||
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| class ReadCommittedCompiler(IsolationCompiler): | ||
| name = 'Read committed' | ||
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| def begin(self): | ||
| return 'BEGIN' | ||
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| class RepeatableReadCompiler(IsolationCompiler): | ||
| name = 'Repeatable read' | ||
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| def begin(self): | ||
| return 'BEGIN ISOLATION LEVEL REPEATABLE READ' | ||
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| class SerializableCompiler(IsolationCompiler): | ||
| name = 'Serializable' | ||
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| def begin(self): | ||
| query = 'BEGIN ISOLATION LEVEL SERIALIZABLE' | ||
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| if self._readonly: | ||
| query += ' READ ONLY' | ||
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| if self._deferrable: | ||
| query += ' DEFERRABLE' | ||
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| return query | ||
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| class IsolationLevel(enum.Enum): | ||
| serializable = SerializableCompiler | ||
| repeatable_read = RepeatableReadCompiler | ||
| read_committed = ReadCommittedCompiler | ||
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| def __call__(self, readonly, deferrable): | ||
| return self.value(readonly, deferrable) | ||
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| class Transaction: | ||
| __slots__ = ('_cur', '_is_begin', '_isolation', '_unique_id') | ||
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| def __init__(self, cur, isolation_level, | ||
| readonly=False, deferrable=False): | ||
| self._cur = cur | ||
| self._is_begin = False | ||
| self._unique_id = None | ||
| self._isolation = isolation_level(readonly, deferrable) | ||
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| @property | ||
| def is_begin(self): | ||
| return self._is_begin | ||
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| @asyncio.coroutine | ||
| def begin(self): | ||
| if self._is_begin: | ||
| raise psycopg2.ProgrammingError( | ||
| 'You are trying to open a new transaction, use the save point') | ||
| self._is_begin = True | ||
| yield from self._cur.execute(self._isolation.begin()) | ||
| return self | ||
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| @asyncio.coroutine | ||
| def commit(self): | ||
| self._check_commit_rollback() | ||
| yield from self._cur.execute(self._isolation.commit()) | ||
| self._is_begin = False | ||
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| @asyncio.coroutine | ||
| def rollback(self): | ||
| self._check_commit_rollback() | ||
| yield from self._cur.execute(self._isolation.rollback()) | ||
| self._is_begin = False | ||
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| @asyncio.coroutine | ||
| def rollback_savepoint(self): | ||
| self._check_release_rollback() | ||
| yield from self._cur.execute( | ||
| self._isolation.rollback_savepoint(self._unique_id)) | ||
| self._unique_id = None | ||
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| @asyncio.coroutine | ||
| def release_savepoint(self): | ||
| self._check_release_rollback() | ||
| yield from self._cur.execute( | ||
| self._isolation.release_savepoint(self._unique_id)) | ||
| self._unique_id = None | ||
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| @asyncio.coroutine | ||
| def savepoint(self): | ||
| self._check_commit_rollback() | ||
| if self._unique_id is not None: | ||
| raise psycopg2.ProgrammingError('You do not shut down savepoint') | ||
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| self._unique_id = 's{}'.format(uuid.uuid1().hex) | ||
| yield from self._cur.execute( | ||
| self._isolation.savepoint(self._unique_id)) | ||
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| return self | ||
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| def point(self): | ||
| return _TransactionPointContextManager(self.savepoint()) | ||
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| def _check_commit_rollback(self): | ||
| if not self._is_begin: | ||
| raise psycopg2.ProgrammingError('You are trying to commit ' | ||
| 'the transaction does not open') | ||
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| def _check_release_rollback(self): | ||
| self._check_commit_rollback() | ||
| if self._unique_id is None: | ||
| raise psycopg2.ProgrammingError('You do not start savepoint') | ||
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| def __repr__(self): | ||
| return "<{} transaction={} id={:#x}>".format( | ||
| self.__class__.__name__, | ||
| self._isolation, | ||
| id(self) | ||
| ) | ||
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| def __del__(self): | ||
| if self._is_begin: | ||
| warnings.warn( | ||
| "You have not closed transaction {!r}".format(self), | ||
| ResourceWarning) | ||
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| if self._unique_id is not None: | ||
| warnings.warn( | ||
| "You have not closed savepoint {!r}".format(self), | ||
| ResourceWarning) | ||
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| if PY_35: | ||
| @asyncio.coroutine | ||
| def __aenter__(self): | ||
| return (yield from self.begin()) | ||
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| @asyncio.coroutine | ||
| def __aexit__(self, exc_type, exc, tb): | ||
| if exc_type is not None: | ||
| yield from self.rollback() | ||
| else: | ||
| yield from self.commit() |
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