Is it possible to cache with a custom key?

[egeres]

I'm looking for a way to cache the output of processing a file, but I want to use the hash of the file, not the path. This code doesn't work, but it would be more or less what I would need, is it possible to do anything similar with this library?

# More code before this...
cache = 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 custom_key_builder(func, *args, **kwargs):
    file_path = args[0]
    file_hash = compute_file_hash(file_path)
    return file_hash

@cache.memoize(key=custom_key_builder)
def process_file(file_path: Path):
    print("Processing!!")

[egeres]

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

[phi-friday]

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