# log.py
# Copyright (C) 2006-2025 the SQLAlchemy authors and contributors
# <see AUTHORS file>
# Includes alterations by Vinay Sajip vinay_sajip@yahoo.co.uk
#
# This module is part of SQLAlchemy and is released under
# the MIT License: https://www.opensource.org/licenses/mit-license.php
"""Logging control and utilities.
Control of logging for SA can be performed from the regular python logging
module. The regular dotted module namespace is used, starting at
'sqlalchemy'. For class-level logging, the class name is appended.
The "echo" keyword parameter, available on SQLA :class:`_engine.Engine`
and :class:`_pool.Pool` objects, corresponds to a logger specific to that
instance only.
"""
from __future__ import annotations
import logging
import sys
from typing import Any
from typing import Optional
from typing import overload
from typing import Set
from typing import Type
from typing import TypeVar
from typing import Union
from .util import py311
from .util import py38
from .util.typing import Literal
if py38:
STACKLEVEL = True
# needed as of py3.11.0b1
# #8019
STACKLEVEL_OFFSET = 2 if py311 else 1
else:
STACKLEVEL = False
STACKLEVEL_OFFSET = 0
_IT = TypeVar("_IT", bound="Identified")
_EchoFlagType = Union[None, bool, Literal["debug"]]
# set initial level to WARN. This so that
# log statements don't occur in the absence of explicit
# logging being enabled for 'sqlalchemy'.
rootlogger = logging.getLogger("sqlalchemy")
if rootlogger.level == logging.NOTSET:
rootlogger.setLevel(logging.WARN)
def _add_default_handler(logger: logging.Logger) -> None:
handler = logging.StreamHandler(sys.stdout)
handler.setFormatter(
logging.Formatter("%(asctime)s %(levelname)s %(name)s %(message)s")
)
logger.addHandler(handler)
_logged_classes: Set[Type[Identified]] = set()
def _qual_logger_name_for_cls(cls: Type[Identified]) -> str:
return (
getattr(cls, "_sqla_logger_namespace", None)
or cls.__module__ + "." + cls.__name__
)
def class_logger(cls: Type[_IT]) -> Type[_IT]:
logger = logging.getLogger(_qual_logger_name_for_cls(cls))
cls._should_log_debug = lambda self: logger.isEnabledFor( # type: ignore[method-assign] # noqa: E501
logging.DEBUG
)
cls._should_log_info = lambda self: logger.isEnabledFor( # type: ignore[method-assign] # noqa: E501
logging.INFO
)
cls.logger = logger
_logged_classes.add(cls)
return cls
_IdentifiedLoggerType = Union[logging.Logger, "InstanceLogger"]
class Identified:
__slots__ = ()
logging_name: Optional[str] = None
logger: _IdentifiedLoggerType
_echo: _EchoFlagType
def _should_log_debug(self) -> bool:
return self.logger.isEnabledFor(logging.DEBUG)
def _should_log_info(self) -> bool:
return self.logger.isEnabledFor(logging.INFO)
class InstanceLogger:
"""A logger adapter (wrapper) for :class:`.Identified` subclasses.
This allows multiple instances (e.g. Engine or Pool instances)
to share a logger, but have its verbosity controlled on a
per-instance basis.
The basic functionality is to return a logging level
which is based on an instance's echo setting.
Default implementation is:
'debug' -> logging.DEBUG
True -> logging.INFO
False -> Effective level of underlying logger (
logging.WARNING by default)
None -> same as False
"""
# Map echo settings to logger levels
_echo_map = {
None: logging.NOTSET,
False: logging.NOTSET,
True: logging.INFO,
"debug": logging.DEBUG,
}
_echo: _EchoFlagType
__slots__ = ("echo", "logger")
def __init__(self, echo: _EchoFlagType, name: str):
self.echo = echo
self.logger = logging.getLogger(name)
# if echo flag is enabled and no handlers,
# add a handler to the list
if self._echo_map[echo] <= logging.INFO and not self.logger.handlers:
_add_default_handler(self.logger)
#
# Boilerplate convenience methods
#
def debug(self, msg: str, *args: Any, **kwargs: Any) -> None:
"""Delegate a debug call to the underlying logger."""
