gh-129817: Use _PyType_HasFeature() to check tp_flags.
#130892
Closed
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
In the free-threaded build, an atomic load is needed to safely read `tp_flags`, avoiding data races. Replace bit tests on `tp->tp_flags` with calls to `_PyType_HasFeature()`. When multiple bits are being returned as a result of the test, use `PyType_GetFlags()`.
|
Closing as I don't think this is the correct approach. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
In the free-threaded build, an atomic load is needed to safely read
tp_flags, avoiding data races. Replace bit tests ontp->tp_flagswith calls to_PyType_HasFeature(). When multiple bits are being returned as a result of the test, usePyType_GetFlags().I think some of these flag tests can safely be a normal load rather than an atomic load. However, it seems better to consistently use
_PyType_HasFeature()unless we are sure there is no data race possible.Implementation notes:
tp_flagsdirectly. I used this command to find all the places:rg -tc -- '->tp_flags \&'and then used editor macros to make the changes._PyType_HasFeature()are not always equivalent since the function only returns 0 and 1 while the test expression might care about individual bits. I wrote a replacement_PyType_HasFeaturefunction that checks how many bits are being passed as the feature and then ensured that only one bit is set. I then manually fixed or confirmed cases were this wasn't so. So, I'm fairly sure using_PyType_HasFeature()as this PR does is correct in all cases.Related PRs: gh-120210 gh-127588
tp_flagswith subinterpreters and static types #129817