Fix deadlock in belongs_to/has_many :through; support polymorphic source_type#336
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Fix deadlock in belongs_to/has_many :through; support polymorphic source_type#336kbrock wants to merge 3 commits into
kbrock wants to merge 3 commits into
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We undefine these classes in the after {}
So in theory, they should not be a duplicate.
rspec often uses stub_const, but active record has issues with this since
they dig into the class.name and stuff
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Move class resolution out of definition time and into method bodies. Call super first so AR registers reflections (preserving eager loading support), then override accessors with runtime ActiveHash checks. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
When source_type is present, resolve the class at runtime and look up by foreign key directly, bypassing AR's polymorphic belongs_to which does not work with ActiveHash. Fixes active-hash#334. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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update: removed class load |
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flavorjones
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@kbrock Sorry for not reviewing this earlier. It looks good, I left one comment about whether using :source_type will generate N+1 queries, but I think we can just collapse that to a where(id: ids).
| klass = source_type.safe_constantize | ||
| if klass < ActiveHash::Base | ||
| ids = send(options[:through]).map { |jm| jm.send(source_foreign_key) }.compact.uniq | ||
| ids.flat_map { |id| klass.find_by_id(id) }.compact |
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This could potentially make a lot of queries. Could we instead do:
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| ids.flat_map { |id| klass.find_by_id(id) }.compact | |
| klass.where(id: ids) |
? If we need to keep the order we could do something like this to keep it to a single query:
records = klass.where(id: ids).index_by(&:id)
ids.filter_map { |id| records[id] }
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Resolving classes at definition time can deadlock in production. AR holds a schema lock and a class-load lock. Loading one class that triggers loading another will hit both locks and hang.
belongs_toandhas_many :throughnow resolve ActiveHash classes at runtime, avoiding the deadlockhas_many :throughwithsource_type(fixes Polymorphichas_manywith asource_typeraise an exception in ActiveHash 4.0 #334)Note:
belongs_to_active_hashis unchanged and still available for direct use.Thank you, @alexgriff, for the reproducer.