Enhancement to IDistributedCache - Allow for bulk remove and key enumeration

[maryamariyan]

As @eerhardt and I were triaging through caching extensions issues, we noticed a theme of requests being around allowing for key enumeration and bulk removal of items in IDistributedCache:

• How to flush all cache? #36547: How to flush all cache
• Bulk remove on IDistributedCache #36568: Bulk remove on IDistributedCache
• How to get the list of keys using IDistributedCache extension. #36402: Enumerating keys using IDistributedCache

We closed a number of items as dupes of the above issues as well.

More information on the intricacies of this issue and ways to approach it:

• When using caching in extensions, we don't want to allow enumerating on keys while elements may get removed within another thread, (keeping as atomic operation). In order to allow for (e.g. bulk remove) we can offer returning a snapshot (say array of elements. For example to allow for bulk remove of items with a certain prefix (e.g. "ZZZ"), given a snapshot, we may use TryGetValue and if already gone it would not throw.

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Issue meta data

Issue content:	As @eerhardt and I were triaging through caching extensions issues, we noticed a theme of requests being around request to allow for key enumeration and bulk removal of items in IDistributedCache: How to flush all cache? #36547: How to flush all cache Bulk remove on IDistributedCache #36568: Bulk remove on IDistributedCach How to get the list of keys using IDistributedCache extension. #36402: Enumerating keys using IDistributedCache We closed a number of items as dupes of the above issues as well. More information on the intricacies of this issue and ways to approach it: When using caching in extensions, we don't want to allow enumerating on keys while elements may get removed within another thread, (keeping as atomic operation). In order to allow for (e.g. bulk remove) we can offer returning a snapshot (say array of elements. For example to allow for bulk remove of items with a certain prefix (e.g. "ZZZ"), given a snapshot, we may use TryGetValue and if already gone it would not throw.
Issue author:	maryamariyan
Assignees:	-
Milestone:	-

[udlose]

• ..... For example to allow for bulk remove of items with a certain prefix (e.g. "ZZZ"), given a snapshot, we may use TryGetValue and if already gone it would not throw.

@maryamariyan, StackExchange.Redis.IDatabase.KeyDeleteAsync(RedisKey[] keys, CommandFlags flags = CommandFlags.None) does not throw an exception if a key is not found. See - https://github.com/StackExchange/StackExchange.Redis/blob/6409b9d1f2afd01a7eab9498a525360d1ca2b752/src/StackExchange.Redis/Interfaces/IDatabaseAsync.cs#L442

Is there a concern I'm missing?

[kosmakoff]

I wonder if it is being worked on. I recently stumbled upon a case when I very much need to enumerate values (or keys at least) by pattern (prefix), otherwise I will have to use underlying caching solution directly, which breaks my abstractions.

[udlose]

It looks like this has been added to the .NET 6.0 milestone (tentatively sched to be released in November 2021 - https://devblogs.microsoft.com/dotnet/announcing-net-6-preview-2/#:~:text=.NET%206%20will%20be%20released,Term%20Support%20(LTS)%20release.