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async_lru.py
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async_lru.py
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import asyncio # noqa # isort:skip
from collections import OrderedDict, namedtuple
from functools import _make_key, partial, wraps
__version__ = '0.0.2'
_CacheInfo = namedtuple('CacheInfo', ['hits', 'misses', 'maxsize', 'currsize'])
def create_future(*, loop):
try:
return loop.create_future()
except AttributeError: # pragma: no cover
return asyncio.Future(loop=loop)
def create_task(*, loop):
try:
return loop.create_task
except AttributeError: # pragma: no cover
try:
return partial(asyncio.ensure_future, loop=loop)
except AttributeError:
return partial(getattr(asyncio, 'async'), loop=loop)
def iscoroutinepartial(fn):
# http://bugs.python.org/issue23519
parent = fn
while fn is not None:
parent, fn = fn, getattr(parent, 'func', None)
return asyncio.iscoroutinefunction(parent)
def unpartial(fn):
while hasattr(fn, 'func'):
fn = fn.func
return fn
def _done_callback(fut, coro):
raised = coro.exception()
if raised is None:
fut.set_result(coro.result())
else:
fut.set_exception(raised)
def _cache_invalidate(cache, typed, *args, **kwargs):
key = _make_key(args, kwargs, typed)
exists = key in cache
if exists:
cache.pop(key)
return exists
def _cache_clear(wrapped):
wrapped.hits = wrapped.misses = 0
wrapped.cache.clear()
def _open(wrapped):
if not wrapped.closed:
raise RuntimeError('alru_cache is not closed')
wrapped.closed = False
def _close(wrapped, cancel=False, return_exceptions=True, *, loop=None):
if wrapped.closed:
raise RuntimeError('alru_cache is closed')
if loop is None:
loop = asyncio.get_event_loop()
wrapped.closed = True
if cancel:
for coro in wrapped.coros:
coro.cancel()
wait_closed = asyncio.gather(
*wrapped.coros,
return_exceptions=return_exceptions,
loop=loop
)
wait_closed.add_done_callback(partial(_closed, wrapped))
return wait_closed
def _closed(wrapped, fut):
wrapped.cache_clear()
def alru_cache(
fn=None,
maxsize=128,
typed=False,
cls=False,
kwargs=False,
*,
cache_exceptions=True,
loop=None
):
def wrapper(fn):
@wraps(fn)
def wrapped(*fn_args, **fn_kwargs):
if wrapped.closed:
raise RuntimeError('alru_cache is closed')
key = _make_key(fn_args, fn_kwargs, typed)
if key in wrapped.cache:
fut = wrapped.cache[key]
if fut.done():
raised = fut.exception()
if raised is None or cache_exceptions:
wrapped.hits += 1
wrapped.cache.move_to_end(key)
return fut
wrapped.cache.pop(key)
else:
wrapped.hits += 1
wrapped.cache.move_to_end(key)
return fut
if isinstance(loop, str):
assert cls ^ kwargs, 'choose self.loop or kwargs["loop"]'
if cls:
_self = getattr(unpartial(fn), '__self__', None)
if _self is None:
assert fn_args, 'seems not unbound function'
_self = fn_args[0]
_loop = getattr(_self, loop)
elif kwargs:
_loop = fn_kwargs[loop]
elif loop is None:
_loop = asyncio.get_event_loop()
else:
_loop = loop
fut = create_future(loop=_loop)
if iscoroutinepartial(fn):
ret = fn(*fn_args, **fn_kwargs)
coro = create_task(loop=_loop)(ret)
coro.add_done_callback(partial(_done_callback, fut))
wrapped.coros.add(coro)
coro.add_done_callback(wrapped.coros.remove)
else:
try:
fut.set_result(fn(*fn_args, **fn_kwargs))
except BaseException as exc:
fut.set_exception(exc)
wrapped.cache[key] = fut
wrapped.misses += 1
if maxsize is not None and len(wrapped.cache) > maxsize:
wrapped.cache.popitem(last=False)
return fut
wrapped.cache = OrderedDict()
wrapped.hits = wrapped.misses = 0
wrapped.cache_info = lambda: _CacheInfo(
wrapped.hits,
wrapped.misses,
maxsize,
len(wrapped.cache),
)
wrapped.cache_clear = partial(_cache_clear, wrapped)
wrapped.coros = set()
wrapped.closed = False
wrapped.invalidate = partial(_cache_invalidate, wrapped.cache, typed)
wrapped.close = partial(_close, wrapped)
wrapped.open = partial(_open, wrapped)
return wrapped
if fn is None:
return wrapper
if callable(fn):
return wrapper(fn)
raise NotImplementedError