[chenBright]

What problem does this PR solve?

Issue Number: Related to #3050

Problem Summary:

When allow_remaining_bytes_after_parsing is enabled, parsing a JSON value that
ends exactly at EOF succeeds but returns parsed_offset == 0. For example, parsing
"{}" returns zero instead of two.

Callers that resume parsing with json.substr(parsed_offset) therefore repeatedly process
the final message and may enter an infinite loop.

What is changed and the side effects?

Changed:

Always record the consumed offset when iterative parsing finishes a JSON value with
kParseStopWhenDoneFlag, including at EOF. This matches the existing non-iterative
behavior.

Side effects:

• Performance effects:

• Breaking backward compatibility:

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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]

Warning

Copilot couldn't run its full agentic review because it didn't start before the timeout. Make sure your repository has a runner available, or add a copilot-code-review.yml file specifying one with the runs-on attribute. See the docs for more details.

Copilot review overview

3 open issues

• The same offset variable is reused for two different semantics in the same loop (string parse… · New
• Since the behavior is being changed specifically to record offsets even at EOF, it would help to… · New
• array_to_single_repeated = true is not required for most of the test cases here and broadens the… · New

What changed in this PR

Fixes incorrect parsed_offset reporting when JSON parsing stops exactly at EOF with allow_remaining_bytes_after_parsing, preventing callers from reprocessing the same bytes and potentially looping indefinitely.

Changes:

• Update RapidJSON iterative parsing to always record the consumed offset when kParseStopWhenDoneFlag is used, even at EOF.
• Add unit tests covering offset behavior at EOF for both string and stream-based parsing.
• Add coverage for parsing multiple concatenated JSON values and resuming correctly at EOF.

File	Description
test/​brpc_protobuf_json_unittest.cpp	Adds regression tests for parsed offset correctness at EOF and for concatenated JSON parsing behavior.
src/​butil/​third_party/​rapidjson/​reader.h	Ensures parseResult_.Offset() is updated at EOF when stop-when-done iterative parsing completes.

_{Review effort: Lite}

[Copilot]

Warning

Copilot couldn't run its full agentic review because it didn't start before the timeout. Make sure your repository has a runner available, or add a copilot-code-review.yml file specifying one with the runs-on attribute. See the docs for more details.

Copilot review overview

2 open issues

• These negative-test assertions depend on string_offset/stream_offset values produced by prior… · New
• This comment is in a third-party RapidJSON header but references a project-specific API… · New

3 resolved since last review

• The same offset variable is reused for two different semantics in the same loop (string parse…
• array_to_single_repeated = true is not required for most of the test cases here and broadens the…
• Since the behavior is being changed specifically to record offsets even at EOF, it would help to…

_{Review effort: Lite}

[Copilot]

Warning

Copilot couldn't run its full agentic review because it didn't start before the timeout. Make sure your repository has a runner available, or add a copilot-code-review.yml file specifying one with the runs-on attribute. See the docs for more details.

Copilot review overview

3 open issues

• This is a vendored third-party header, but the comment is project-specific (JsonToProtoMessage())… · New
• Using SetParseError(kParseErrorNone, ...) to update a successful parse offset is non-obvious… · New
• The test name parse_json_offset_at_eof is misleading because the cases include non-EOF-stop… · New

2 resolved since last review

• These negative-test assertions depend on string_offset/stream_offset values produced by prior…
• This comment is in a third-party RapidJSON header but references a project-specific API…

_{Review effort: Lite}

[chenBright]

@wwbmmm These are optional readability/style improvements of copilot, so no further changes are needed. This PR is ready for maintainer review.