src/hunter/event.py
import linecache
from functools import partial
from os.path import basename
from os.path import exists
from os.path import splitext
from threading import current_thread
from tokenize import TokenError
from tokenize import generate_tokens
from .const import SITE_PACKAGES_PATHS
from .const import SYS_PREFIX_PATHS
from .util import CYTHON_SUFFIX_RE
from .util import LEADING_WHITESPACE_RE
from .util import MISSING
from .util import cached_property
from .util import get_func_in_mro
from .util import get_main_thread
from .util import if_same_code
__all__ = ('Event',)
class Event:
"""
A wrapper object for Frame objects. Instances of this are passed to your custom functions or predicates.
Provides few convenience properties.
Args:
frame (Frame): A python `Frame <https://docs.python.org/3/reference/datamodel.html#frame-objects>`_ object.
kind (str): A string like ``'call'``, ``'line'``, ``'return'`` or ``'exception'``.
arg: A value that depends on ``kind``. Usually is ``None`` but for ``'return'`` or ``'exception'`` other values
may be expected.
tracer (:class:`hunter.tracer.Tracer`): The :class:`~hunter.tracer.Tracer` instance that created the event.
Needed for the ``calls`` and ``depth`` fields.
"""
frame = None
kind = None
arg = None
depth = None
calls = None
builtin = None
def __init__(
self,
frame,
kind,
arg,
tracer=None,
depth=None,
calls=None,
threading_support=MISSING,
):
if tracer is None:
if depth is None:
raise TypeError('Missing argument: depth (required because tracer was not given).')
if calls is None:
raise TypeError('Missing argument: calls (required because tracer was not given).')
if threading_support is MISSING:
raise TypeError('Missing argument: threading_support (required because tracer was not given).')
else:
depth = tracer.depth
calls = tracer.calls
threading_support = tracer.threading_support
#: The original Frame object.
#:
#: .. note::
#:
#: Not allowed in the builtin predicates (it's the actual Frame object).
#: You may access it from your custom predicate though.
self.frame = frame
if kind.startswith('c_'):
kind = kind[2:]
builtin = True
else:
builtin = False
#: If kind of the event is one of ``'c_call'``, ``'c_return'``, or ``'c_exception'`` then this will be True.
#:
#: :type: bool
self.builtin = builtin
#: The kind of the event, could be one of ``'call'``, ``'line'``, ``'return'``, ``'exception'``.
#:
#: :type: str
self.kind = kind
#: A value that depends on ``kind``
self.arg = arg
#: Tracing depth (increases on calls, decreases on returns).
#:
#: :type: int
self.depth = depth
#: A counter for total number of calls up to this Event.
#:
#: :type: int
self.calls = calls
#: A copy of the :attr:`hunter.tracer.Tracer.threading_support` flag.
#:
#: .. note::
#:
#: Not allowed in the builtin predicates. You may access it from your custom predicate though.
#:
#: :type: bool or None
self.threading_support = threading_support
#: Flag that is ``True`` if the event was created with :meth:`~hunter.event.Event.detach`.
#:
#: :type: bool
self.detached = False
def __repr__(self):
return '<Event kind={!r} function={!r} module={!r} filename={!r} lineno={}>'.format(
self.kind,
self.function,
self.module,
self.filename,
self.lineno,
)
def __eq__(self, other):
return self is other
def __reduce__(self):
raise TypeError("cannot pickle 'hunter.event.Event' object")
def detach(self, value_filter=None):
"""
Return a copy of the event with references to live objects (like the frame) removed. You should use this if you
want to store or use the event outside the handler.
You should use this if you want to avoid memory leaks or side-effects when storing the events.
Args:
value_filter:
Optional callable that takes one argument: ``value``.
If not specified then the ``arg``, ``globals`` and ``locals`` fields will be ``None``.
Example usage in a :class:`~hunter.actions.ColorStreamAction` subclass:
.. sourcecode:: python
def __call__(self, event):
self.events = [event.detach(lambda field, value: self.try_repr(value))]
"""
event = Event.__new__(Event)
event.__dict__['code'] = self.code
event.__dict__['filename'] = self.filename
event.__dict__['fullsource'] = self.fullsource
event.__dict__['function'] = self.function
event.__dict__['lineno'] = self.lineno
event.__dict__['module'] = self.module
event.__dict__['source'] = self.source
event.__dict__['stdlib'] = self.stdlib
event.__dict__['threadid'] = self.threadid
event.__dict__['threadname'] = self.threadname
event.__dict__['instruction'] = self.instruction
if value_filter:
event.__dict__['arg'] = value_filter(self.arg)
event.__dict__['globals'] = {key: value_filter(value) for key, value in self.globals.items()}
event.__dict__['locals'] = {key: value_filter(value) for key, value in self.locals.items()}
else:
event.__dict__['globals'] = {}
event.__dict__['locals'] = {}
event.__dict__['arg'] = None
event.threading_support = self.threading_support
event.calls = self.calls
event.depth = self.depth
event.kind = self.kind
event.builtin = self.builtin
event.detached = True
return event
def clone(self):
event = Event.__new__(Event)
event.__dict__ = dict(self.__dict__)
return event
@cached_property
def instruction(self):
"""
Last byte instruction. If no bytecode was used (Cython code) then it returns ``None``.
Depending on Python version it might be an int or a single char string.
:type: int or single char string or None
"""
if self.frame.f_lasti >= 0 and self.frame.f_code.co_code:
return self.frame.f_code.co_code[self.frame.f_lasti]
@cached_property
def threadid(self):
"""
Current thread ident. If current thread is main thread then it returns ``None``.
