Can we use `IsEqualGUID` in the `GUID.__eq__`?

[junkmd]

The module defining GUID includes the following "Note":

comtypes/comtypes/_post_coinit/guid.py

Lines 26 to 27 in 083c19e

	# Note: Comparing GUID instances by comparing their buffers
	# is slightly faster than using ole32.IsEqualGUID.

However, this note was written at the very start of this project, even before the release of Python 3.0.

CPython and ctypes have improved over the past years.
Is there a performance difference between the current implementation and an implementation with IsEqualGUID like the following?

@@ -13,6 +13,7 @@ def binary(obj: "GUID") -> bytes:
 BYTE = c_byte
 WORD = c_ushort
 DWORD = c_ulong
+TRUE = 1

 _ole32 = oledll.ole32

@@ -22,9 +23,7 @@ _ProgIDFromCLSID = _ole32.ProgIDFromCLSID
 _CLSIDFromString = _ole32.CLSIDFromString
 _CLSIDFromProgID = _ole32.CLSIDFromProgID
 _CoCreateGuid = _ole32.CoCreateGuid
-
-# Note: Comparing GUID instances by comparing their buffers
-# is slightly faster than using ole32.IsEqualGUID.
+_IsEqualGUID = _ole32.IsEqualGUID


 class GUID(Structure):
@@ -50,7 +49,7 @@ class GUID(Structure):
         return self != GUID_null

     def __eq__(self, other) -> bool:
-        return isinstance(other, GUID) and binary(self) == binary(other)
+        return isinstance(other, GUID) and _IsEqualGUID(byref(self), byref(other)) == TRUE

     def __hash__(self) -> int:
         # We make GUID instances hashable, although they are mutable.

After comparing benchmarks, if it proves effective, feel free to submit a PR.

[jegg-dev]

New contributor here, I've benchmarked both implementations of GUID.__eq__ using the existing GUID unit tests (but modified to run each test repeatedly).

Buffer implementation:

ncalls  tottime  percall  cumtime  percall filename:lineno(function)
400000    0.294    0.000    0.527    0.000 guid.py:55(__eq__)

IsEqualGUID Implementation:

ncalls  tottime  percall  cumtime  percall filename:lineno(function)
400000    0.355    0.000    0.467    0.000 guid.py:55(__eq__)

There is a performance difference of ~12% (150 ns/exec, 60 ms total) in favor of IsEqualGUID for cumulative execution time. I've observed similar results on repeated runs.

[junkmd]

@jegg-dev

Thank you for your investigation.

Welcome to our community!

Which Python version did you test this on?

From your investigation, I understand that the Buffer implementation performs better when the number of calls is low, whereas the IsEqualGUID implementation becomes more advantageous when the number of calls is high.

How frequently is GUID.__eq__ called in this project?
This will determine whether we should replace the current implementation.

[jegg-dev]

Python 3.11.0 was used for testing.

I'm not exactly sure how to give a good answer for frequency of GUID.__eq__ calls but I ran the test suite (excluding test_GUID) and counted 49 calls. As for references to the function in the codebase, I was not able to find any explicit uses after manually searching for GUID references.

[junkmd]

@jegg-dev

Sorry for the delayed response.

A new issue, #696, has been opened regarding GUID.
We should address that first before proceeding with this performance comparison.

If you’re interested in contributing to the codebase of this project, it would be great if you could work on #696.