Implementation Plan

• 1. Create cache module with core data structures

  • Create src/cache.rs module file
  • Define CrcParamsCacheKey struct with width, poly, and reflected fields
  • Implement Debug, Clone, PartialEq, Eq, and Hash traits for the cache key
  • Add module declaration to src/lib.rs
  • Requirements: 1.1, 3.1, 3.2

• 2. Implement thread-safe cache storage

  • Define global cache using std::sync::OnceLock<RwLock<HashMap<CrcParamsCacheKey, [u64; 23]>>>
  • Implement get_cache() function to initialize and return cache reference
  • Add necessary imports for std::collections::HashMap, std::sync::{OnceLock, RwLock}
  • Requirements: 1.3, 2.3

• 3. Implement cache lookup and storage functions

  • Create get_or_generate_keys(width: u8, poly: u64, reflected: bool) -> [u64; 23] function
  • Implement cache hit path with read lock and HashMap lookup
  • Implement cache miss path with key generation followed by write lock and storage
  • Add error handling for lock poisoning with fallback to direct key generation
  • Requirements: 1.1, 1.2, 4.1

• 4. Add cache management utilities

  • Implement clear_cache() function for testing and memory management
  • Add proper error handling for all cache operations
  • Ensure all cache operations are best-effort with graceful degradation
  • Requirements: 4.3

• 5. Integrate cache into CrcParams::new()

  • Modify CrcParams::new() in src/structs.rs to use cache::get_or_generate_keys()
  • Replace direct call to generate::keys() with cache lookup
  • Ensure all existing functionality remains unchanged
  • Verify that the function signature and behavior are identical
  • Requirements: 1.1, 1.2, 5.1, 5.2, 5.3

• 6. Create comprehensive unit tests for cache functionality

  • Add tests to src/cache.rs
  • Write tests for cache key creation, equality, and hashing
  • Test cache hit scenarios (same parameters return cached keys)
  • Test cache miss scenarios (new parameters generate and cache keys)
  • Test that cached keys are identical to directly generated keys
  • Requirements: 1.1, 1.2, 3.1, 3.2

• 7. Add thread safety tests

  • Write concurrent access tests using std::thread
  • Test multiple threads reading from cache simultaneously
  • Test read-write contention scenarios
  • Verify cache consistency under concurrent access
  • Test lock poisoning recovery behavior
  • Requirements: 1.3

• 8. Create integration tests for CrcParams compatibility

  • Add tests to verify CrcParams::new() behavior is unchanged
  • Test that all existing CRC parameter combinations work correctly
  • Verify that cached and uncached results are identical
  • Test multiple CrcParams instances with same parameters use cached keys
  • Requirements: 5.1, 5.2, 5.3

• 9. Add comprehensive error handling tests

  • Test cache behavior when locks are poisoned
  • Test memory allocation failure scenarios
  • Verify fallback to direct key generation works correctly
  • Test cache operations under memory pressure
  • Requirements: 4.1, 4.2

• 10. Update existing tests to work with caching

  • Run all existing tests to ensure no regressions
  • Update any tests that might be affected by caching behavior
  • Ensure test isolation by clearing cache between tests if needed
  • Verify all CRC algorithm tests still pass
  • Requirements: 5.1, 5.2, 5.3

• 11. Add documentation and finalize implementation

  • Add inline documentation for all new public and internal functions
  • Update module-level documentation
  • Add usage examples in code comments
  • Ensure all code follows existing project style and conventions
  • Requirements: 5.3