pdpb: preserve caller components in QueryRegion requests

[JmPotato]

QueryRegion can contain logical queries from different caller components, but its shared request header carries only one component. Per-query metadata lets PD attribute these queries correctly while retaining mixed batches.

Add optional id_caller_components, key_caller_components, and prev_key_caller_components arrays, aligned by position with ids, keys, and prev_keys. An absent or mismatched array falls back to header.caller_component; an empty entry represents an unknown component. Existing field numbers and response encoding remain unchanged, and older receivers ignore the new fields.

Update the generated Go bindings and protocol lock. Related: tikv/pd#11180.

Validation: make go (protocol formatting, compatibility checks, generation, module tidy, and Go build), go build ./pkg/..., and go test ./pkg/pdpb ./pkg/routerpb.

Summary by CodeRabbit

• New Features
  • Query requests now support optional caller-component information for ID, key, and previous-key lookups.
  • Caller components can be specified per query, with unspecified or unknown entries handled automatically.

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📝 Walkthrough

Walkthrough

QueryRegionRequest adds optional caller-component arrays for ID, key, and previous-key queries. Arrays use positional matching. Missing or incorrectly sized arrays fall back to header.caller_component; empty entries represent unknown components.

Changes

Query caller components

Layer / File(s)	Summary
QueryRegionRequest caller-component fields proto/pdpb.proto	QueryRegionRequest adds id_caller_components, key_caller_components, and prev_key_caller_components. Each array aligns with its query category and defines fallback behavior.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Feature

Suggested reviewers: disksing

Merge Risk: ⚪ Minimal · up to fa85d

The request can preserve per-query caller metadata while remaining compatible with existing receivers; no merge-blocking risk is currently identified.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: preserving caller components in QueryRegion requests.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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_{I’m a rabbit with fields in a row
Caller components now know where to go
IDs, keys, and old keys align
Empty hops mark unknown by design
If lengths go astray
The header leads the way}

_{Comment @coderabbitai help to get the list of available commands.}

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