File: //home/arjun/projects/aigenerator/venv/lib/python3.12/site-packages/psycopg/_connection_base.py
"""
psycopg connection objects
"""
# Copyright (C) 2020 The Psycopg Team
from __future__ import annotations
import sys
import logging
from typing import Callable, Generic, NamedTuple, TYPE_CHECKING
from weakref import ref, ReferenceType
from warnings import warn
from functools import partial
from . import pq
from . import errors as e
from . import postgres
from . import generators
from .abc import PQGen, PQGenConn, Query
from .sql import Composable, SQL
from ._tpc import Xid
from .rows import Row
from .adapt import AdaptersMap
from ._enums import IsolationLevel
from ._compat import LiteralString, Self, TypeAlias, TypeVar
from .pq.misc import connection_summary
from ._pipeline import BasePipeline
from ._preparing import PrepareManager
from ._capabilities import capabilities
from ._connection_info import ConnectionInfo
if TYPE_CHECKING:
from .pq.abc import PGconn, PGresult
from psycopg_pool.base import BasePool
# Row Type variable for Cursor (when it needs to be distinguished from the
# connection's one)
CursorRow = TypeVar("CursorRow")
TEXT = pq.Format.TEXT
BINARY = pq.Format.BINARY
OK = pq.ConnStatus.OK
BAD = pq.ConnStatus.BAD
COMMAND_OK = pq.ExecStatus.COMMAND_OK
TUPLES_OK = pq.ExecStatus.TUPLES_OK
FATAL_ERROR = pq.ExecStatus.FATAL_ERROR
IDLE = pq.TransactionStatus.IDLE
INTRANS = pq.TransactionStatus.INTRANS
_HAS_SEND_CLOSE = capabilities.has_send_close_prepared()
logger = logging.getLogger("psycopg")
class Notify(NamedTuple):
"""An asynchronous notification received from the database."""
channel: str
"""The name of the channel on which the notification was received."""
payload: str
"""The message attached to the notification."""
pid: int
"""The PID of the backend process which sent the notification."""
Notify.__module__ = "psycopg"
NoticeHandler: TypeAlias = Callable[[e.Diagnostic], None]
NotifyHandler: TypeAlias = Callable[[Notify], None]
class BaseConnection(Generic[Row]):
"""
Base class for different types of connections.
Share common functionalities such as access to the wrapped PGconn, but
allow different interfaces (sync/async).
"""
# DBAPI2 exposed exceptions
Warning = e.Warning
Error = e.Error
InterfaceError = e.InterfaceError
DatabaseError = e.DatabaseError
DataError = e.DataError
OperationalError = e.OperationalError
IntegrityError = e.IntegrityError
InternalError = e.InternalError
ProgrammingError = e.ProgrammingError
NotSupportedError = e.NotSupportedError
def __init__(self, pgconn: PGconn):
self.pgconn = pgconn
self._autocommit = False
# None, but set to a copy of the global adapters map as soon as requested.
self._adapters: AdaptersMap | None = None
self._notice_handlers: list[NoticeHandler] = []
self._notify_handlers: list[NotifyHandler] = []
# Number of transaction blocks currently entered
self._num_transactions = 0
self._closed = False # closed by an explicit close()
self._prepared: PrepareManager = PrepareManager()
self._tpc: tuple[Xid, bool] | None = None # xid, prepared
wself = ref(self)
pgconn.notice_handler = partial(BaseConnection._notice_handler, wself)
pgconn.notify_handler = partial(BaseConnection._notify_handler, wself)
# Attribute is only set if the connection is from a pool so we can tell
# apart a connection in the pool too (when _pool = None)
self._pool: BasePool | None
self._pipeline: BasePipeline | None = None
# Time after which the connection should be closed
self._expire_at: float
self._isolation_level: IsolationLevel | None = None
self._read_only: bool | None = None
self._deferrable: bool | None = None
self._begin_statement = b""
def __del__(self) -> None:
# If fails on connection we might not have this attribute yet
if not hasattr(self, "pgconn"):
return
# Connection correctly closed
if self.closed:
return
# Connection in a pool so terminating with the program is normal
if hasattr(self, "_pool"):
return
warn(
f"connection {self} was deleted while still open."
