Issue 25462: Avoid repeated hash calculation in C implementation of OrderedDict (original) (raw)

Issue25462

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This issue has been migrated to GitHub: https://github.com/python/cpython/issues/69648

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Created on 2015-10-22 18:15 by serhiy.storchaka, last changed 2022-04-11 14:58 by admin. This issue is now closed.

Messages (6)
msg253343 - (view)	Author: Serhiy Storchaka (serhiy.storchaka) *	Date: 2015-10-22 18:15
There are private _PyDict_*_KnownHash functions that allow to avoid repeated hash calculation in complex operations with a dict. Proposed patch makes C implementation of OrderedDict to use these functions. It is not just an optimization, it makes some OrderedDict methods atomic (or almost atomic), that decreases a chance to desynchronize the linked list with the dict. That is why I suggest to commit the patch in 3.5.
msg254182 - (view)	Author: Serhiy Storchaka (serhiy.storchaka) *	Date: 2015-11-06 10:18
Could you please make a review of this patch Eric? It is moved to separate issue because it is enough large and complex.
msg254294 - (view)	Author: Raymond Hettinger (rhettinger) *	Date: 2015-11-07 20:07
The patch looks correct, and it improves the integrity of the C implementation.
msg254296 - (view)	Author: Eric Snow (eric.snow) *	Date: 2015-11-07 20:22
I agree with Raymond.
msg254603 - (view)	Author: Roundup Robot (python-dev)	Date: 2015-11-13 13:19
New changeset 52ff0c00a404 by Serhiy Storchaka in branch '3.5': Issue #25462: The hash of the key now is calculated only once in most https://hg.python.org/cpython/rev/52ff0c00a404 New changeset 828c9b920532 by Serhiy Storchaka in branch 'default': Issue #25462: The hash of the key now is calculated only once in most https://hg.python.org/cpython/rev/828c9b920532
msg254604 - (view)	Author: Serhiy Storchaka (serhiy.storchaka) *	Date: 2015-11-13 13:20
Thank you Raymond and Eric.