revamp startup and shutdown flow

[WindzCUHK]

Description

• revamp startup flow
  • retry
  • allow cancel during retry
  • mode=init, max. retry time = 3 min
  • control New() phase by initCtx
  • On error, fatal
  • On signal, finish current function block to ensure integrity, skip further function block, handle context
  • control Start() phase by runCtx
  • On error in main go routine, cancel context
  • On error in sub go routine, should continue except for fatal error
  • On signal, finish current function block to ensure integrity, skip further function block, handle context
  • On context cancel, should stop all sub go routine gracefully, and skip further process or retry
• revamp shutdown flow
  • Once Start(), should always Shutdown()
  • Shutdown() is graceful and blocking

Type of change

• [ ] Bug fix
• [ ] New feature
• [ ] 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

• Related #95
• Fixes #98
• Fixes #101
• Created #108

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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
• [ ] 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

[ctyano]

Description

• revamp startup flow
• revamp shutdown flow

Regardless of this description, I see a lot of changes and I think this description itself needs to be updated to explain it in more detail.