Is it possible to cache with a custom key? #329

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1. egeres commented on Aug 15, 2024

   

   egeres

   on Aug 15, 2024

   Last edited by egeres

   Author

   More actions

   I guess I could just do:

   c = FanoutCache(cache_dir)
   
   def compute_file_hash(file_path: Path) -> str:
       hash_func = hashlib.sha256()
       with file_path.open("rb") as f:
           while chunk := f.read(8192):
               hash_func.update(chunk)
       return hash_func.hexdigest()
   
   def cache_mine(method):
   
       def wrapper(*args, **kwargs):
           file_path = args[0]
           assert isinstance(file_path, Path), f"Expected Path, got {type(file_path)}"
           file_hash = compute_file_hash(file_path)
           with c as reference:
               if file_hash in reference:
                   return reference[file_hash]
               out = method(*args, **kwargs)
               if out is not None:
                   reference.set(file_hash, out)
           return out
   
       return wrapper
   
   @cache_mine
   def process_file(file_path: Path):
       print("Processing!!")
       return -1
2. phi-friday commented on Aug 18, 2024

   

   phi-friday

   on Aug 18, 2024

   More actions

   Override the __cache_key__ attribute of the function.

   see more:
   

   python-diskcache/diskcache/core.py

   Lines 1864 to 1888 in ebfa37c

   	def decorator(func):
   	"""Decorator created by memoize() for callable `func`."""
   	base = (full_name(func),) if name is None else (name,)
   	@ft.wraps(func)
   	def wrapper(*args, **kwargs):
   	"""Wrapper for callable to cache arguments and return values."""
   	key = wrapper.__cache_key__(*args, **kwargs)
   	result = self.get(key, default=ENOVAL, retry=True)
   	if result is ENOVAL:
   	result = func(*args, **kwargs)
   	if expire is None or expire > 0:
   	self.set(key, result, expire, tag=tag, retry=True)
   	return result
   	def __cache_key__(*args, **kwargs):
   	"""Make key for cache given function arguments."""
   	return args_to_key(base, args, kwargs, typed, ignore)
   	wrapper.__cache_key__ = __cache_key__
   	return wrapper
   	return decorator