[Feat] Support LHD #38
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Summary of Changes
Hello @haochengxia, 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!
I've introduced support for the LHD (Least Hit Density) cache algorithm. This enhancement integrates LHD into our cache simulation framework, making it available for use and testing alongside existing algorithms.
Highlights
- LHD Cache Algorithm Implementation: I've added the LHD class and its initialization function (LHD_init) to libcachesim/cache.py, providing the core logic for the Least Hit Density cache.
- Python API Exposure: The new LHD cache algorithm is now exposed through the main libcachesim package by updating libcachesim/init.py, allowing users to import and utilize it directly.
- C++ Binding Adjustments for LHD: I've modified the find method in src/export_cache.cpp to specifically handle the LHD algorithm's behavior, returning a dummy object for cache hits to ensure proper Python binding interaction.
- Comprehensive Test Integration: The LHD algorithm has been integrated into the existing test suite (tests/test_cache.py), ensuring its basic functionality, eviction, and find methods are covered, with a specific skip for test_basic_get_and_insert due to LHD's unique insert behavior.
- Build System Streamlining: I've removed the scripts/smart_build.py script and updated scripts/install.sh to use pip3, simplifying the build process.
- Dependency Management Refinement: The uv.lock file has been updated to reflect the new libcachesim version and to remove previously included lightgbm and xgboost dependencies, streamlining the project's dependency graph.
- Subproject Update: The src/libCacheSim subproject has been updated to its latest commit, likely incorporating the underlying C++ LHD implementation.
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Pull Request Overview
This PR adds support for the LHD (Least Hit Density) cache algorithm to the libcachesim library. The implementation includes a new cache class with appropriate initialization parameters and comprehensive test coverage.
- Add LHD cache algorithm implementation with initialization function
- Integrate LHD into existing test suites with special handling for its unique behavior
- Update submodule reference and build infrastructure
Reviewed Changes
Copilot reviewed 7 out of 9 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| libcachesim/init.py | Exports the new LHD class in the public API |
| libcachesim/cache.py | Implements the LHD cache class with standard initialization parameters |
| tests/test_cache.py | Adds LHD to all parameterized test suites with special skip logic for insert behavior |
| src/export_cache.cpp | Adds special handling for LHD's unique find method return behavior |
| src/libCacheSim | Updates submodule commit reference |
| scripts/install.sh | Minor change from pip to pip3 command |
| scripts/smart_build.py | Complete file removal |
Comments suppressed due to low confidence (1)
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Code Review
This pull request adds support for the LHD cache algorithm, including the Python class wrapper and test cases. The changes are generally good, but I've identified a few issues. There's an incorrect command in the installation script that will cause it to fail. More critically, in the C++ bindings, there's a memory management mismatch that could lead to undefined behavior, and a magic number is used which is detrimental to maintainability. I've provided detailed comments and suggestions for these points.
LHD