Can we make the proxy struct and related methods public?

[qweeah]

When working on upgrading pull command for ORAS CLI, I need to create a OCI store to avoid fetching duplicated blobs again and again from the remote source. I found the internal Proxy struct in ORAS-go's internal cas package is just what I need. Can we make the proxy struct public so clients can reuse it to build light-weight read-through caches?

Pros:
ORAS-go users can reuse the code to build caches in their software.

Cons:
The current implementation is only a read-through cache with no consistency guaranteed. If any blob is deleted on the origin storage side, the change won't be reflected in the proxy.

[shizhMSFT]

The Proxy can be easily misused. For examples,

• Accidentally caching everything in the memory and blow up the memory.
• Cache is never invalidated and may cause data inconsistency.

Also, Proxy is a content.Storage and is not an oras.Target. Thus, it cannot be used in other copy functions except CopyGraph().

Therefore, it is not suitable to be made public.