mirror of
https://github.com/openfoodfoundation/openfoodnetwork
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50093c325a
It gives this complex logic more space and allows for better structure and more comments at the right places.
41 lines
1.4 KiB
Ruby
41 lines
1.4 KiB
Ruby
# Locks a controller's current order including its variants.
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#
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# It should be used when making major changes like checking out the order.
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# It can keep stock checking in sync and prevent overselling of an item.
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class CurrentOrderLocker
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# This interface follows the ActionController filters convention:
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#
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# https://guides.rubyonrails.org/action_controller_overview.html#filters
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#
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def self.around(controller)
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lock_order_and_variants(controller.current_order) { yield }
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end
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# Locking will not prevent all access to these rows. Other processes are
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# only waiting if they try to lock one of these rows as well.
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#
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# https://api.rubyonrails.org/classes/ActiveRecord/Locking/Pessimistic.html
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#
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def self.lock_order_and_variants(order)
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return yield if order.nil?
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order.with_lock do
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lock_variants_of(order)
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yield
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end
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end
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private_class_method :lock_order_and_variants
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# There are many places in which stock is stored in the database. Row locking
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# on variant level ensures that there are no conflicts even when an item is
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# sold through multiple shops.
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def self.lock_variants_of(order)
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variant_ids = order.line_items.select(:variant_id)
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# Ordering the variants by id prevents deadlocks. Plucking the ids sends
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# the locking query without building Spree::Variant objects.
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Spree::Variant.where(id: variant_ids).order(:id).lock.pluck(:id)
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end
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private_class_method :lock_variants_of
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end
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