Flask Redis Cache

flask_redis_cache.py

import redis
import time

def cache_or_get(fp, expiry=300, r=redis.Redis(db=5)):
    ''' 
    Input fp: file to cache or get
    Input expiry: time to expire for file (default 300 seconds)
    Input r: redis instance (default new instance with db set to 4)
    
    Usage:
        Wherever you have a render_template(), replace it with a 
        render_from_string(get_or_cache(FilePath))

        You may need to prefix the templates/ to your html files.
    '''

    fpKey = "cached:"+fp
    
    if r.exists(fpKey):
        return r.get(fpKey)

    else:
        with open(fp, "rb") as f:
            data = f.read()
        p = r.pipeline()
        p.set(fpKey, data)
        p.expire(fpKey, expiry)
        p.execute()
        return data


def stressTest(fp="templates/index.html", trials = 10000):
    '''
    Input fp: File path of cached files
    Input trials: number of runs
    '''
    
    # Read the file x number of times
    a = time.time()
    for x in range(trials):
        with open(fp, "rb") as f:
            data = f.readlines()
    b = time.time()
    readAvg = trials/(b-a)

    # Read the file, cache it, read it with a new instance each time
    a = time.time()
    for x in range(trials):
        data = cache_or_get(fp)
    b = time.time()
    cachedAvg = trials/(b-a)

    # Read file, cache it, pass in redis instance each time
    a = time.time()
    r = redis.Redis(db=6)
    for x in range(trials):
        data = cache_or_get(fp, r=r)
    b = time.time()
    inCachedAvg = trials/(b-a)

    print "Average time for reading file %s times: %.2f ms" %(trials, readAvg)
    print "Average time for cached file with new instance %s times: %.2f ms" %(trials, cachedAvg)
    print "Average time for reading file with set instance %s times: %.2f ms" %(trials, inCachedAvg)
    print "New Instance Caching yields a %.1f percent increase in access time" %(100*cachedAvg/(cachedAvg+readAvg))
    print "Persistent Instance Caching yields a %.1f percent increase in access time" %(100*inCachedAvg/(inCachedAvg+readAvg))

if __name__ == "__main__":
    stressTest()