Feature request: key tags

[josser]

Hi! It would be very useful to specify 'tag' for keys, i.e:
cache.set(key, value, { ttl, tags })

so if we want invalidate several keys simultaneously we can do something like:

cache.delByTag(tag)

[BryanDonovan]

Seems like that would be specific to a certain data store?

[josser]

I guess not.
Maybe it's possible to do something like:
cache.set('key', value, {ttl, tags: ['foo'])
// cache.set('tag:foo', cache.get('tag:foo').push(key), { ttl })
// atomicity?

cache.delTag('foo')
// keys = cache.get('tag:foo')
// keys.forEach(key => cache.del(key))

[BryanDonovan]

I don't think this is feasible for this library to make it generic enough to work with any cache store.

[josser]

This is very common thing in caching libraries:
http://symfony.com/doc/current/components/cache/cache_invalidation.html
https://github.com/ahawkins/cashier
https://framework.zend.com/manual/1.10/en/zend.cache.introduction.html

[BryanDonovan]

I think the problem is that various caches implement this differently. Redis likely uses hset or similar. I can't think of a clean way to put this in this library.

[josser]

If you take a look at http://symfony.com/doc/current/components/cache/cache_invalidation.html they have 'TagAwareAdapter' abstraction for this. So if backend storage can't support tags, developer should provide two adapters, one for tags and one for items.

[BryanDonovan]

Do you want to try to add this feature? As long as it doesn't break any existing functionality and works with the existing adapters, it's fine with me.

[josser]

@BryanDonovan I'm not sure I have enough skills but I'll try )

[apetta]

Was this implemented in the end? Can't see anything relevant to tags in the docs