:type: int or None
"""
current = self._thread.ident
main = get_main_thread()
if main is None:
return current
else:
return current if current != main.ident else None
@cached_property
def threadname(self):
"""
Current thread name.
:type: str
"""
return self._thread.name
@cached_property
def _thread(self):
return current_thread()
@cached_property
def locals(self):
"""
A dict with local variables.
:type: dict
"""
if self.builtin:
return {}
return self.frame.f_locals
@cached_property
def globals(self):
"""
A dict with global variables.
:type: dict
"""
if self.builtin:
return {}
return self.frame.f_globals
@cached_property
def function(self):
"""
A string with function name.
:type: str
"""
if self.builtin:
return self.arg.__name__
else:
return self.code.co_name
@cached_property
def function_object(self):
"""
The function instance.
.. warning:: Use with prudence.
* Will be ``None`` for decorated functions on Python 2 (methods may still work tho).
* May be ``None`` if tracing functions or classes not defined at module level.
* May be very slow if tracing modules with lots of variables.
:type: function or None
"""
# Based on MonkeyType's get_func
if self.builtin:
return self.builtin
code = self.code
if code.co_name is None:
return None
# First, try to find the function in globals
candidate = self.globals.get(code.co_name, None)
func = if_same_code(candidate, code)
# If that failed, as will be the case with class and instance methods, try
# to look up the function from the first argument. In the case of class/instance
# methods, this should be the class (or an instance of the class) on which our
# method is defined.
if func is None and code.co_argcount >= 1:
first_arg = self.locals.get(code.co_varnames[0])
func = get_func_in_mro(first_arg, code)
# If we still can't find the function, as will be the case with static methods,
# try looking at classes in global scope.
if func is None:
for v in self.globals.values():
if not isinstance(v, type):
continue
func = get_func_in_mro(v, code)
if func is not None:
break
return func
@cached_property
def module(self):
"""
A string with module name (like ``'foo.bar'``).
:type: str
"""
if self.builtin:
module = self.arg.__module__
else:
module = self.frame.f_globals.get('__name__', '')
if module is None:
module = '?'
return module
@cached_property
def filename(self):
"""
A string with the path to the module's file. May be empty if ``__file__`` attribute is missing.
May be relative if running scripts.
:type: str
"""
# if self.builtin:
# return '<builtin>'
# if self.builtin:
# return '<builtin>'
filename = self.frame.f_code.co_filename
if not filename:
filename = self.frame.f_globals.get('__file__')
if not filename:
filename = '?'
if filename.endswith(('.pyc', '.pyo')):
filename = filename[:-1]
elif filename.endswith('$py.class'): # Jython
filename = filename[:-9] + '.py'
elif filename.endswith(('.so', '.pyd')):
basename = CYTHON_SUFFIX_RE.sub('', filename)
for ext in ('.pyx', '.py'):
cyfilename = basename + ext
if exists(cyfilename):
filename = cyfilename
break
return filename
@cached_property
def lineno(self):
"""
An integer with line number in file.
:type: int
"""
return self.frame.f_lineno
@cached_property
def code(self):
"""
A code object (not a string).
"""
return self.frame.f_code
@cached_property
def stdlib(self):
"""
A boolean flag. ``True`` if frame is in stdlib.
:type: bool
"""
module_parts = self.module.split('.')
if 'pkg_resources' in module_parts:
# skip this over-vendored module
return True
elif self.filename == '<string>' and (self.module.startswith('namedtuple_') or self.module == 'site'):
# skip namedtuple exec garbage
return True
elif self.filename.startswith(SITE_PACKAGES_PATHS):
# if it's in site-packages then its definitely not stdlib
return False
elif self.filename.startswith(SYS_PREFIX_PATHS):
return True
else:
return False
@cached_property
def fullsource(self):
"""
A string with the sourcecode for the current statement (from ``linecache`` - failures are ignored).
May include multiple lines if it's a class/function definition (will include decorators).
:type: str
"""
try:
if self.kind == 'call' and self.code.co_name != '<module>':
lines = []
try:
for _, token, _, _, _ in generate_tokens(
partial(
next,
yield_lines(
self.filename,
self.frame.f_globals,
self.lineno - 1,
lines.append,
),
)
):
if token in ('def', 'class', 'lambda'):
return ''.join(lines)
except TokenError:
pass
return linecache.getline(self.filename, self.lineno, self.frame.f_globals)
except Exception as exc:
return f'??? NO SOURCE: {exc!r}'
@cached_property
def source(self):
"""
A string with the sourcecode for the current line (from ``linecache`` - failures are ignored).
Fast but sometimes incomplete.
:type: str
"""
if self.filename.endswith(('.so', '.pyd')):
return f'??? NO SOURCE: not reading binary {splitext(basename(self.filename))[1]} file'
try:
return linecache.getline(self.filename, self.lineno, self.frame.f_globals)
except Exception as exc:
return f'??? NO SOURCE: {exc!r}'
__getitem__ = object.__getattribute__
def yield_lines(
filename,
module_globals,
start,
collector,
limit=10,
leading_whitespace_re=LEADING_WHITESPACE_RE,
):
dedent = None
amount = 0
for line in linecache.getlines(filename, module_globals)[start : start + limit]:
if dedent is None:
dedent = leading_whitespace_re.findall(line)
dedent = dedent[0] if dedent else ''
amount = len(dedent)
elif not line.startswith(dedent):
break
collector(line)
yield line[amount:]