"""
See the :class:`Logger` class.
"""
import gzip
import os
import pathlib
from abc import ABC, abstractmethod
from datetime import datetime
from types import TracebackType
from typing import Any, Callable, Dict, Literal, Optional, Set, Tuple, Type, cast
from typing_extensions import Self
from .._entry_points import read_entry_points
from ..listener import Listener
from ..message import Message
from ..typechecking import AcceptedIOType, FileLike, StringPathLike
from .asc import ASCWriter
from .blf import BLFWriter
from .canutils import CanutilsLogWriter
from .csv import CSVWriter
from .generic import (
BaseIOHandler,
BinaryIOMessageWriter,
FileIOMessageWriter,
MessageWriter,
)
from .mf4 import MF4Writer
from .printer import Printer
from .sqlite import SqliteWriter
from .trc import TRCWriter
[docs]
class Logger(MessageWriter):
"""
Logs CAN messages to a file.
The format is determined from the file suffix which can be one of:
* .asc: :class:`can.ASCWriter`
* .blf :class:`can.BLFWriter`
* .csv: :class:`can.CSVWriter`
* .db: :class:`can.SqliteWriter`
* .log :class:`can.CanutilsLogWriter`
* .trc :class:`can.TRCWriter`
* .txt :class:`can.Printer`
* .mf4 :class:`can.MF4Writer` (optional, depends on asammdf)
Any of these formats can be used with gzip compression by appending
the suffix .gz (e.g. filename.asc.gz). However, third-party tools might not
be able to read these files.
The **filename** may also be *None*, to fall back to :class:`can.Printer`.
The log files may be incomplete until `stop()` is called due to buffering.
.. note::
This class itself is just a dispatcher, and any positional and keyword
arguments are passed on to the returned instance.
"""
fetched_plugins = False
message_writers: Dict[str, Type[MessageWriter]] = {
".asc": ASCWriter,
".blf": BLFWriter,
".csv": CSVWriter,
".db": SqliteWriter,
".log": CanutilsLogWriter,
".mf4": MF4Writer,
".trc": TRCWriter,
".txt": Printer,
}
@staticmethod
def __new__( # type: ignore
cls: Any, filename: Optional[StringPathLike], **kwargs: Any
) -> MessageWriter:
"""
:param filename:
the filename/path of the file to write to,
may be a path-like object or None to
instantiate a :class:`~can.Printer`
:raises ValueError:
if the filename's suffix is of an unknown file type
"""
if filename is None:
return Printer(**kwargs)
if not Logger.fetched_plugins:
Logger.message_writers.update(
{
writer.key: cast(Type[MessageWriter], writer.load())
for writer in read_entry_points("can.io.message_writer")
}
)
Logger.fetched_plugins = True
suffix = pathlib.PurePath(filename).suffix.lower()
file_or_filename: AcceptedIOType = filename
if suffix == ".gz":
logger_type, file_or_filename = Logger.compress(filename, **kwargs)
else:
logger_type = cls._get_logger_for_suffix(suffix)
return logger_type(file=file_or_filename, **kwargs)
@classmethod
def _get_logger_for_suffix(cls, suffix: str) -> Type[MessageWriter]:
try:
logger_type = Logger.message_writers[suffix]
if logger_type is None:
raise ValueError(f'failed to import logger for extension "{suffix}"')
return logger_type
except KeyError:
raise ValueError(
f'No write support for this unknown log format "{suffix}"'
) from None
[docs]
@classmethod
def compress(
cls, filename: StringPathLike, **kwargs: Any
) -> Tuple[Type[MessageWriter], FileLike]:
"""
Return the suffix and io object of the decompressed file.
File will automatically recompress upon close.
"""
real_suffix = pathlib.Path(filename).suffixes[-2].lower()
if real_suffix in (".blf", ".db"):
raise ValueError(
f"The file type {real_suffix} is currently incompatible with gzip."
