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Plugin V2 Example - LRU Cache with Hooks

This example demonstrates how to create a plugin for libCacheSim using the v2 hook-based plugin system. The plugin implements a standalone LRU (Least Recently Used) cache algorithm that integrates with libCacheSim's plugin_cache.c framework.

Files

  • plugin_lru.cpp - The main LRU cache plugin implementation using hooks
  • test_hooks_plugin.c - Comprehensive test program for the plugin
  • CMakeLists.txt - Build configuration for creating the shared library

Dependencies

Make sure you have followed the root README instructions to set up development tools and install libCacheSim.

Building

To compile the plugin into a shared library:

mkdir -p build && cd build/
cmake -G Ninja .. && ninja

This will create:

  • libplugin_lru_hooks.so - Shared library
  • test_hooks_plugin - Test executable for validation

Plugin Architecture

The plugin implements a standalone LRU cache using C++ with a C interface for compatibility with libCacheSim. It uses:

  • StandaloneLRU Class: C++ implementation with doubly-linked list and hash map
  • Hook Functions: C interface functions that plugin_cache.c calls

Hook Functions

The plugin implements these required hook functions:

  • cache_init_hook() - Initialize the LRU cache data structure
  • cache_hit_hook() - Handle cache hits (move object to head of LRU list)
  • cache_miss_hook() - Handle cache misses (insert new object)
  • cache_eviction_hook() - Evict least recently used object and return its ID
  • cache_remove_hook() - Remove specific object from cache
  • cache_free_hook() - Clean up and free the LRU cache data structure

Usage

With cachesim Binary

../../../_build/bin/cachesim ../../../data/cloudPhysicsIO.vscsi vscsi lru,pluginCache 0.01,0.1 \
  -e "plugin_path=libplugin_lru_hooks.so"

Testing the Plugin

Run the included test to verify plugin functionality:

./test_hooks_plugin

The test compares the plugin LRU implementation against libCacheSim's built-in LRU to ensure identical behavior.

Implementation Notes

  • The plugin uses C++ internally but exports C functions for compatibility
  • Memory management is handled automatically by the StandaloneLRU destructor
  • The implementation maintains the same LRU semantics as libCacheSim's built-in LRU
  • Thread safety is not implemented - suitable for single-threaded use cases

Troubleshooting

  • Ensure the plugin path uses the plugin_path= prefix format
  • Verify all dependencies are available (check with ldd libplugin_lru_hooks.so)
  • If relative paths don't work, use absolute paths when specifying the plugin location