Allow storageclass to be specified on mc ls

[Willena]

The current version of the ls command omits GLACIER objects.
Sometimes you need to get a list of those files that are located under another storage class.

This commit allows filtering a given storage class and only list this class, or list all objects in all storage classes. The default value is STANDARD.

Usage example:

• List only GLACIER objects: mc ls -r -sc GLACIER myAlias/
• List only STANDARD objects (default): mc ls -r myAlias/
• List all objects in all storage classes: mc ls -r -sc '*' myAlias/

output example:

[2022-01-05 21:17:32 CET] 237KiB STANDARD gu-952f-8404d1f1a068/bl78af97a0f4de9155e56d709e70e81db820eb90f397b39d547f9f9fa0ff84b.blk
[2022-01-05 21:17:49 CET]  19KiB STANDARD gu-952f-8404d1f1a068/bla1889f63d333c93f14f9930dd52526db68ea0073a8336316f24ac2486f98d.blk
[2022-01-05 21:18:06 CET] 160KiB STANDARD gu-952f-8404d1f1a068/bla05d10933062879e669c465f57e5445fbec4f7ed8a4c9690d139c89a05867.blk
[2022-01-08 10:26:41 CET]   635B STANDARD gu-952f-8404d1f1a068/data.cfg
[2022-01-08 10:45:40 CET]  15MiB GLACIER  gu-952f-8404d1f1a068/bkp.blk

[harshavardhana]

I think instead of providing storage-class we can bring in an option called -a to list all hidden files like Unix.

In case of object storage this prints storage class as well.

[Willena]

Not a bad idea. I'll add to -a option.
But I do like the fact that we can also specify the storageClass we want to see.
It seems like AWS for example (https://aws.amazon.com/s3/storage-classes/?nc1=h_ls#Performance_across_the_S3_Storage_Classes) provides more than two (S3 Standard, S3 Intelligent-Tiering*, S3 Standard-IA, S3 One Zone-IA, S3 Glacier Instant Retrieval, S3 Glacier Flexible Retrieval, S3 Glacier, Deep Archive) storageClass types. It might still be useful to filter a specific one.

@harshavardhana What do you think about it ?

[harshavardhana]

Not a bad idea. I'll add to -a option.
But I do like the fact that we can also specify the storageClass we want to see.
It seems like AWS for example (https://aws.amazon.com/s3/storage-classes/?nc1=h_ls#Performance_across_the_S3_Storage_Classes) provides more than two (S3 Standard, S3 Intelligent-Tiering*, S3 Standard-IA, S3 One Zone-IA, S3 Glacier Instant Retrieval, S3 Glacier Flexible Retrieval, S3 Glacier, Deep Archive) storageClass types. It might still be useful to filter a specific one.

@harshavardhana What do you think about it ?

Yes buts not really useful to filter in this manner since Listing is slow and it may never provide any output if you incorrectly provide the storage-class. This in-turn might be assumed as listing is not working.

The best way is print everything -a and use grep instead to filter what you want.

There are many ways to do it - trying to see what makes sense for our command line.

Note: mc ls is used for filesystem folders and files as well which may provide empty results here with storage-class.

I will circle back later on what makes sense let me think about it more.

[Willena]

Listing is slow and it may never provide any output if you incorrectly provide the storage-class. This in-turn might be assumed as listing is not working

Totally true, I agree with that. That exactly what could happen if the storage class provided is invalid or if objects are not of this storage class.

The best way is print everything -a and use grep instead to filter what you want.

Didn't thought about it...

Note: mc ls is used for filesystem folders and files as well which may provide empty results here with storage-class.

As implemented in the PR the storage class filter only applies when a storage class is present ( != "" )

[vadmeste]

Why not simply list GLACIER objects in mc ls without any flags but still avoid them in mc cp/mirror (as it is now) ?

[harshavardhana]

Why not simply list GLACIER objects in mc ls without any flags but still avoid them in mc cp/mirror (as it is now) ?

We can change the format and print always, and keep filtering for specific storage classes if needed.

[Willena]

We can change the format and print always, and keep filtering for specific storage classes if needed.

I applied a small change to have the described behavior.
mc ls will always print the storageClass if available.
If -sc <STORAGECLASS> is provided, then filter the result looking only for <STORAGECLASS>.

[harshavardhana]

I applied a small change to have the described behavior.
mc ls will always print the storageClass if available.
If -sc <STORAGECLASS> is provided, then filter the result looking only for <STORAGECLASS>.

Looks great @Willena