)
logger_type = cls._get_logger_for_suffix(real_suffix)
append = kwargs.get("append", False)
if issubclass(logger_type, BinaryIOMessageWriter):
mode = "ab" if append else "wb"
else:
mode = "at" if append else "wt"
return logger_type, gzip.open(filename, mode)
[docs]
def on_message_received(self, msg: Message) -> None:
pass
[docs]
class BaseRotatingLogger(Listener, BaseIOHandler, ABC):
"""
Base class for rotating CAN loggers. This class is not meant to be
instantiated directly. Subclasses must implement the :meth:`should_rollover`
and :meth:`do_rollover` methods according to their rotation strategy.
The rotation behavior can be further customized by the user by setting
the :attr:`namer` and :attr:`rotator` attributes after instantiating the subclass.
These attributes as well as the methods :meth:`rotation_filename` and :meth:`rotate`
and the corresponding docstrings are carried over from the python builtin
:class:`~logging.handlers.BaseRotatingHandler`.
Subclasses must set the `_writer` attribute upon initialization.
"""
_supported_formats: Set[str] = set()
#: If this attribute is set to a callable, the :meth:`~BaseRotatingLogger.rotation_filename`
#: method delegates to this callable. The parameters passed to the callable are
#: those passed to :meth:`~BaseRotatingLogger.rotation_filename`.
namer: Optional[Callable[[StringPathLike], StringPathLike]] = None
#: If this attribute is set to a callable, the :meth:`~BaseRotatingLogger.rotate` method
#: delegates to this callable. The parameters passed to the callable are those
#: passed to :meth:`~BaseRotatingLogger.rotate`.
rotator: Optional[Callable[[StringPathLike, StringPathLike], None]] = None
#: An integer counter to track the number of rollovers.
rollover_count: int = 0
def __init__(self, **kwargs: Any) -> None:
Listener.__init__(self)
BaseIOHandler.__init__(self, file=None)
self.writer_kwargs = kwargs
# Expected to be set by the subclass
self._writer: FileIOMessageWriter = None # type: ignore
@property
def writer(self) -> FileIOMessageWriter:
"""This attribute holds an instance of a writer class which manages the actual file IO."""
return self._writer
[docs]
def rotation_filename(self, default_name: StringPathLike) -> StringPathLike:
"""Modify the filename of a log file when rotating.
This is provided so that a custom filename can be provided.
The default implementation calls the :attr:`namer` attribute of the
handler, if it's callable, passing the default name to
it. If the attribute isn't callable (the default is :obj:`None`), the name
is returned unchanged.
:param default_name:
The default name for the log file.
"""
if not callable(self.namer):
return default_name
return self.namer(default_name) # pylint: disable=not-callable
[docs]
def rotate(self, source: StringPathLike, dest: StringPathLike) -> None:
"""When rotating, rotate the current log.
The default implementation calls the :attr:`rotator` attribute of the
handler, if it's callable, passing the `source` and `dest` arguments to
it. If the attribute isn't callable (the default is :obj:`None`), the source
is simply renamed to the destination.
:param source:
The source filename. This is normally the base
filename, e.g. `"test.log"`
:param dest:
The destination filename. This is normally
what the source is rotated to, e.g. `"test_#001.log"`.
"""
if not callable(self.rotator):
if os.path.exists(source):
os.rename(source, dest)
else:
self.rotator(source, dest) # pylint: disable=not-callable
[docs]
def on_message_received(self, msg: Message) -> None:
"""This method is called to handle the given message.
:param msg:
the delivered message
"""
if self.should_rollover(msg):
self.do_rollover()
self.rollover_count += 1
self.writer.on_message_received(msg)
def _get_new_writer(self, filename: StringPathLike) -> FileIOMessageWriter:
"""Instantiate a new writer.
.. note::
The :attr:`self.writer` should be closed prior to calling this function.
:param filename:
Path-like object that specifies the location and name of the log file.
The log file format is defined by the suffix of `filename`.
:return:
An instance of a writer class.
