Python functools._make_key() Examples

def test_async_ttl_cache_dont_overwrite_new_cache_entry():
    """Make sure that we don't overwrite a new cache entry that was placed
    while we were waiting to handle the result of a previously cached future
    """
    range_continue_event = asyncio.Event()
    update_cache_event = asyncio.Event()
    return_values = iter(range(10))

    # Wait until awaiter has had a chance to get the in-flight future out of
    # the cache, then signal to the cache_updater to replace the cached future
    # before returning.  Because cache_updater is signalled first, it will
    # replace the previously cached future before async_ttl_cache decides
    # whether save the result of that future in the cache
    async def range_coroutine():
        await range_continue_event.wait()
        update_cache_event.set()
        return next(return_values)

    range_coroutine_future = asyncio.ensure_future(range_coroutine())
    cache_key = functools._make_key((), {}, typed=False)
    cache = {cache_key: (range_coroutine_future, float("Inf"))}

    cached_range_coroutine = async_ttl_cache(cache=cache, ttl=0)(range_coroutine)

    new_range_coroutine_future = asyncio.ensure_future(range_coroutine())

    async def awaiter():
        range_continue_event.set()
        await cached_range_coroutine()

    async def cache_updater():
        await update_cache_event.wait()
        cache[cache_key] = (new_range_coroutine_future, float("Inf"))

    await asyncio.gather(awaiter(), cache_updater())
    assert cache[cache_key] == (new_range_coroutine_future, float("Inf")) 

def test_async_ttl_cache_recover_if_cache_entry_removed():
    """Ensure we handle the case where we encounter an exception in the cached
    future but another coroutine awaiting the same future ran first and alraedy
    deleted the cache entry"""
    range_continue_event = asyncio.Event()
    num_awaiters_awaiting = DataHolder(value=0)

    class TestException(Exception):
        pass

    async def range_coroutine():
        await range_continue_event.wait()
        raise TestException

    range_coroutine_future = asyncio.ensure_future(range_coroutine())
    cache_key = functools._make_key((), {}, typed=False)
    cache = {cache_key: (range_coroutine_future, float("Inf"))}

    cached_range_coroutine = async_ttl_cache(cache=cache, ttl=0)(range_coroutine)

    async def awaiter():
        num_awaiters_awaiting.value += 1
        if num_awaiters_awaiting.value == 2:
            range_continue_event.set()

        try:
            await cached_range_coroutine()
        except TestException:
            pass

    # should not raise a KeyError!
    await asyncio.gather(awaiter(), awaiter()) 

def __call__(self, func=None, *, validator=None):
        if validator and not func:
            return partial(self.__call__, validator=validator)

        validator = validator and kwargs_resilient(validator)

        @wraps(func)
        def inner(*args, **kwargs):
            key_kwargs = {k: v for k, v in kwargs.items() if k not in self.ignored_keywords}
            key = str(_make_key(
                (func.__module__, func.__qualname__,) + args, key_kwargs,
                typed=False, kwd_mark=("_KWD_MARK_",)))

            try:
                value = self.get(key)
            except KeyError:
                pass
            else:
                if not validator:
                    return value
                validated_value = validator(value, args=args, kwargs=kwargs)
                if validated_value:
                    self.set(key, validated_value)
                    return validated_value
                self.set(key, DELETED)
                return inner(*args, **kwargs)
            ret = func(*args, **kwargs)
            self.set(key, ret)
            return ret
        inner.clear_cache = self.clear
        return inner 

def locking_lru_cache(maxsize=128, typed=False):
    """
    DEPRECATED!

    An lru cache decorator with a lock, to prevent concurrent invocations and allow reusing from cache.

    :param maxsize: LRU cache maximum size, defaults to 128
    :type maxsize: number, optional
    :param typed: If typed is set to true, function arguments of different types will be cached separately. defaults to False.
    :type typed: bool, optional
    """

    def deco(func):
        caching_func = lru_cache(maxsize, typed)(func)
        func._main_lock = RLock()
        func._keyed_locks = defaultdict(RLock)

        @wraps(func)
        def inner(*args, **kwargs):
            key = _make_key(args, kwargs, typed=typed)
            with func._main_lock:
                key_lock = func._keyed_locks[key]
            with key_lock:
                return caching_func(*args, **kwargs)

