Fix issue where counter_cache could get decremented twice under specific conditions#31494
Fix issue where counter_cache could get decremented twice under specific conditions#31494zhouguangming wants to merge 1 commit intorails:masterfrom
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Thanks for the pull request, and welcome! The Rails team is excited to review your changes, and you should hear from @schneems (or someone else) soon. If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes. This repository is being automatically checked for code quality issues using Code Climate. You can see results for this analysis in the PR status below. Newly introduced issues should be fixed before a Pull Request is considered ready to review. Please see the contribution instructions for more information. |
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You are not considering previous value of hash, It will be better to add / merge key, value pair
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Yes you are right, I will fix it soon
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Anyone can review my PR? |
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Hi @zhouguangming! Can you add a test that would fail without your change? |
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@eugeneius Hi, I have wrote a test case on #31493 |
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I mean adding a new test to the test suite. This change appears to build on #24713; check out the test added there for an example. |
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I posted a full failing test case in #32079 as well. Maybe it will come in a handy. https://gist.github.com/malikolivier/87904c9ed078dca186cf455a09a4f30e |
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@zhouguangming hopefully you can add the failing test @malikolivier suggested so this can get merged before Rails 5.2 final is released! |
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Since @zhouguangming seems busy now, I added a failing test on top of his contribution in #32372. Hope the fix gets release before 5.2! |
This is a 4th attempt to make counter cache transactional completely. Past attempts: rails#9236, rails#14849, rails#23357. All existing counter cache issues (increment/decrement twice, lost increment) are caused due to updating counter cache on the outside of the record saving transaction by assigning belongs_to record, even though assigning that doesn't cause the record saving. We have the `@_after_replace_counter_called` guard condition to mitigate double increment/decrement issues, but we can't completely prevent that inconsistency as long as updating counter cache on the outside of the transaction, since saving the record is not always happened after that. We already have handling counter cache after create/update/destroy, https://github.com/rails/rails/blob/1b90f614b1b3d06b7f02a8b9ea6cd84f15d58643/activerecord/lib/active_record/counter_cache.rb#L162-L189 https://github.com/rails/rails/blob/1b90f614b1b3d06b7f02a8b9ea6cd84f15d58643/activerecord/lib/active_record/associations/builder/belongs_to.rb#L33-L59 so just removing assigning logic on the belongs_to association makes counter cache transactional completely. Closes rails#14849. Closes rails#23357. Closes rails#31493. Closes rails#31494. Closes rails#32372. Closes rails#33113. Closes rails#33117 Closes rails#33129. Closes rails#33458.
Fix #31493