self.log(logging.DEBUG, msg, *args, **kwargs)
def info(self, msg: str, *args: Any, **kwargs: Any) -> None:
"""Delegate an info call to the underlying logger."""
self.log(logging.INFO, msg, *args, **kwargs)
def warning(self, msg: str, *args: Any, **kwargs: Any) -> None:
"""Delegate a warning call to the underlying logger."""
self.log(logging.WARNING, msg, *args, **kwargs)
warn = warning
def error(self, msg: str, *args: Any, **kwargs: Any) -> None:
"""
Delegate an error call to the underlying logger.
"""
self.log(logging.ERROR, msg, *args, **kwargs)
def exception(self, msg: str, *args: Any, **kwargs: Any) -> None:
"""Delegate an exception call to the underlying logger."""
kwargs["exc_info"] = 1
self.log(logging.ERROR, msg, *args, **kwargs)
def critical(self, msg: str, *args: Any, **kwargs: Any) -> None:
"""Delegate a critical call to the underlying logger."""
self.log(logging.CRITICAL, msg, *args, **kwargs)
def log(self, level: int, msg: str, *args: Any, **kwargs: Any) -> None:
"""Delegate a log call to the underlying logger.
The level here is determined by the echo
flag as well as that of the underlying logger, and
logger._log() is called directly.
"""
# inline the logic from isEnabledFor(),
# getEffectiveLevel(), to avoid overhead.
if self.logger.manager.disable >= level:
return
selected_level = self._echo_map[self.echo]
if selected_level == logging.NOTSET:
selected_level = self.logger.getEffectiveLevel()
if level >= selected_level:
if STACKLEVEL:
kwargs["stacklevel"] = (
kwargs.get("stacklevel", 1) + STACKLEVEL_OFFSET
)
self.logger._log(level, msg, args, **kwargs)
def isEnabledFor(self, level: int) -> bool:
"""Is this logger enabled for level 'level'?"""
if self.logger.manager.disable >= level:
return False
return level >= self.getEffectiveLevel()
def getEffectiveLevel(self) -> int:
"""What's the effective level for this logger?"""
level = self._echo_map[self.echo]
if level == logging.NOTSET:
level = self.logger.getEffectiveLevel()
return level
def instance_logger(
instance: Identified, echoflag: _EchoFlagType = None
) -> None:
"""create a logger for an instance that implements :class:`.Identified`."""
if instance.logging_name:
name = "%s.%s" % (
_qual_logger_name_for_cls(instance.__class__),
instance.logging_name,
)
else:
name = _qual_logger_name_for_cls(instance.__class__)
instance._echo = echoflag # type: ignore
logger: Union[logging.Logger, InstanceLogger]
if echoflag in (False, None):
# if no echo setting or False, return a Logger directly,
# avoiding overhead of filtering
logger = logging.getLogger(name)
else:
# if a specified echo flag, return an EchoLogger,
# which checks the flag, overrides normal log
# levels by calling logger._log()
logger = InstanceLogger(echoflag, name)
instance.logger = logger # type: ignore
class echo_property:
__doc__ = """\
When ``True``, enable log output for this element.
This has the effect of setting the Python logging level for the namespace
of this element's class and object reference. A value of boolean ``True``
indicates that the loglevel ``logging.INFO`` will be set for the logger,
whereas the string value ``debug`` will set the loglevel to
``logging.DEBUG``.
"""
@overload
def __get__(
self, instance: Literal[None], owner: Type[Identified]
) -> echo_property: ...
@overload
def __get__(
self, instance: Identified, owner: Type[Identified]
) -> _EchoFlagType: ...
def __get__(
self, instance: Optional[Identified], owner: Type[Identified]
) -> Union[echo_property, _EchoFlagType]:
if instance is None:
return self
else:
return instance._echo
def __set__(self, instance: Identified, value: _EchoFlagType) -> None:
instance_logger(instance, echoflag=value)