        @wraps(caching_func.cache_clear)
        def clear():
            with func._main_lock:
                return caching_func.cache_clear()

        inner.cache_clear = clear
        return inner

    return deco 

def __init__(self, func, **kwargs):
        update_wrapper(self, func)  # this needs to be first to avoid overriding attributes we set
        super().__init__(func=func, cached=True)
        self.func = func
        self.kwargs = kwargs
        self.expiration = kwargs['expiration']
        self.typed = kwargs['typed']
        self.get_ts_func = kwargs['get_ts_func']
        self.log_recalculation = kwargs['log_recalculation']
        self.ignored_keywords = kwargs['ignored_keywords']

        if self.ignored_keywords:
            assert not kwargs['key_func'], "can't specify both `ignored_keywords` AND `key_func`"
            self.ignored_keywords = set(ilistify(self.ignored_keywords))

            def key_func(**kw):
                return tuple(v for k, v in sorted(kw.items()) if k not in self.ignored_keywords)
        else:
            key_func = kwargs['key_func']

        self.NOT_FOUND = object()
        self.NOT_CACHED = self.NOT_FOUND, 0

        self.cache = {}
        self.main_lock = RLock()
        self.keyed_locks = defaultdict(RLock)

        if key_func:
            sig = inspect.signature(func)

            def make_key(args, kwargs):
                bound = sig.bind(*args, **kwargs)
                _apply_defaults(bound)
                return kwargs_resilient(key_func)(**bound.arguments)
        else:
            def make_key(args, kwargs):
                return _make_key(args, kwargs, typed=self.typed)

        self.make_key = make_key 

def timecache(expiration=0, typed=False, get_ts_func=time.time, log_recalculation=False, ignored_keywords=None, key_func=None):
    """
    A thread-safe cache decorator with time expiration.

    :param expiration: if a positive number, set an expiration on the cache, defaults to 0
    :type expiration: number, optional
    :param typed: If typed is set to true, function arguments of different types will be cached separately, defaults to False
    :type typed: bool, optional
    :param get_ts_func: The function to be used in order to get the current time, defaults to time.time
    :type get_ts_func: callable, optional
    :param log_recalculation: Whether or not to log cache misses, defaults to False
    :type log_recalculation: bool, optional
    :param ignored_keywords: Arguments to ignore when caculating item key, defaults to None
    :type ignored_keywords: iterable, optional
    :param key_func: The function to use in order to create the item key, defaults to functools._make_key
    :type key_func: callable, optional
    """

    def deco(func):
        return _TimeCache(
            func=func,
            expiration=expiration,
            typed=typed,
            get_ts_func=get_ts_func,
            log_recalculation=log_recalculation,
            ignored_keywords=ignored_keywords,
            key_func=key_func)

    return deco 

def _cache_invalidate(wrapped, typed, *args, **kwargs):
    key = _make_key(args, kwargs, typed)

    exists = key in wrapped._cache

    if exists:
        wrapped._cache.pop(key)

    return exists 

def test_cache_invalidate_typed():
    wrapped = Wrapped()
    wrapped._cache = {}

    args = (1,)
    kwargs = {'1': 1}

    from_cache = _cache_invalidate(wrapped, True, *args, **kwargs)

    assert not from_cache

    key = _make_key(args, kwargs, True)

    wrapped._cache[key] = 0

    from_cache = _cache_invalidate(wrapped, True, *args, **kwargs)

    assert from_cache

    assert len(wrapped._cache) == 0

    wrapped._cache[key] = 0

    args = (1.0,)

    from_cache = _cache_invalidate(wrapped, True, *args, **kwargs)

    assert not from_cache

    wrapped._cache[key] = 1 

def test_cache_invalidate_not_typed():
    wrapped = Wrapped()
    wrapped._cache = {}

    args = (1,)
    kwargs = {'1': 1}

    from_cache = _cache_invalidate(wrapped, False, *args, **kwargs)

    assert not from_cache

    key = _make_key(args, kwargs, False)

    wrapped._cache[key] = 0

    from_cache = _cache_invalidate(wrapped, False, *args, **kwargs)

    assert from_cache

    assert len(wrapped._cache) == 0

    wrapped._cache[key] = 0

    args = (1.0,)

    from_cache = _cache_invalidate(wrapped, False, *args, **kwargs)

    assert from_cache

    assert len(wrapped._cache) == 0