250 lines
7.7 KiB
Python
250 lines
7.7 KiB
Python
"""
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psycopg async cursor objects
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"""
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# Copyright (C) 2020 The Psycopg Team
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from types import TracebackType
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from typing import Any, AsyncIterator, Iterable, List
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from typing import Optional, Type, TypeVar, TYPE_CHECKING, overload
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from contextlib import asynccontextmanager
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from . import pq
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from . import errors as e
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from .abc import Query, Params
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from .copy import AsyncCopy, AsyncWriter as AsyncCopyWriter
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from .rows import Row, RowMaker, AsyncRowFactory
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from .cursor import BaseCursor
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from ._pipeline import Pipeline
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if TYPE_CHECKING:
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from .connection_async import AsyncConnection
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ACTIVE = pq.TransactionStatus.ACTIVE
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class AsyncCursor(BaseCursor["AsyncConnection[Any]", Row]):
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__module__ = "psycopg"
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__slots__ = ()
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_Self = TypeVar("_Self", bound="AsyncCursor[Any]")
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@overload
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def __init__(self: "AsyncCursor[Row]", connection: "AsyncConnection[Row]"):
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...
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@overload
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def __init__(
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self: "AsyncCursor[Row]",
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connection: "AsyncConnection[Any]",
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*,
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row_factory: AsyncRowFactory[Row],
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):
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...
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def __init__(
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self,
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connection: "AsyncConnection[Any]",
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*,
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row_factory: Optional[AsyncRowFactory[Row]] = None,
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):
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super().__init__(connection)
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self._row_factory = row_factory or connection.row_factory
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async def __aenter__(self: _Self) -> _Self:
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return self
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async def __aexit__(
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self,
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exc_type: Optional[Type[BaseException]],
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exc_val: Optional[BaseException],
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exc_tb: Optional[TracebackType],
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) -> None:
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await self.close()
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async def close(self) -> None:
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self._close()
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@property
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def row_factory(self) -> AsyncRowFactory[Row]:
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return self._row_factory
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@row_factory.setter
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def row_factory(self, row_factory: AsyncRowFactory[Row]) -> None:
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self._row_factory = row_factory
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if self.pgresult:
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self._make_row = row_factory(self)
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def _make_row_maker(self) -> RowMaker[Row]:
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return self._row_factory(self)
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async def execute(
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self: _Self,
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query: Query,
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params: Optional[Params] = None,
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*,
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prepare: Optional[bool] = None,
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binary: Optional[bool] = None,
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) -> _Self:
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try:
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async with self._conn.lock:
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await self._conn.wait(
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self._execute_gen(query, params, prepare=prepare, binary=binary)
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)
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except e._NO_TRACEBACK as ex:
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raise ex.with_traceback(None)
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return self
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async def executemany(
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self,
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query: Query,
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params_seq: Iterable[Params],
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*,
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returning: bool = False,
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) -> None:
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try:
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if Pipeline.is_supported():
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# If there is already a pipeline, ride it, in order to avoid
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# sending unnecessary Sync.
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async with self._conn.lock:
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p = self._conn._pipeline
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if p:
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await self._conn.wait(
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self._executemany_gen_pipeline(query, params_seq, returning)
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)
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# Otherwise, make a new one
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if not p:
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async with self._conn.pipeline(), self._conn.lock:
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await self._conn.wait(
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self._executemany_gen_pipeline(query, params_seq, returning)
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)
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else:
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await self._conn.wait(
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self._executemany_gen_no_pipeline(query, params_seq, returning)
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)
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except e._NO_TRACEBACK as ex:
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raise ex.with_traceback(None)
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async def stream(
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self,
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query: Query,
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params: Optional[Params] = None,
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*,
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binary: Optional[bool] = None,
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) -> AsyncIterator[Row]:
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if self._pgconn.pipeline_status:
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raise e.ProgrammingError("stream() cannot be used in pipeline mode")
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async with self._conn.lock:
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try:
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await self._conn.wait(
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self._stream_send_gen(query, params, binary=binary)
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)
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first = True
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while await self._conn.wait(self._stream_fetchone_gen(first)):
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# We know that, if we got a result, it has a single row.
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rec: Row = self._tx.load_row(0, self._make_row) # type: ignore
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yield rec
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first = False
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except e._NO_TRACEBACK as ex:
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raise ex.with_traceback(None)
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finally:
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if self._pgconn.transaction_status == ACTIVE:
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# Try to cancel the query, then consume the results
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# already received.
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self._conn.cancel()
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try:
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while await self._conn.wait(
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self._stream_fetchone_gen(first=False)
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):
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pass
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except Exception:
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pass
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# Try to get out of ACTIVE state. Just do a single attempt, which
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# should work to recover from an error or query cancelled.
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try:
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await self._conn.wait(self._stream_fetchone_gen(first=False))
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except Exception:
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pass
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async def fetchone(self) -> Optional[Row]:
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await self._fetch_pipeline()
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self._check_result_for_fetch()
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record = self._tx.load_row(self._pos, self._make_row)
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if record is not None:
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self._pos += 1
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return record
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async def fetchmany(self, size: int = 0) -> List[Row]:
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await self._fetch_pipeline()
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self._check_result_for_fetch()
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assert self.pgresult
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if not size:
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size = self.arraysize
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records = self._tx.load_rows(
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self._pos,
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min(self._pos + size, self.pgresult.ntuples),
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self._make_row,
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)
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self._pos += len(records)
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return records
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async def fetchall(self) -> List[Row]:
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await self._fetch_pipeline()
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self._check_result_for_fetch()
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assert self.pgresult
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records = self._tx.load_rows(self._pos, self.pgresult.ntuples, self._make_row)
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self._pos = self.pgresult.ntuples
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return records
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async def __aiter__(self) -> AsyncIterator[Row]:
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await self._fetch_pipeline()
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self._check_result_for_fetch()
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def load(pos: int) -> Optional[Row]:
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return self._tx.load_row(pos, self._make_row)
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while True:
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row = load(self._pos)
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if row is None:
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break
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self._pos += 1
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yield row
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async def scroll(self, value: int, mode: str = "relative") -> None:
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self._scroll(value, mode)
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@asynccontextmanager
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async def copy(
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self,
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statement: Query,
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params: Optional[Params] = None,
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*,
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writer: Optional[AsyncCopyWriter] = None,
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) -> AsyncIterator[AsyncCopy]:
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"""
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:rtype: AsyncCopy
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"""
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try:
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async with self._conn.lock:
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await self._conn.wait(self._start_copy_gen(statement, params))
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async with AsyncCopy(self, writer=writer) as copy:
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yield copy
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except e._NO_TRACEBACK as ex:
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raise ex.with_traceback(None)
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self._select_current_result(0)
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async def _fetch_pipeline(self) -> None:
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if (
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self._execmany_returning is not False
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and not self.pgresult
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and self._conn._pipeline
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):
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async with self._conn.lock:
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await self._conn.wait(self._conn._pipeline._fetch_gen(flush=True))
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