MRT updates iterator

[digizeph]

This pull request introduces a new intermediate data structure, MrtUpdate, and associated iterators to the BGPKit parser, providing a more efficient way to process BGP announcements. It updates documentation, benchmarks, and examples to reflect and demonstrate these new capabilities. The changes are grouped below by theme.

New Features and API Additions

• Added UpdateIterator and FallibleUpdateIterator for iterating over BGP announcements, with the new MrtUpdate enum supporting both BGP4MP UPDATE messages and TableDumpV2 RIB entries. Also introduced Bgp4MpUpdate and TableDumpV2Entry structs, and new methods (into_update_iter, into_fallible_update_iter) on BgpkitParser for efficient batch processing. [1] [2]

Documentation and Examples

• Updated README.md, crate-level docs (src/lib.rs), and changelog to describe the new MrtUpdate representation, compare it to existing approaches, and clarify memory/performance trade-offs. Added a new example (examples/update_messages_iter.rs) to demonstrate usage and performance comparison.

Benchmarking

• Added new benchmarks for into_update_iter on both updates and rib dump files to measure and compare performance with existing iterators. [1] [2]

These changes enhance the parser's flexibility and efficiency, making it easier to choose the right data structure for different BGP analysis tasks.

[digizeph]

This addresses issue #250

[codecov]

Codecov Report

❌ Patch coverage is 75.38803% with 111 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.50%. Comparing base (0453969) to head (e504b54).
⚠️ Report is 16 commits behind head on main.

Files with missing lines	Patch %	Lines
src/parser/iters/update.rs	81.06%	78 Missing ⚠️
src/parser/iters/mod.rs	15.38%	33 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #254      +/-   ##
==========================================
- Coverage   90.87%   90.50%   -0.37%     
==========================================
  Files          80       81       +1     
  Lines       12588    13006     +418     
==========================================
+ Hits        11439    11771     +332     
- Misses       1149     1235      +86     

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[Copilot]

Pull request overview

This pull request introduces a new intermediate data structure MrtUpdate and associated iterators (UpdateIterator and FallibleUpdateIterator) to the BGPKit parser. This provides a middle ground between the low-level MrtRecord and high-level BgpElem representations, optimizing for cases where per-prefix attribute duplication is unnecessary. The change enhances the parser's flexibility and performance for batch processing of BGP announcements without expanding them into individual per-prefix elements.

Key changes:

• New MrtUpdate enum with variants for BGP4MP updates, TableDumpV2 RIB entries, and legacy TableDump messages
• Two new iterator types: UpdateIterator (error-skipping) and FallibleUpdateIterator (error-exposing)
• Comprehensive documentation and examples demonstrating the performance benefits

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/parser/iters/update.rs	Core implementation of the new iterator types, data structures (Bgp4MpUpdate, TableDumpV2Entry, MrtUpdate), and error handling logic
src/parser/iters/mod.rs	Integration of new iterators into the parser module, exposing into_update_iter() and into_fallible_update_iter() methods with documentation
src/lib.rs	Updated crate-level documentation to describe the three-way data representation model and provide usage guidance
examples/update_messages_iter.rs	New comprehensive example demonstrating UpdateIterator usage and comparing performance with ElemIterator
examples/README.md	Added documentation entry for the new example
benches/internals.rs	Added benchmarks for the new into_update_iter() method on both updates and RIB dump files
README.md	Updated data representation documentation to include MrtUpdate in the three-way model
CHANGELOG.md	Documented the new feature, structs, and methods in the unreleased section

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