expose token cache size in metrics and log

[WindzCUHK]

Description

major changes

log

INFO[2023-12-25T16:35:32+09:00] system_memory_inuse[576.2MB]; go_memstats_heap_alloc_bytes[426.8MB]; accesstoken:cached_token_bytes[218.0MB],entries[200001]; roletoken:cached_token_bytes[176.8MB],entries[200001]; total:cached_token_bytes[394.7MB],entries[400002]; cache_token_ratio:sys[68.2%],heap[92.5%]

metrics

$ curl -sSi http://127.0.0.1:9999/metrics
# HELP go_memstats_heap_alloc_bytes Number of heap bytes allocated and still in use.
# TYPE go_memstats_heap_alloc_bytes gauge
go_memstats_heap_alloc_bytes 2.120936e+06
# HELP go_memstats_sys_bytes Number of bytes obtained from system.
# TYPE go_memstats_sys_bytes gauge
go_memstats_sys_bytes 1.471592e+07
...
# HELP cached_token_bytes Number of bytes cached.
# TYPE cached_token_bytes gauge
cached_token_bytes{type="accesstoken"} 4353
cached_token_bytes{type="roletoken"} 557
# HELP cached_token_entries Number of entries cached.
# TYPE cached_token_entries gauge
cached_token_entries{type="accesstoken"} 5
cached_token_entries{type="roletoken"} 1

minor changes

• github workflow: prevent github release creation on non-tagging events

Type of change

• [ ] Bug fix
• [x] New feature
• [x] Refactoring (no functional changes, no api changes)
• [ ] Non-code changes (update documentation, pipeline, etc.)

Flags

• [ ] Breaks backward compatibility
• [ ] Requires a documentation update
• [ ] Has untestable code

Related issue/PR

• Closes #70

---

Checklist

• [x] Followed the guidelines in the CONTRIBUTING document
• [x] Added prefix [skip ci]/[ci skip]/[no ci]/[skip actions]/[actions skip] in the PR title if necessary
• [x] Tested and linted the code
• [x] Commented the code
• [x] Made corresponding changes to the documentation
• [x] Passed all pipeline checking

Checklist for maintainer

• Use Squash and merge
• Double-confirm the merge message has prefix [skip ci]/[ci skip]/[no ci]/[skip actions]/[actions skip]
• Delete the branch after merge