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"""Function decorator helpers."""
import functools
def _condition_info(func, cache, key, lock, cond, info):
hits = misses = 0
pending = set()
def wrapper(*args, **kwargs):
nonlocal hits, misses
k = key(*args, **kwargs)
with lock:
cond.wait_for(lambda: k not in pending)
try:
result = cache[k]
hits += 1
return result
except KeyError:
pending.add(k)
misses += 1
try:
v = func(*args, **kwargs)
with lock:
try:
cache[k] = v
except ValueError:
pass # value too large
return v
finally:
with lock:
pending.remove(k)
cond.notify_all()
def cache_clear():
nonlocal hits, misses
with lock:
cache.clear()
hits = misses = 0
def cache_info():
with lock:
return info(hits, misses)
wrapper.cache_clear = cache_clear
wrapper.cache_info = cache_info
return wrapper
def _locked_info(func, cache, key, lock, info):
hits = misses = 0
def wrapper(*args, **kwargs):
nonlocal hits, misses
k = key(*args, **kwargs)
with lock:
try:
result = cache[k]
hits += 1
return result
except KeyError:
misses += 1
v = func(*args, **kwargs)
with lock:
try:
# In case of a race condition, i.e. if another thread
# stored a value for this key while we were calling
# func(), prefer the cached value.
return cache.setdefault(k, v)
except ValueError:
return v # value too large
def cache_clear():
nonlocal hits, misses
with lock:
cache.clear()
hits = misses = 0
def cache_info():
with lock:
return info(hits, misses)
wrapper.cache_clear = cache_clear
wrapper.cache_info = cache_info
return wrapper
def _unlocked_info(func, cache, key, info):
hits = misses = 0
def wrapper(*args, **kwargs):
nonlocal hits, misses
k = key(*args, **kwargs)
try:
result = cache[k]
hits += 1
return result
except KeyError:
misses += 1
v = func(*args, **kwargs)
try:
cache[k] = v
except ValueError:
pass # value too large
return v
def cache_clear():
nonlocal hits, misses
cache.clear()
hits = misses = 0
wrapper.cache_clear = cache_clear
wrapper.cache_info = lambda: info(hits, misses)
return wrapper
def _uncached_info(func, info):
misses = 0
def wrapper(*args, **kwargs):
nonlocal misses
misses += 1
return func(*args, **kwargs)
def cache_clear():
nonlocal misses
misses = 0
wrapper.cache_clear = cache_clear
wrapper.cache_info = lambda: info(0, misses)
return wrapper
def _condition(func, cache, key, lock, cond):
pending = set()
def wrapper(*args, **kwargs):
k = key(*args, **kwargs)
with lock:
cond.wait_for(lambda: k not in pending)
try:
result = cache[k]
return result
except KeyError:
pending.add(k)
try:
v = func(*args, **kwargs)
with lock:
try:
cache[k] = v
except ValueError:
pass # value too large
return v
finally:
with lock:
pending.remove(k)
cond.notify_all()
def cache_clear():
with lock:
cache.clear()
wrapper.cache_clear = cache_clear
return wrapper
def _locked(func, cache, key, lock):
def wrapper(*args, **kwargs):
k = key(*args, **kwargs)
with lock:
try:
return cache[k]
except KeyError:
pass # key not found
v = func(*args, **kwargs)
with lock:
try:
# possible race condition: see above
return cache.setdefault(k, v)
except ValueError:
return v # value too large
def cache_clear():
with lock:
cache.clear()
wrapper.cache_clear = cache_clear
return wrapper
def _unlocked(func, cache, key):
def wrapper(*args, **kwargs):
k = key(*args, **kwargs)
try:
return cache[k]
except KeyError:
pass # key not found
v = func(*args, **kwargs)
try:
cache[k] = v
except ValueError:
pass # value too large
return v
wrapper.cache_clear = lambda: cache.clear()
return wrapper
def _uncached(func):
def wrapper(*args, **kwargs):
return func(*args, **kwargs)
wrapper.cache_clear = lambda: None
return wrapper
def _wrapper(func, cache, key, lock=None, cond=None, info=None):
if info is not None:
if cache is None:
wrapper = _uncached_info(func, info)
elif cond is not None and lock is not None:
wrapper = _condition_info(func, cache, key, lock, cond, info)
elif cond is not None:
wrapper = _condition_info(func, cache, key, cond, cond, info)
elif lock is not None:
wrapper = _locked_info(func, cache, key, lock, info)
else:
wrapper = _unlocked_info(func, cache, key, info)
else:
if cache is None:
wrapper = _uncached(func)
elif cond is not None and lock is not None:
wrapper = _condition(func, cache, key, lock, cond)
elif cond is not None:
wrapper = _condition(func, cache, key, cond, cond)
elif lock is not None:
wrapper = _locked(func, cache, key, lock)
else:
wrapper = _unlocked(func, cache, key)
wrapper.cache_info = None
wrapper.cache = cache
wrapper.cache_key = key
wrapper.cache_lock = lock if lock is not None else cond
wrapper.cache_condition = cond
return functools.update_wrapper(wrapper, func)
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