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Create comprehensive GitHub Copilot instructions for libCacheSim-python development (#51)
* Initial plan * Initial exploration and build validation - fixed pybind11 compatibility issue Co-authored-by: haochengxia <[email protected]> * Complete copilot-instructions.md with comprehensive build, test, and validation procedures Co-authored-by: haochengxia <[email protected]> --------- Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: haochengxia <[email protected]>
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‎.github/copilot-instructions.md‎

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# libCacheSim-python
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libCacheSim-python is a high-performance Python binding for the libCacheSim library, providing cache simulation and analysis capabilities. It uses CMake, pybind11, and scikit-build-core for building Python extensions around a C++ core library.
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Always reference these instructions first and fallback to search or bash commands only when you encounter unexpected information that does not match the info here.
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## Working Effectively
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### Prerequisites and System Dependencies
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- Install system dependencies: `sudo bash src/libCacheSim/scripts/install_dependency.sh` -- takes 66 seconds. NEVER CANCEL.
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- Install Python build dependencies: `sudo apt install -y python3-numpy python3-pytest pybind11-dev`
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- **CRITICAL**: Git submodules are required: `git submodule update --init --recursive` -- takes 2.4 seconds.
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### Build Process (Manual CMake - RECOMMENDED)
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**NEVER CANCEL builds** - CMake configuration + build takes 20-35 seconds total. Set timeout to 120+ seconds.
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1. **Standard build (Debug)**:
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```bash
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mkdir build && cd build
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cmake .. -G Ninja
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ninja
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```
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- Configuration: ~2.4 seconds
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- Build: ~3 seconds
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- Total: ~6 seconds
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2. **Optimized build (Release)**:
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```bash
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mkdir build && cd build
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cmake .. -G Ninja -DCMAKE_BUILD_TYPE=Release
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ninja
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```
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- Configuration: ~17 seconds (includes libCacheSim build with 175 targets)
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- Build: ~18 seconds (includes LTO optimization)
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- Total: ~35 seconds
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3. **Test the build**:
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```bash
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export PYTHONPATH=$(pwd)/build:$PYTHONPATH
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python3 -c "import libcachesim_python as lcs; print('✓ Import successful')"
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```
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### Python Package Installation (pip install -e .)
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**WARNING**: pip install may experience network timeouts in CI environments. This is NORMAL.
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- If `pip install -e .` fails with network timeouts, use the manual CMake build approach above.
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- pip installation typically takes 30-60 seconds when network is stable.
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- Use longer timeouts (120+ seconds) and retry if needed.
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### Testing
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- **Manual validation** (always works):
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```bash
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export PYTHONPATH=$(pwd)/build:$PYTHONPATH
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python3 -c "
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import libcachesim_python as lcs
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common_params = lcs.CommonCacheParams(cache_size=1024)
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cache = lcs.LRU_init(common_params)
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req = lcs.Request()
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req.obj_id = 1
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req.obj_size = 10
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req.op = lcs.OP_GET
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cache.get(req)
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print(f'Cache has {cache.get_n_obj()} objects')
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"
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```
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- **pytest** (if available):
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```bash
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python3 -m pytest tests/ -v -m "not optional"
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```
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- NOTE: System pytest is version 7.4.4, but pyproject.toml requires 8.0+
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- Use manual validation instead if pytest version conflicts occur
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### Performance Validation
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- **Debug build**: ~65,000 requests/second
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- **Release build**: ~571,000 requests/second
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- Test with: `python3 -c "import time; import libcachesim_python as lcs; start=time.time(); common_params=lcs.CommonCacheParams(cache_size=10000); cache=lcs.LRU_init(common_params); [cache.get(lcs.Request(obj_id=i%1000, obj_size=10, op=lcs.OP_GET)) for i in range(100000)]; print(f'Rate: {100000/(time.time()-start):.0f} req/s')"`
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## Critical Build Issues & Solutions
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### Network Timeouts
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**COMMON**: pip install may timeout due to PyPI network issues.
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- **Solution**: Use manual CMake build instead of pip install
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- **NOT a code issue** - this is an infrastructure limitation
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### pybind11 Compatibility
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**FIXED**: If you see `py::set_error` compilation errors:
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- This was already fixed in src/exception.cpp (lines 24, 26)
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- The fix changed `py::set_error(exc, msg)` to `exc(msg)` for pybind11 2.10+ compatibility
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### Optional Features (Advanced Algorithms)
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Optional cache algorithms (LRB, GLCache, 3LCache) require additional dependencies:
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- **XGBoost** and **LightGBM** libraries