" Please use 'with' or '.close()' to close the connection",
ResourceWarning,
)
def __repr__(self) -> str:
cls = f"{self.__class__.__module__}.{self.__class__.__qualname__}"
info = connection_summary(self.pgconn)
return f"<{cls} {info} at 0x{id(self):x}>"
@property
def closed(self) -> bool:
"""`!True` if the connection is closed."""
return self.pgconn.status == BAD
@property
def broken(self) -> bool:
"""
`!True` if the connection was interrupted.
A broken connection is always `closed`, but wasn't closed in a clean
way, such as using `close()` or a `!with` block.
"""
return self.pgconn.status == BAD and not self._closed
@property
def autocommit(self) -> bool:
"""The autocommit state of the connection."""
return self._autocommit
@autocommit.setter
def autocommit(self, value: bool) -> None:
self._set_autocommit(value)
def _set_autocommit(self, value: bool) -> None:
raise NotImplementedError
def _set_autocommit_gen(self, value: bool) -> PQGen[None]:
yield from self._check_intrans_gen("autocommit")
self._autocommit = bool(value)
@property
def isolation_level(self) -> IsolationLevel | None:
"""
The isolation level of the new transactions started on the connection.
"""
return self._isolation_level
@isolation_level.setter
def isolation_level(self, value: IsolationLevel | None) -> None:
self._set_isolation_level(value)
def _set_isolation_level(self, value: IsolationLevel | None) -> None:
raise NotImplementedError
def _set_isolation_level_gen(self, value: IsolationLevel | None) -> PQGen[None]:
yield from self._check_intrans_gen("isolation_level")
self._isolation_level = IsolationLevel(value) if value is not None else None
self._begin_statement = b""
@property
def read_only(self) -> bool | None:
"""
The read-only state of the new transactions started on the connection.
"""
return self._read_only
@read_only.setter
def read_only(self, value: bool | None) -> None:
self._set_read_only(value)
def _set_read_only(self, value: bool | None) -> None:
raise NotImplementedError
def _set_read_only_gen(self, value: bool | None) -> PQGen[None]:
yield from self._check_intrans_gen("read_only")
self._read_only = bool(value) if value is not None else None
self._begin_statement = b""
@property
def deferrable(self) -> bool | None:
"""
The deferrable state of the new transactions started on the connection.
"""
return self._deferrable
@deferrable.setter
def deferrable(self, value: bool | None) -> None:
self._set_deferrable(value)
def _set_deferrable(self, value: bool | None) -> None:
raise NotImplementedError
def _set_deferrable_gen(self, value: bool | None) -> PQGen[None]:
yield from self._check_intrans_gen("deferrable")
self._deferrable = bool(value) if value is not None else None
self._begin_statement = b""
def _check_intrans_gen(self, attribute: str) -> PQGen[None]:
# Raise an exception if we are in a transaction
status = self.pgconn.transaction_status
if status == IDLE and self._pipeline:
yield from self._pipeline._sync_gen()
status = self.pgconn.transaction_status
if status != IDLE:
if self._num_transactions:
raise e.ProgrammingError(
f"can't change {attribute!r} now: "
"connection.transaction() context in progress"
)
else:
raise e.ProgrammingError(
f"can't change {attribute!r} now: "
"connection in transaction status "
f"{pq.TransactionStatus(status).name}"
)
@property
def info(self) -> ConnectionInfo:
"""A `ConnectionInfo` attribute to inspect connection properties."""
return ConnectionInfo(self.pgconn)
@property
def adapters(self) -> AdaptersMap:
if not self._adapters:
self._adapters = AdaptersMap(postgres.adapters)
return self._adapters
@property
def connection(self) -> BaseConnection[Row]:
# implement the AdaptContext protocol
return self
def fileno(self) -> int:
"""Return the file descriptor of the connection.
