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from abc import ABCMeta
import logging
from .trace_call import trace_call
class AbstractTraceMeta(type):
"""
An abstract metaclass for tracing classes
"""
@classmethod
def _filter_attribute(mcs, attribute_name, attribute_value):
"""
decides whether the given attribute should be excluded from tracing or not
"""
if attribute_name == '__module__':
return True
elif hasattr(attribute_value, '_trace_disable'):
return True
return False
def __new__(mcs, name, bases, attrs, **kwargs):
# *magic*: an educated guess is made on how the module that the
# processed class is created in would get its logger.
# It is assumed that the popular convention recommended by the
# developers of standard library (`logger = logging.getLogger(__name__)`)
# is used.
target_logger = logging.getLogger(attrs['__module__'])
for attribute_name in attrs:
attribute_value = attrs[attribute_name]
if mcs._filter_attribute(attribute_name, attribute_value):
continue
# attrs['__module__'] + '.' + attribute_name is worth logging
# collect the `only` and `skip` sets from mro
only = getattr(attribute_value, '_trace_only', None)
skip = getattr(attribute_value, '_trace_skip', None)
disable = False
for base in bases:
base_attribute_value = getattr(base, attribute_name, None)
if base_attribute_value is None:
continue # the base class did not define this
if hasattr(base_attribute_value, '_trace_disable'): # that's probably done by @disable_trace
# ex. inheriting from Abstract class, where getters are marked
disable = True
break
only_candidates = getattr(base_attribute_value, '_trace_only', None)
if only_candidates is not None:
if only is not None:
only.update(only_candidates)
else:
only = set(only_candidates)
skip_candidates = getattr(base_attribute_value, '_trace_skip', None) # is this 5 LOC clone worth refactoring?
if skip_candidates is not None:
if skip is not None:
skip.update(skip_candidates)
else:
skip = set(skip_candidates)
if disable:
continue # the base class does not wish to trace it at all
# create a wrapper (decorator object)
wrapper = trace_call(
target_logger,
only=only,
skip=skip,
)
original_wrapper = None
# Special case for staticmethod/classmethod
if isinstance(attribute_value, staticmethod):
attribute_value = attribute_value.__func__
original_wrapper = staticmethod
elif isinstance(attribute_value, classmethod):
attribute_value = attribute_value.__func__
original_wrapper = classmethod
# wrap the callable in it
wrapped_value = wrapper(attribute_value)
# apply the original wrapper if provided
if original_wrapper is not None:
wrapped_value = original_wrapper(wrapped_value)
# substitute the trace-wrapped method for the original
attrs[attribute_name] = wrapped_value
return super(AbstractTraceMeta, mcs).__new__(mcs, name, bases, attrs)
class TraceAllPublicCallsMeta(AbstractTraceMeta):
"""
traces all public method calls
"""
@classmethod
def _filter_attribute(mcs, attribute_name, attribute_value):
if super(TraceAllPublicCallsMeta, mcs)._filter_attribute(attribute_name, attribute_value):
return True
elif not callable(attribute_value):
# Special case for staticmethod/classmethod as prior to Python 3.10
# staticmethod/classmethod are not callable
if not isinstance(attribute_value, (classmethod, staticmethod)):
return True # it is a field
elif attribute_name.startswith('_'):
return True # it is a _protected or a __private method (or __magic__)
return False
class AbstractTracePublicCallsMeta(ABCMeta, TraceAllPublicCallsMeta):
pass
class DefaultTraceMeta(TraceAllPublicCallsMeta):
"""
traces all public method calls, except for ones with names that begin with 'get_'
"""
@classmethod
def _filter_attribute(mcs, attribute_name, attribute_value):
if super(DefaultTraceMeta, mcs)._filter_attribute(attribute_name, attribute_value):
return True
elif attribute_name.startswith('get_'):
return True
return False
class DefaultTraceAbstractMeta(ABCMeta, DefaultTraceMeta):
pass
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