"""
suffix = "".join(pathlib.Path(filename).suffixes[-2:]).lower()
if suffix in self._supported_formats:
logger = Logger(filename=filename, **self.writer_kwargs)
if isinstance(logger, FileIOMessageWriter):
return logger
elif isinstance(logger, Printer) and logger.file is not None:
return cast(FileIOMessageWriter, logger)
raise ValueError(
f'The log format "{suffix}" '
f"is not supported by {self.__class__.__name__}. "
f"{self.__class__.__name__} supports the following formats: "
f"{', '.join(self._supported_formats)}"
)
[docs]
def stop(self) -> None:
"""Stop handling new messages.
Carry out any final tasks to ensure
data is persisted and cleanup any open resources.
"""
self.writer.stop()
def __enter__(self) -> Self:
return self
def __exit__(
self,
exc_type: Optional[Type[BaseException]],
exc_val: Optional[BaseException],
exc_tb: Optional[TracebackType],
) -> Literal[False]:
return self._writer.__exit__(exc_type, exc_val, exc_tb)
[docs]
@abstractmethod
def should_rollover(self, msg: Message) -> bool:
"""Determine if the rollover conditions are met."""
[docs]
@abstractmethod
def do_rollover(self) -> None:
"""Perform rollover."""
[docs]
class SizedRotatingLogger(BaseRotatingLogger):
"""Log CAN messages to a sequence of files with a given maximum size.
The logger creates a log file with the given `base_filename`. When the
size threshold is reached the current log file is closed and renamed
by adding a timestamp and the rollover count. A new log file is then
created and written to.
This behavior can be customized by setting the
:attr:`~can.io.BaseRotatingLogger.namer` and
:attr:`~can.io.BaseRotatingLogger.rotator`
attribute.
Example::
from can import Notifier, SizedRotatingLogger
from can.interfaces.vector import VectorBus
bus = VectorBus(channel=[0], app_name="CANape", fd=True)
logger = SizedRotatingLogger(
base_filename="my_logfile.asc",
max_bytes=5 * 1024 ** 2, # =5MB
)
logger.rollover_count = 23 # start counter at 23
notifier = Notifier(bus=bus, listeners=[logger])
The SizedRotatingLogger currently supports the formats
* .asc: :class:`can.ASCWriter`
* .blf :class:`can.BLFWriter`
* .csv: :class:`can.CSVWriter`
* .log :class:`can.CanutilsLogWriter`
* .txt :class:`can.Printer` (if pointing to a file)
.. note::
The :class:`can.SqliteWriter` is not supported yet.
The log files on disk may be incomplete due to buffering until
:meth:`~can.Listener.stop` is called.
"""
_supported_formats = {".asc", ".blf", ".csv", ".log", ".txt"}
def __init__(
self,
base_filename: StringPathLike,
max_bytes: int = 0,
**kwargs: Any,
) -> None:
"""
:param base_filename:
A path-like object for the base filename. The log file format is defined by
the suffix of `base_filename`.
:param max_bytes:
The size threshold at which a new log file shall be created. If set to 0, no
rollover will be performed.
"""
super().__init__(**kwargs)
self.base_filename = os.path.abspath(base_filename)
self.max_bytes = max_bytes
self._writer = self._get_new_writer(self.base_filename)
[docs]
def should_rollover(self, msg: Message) -> bool:
if self.max_bytes <= 0:
return False
if self.writer.file_size() >= self.max_bytes:
return True
return False
[docs]
def do_rollover(self) -> None:
if self.writer:
self.writer.stop()
sfn = self.base_filename
dfn = self.rotation_filename(self._default_name())
self.rotate(sfn, dfn)
self._writer = self._get_new_writer(self.base_filename)
def _default_name(self) -> StringPathLike:
"""Generate the default rotation filename."""
path = pathlib.Path(self.base_filename)
new_name = (
path.stem.split(".")[0]
+ "_"
+ datetime.now().strftime("%Y-%m-%dT%H%M%S")
+ "_"
+ f"#{self.rollover_count:03}"
+ "".join(path.suffixes[-2:])
)
return str(path.parent / new_name)