feat(dashboard): enable compression for API & minor refactors

[BugenZhao]

Signed-off-by: Bugen Zhao [email protected]I hereby agree to the terms of the RisingWave Labs, Inc. Contributor License Agreement.

What's changed and what's your intention?

Add a CompressionLayer for the API backend. This should effectively reduce the transmit size and relieve #15127 in the fastest way.

Take the response size of /fragments/ as an example, which is used for visualizing the stream fragment graph:

Workload	Before this PR	After this PR
Table (1 parallelism)	4.3 kB	1.5 kB
Table (100 parallelism)	559 kB	9.5 kB
Nexmark Q7 (1 parallelism)	28.5 kB	3.7 kB
Nexmark Q7 (100 parallelism)	3.3 MB	49.8 kB

So I think there's no more need to do manual compression any more, mentioned as a candidate solution in #15127.

Manually reduce the data amount somehow like #13598, as in most cases except for the dispatcher, we do not care about the difference between the node bodies from different actors in the same fragment.

Also do some minor refactors and fixes.

• Remove unused list_actors API.
• Correctly handle the NULL value for embedded back pressure metrics where the graph is empty.

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• All checks passed in ./risedev check (or alias, ./risedev c)

Documentation

• My PR needs documentation updates. (Please use the Release note section below to summarize the impact on users)

Release note

If this PR includes changes that directly affect users or other significant modifications relevant to the community, kindly draft a release note to provide a concise summary of these changes. Please prioritize highlighting the impact these changes will have on users.

[yezizp2012]

LGTM

[xxchan]

rubber stamp