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gsteff on 03/23/11

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Last Edited at 03/23/11 01:08pm

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Caching decorator

/ Published in: Python

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from datetime import datetime, timedelta
from copy import deepcopy
from threading import RLock

def timed_cache(seconds=0, minutes=0, hours=0, days=0):

time_delta = timedelta( seconds=seconds,
                            minutes=minutes,
                            hours=hours,
                            days=days )

def decorate(f):

f._lock = RLock()
        f._updates = {}
        f._results = {}

def do_cache(*args, **kwargs):

lock = f._lock
            lock.acquire()

try:
                key = (args, tuple(sorted(kwargs.items(), key=lambda i:i[0])))

updates = f._updates
                results = f._results

t = datetime.now()
                updated = updates.get(key, t)

if key not in results or t-updated > time_delta:
                    # Calculate
                    updates[key] = t
                    result = f(*args, **kwargs)
                    results[key] = deepcopy(result)
                    return result

else:
                    # Cache
                    return deepcopy(results[key])

finally:
                lock.release()

return do_cache

return decorate

URL: http://www.willmcgugan.com/blog/tech/2007/10/14/timed-caching-decorator/

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