Hi,
I am facing a racing conditions in `touch`. Let me use this example to
explain:
class Order < ApplicationRecord
has_many :items
end
class Item < ApplicationRecord
belongs_to :order, touch: true
# More relationship:
# belongs_to :other_model, touch: true
# belongs_to :other_model_2, touch: true
# has_many :other_model_3
end
For example, I have a one to many relationship, Order has many Items. When
an Item get update, it `touch` Order.
Order table has `lock_version` column, which means Optimistic Locking is
enabled.
When some logic update an Item, the relationship will auto trigger `touch`
Order, which has a chance that StaleObjectError error being raised.
The problem is here, coding which modify Item is everywhere. Implement a
rescue/retry logic manually in all the places is not a possible solution...
There are many relationship in my project having this `touch` mechanism.
Some of them are even a chain: A touch B touch C touch D.
However, I always have a clear answer in my mind of the question: *How
important is the touch?*
1. very important, need retry until success.
2. accuracy is not that important (updated_at datetime value). In this
case, if it raise StaleObjectError error, which means someone else has
updated the record, right before my touch. So my touch can actually skip.
I can write some workaround code like:
class Item < ApplicationRecord
belongs_to :order
# More relationship:
# belongs_to :other_model
# belongs_to :other_model_2
# has_many :other_model_3
after_commit :touch_all_belongs_to_models
def touch_all_belongs_to_models
[order, other_model, other_model_2].each do |model|
begin
model.touch
rescue ActiveRecord::StaleObjectError
begin
# Reload lock_version in particular.
reload
rescue ActiveRecord::RecordNotFound
# if the record is gone there is nothing to do.
else
retry
end
end
end
end
end
Which basically I write my own touch, don't use Rails build-in solution. A
lot more complex.
So I am thinking, maybe we can have more *options* for touch? Something
like:
belongs_to :order, touch: :retry # retry until success.
belongs_to :order, touch: :soft # skip touch if StableObjectError is raise,
other modification of records should still save to DB.
PS: Sorry for my poor english.
Thanks,
Leonardo
--
You received this message because you are subscribed to the Google Groups "Ruby
on Rails: Core" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to rubyonrails-core+unsubscr...@googlegroups.com.
To post to this group, send email to rubyonrails-core@googlegroups.com.
Visit this group at https://groups.google.com/group/rubyonrails-core.
For more options, visit https://groups.google.com/d/optout.