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- Install with: `bash scripts/install_deps.sh` or `bash scripts/install_deps_user.sh`
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- Build with: `cmake -DENABLE_LRB=ON -DENABLE_GLCACHE=ON -DENABLE_3L_CACHE=ON`
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- **Skip optional features** for basic development - they are not required
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## Development Workflow
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### Standard Development Process
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1. **Initialize**: `git submodule update --init --recursive`
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2. **Install system deps**: `sudo bash src/libCacheSim/scripts/install_dependency.sh`
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3. **Build**: `mkdir build && cd build && cmake .. -G Ninja && ninja`
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4. **Test**: `export PYTHONPATH=$(pwd)/build:$PYTHONPATH && python3 -c "import libcachesim_python"`
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5. **Validate changes**: Run manual performance test
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### After Making Code Changes
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1. **Rebuild**: `ninja` (from build directory) -- takes 2-3 seconds
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2. **Test import**: `python3 -c "import libcachesim_python"`
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3. **Run validation scenarios**: Test cache algorithms manually
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4. **Performance check**: Verify >500k requests/second in Release mode
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### Common Validation Scenarios
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Always test these scenarios after making changes:
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1. **Basic cache creation**: LRU, FIFO, LFU, ARC, S3FIFO
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2. **Request processing**: Insert/get operations with different object sizes
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3. **Performance**: Ensure >500k requests/second (Release build)
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4. **Memory usage**: Verify reasonable memory consumption
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## Code Navigation
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### Key Directories
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- `src/`: Python binding source code (C++)
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- `src/libCacheSim/`: Git submodule containing the core C++ library
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- `tests/`: Python test suite
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- `examples/`: Usage examples
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- `benchmark/`: Performance benchmarks
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- `scripts/`: Build and installation scripts
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### Core Source Files
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- `src/export.cpp`: Main pybind11 module definition
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- `src/export_cache.cpp`: Cache algorithm exports
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- `src/export_reader.cpp`: Trace reader exports
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- `src/exception.cpp`: Exception handling (recently fixed for pybind11 compatibility)
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- `CMakeLists.txt`: Build configuration
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- `pyproject.toml`: Python package configuration
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### Native Tools
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The build also produces native C++ binaries in `src/libCacheSim/build/bin/`:
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- `cachesim`: Command-line cache simulator
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- `traceAnalyzer`: Trace analysis tool
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- `MRC`: Miss ratio curve generation
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- Use: `./cachesim trace_path csv LRU 100MB`
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## Timing Expectations
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### Build Times (NEVER CANCEL - set timeouts 120+ seconds)
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- Git submodule init: 2.4 seconds
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- System dependency install: 66 seconds
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- CMake configuration (Debug): 2.4 seconds
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- CMake configuration (Release): 17 seconds (includes full libCacheSim build)
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- Build (Debug): 3 seconds
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- Build (Release): 18 seconds (includes LTO)
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- **Total fresh build**: 75-110 seconds depending on build type
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### Test Times
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- Manual validation: <1 second
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- Performance test (100k requests): 0.2 seconds
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- pytest (when working): 10-30 seconds
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### Network Dependencies
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- pip install: 30-300 seconds (may timeout, use manual build instead)
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- Git submodule clone: 2-5 seconds
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## Troubleshooting
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### Build Failures
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- **pybind11 not found**: `sudo apt install pybind11-dev`
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- **Network timeouts**: Use manual CMake build instead of pip install
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- **Missing submodules**: `git submodule update --init --recursive`
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- **XGBoost/LightGBM missing**: Disable optional features or install via `scripts/install_deps.sh`
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### Import Failures
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- **Module not found**: `export PYTHONPATH=$(pwd)/build:$PYTHONPATH`
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- **Symbol errors**: Rebuild with `ninja` from build directory
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- **Version mismatch**: Check pybind11 version compatibility
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### Performance Issues
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- **Slow performance**: Use Release build (`cmake -DCMAKE_BUILD_TYPE=Release`)
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- **Memory leaks**: Check exception handling and object lifecycle
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Always use the manual CMake build approach for reliable development - the pip install method may fail due to network issues beyond your control.

‎src/exception.cpp‎

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try {
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if (p) std::rethrow_exception(p);
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} catch (const CacheException& e) {
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py::set_error(exc_cache, e.what());
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exc_cache(e.what());
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} catch (const ReaderException& e) {
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py::set_error(exc_reader, e.what());
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exc_reader(e.what());
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}
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});
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