src/aspectlib/debug.py
import logging
import os
import string
import sys
from itertools import islice
from aspectlib import Aspect
from aspectlib import mimic
try:
from types import InstanceType
except ImportError:
InstanceType = type(None)
logger = logging.getLogger(__name__)
def frame_iterator(frame):
"""
Yields frames till there are no more.
"""
while frame:
yield frame
frame = frame.f_back
def format_stack(skip=0, length=6, _sep=os.path.sep):
"""
Returns a one-line string with the current callstack.
"""
return ' < '.join("%s:%s:%s" % (
'/'.join(f.f_code.co_filename.split(_sep)[-2:]),
f.f_lineno,
f.f_code.co_name
) for f in islice(frame_iterator(sys._getframe(1 + skip)), length))
PRINTABLE = string.digits + string.ascii_letters + string.punctuation + ' '
ASCII_ONLY = ''.join(i if i in PRINTABLE else '.' for i in (chr(c) for c in range(256)))
def strip_non_ascii(val):
"""
Convert to string (using `str`) and replace non-ascii characters with a dot (``.``).
"""
return str(val).translate(ASCII_ONLY)
def log(func=None,
stacktrace=10,
stacktrace_align=60,
attributes=(),
module=True,
call=True,
call_args=True,
call_args_repr=repr,
result=True,
exception=True,
exception_repr=repr,
result_repr=strip_non_ascii,
use_logging='CRITICAL',
print_to=None):
"""
Decorates `func` to have logging.
Args
func (function):
Function to decorate. If missing log returns a partial which you can use as a decorator.
stacktrace (int):
Number of frames to show.
stacktrace_align (int):
Column to align the framelist to.
attributes (list):
List of instance attributes to show, in case the function is a instance method.
module (bool):
Show the module.
call (bool):
If ``True``, then show calls. If ``False`` only show the call details on exceptions (if ``exception`` is
enabled) (default: ``True``)
call_args (bool):
If ``True``, then show call arguments. (default: ``True``)
call_args_repr (bool):
Function to convert one argument to a string. (default: ``repr``)
result (bool):
If ``True``, then show result. (default: ``True``)
exception (bool):
If ``True``, then show exceptions. (default: ``True``)
exception_repr (function):
Function to convert an exception to a string. (default: ``repr``)
result_repr (function):
Function to convert the result object to a string. (default: ``strip_non_ascii`` - like ``str`` but nonascii
characters are replaced with dots.)
use_logging (string):
Emit log messages with the given loglevel. (default: ``"CRITICAL"``)
print_to (fileobject):
File object to write to, in case you don't want to use logging module. (default: ``None`` - printing is
disabled)
Returns:
A decorator or a wrapper.
Example::
>>> @log(print_to=sys.stdout)
... def a(weird=False):
... if weird:
... raise RuntimeError('BOOM!')
>>> a()
a() <<< ...
a => None
>>> try:
... a(weird=True)
... except Exception:
... pass # naughty code!
a(weird=True) <<< ...
a ~ raised RuntimeError('BOOM!',)
You can conveniently use this to logs just errors, or just results, example::
>>> import aspectlib
>>> with aspectlib.weave(float, log(call=False, result=False, print_to=sys.stdout)):
... try:
... float('invalid')
... except Exception as e:
... pass # naughty code!
float('invalid') <<< ...
float ~ raised ValueError(...float...invalid...)
This makes debugging naughty code easier.
PS: Without the weaving it looks like this::
>>> try:
... log(call=False, result=False, print_to=sys.stdout)(float)('invalid')
... except Exception:
... pass # naughty code!
float('invalid') <<< ...
float ~ raised ValueError(...float...invalid...)
.. versionchanged:: 0.5.0
Renamed `arguments` to `call_args`.
Renamed `arguments_repr` to `call_args_repr`.
Added `call` option.
"""
loglevel = use_logging and (
logging._levelNames if hasattr(logging, '_levelNames') else logging._nameToLevel
).get(use_logging, logging.CRITICAL)
_missing = object()
def dump(buf):
try:
if use_logging:
logger._log(loglevel, buf, ())
if print_to:
buf += '\n'
print_to.write(buf)
except Exception as exc:
logger.critical('Failed to log a message: %s', exc, exc_info=True)
class __logged__(Aspect):
__slots__ = 'cutpoint_function', 'final_function', 'binding', '__name__', '__weakref__'
bind = False
def __init__(self, cutpoint_function, binding=None):
mimic(self, cutpoint_function)
self.cutpoint_function = cutpoint_function
self.final_function = super(__logged__, self).__call__(cutpoint_function)
self.binding = binding
def __get__(self, instance, owner):
return __logged__(self.cutpoint_function.__get__(instance, owner), instance)
def __call__(self, *args, **kwargs):
return self.final_function(*args, **kwargs)
def advising_function(self, *args, **kwargs):
name = self.cutpoint_function.__name__
instance = self.binding
if instance is not None:
if isinstance(instance, InstanceType):
instance_type = instance.__class__
else:
instance_type = type(instance)
info = []
for key in attributes:
if key.endswith('()'):
callarg = key = key.rstrip('()')
else:
callarg = False
val = getattr(instance, key, _missing)
if val is not _missing and key != name:
info.append(' %s=%s' % (
key, call_args_repr(val() if callarg else val)
))
sig = buf = '{%s%s%s}.%s' % (
instance_type.__module__ + '.' if module else '',
instance_type.__name__,
''.join(info),
name
)
else:
sig = buf = name
if call_args:
buf += '(%s%s)' % (
', '.join(repr(i) for i in (args if call_args is True else args[:call_args])),
((', ' if args else '') + ', '.join('%s=%r' % i for i in kwargs.items()))
if kwargs and call_args is True
else '',
)
if stacktrace:
buf = ("%%-%ds <<< %%s" % stacktrace_align) % (buf, format_stack(skip=1, length=stacktrace))
if call:
dump(buf)
try:
res = yield
except Exception as exc:
if exception:
if not call:
dump(buf)
dump('%s ~ raised %s' % (sig, exception_repr(exc)))
raise
if result:
dump('%s => %s' % (sig, result_repr(res)))
if func:
return __logged__(func)
else:
return __logged__