[songgaoye]

What problem does this PR solve?

Issue Number: resolve

Problem Summary:

AsyncLogger::Log(const LogInfo&) and AsyncLogger::Log(LogInfo&&) duplicate
the same queue admission, shutdown, and synchronous fallback logic. Keeping
these paths separate makes future changes easier to diverge.

What is changed and the side effects?

Changed:

• Consolidate the shared logging flow into an internal forwarding helper.
• Keep lvalue inputs copied and rvalue inputs moved only after a log request is
  successfully allocated.
• Preserve the existing synchronous fallback behavior when the logger is full,
  stopped, or allocation fails.

Side effects:

• No intended behavioral change.

• Performance effects:

  No expected material performance change. The rvalue path still moves the
  LogInfo into the queued request.

• Breaking backward compatibility:

  No. This refactors private implementation details only.

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Check List:

• Please make sure your changes are compilable.
• When providing us with a new feature, it is best to add related tests.
• Please follow Contributor Covenant Code of Conduct.

[Copilot]

🟢 Approval recommended

The focused refactor preserves existing behavior and has no identified blocking issues; builds and tests were not run.

No open issues 🎉

What changed in this PR

This PR consolidates AsyncLogger’s duplicated enqueue logic into a private forwarding helper while preserving existing logging behavior.

Changes:

• Share queue admission, shutdown checks, and synchronous fallback logic between both Log overloads.
• Preserve copying for lvalues and moving for rvalues only after successful request allocation.

File	Description
src/​butil/​logging.cc	Introduces LogInternal and copy/move enqueue helpers to remove duplicated control flow.

_{Review effort: Balanced}