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import contextlib
import hashlib
import logging
import pickle
import time
from collections.abc import Callable
from functools import wraps
from pathlib import Path
from typing import Any, TypeVar
logger = logging.getLogger(__name__)
F = TypeVar("F", bound=Callable[..., Any])
class CacheManager:
"""Manages file-based caching for function results."""
def __init__(self, cache_dir: str | Path = "cache", max_age: int | None = None):
"""Initialize the cache manager.
Args:
cache_dir: Directory to store cache files
max_age: Maximum age of cache files in seconds (None for no expiration)
"""
self.cache_dir = Path(cache_dir)
self.max_age = max_age
self.cache_dir.mkdir(exist_ok=True)
def _get_cache_key(self, func: Callable, args: tuple, kwargs: dict) -> str:
"""Generate a unique cache key for function call.
Args:
func: The function being cached
args: Positional arguments
kwargs: Keyword arguments
Returns:
Unique cache key string
"""
# Create a unique key based on function name, args, and kwargs
key_data = {
"func_name": func.__name__,
"module": func.__module__,
"args": args,
"kwargs": kwargs,
}
# Serialize to bytes for consistent hashing
key_bytes = pickle.dumps(key_data, protocol=pickle.HIGHEST_PROTOCOL)
# Generate hash
return hashlib.sha256(key_bytes).hexdigest()
def _get_cache_path(self, cache_key: str) -> Path:
"""Get the file path for a cache key.
Args:
cache_key: The cache key
Returns:
Path to cache file
"""
return self.cache_dir / f"{cache_key}.pkl"
def _is_cache_valid(self, cache_path: Path) -> bool:
"""Check if cache file is valid and not expired.
Args:
cache_path: Path to cache file
Returns:
True if cache is valid, False otherwise
"""
if not cache_path.exists():
return False
if self.max_age is None:
return True
# Check if file is within max_age
file_age = time.time() - cache_path.stat().st_mtime
return file_age <= self.max_age
def _save_to_cache(self, cache_path: Path, data: Any) -> None:
"""Save data to cache file using pickle serialization.
Args:
cache_path: Path to save cache file
data: Data to cache
"""
try:
cache_path.parent.mkdir(parents=True, exist_ok=True)
with open(cache_path, "wb") as f:
pickle.dump(data, f, protocol=pickle.HIGHEST_PROTOCOL)
logger.debug(f"Cached result to {cache_path}")
except Exception as e:
logger.warning(f"Failed to save cache to {cache_path}: {e}")
def _load_from_cache(self, cache_path: Path) -> Any:
"""Load data from cache file using pickle deserialization.
Args:
cache_path: Path to cache file
Returns:
Cached data
"""
try:
with open(cache_path, "rb") as f:
data = pickle.load(f)
logger.debug(f"Loaded cached result from {cache_path}")
return data
except Exception as e:
logger.warning(f"Failed to load cache from {cache_path}: {e}")
# Remove corrupted cache file
with contextlib.suppress(Exception):
cache_path.unlink()
raise
def get_cached_result(
self, func: Callable, args: tuple, kwargs: dict
) -> tuple[bool, Any]:
"""Get cached result if available and valid.
Args:
func: The function being cached
args: Positional arguments
kwargs: Keyword arguments
Returns:
Tuple of (cache_hit: bool, result: Any)
"""
cache_key = self._get_cache_key(func, args, kwargs)
cache_path = self._get_cache_path(cache_key)
if self._is_cache_valid(cache_path):
try:
result = self._load_from_cache(cache_path)
return True, result
except Exception:
# Cache loading failed, will recompute
pass
return False, None
def save_result(
self, func: Callable, args: tuple, kwargs: dict, result: Any
) -> None:
"""Save function result to cache using pickle serialization.
Args:
func: The function being cached
args: Positional arguments
kwargs: Keyword arguments
result: Result to cache
"""
cache_key = self._get_cache_key(func, args, kwargs)
cache_path = self._get_cache_path(cache_key)
self._save_to_cache(cache_path, result)
def clear_cache(self, func: Callable | None = None) -> None:
"""Clear cache files.
Args:
func: If provided, only clear cache for this function. Otherwise clear all.
"""
if func is None:
# Clear all cache files
for cache_file in self.cache_dir.glob("*"):
if cache_file.is_file():
try:
cache_file.unlink()
logger.debug(f"Removed cache file {cache_file}")
except Exception as e:
logger.warning(f"Failed to remove cache file {cache_file}: {e}")
else:
# Clear cache for specific function (this is approximate since we don't have args/kwargs)
func_pattern = f"*{func.__name__}*"
for cache_file in self.cache_dir.glob(func_pattern):
if cache_file.is_file():
try:
cache_file.unlink()
logger.debug(f"Removed cache file {cache_file}")
except Exception as e:
logger.warning(f"Failed to remove cache file {cache_file}: {e}")
def get_cache_stats(self) -> dict[str, Any]:
"""Get cache statistics.
Returns:
Dictionary with cache statistics
"""
cache_files = list(self.cache_dir.glob("*"))
total_files = len([f for f in cache_files if f.is_file()])
total_size = sum(f.stat().st_size for f in cache_files if f.is_file())
return {
"cache_dir": str(self.cache_dir),
"total_files": total_files,
"total_size_bytes": total_size,
"total_size_mb": round(total_size / (1024 * 1024), 2),
}
def cached(
cache_dir: str | Path = "cache",
max_age: int | None = None,
ignore_errors: bool = True,
) -> Callable[[F], F]:
"""Decorator to cache function results to disk using pickle serialization.
Args:
cache_dir: Directory to store cache files
max_age: Maximum age of cache files in seconds (None for no expiration)
ignore_errors: If True, ignore cache errors and proceed with function execution
Returns:
Decorated function with caching capability
"""
cache_manager = CacheManager(cache_dir, max_age)
def decorator(func: F) -> F:
@wraps(func)
def wrapper(*args, **kwargs):
try:
# Try to get cached result
cache_hit, cached_result = cache_manager.get_cached_result(
func, args, kwargs
)
if cache_hit:
logger.debug(f"Cache hit for {func.__name__}")
return cached_result
except Exception as e:
if not ignore_errors:
raise
logger.warning(f"Cache read error for {func.__name__}: {e}")
# Execute function
logger.debug(f"Cache miss for {func.__name__}, executing function")
result = func(*args, **kwargs)
try:
# Save result to cache
cache_manager.save_result(func, args, kwargs, result)
except Exception as e:
if not ignore_errors:
raise
logger.warning(f"Cache write error for {func.__name__}: {e}")
return result
# Add cache management methods to the wrapped function
wrapper.clear_cache = lambda: cache_manager.clear_cache(func)
wrapper.clear_all_cache = lambda: cache_manager.clear_cache()
wrapper.get_cache_stats = cache_manager.get_cache_stats
return wrapper
return decorator
# Convenience decorators with common configurations
def cached_temporary(max_age: int = 3600, cache_dir: str | Path = "temp_cache"):
"""Convenience decorator for temporary caching (1 hour default)."""
return cached(cache_dir=cache_dir, max_age=max_age)
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