brontide: implement tiered buffer pool for message encryption

[hxrshxz]

Change Description

Implements a tiered buffer pool for the brontide package's encrypted message body buffers. Instead of always allocating 65KB buffers (the maximum message size), the pool now provides appropriately sized buffers based on actual message size.

Most Lightning Network messages are much smaller than the 65KB maximum. This change reduces per-message memory overhead while maintaining the allocation reduction benefits of buffer pooling.

The pool uses four tiers:

• 256B (+MAC): very small messages
• 1KB (+MAC): small messages
• 4KB (+MAC): medium messages
• 64KB (+MAC): large messages

Fixes #10246

Steps to Test

1. Run all brontide tests:

   go test -v ./brontide/... -count=1

2. Run benchmarks to verify performance across message sizes:

   go test -bench="BenchmarkWriteMessageSizes" -benchmem ./brontide/...

3. Verify zero allocations in benchmarks - all should show 0 allocs/op

Pull Request Checklist

Testing

• Your PR passes all CI checks.
• Tests covering the positive and negative (error paths) are included.
• Unit tests for tier selection, buffer reuse, nil handling, and concurrency added.

Code Style and Documentation

• The change is not insubstantial. Typo fixes are not accepted to fight bot spam.
• The change obeys the Code Documentation and Commenting guidelines, and lines wrap at 80.
• Commits follow the Ideal Git Commit Structure.
• Any new logging statements use an appropriate subsystem and logging level.
• Any new lncli commands have appropriate tags in the comments for the rpc in the proto file.
• There is a change description in the release notes, or [skip ci] in the commit message for small changes.

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[gemini-code-assist]

Summary of Changes

Hello @hxrshxz, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a sophisticated tiered buffer pooling mechanism to the brontide package, specifically for handling encrypted message bodies. By moving away from a fixed-size buffer allocation to a dynamic, tiered approach, the system can now provision memory more precisely according to message size. This enhancement aims to substantially reduce memory footprint and improve overall efficiency, particularly for smaller messages, while preserving the performance benefits of buffer reuse.

Highlights

• Memory Optimization: Implemented a tiered buffer pool in the brontide package to manage encrypted message body buffers more efficiently.
• Dynamic Buffer Sizing: Replaced the previous single-size buffer pool (always allocating 65KB) with a system that provides appropriately sized buffers based on actual message size.
• Tiered Structure: The new pool utilizes four distinct tiers (256B, 1KB, 4KB, 64KB, including MAC overhead) to cater to various message sizes.
• Reduced Overhead: This change significantly reduces per-message memory overhead, especially for the majority of Lightning Network messages which are smaller than the maximum size.
• Comprehensive Testing: Added new benchmarks (BenchmarkWriteMessageSizes, BenchmarkTieredBufferPoolTakeAndPut) and extensive unit tests (TestTierForSize, TestTieredBufferPoolTakeAndPut, TestTieredBufferPoolReuse, TestTieredBufferPoolNilPut, TestTieredBufferPoolConcurrency) to validate the functionality, performance, and concurrency safety of the tiered buffer pool.

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[gemini-code-assist]

Code Review

This pull request introduces a tiered buffer pool for message encryption, which is an excellent optimization to reduce memory overhead for smaller messages. The implementation is robust, and the addition of comprehensive unit tests, concurrency tests, and benchmarks is commendable. My review includes a few suggestions to align the code with the repository's style guide and a minor refactoring to reduce code duplication, further improving maintainability.

[Copilot]

Pull request overview

This PR implements a tiered buffer pool system for the brontide package to optimize memory usage during message encryption. Instead of always allocating 65KB buffers for all messages, the implementation now provides four tiers of buffer sizes (256B, 1KB, 4KB, and 64KB) to match the actual message size needs, reducing memory overhead for the majority of Lightning Network messages that are much smaller than the maximum size.

Key Changes

• Introduced a four-tier buffer pool structure that selects buffer sizes based on plaintext message length
• Replaced the single-tier bodyBufferPool with tieredBodyPool that intelligently manages multiple size tiers
• Added comprehensive test coverage for tier selection, buffer reuse, and concurrent access patterns

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
brontide/noise.go	Implemented tieredBufferPool struct with tier selection logic, integrated with existing WriteMessage and buffer release flows
brontide/tiered_buffer_pool_test.go	Added comprehensive unit tests for tier selection, buffer allocation/reuse, nil handling, and concurrency
brontide/bench_test.go	Added benchmarks to measure performance across different message sizes and verify zero-allocation behavior

---

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[hxrshxz]

@gemini-code-assist please review

[gemini-code-assist]

Code Review

This pull request introduces a tiered buffer pool for message encryption, which is a solid improvement for memory efficiency. The implementation is clean and well-tested, including new benchmarks to validate the performance benefits. I've identified a potential bug in the buffer pooling logic that could lead to unexpected memory allocations, and a minor improvement for the new tests. Overall, this is a great contribution.

[hxrshxz]

@gemini-code-assist please review

[gemini-code-assist]

Code Review

This pull request introduces a tiered buffer pool for message encryption to optimize memory usage. Instead of allocating a fixed 65KB buffer for all messages, the new implementation selects a buffer from one of four tiers based on the message size. The changes are well-structured, and the new tieredBufferPool is thoroughly tested, including for concurrency. My review focuses on improving code style and consistency with the project's guidelines and general best practices.

[hxrshxz]

@gemini-code-assist please review

[gemini-code-assist]

Code Review

This pull request introduces a tiered buffer pool for message encryption, which is a great optimization to reduce memory overhead for smaller messages. The implementation is clean and well-encapsulated within the new tieredBufferPool type. The addition of comprehensive unit tests covering various scenarios, including concurrency, and new benchmarks to validate the performance is excellent. I have a couple of suggestions to improve code maintainability by reducing duplication and magic numbers. Overall, this is a solid improvement.

[hxrshxz]

@gemini-code-assist please review

[gemini-code-assist]

Code Review

This pull request introduces a tiered buffer pool for message encryption in the brontide package, which is a great optimization to reduce memory overhead for smaller messages. The implementation is solid, with comprehensive unit tests covering various scenarios including concurrency, and new benchmarks to validate the performance improvements. I have a couple of suggestions to further improve the code's clarity and adherence to the style guide.

[hxrshxz]

@gemini-code-assist please review

[gemini-code-assist]

Code Review

This pull request introduces a tiered buffer pool for message encryption in the brontide package, which is a great optimization to reduce memory overhead for smaller messages. The implementation of tieredBufferPool is robust, thread-safe, and well-designed. The logic for selecting buffer tiers based on message size is sound. The changes are supported by a comprehensive suite of new unit tests that cover functionality, edge cases, and concurrency, as well as new benchmarks to measure the performance impact. The code quality is high and adheres to the project's style guidelines. I have one minor suggestion regarding the release notes.

[lightninglabs-deploy]

@hxrshxz, remember to re-request review from reviewers when ready

[hxrshxz]

@yyforyongyu Please have a look thank you

[saubyk]

@hxrshxz please don't tag developers for review. This pr is in the review queue for LND v0.21 now and will be picked up eventually.

[hxrshxz]

@hxrshxz please don't tag developers for review. This pr is in the review queue for LND v0.21 now and will be picked up eventually.

Sorry , I got confused coz of the bot