bpo-33165: Remove redundant stack unwind for findCaller() #17714
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the right frame on Lib/logging/__init__.py:currentframe()
because when extending the default Logger and implementing/specializing the `_log` function, all stacktraces need to be increased by 1. For example, the debug_tools pypi module inherits from Logger and defines its own _log() function: https://github.com/evandrocoan/debugtools/blob/d279bf3278f501294a72159f3aa189b7237528b2/all/debug_tools/logger.py#L166 https://github.com/evandrocoan/debugtools/blob/d279bf3278f501294a72159f3aa189b7237528b2/all/debug_tools/logger.py#L970 https://github.com/evandrocoan/debugtools/blob/d279bf3278f501294a72159f3aa189b7237528b2/all/debug_tools/logger.py#L1317
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bpo-33165: Remove redundant stack unwind for findCaller() python/cpython#17714
evandrocoan
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bpo-33165: Remove redundant stack unwind for findCaller() python/cpython#17714
| @@ -1506,17 +1507,11 @@ def findCaller(self, stack_info=False, stacklevel=1): | |||
| Find the stack frame of the caller so that we can note the source | |||
| file name, line number and function name. | |||
| """ | |||
| f = currentframe() | |||
| f = currentframe(self.default_stack_level + stacklevel) | |||
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Shouldn't the unwinding really be done later? A few lines down, we read:
while hasattr(f, "f_code"):
co = f.f_code
filename = os.path.normcase(co.co_filename)
if filename == _srcfile:
f = f.f_back
continueThis 'escapes' the stack frames generated inside the current file. I would expect any additional stacklevel treatment to happen afterwards.
As a result of the current implementation (with or without the proposed changes in the current PR), the stacklevel parameter to .warn must be one higher than the parameter to .warning in order to get to the same frame.
| """Return the frame object for the caller's stack frame.""" | ||
| try: | ||
| raise Exception | ||
| except Exception: | ||
| return sys.exc_info()[2].tb_frame.f_back | ||
| return sys.exc_info()[level-1].tb_frame.f_back |
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I believe this is incorrect. exc_info returns three items and probably all we can do is
Suggested change
| return sys.exc_info()[level-1].tb_frame.f_back | |
| frame = sys.exc_info()[2].tb_frame.f_back | |
| while frame and stacklevel > 0: | |
| frame = frame.f_back | |
| stacklevel -= 1 | |
| if not frame: | |
| raise ValueError("call stack is not deep enough") | |
| return frame |
|
This was already fixed/implemented by dde9fdb |
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by directly getting the right frame on Lib/logging/init.py:currentframe()
This is a slight improvement for #7424 (bpo-33165: Added stacklevel parameter to logging APIs)
Instead of getting the fullstack trace and only then unwind the desired frames, just pass the required frame index and get it directly, i.e., without "unstacking" n frames.
I also added the frame level as a Logger attribute because when extending the default Logger and implementing/specializing the
_logfunction, all stacktraces need to be increased by 1. For example, the debug_tools pypi module inherits from Logger and defines its own _log() function:https://github.com/evandrocoan/debugtools/blob/d279bf3278f501294a72159f3aa189b7237528b2/all/debug_tools/logger.py#L166
https://github.com/evandrocoan/debugtools/blob/d279bf3278f501294a72159f3aa189b7237528b2/all/debug_tools/logger.py#L970
https://github.com/evandrocoan/debugtools/blob/d279bf3278f501294a72159f3aa189b7237528b2/all/debug_tools/logger.py#L1317
https://bugs.python.org/issue33165