Incrementing/decrementing in Collections - avoiding race conditions

I have a Collection with a list of items and our stock level for them. When someone makes an order, I need to decrement stock, and when new stock is added, I need to increment stock.

The simplest way would be to getDocument, then updateDocument with stock-1, but that would be an issue if there are two orders at the same time.

The only method I can think of to deal with this is:
Create a new record in a collection order_updates.
Check order_updates for any records created before the one I just created.
If there are, wait 0.5 seconds and check again.
Once there are no more records before my new one, get the current stock level and update it.
Delete the order_updates record.

This seems a bit roundabout, though - does anyone have any better ways to deal with this? TIA!

One way to create a lock is to create a locks collection. A process that wants to obtain a lock will create a document with id == id of the resource. If it can create the document successfully, it has obtained the lock. If any other document tries to obtain a lock, they'll get an error because the document already exists with the same id. When the process that obtained the lock is done, it can delete the lock document to release the lock

I’m not sure how that’s really any more efficient than my method (although it is tidier)

I’d really prefer if there were a way to just directly increment/decrement a number in a collection, but I don’t really expect that to happen

You can 👍 the related feature request: https://github.com/appwrite/appwrite/issues/3905

It's on our roadmap, but I'm not sure when it'll be completed

Oh cool, and it’s got a PR already too!

Eh I ran into complications 😅

Following

Here might be relevant information: https://discord.com/channels/564160730845151244/1169995985922031728/1170035273837596672