This function allows to use the connection as file-like object in
functions waiting for readiness, such as the ones defined in the
`selectors` module.
"""
return self.pgconn.socket
def cancel(self) -> None:
"""Cancel the current operation on the connection."""
if self._should_cancel():
c = self.pgconn.get_cancel()
c.cancel()
def _should_cancel(self) -> bool:
"""Check whether the current command should actually be cancelled when
invoking cancel*().
"""
# cancel() is a no-op if the connection is closed;
# this allows to use the method as callback handler without caring
# about its life.
if self.closed:
return False
if self._tpc and self._tpc[1]:
raise e.ProgrammingError(
"cancel() cannot be used with a prepared two-phase transaction"
)
return True
def _cancel_gen(self, *, timeout: float) -> PQGenConn[None]:
cancel_conn = self.pgconn.cancel_conn()
cancel_conn.start()
yield from generators.cancel(cancel_conn, timeout=timeout)
def add_notice_handler(self, callback: NoticeHandler) -> None:
"""
Register a callable to be invoked when a notice message is received.
:param callback: the callback to call upon message received.
:type callback: Callable[[~psycopg.errors.Diagnostic], None]
"""
self._notice_handlers.append(callback)
def remove_notice_handler(self, callback: NoticeHandler) -> None:
"""
Unregister a notice message callable previously registered.
:param callback: the callback to remove.
:type callback: Callable[[~psycopg.errors.Diagnostic], None]
"""
self._notice_handlers.remove(callback)
@staticmethod
def _notice_handler(
wself: ReferenceType[BaseConnection[Row]], res: PGresult
) -> None:
self = wself()
if not (self and self._notice_handlers):
return
diag = e.Diagnostic(res, self.pgconn._encoding)
for cb in self._notice_handlers:
try:
cb(diag)
except Exception as ex:
logger.exception("error processing notice callback '%s': %s", cb, ex)
def add_notify_handler(self, callback: NotifyHandler) -> None:
"""
Register a callable to be invoked whenever a notification is received.
:param callback: the callback to call upon notification received.
:type callback: Callable[[~psycopg.Notify], None]
"""
self._notify_handlers.append(callback)
def remove_notify_handler(self, callback: NotifyHandler) -> None:
"""
Unregister a notification callable previously registered.
:param callback: the callback to remove.
:type callback: Callable[[~psycopg.Notify], None]
"""
self._notify_handlers.remove(callback)
@staticmethod
def _notify_handler(
wself: ReferenceType[BaseConnection[Row]], pgn: pq.PGnotify
) -> None:
self = wself()
if not (self and self._notify_handlers):
return
enc = self.pgconn._encoding
n = Notify(pgn.relname.decode(enc), pgn.extra.decode(enc), pgn.be_pid)
for cb in self._notify_handlers:
cb(n)
@property
def prepare_threshold(self) -> int | None:
"""
Number of times a query is executed before it is prepared.
- If it is set to 0, every query is prepared the first time it is
executed.
- If it is set to `!None`, prepared statements are disabled on the
connection.
Default value: 5
"""
return self._prepared.prepare_threshold
@prepare_threshold.setter
def prepare_threshold(self, value: int | None) -> None:
self._prepared.prepare_threshold = value
@property
def prepared_max(self) -> int | None:
"""
Maximum number of prepared statements on the connection.
`!None` means no max number of prepared statements. The default value
is 100.
"""
rv = self._prepared.prepared_max
return rv if rv != sys.maxsize else None
@prepared_max.setter
def prepared_max(self, value: int | None) -> None:
if value is None:
value = sys.maxsize
self._prepared.prepared_max = value
# Generators to perform high-level operations on the connection
#
# These operations are expressed in terms of non-blocking generators
# and the task of waiting when needed (when the generators yield) is left
# to the connections subclass, which might wait either in blocking mode
# or through asyncio.
#
# All these generators assume exclusive access to the connection: subclasses
# should have a lock and hold it before calling and consuming them.
@classmethod
def _connect_gen(
cls, conninfo: str = "", *, timeout: float = 0.0
) -> PQGenConn[Self]:
"""Generator to connect to the database and create a new instance."""
pgconn = yield from generators.connect(conninfo, timeout=timeout)
conn = cls(pgconn)
return conn
def _exec_command(
self, command: Query, result_format: pq.Format = TEXT
) -> PQGen[PGresult | None]:
"""
Generator to send a command and receive the result to the backend.
