def __init__ (self, logger, size=CACHE_DEFAULT_SIZE, ttl=CACHE_DEFAULT_TTL) :
if int (size) < 1 :
raise AttributeError ('size < 1 or not a number')
if int (ttl) < 0 :
raise AttributeError ('ttl < 0 or not a number')
self.size = size
self.ttl = ttl
self.dict = OrderedDict ()
self.lock = Lock ()
self.logger = logger
self.hit = 0
self.miss = 0
class Cache :
# ----------------------------------------------------------------
#
def __init__ (self, logger, size=CACHE_DEFAULT_SIZE, ttl=CACHE_DEFAULT_TTL) :
if int (size) < 1 :
raise AttributeError ('size < 1 or not a number')
if int (ttl) < 0 :
raise AttributeError ('ttl < 0 or not a number')
self.size = size
self.ttl = ttl
self.dict = OrderedDict ()
self.lock = Lock ()
self.logger = logger
self.hit = 0
self.miss = 0
# start a thread which, with low priority, cleans out the dict now and
# then (pops items until a live one is found
# ----------------------------------------------------------------
#
def _dump (self) :
print " ---------------------------------------------- "
print " CACHE STATISTICS : "
print " size: %5d" % len(self.dict)
print " hit : %5d" % self.hit
print " miss: %5d" % self.miss
print self.dict.keys()
print " ---------------------------------------------- "
# ----------------------------------------------------------------
#
def get (self, key) :
self.logger.debug ("redis_cache_get %s", key)
with self.lock:
# check if we have a live entry
if key in self.dict :
now = time.time ()
if self.ttl and self.dict[key][TTL] > now :
# if yes, cache hit!
# return data -- doh!
self.hit += 1
return self.dict[key][VAL]
else :
# entry timed out
self.miss += 1
del self.dict[key]
# cache entry not found, or timed out
self.miss += 1
raise AttributeError ("cache miss for '%s' " % key)
# ----------------------------------------------------------------
#
def set (self, key, value) :
with self.lock :
# remove superfluous(?) entries
while len (self.dict) >= self.size :
self.dict.popitem (last=False)
self.dict[key] = {}
self.dict[key][VAL] = value
self.dict[key][TTL] = time.time () + self.ttl
# ----------------------------------------------------------------
#
def delete (self, key) :
with self.lock :
del self.dict[key]
