Feature: add metrics in metasrv

[lichuang]

I hereby agree to the terms of the CLA available at: https://databend.rs/dev/policies/cla/

Summary

Feature: add metrics framework in metasrv.
More metrics will be added after this pr.

Changelog

• New Feature

Related Issues

part of metrics API providing requests/sec, active watchers, outstanding(uncommitted) raft logs, number of raft logs, state machine size etc. · Issue #4938 · datafuselabs/databend

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Name	Status	Preview	Updated
databend	✅ Ready (Inspect)	Visit Preview	May 13, 2022 at 5:51AM (UTC)

[mergify]

Thanks for the contribution!
I have applied any labels matching special text in your PR Changelog.

Please review the labels and make any necessary changes.

[drmingdrmer]

I think this can be derived.

But it's not a big deal and should not be a blocker for this PR.

[BohuTANG]

+1

[BohuTANG]

@mergify update

[mergify]

update

✅ Branch has been successfully updated

[BohuTANG]

This patch broke the CI:

---- api::http::cluster_state_test::test_cluster_state stdout ----
thread 'api::http::cluster_state_test::test_cluster_state' panicked at 'metametrics is not initialized', metasrv/src/metrics/meta_metrics.rs:42:24
stack backtrace:
   0:     0x5590aa0c088d - std::backtrace_rs::backtrace::libunwind::trace::h701a19af54e96518
                               at /rustc/76d770ac21d9521db6a92a48c7b3d5b2cc535941/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5

https://github.com/datafuselabs/databend/runs/6334802517?check_suite_focus=true#step:3:954

[BohuTANG]

This patch broke the CI:

---- api::http::cluster_state_test::test_cluster_state stdout ----
thread 'api::http::cluster_state_test::test_cluster_state' panicked at 'metametrics is not initialized', metasrv/src/metrics/meta_metrics.rs:42:24
stack backtrace:
   0:     0x5590aa0c088d - std::backtrace_rs::backtrace::libunwind::trace::h701a19af54e96518
                               at /rustc/76d770ac21d9521db6a92a48c7b3d5b2cc535941/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5

https://github.com/datafuselabs/databend/runs/6334802517?check_suite_focus=true#step:3:954

cc @lichuang

[lichuang]

https://github.com/datafuselabs/databend/runs/6334802517?check_suite_focus=true#step:3:954

fixed.

[BohuTANG]

@mergify update

[mergify]

update

☑️ Nothing to do

• -closed [:pushpin: update requirement]
• #commits-behind>0 [:pushpin: update requirement]