Only used to implement internal commands such as "commit", with eventual
arguments bound client-side. The cursor can do more complex stuff.
"""
self._check_connection_ok()
if isinstance(command, str):
command = command.encode(self.pgconn._encoding)
elif isinstance(command, Composable):
command = command.as_bytes(self)
if self._pipeline:
cmd = partial(
self.pgconn.send_query_params,
command,
None,
result_format=result_format,
)
self._pipeline.command_queue.append(cmd)
self._pipeline.result_queue.append(None)
return None
# Unless needed, use the simple query protocol, e.g. to interact with
# pgbouncer. In pipeline mode we always use the advanced query protocol
# instead, see #350
if result_format == TEXT:
self.pgconn.send_query(command)
else:
self.pgconn.send_query_params(command, None, result_format=result_format)
result = (yield from generators.execute(self.pgconn))[-1]
if result.status != COMMAND_OK and result.status != TUPLES_OK:
if result.status == FATAL_ERROR:
raise e.error_from_result(result, encoding=self.pgconn._encoding)
else:
raise e.InterfaceError(
f"unexpected result {pq.ExecStatus(result.status).name}"
f" from command {command.decode()!r}"
)
return result
def _deallocate(self, name: bytes | None) -> PQGen[None]:
"""
Deallocate one, or all, prepared statement in the session.
``name == None`` stands for DEALLOCATE ALL.
If possible, use protocol-level commands; otherwise use SQL statements.
Note that PgBouncer doesn't support DEALLOCATE name, but it supports
protocol-level Close from 1.21 and DEALLOCATE ALL from 1.22.
"""
if name is None or not _HAS_SEND_CLOSE:
stmt = b"DEALLOCATE " + name if name is not None else b"DEALLOCATE ALL"
yield from self._exec_command(stmt)
return
self._check_connection_ok()
if self._pipeline:
cmd = partial(
self.pgconn.send_close_prepared,
name,
)
self._pipeline.command_queue.append(cmd)
self._pipeline.result_queue.append(None)
return
self.pgconn.send_close_prepared(name)
result = (yield from generators.execute(self.pgconn))[-1]
if result.status != COMMAND_OK:
if result.status == FATAL_ERROR:
raise e.error_from_result(result, encoding=self.pgconn._encoding)
else:
raise e.InterfaceError(
f"unexpected result {pq.ExecStatus(result.status).name}"
" from sending closing prepared statement message"
)
def _check_connection_ok(self) -> None:
if self.pgconn.status == OK:
return
if self.pgconn.status == BAD:
raise e.OperationalError("the connection is closed")
raise e.InterfaceError(
"cannot execute operations: the connection is"
f" in status {self.pgconn.status}"
)
def _start_query(self) -> PQGen[None]:
"""Generator to start a transaction if necessary."""
if self._autocommit:
return
if self.pgconn.transaction_status != IDLE:
return
yield from self._exec_command(self._get_tx_start_command())
if self._pipeline:
yield from self._pipeline._sync_gen()
def _get_tx_start_command(self) -> bytes:
if self._begin_statement:
return self._begin_statement
parts = [b"BEGIN"]
if self.isolation_level is not None:
val = IsolationLevel(self.isolation_level)
parts.append(b"ISOLATION LEVEL")
parts.append(val.name.replace("_", " ").encode())
if self.read_only is not None:
parts.append(b"READ ONLY" if self.read_only else b"READ WRITE")
if self.deferrable is not None:
parts.append(b"DEFERRABLE" if self.deferrable else b"NOT DEFERRABLE")
self._begin_statement = b" ".join(parts)
return self._begin_statement
def _commit_gen(self) -> PQGen[None]:
"""Generator implementing `Connection.commit()`."""
if self._num_transactions:
raise e.ProgrammingError(
"Explicit commit() forbidden within a Transaction "
"context. (Transaction will be automatically committed "
"on successful exit from context.)"
