`scan` for redis service

[TD-Sky]

Wanted feature

The Operator built from Redis could use scan to list entries matching the glob-style pattern of redis.

Real scene

There is a function called move registration in our system. Users register via the function where the uploading file should be move to after its transmission done. Every registration record has its own ID (move_id), and every file also has its own ID (meta_id). Then we format them into movreg_{move_id}_{meta_id} as the key in redis.

We may have only one of the two IDs to query the value. For example, we have only meta_id 832917 and it was stored as movreg_432432_832917; to get the value, we need to excute:

> keys movreg_*_832917
"movreg_432432_832917"

> get movreg_432432_832917

That's why we need glob-style scan in opendal; we want to get all the value whose key matches the given pattern.

Conjectures about implementation

I think KEYS or SCAN can work. Both of them could do glob-match on whole database. But KEYS is slower in general.

[Xuanwo]

This feature request is related to https://github.com/apache/incubator-opendal/issues/1251.

Maybe it's possible for us to add glob and regex support for list, so users can use opendal in this way:

let entries = op.list_with("prefix/").glob("ab[1-9][a-b]").await?;

• For services that have native support for glob patterns, we can forward the glob pattern directly.
• For services not support glob patterns, we can perform the filter at Lister level.

This is a zero-cost abstraction because:

• Users don't use glob won't be affected.
• Users use glob upon supported services can use native API.
• Users use glob upon un-supported services can use the best implemention.