Fix thumbnail writing for multi-concurrent and multi-db setups #2433
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This makes sure we only load from the DB if necessary. Theoretically this would also happen with the former implementation, but ActiveStorage is doing this as well, so I can't hurt to do it explicilty.
In a multi concurrent application server (like Puma) it happens that a thumb might already exist for a given signature during the very short timeframe of finding it vs creating it. Using ARs [create_or_find_by!](https://github.com/rails/rails/blob/8015c2c2cf5c8718449677570f372ceb01318a32/activerecord/lib/active_record/relation.rb#L218) do avoid ActiveRecord::RecordNotUnique errors. ActiveStorage does the exact same thing to avoid concurrency issues. Closes AlchemyCMS#2429
This was referenced Feb 26, 2023
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In a multi db setup where you have a reading and a writing database we need to make sure that we are using the writing database. This is necessary, because we are writing (caching) picture thumbnails in a GET request. Usually Rails would handle this for us on POST, PATCH/PUT and DELETE requests. ActiveStorage does the same thing to support multi database setups. Closes AlchemyCMS#2428
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What is this pull request for?
Fix race condition in PictureThumb::Create
In a multi concurrent application server (like Puma) it happens that
a thumb might already exist for a given signature during the very
short timeframe of finding it vs creating it.
Using ARs create_or_find_by! do avoid
ActiveRecord::RecordNotUniqueerrors. ActiveStorage does theexact same thing to avoid concurrency issues.
Closes #2429
Connect to writing database during thumbnail generation
In a multi db setup where you have a reading and a writing database
we need to make sure that we are using the writing database.
This is necessary, because we are writing (caching) picture
thumbnails in a GET request. Usually Rails would handle this for us
on POST, PATCH/PUT and DELETE requests.
ActiveStorage does the same thing to support multi database
setups.
Closes #2428
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