)
if self._tpc:
raise e.ProgrammingError(
"commit() cannot be used during a two-phase transaction"
)
if self.pgconn.transaction_status == IDLE:
return
yield from self._exec_command(b"COMMIT")
if self._pipeline:
yield from self._pipeline._sync_gen()
def _rollback_gen(self) -> PQGen[None]:
"""Generator implementing `Connection.rollback()`."""
if self._num_transactions:
raise e.ProgrammingError(
"Explicit rollback() forbidden within a Transaction "
"context. (Either raise Rollback() or allow "
"an exception to propagate out of the context.)"
)
if self._tpc:
raise e.ProgrammingError(
"rollback() cannot be used during a two-phase transaction"
)
# Get out of a "pipeline aborted" state
if self._pipeline:
yield from self._pipeline._sync_gen()
if self.pgconn.transaction_status == IDLE:
return
yield from self._exec_command(b"ROLLBACK")
self._prepared.clear()
yield from self._prepared.maintain_gen(self)
if self._pipeline:
yield from self._pipeline._sync_gen()
def xid(self, format_id: int, gtrid: str, bqual: str) -> Xid:
"""
Returns a `Xid` to pass to the `!tpc_*()` methods of this connection.
The argument types and constraints are explained in
:ref:`two-phase-commit`.
The values passed to the method will be available on the returned
object as the members `~Xid.format_id`, `~Xid.gtrid`, `~Xid.bqual`.
"""
self._check_tpc()
return Xid.from_parts(format_id, gtrid, bqual)
def _tpc_begin_gen(self, xid: Xid | str) -> PQGen[None]:
self._check_tpc()
if not isinstance(xid, Xid):
xid = Xid.from_string(xid)
if self.pgconn.transaction_status != IDLE:
raise e.ProgrammingError(
"can't start two-phase transaction: connection in status"
f" {pq.TransactionStatus(self.pgconn.transaction_status).name}"
)
if self._autocommit:
raise e.ProgrammingError(
"can't use two-phase transactions in autocommit mode"
)
self._tpc = (xid, False)
yield from self._exec_command(self._get_tx_start_command())
def _tpc_prepare_gen(self) -> PQGen[None]:
if not self._tpc:
raise e.ProgrammingError(
"'tpc_prepare()' must be called inside a two-phase transaction"
)
if self._tpc[1]:
raise e.ProgrammingError(
"'tpc_prepare()' cannot be used during a prepared two-phase transaction"
)
xid = self._tpc[0]
self._tpc = (xid, True)
yield from self._exec_command(SQL("PREPARE TRANSACTION {}").format(str(xid)))
if self._pipeline:
yield from self._pipeline._sync_gen()
def _tpc_finish_gen(
self, action: LiteralString, xid: Xid | str | None
) -> PQGen[None]:
fname = f"tpc_{action.lower()}()"
if xid is None:
if not self._tpc:
raise e.ProgrammingError(
f"{fname} without xid must must be"
" called inside a two-phase transaction"
)
xid = self._tpc[0]
else:
if self._tpc:
raise e.ProgrammingError(
f"{fname} with xid must must be called"
" outside a two-phase transaction"
)
if not isinstance(xid, Xid):
xid = Xid.from_string(xid)
if self._tpc and not self._tpc[1]:
meth: Callable[[], PQGen[None]]
meth = getattr(self, f"_{action.lower()}_gen")
self._tpc = None
yield from meth()
else:
yield from self._exec_command(
SQL("{} PREPARED {}").format(SQL(action), str(xid))
)
self._tpc = None
def _check_tpc(self) -> None:
"""Raise NotSupportedError if TPC is not supported."""
# TPC supported on every supported PostgreSQL version.
pass