def cached(function, key_, duration=DEFAULT_TIMEOUT):
"""Only calls the function if ``key`` is not already in the cache."""
key = _function_cache_key(key_)
val = cache.get(key)
if val is None:
log.debug('cache miss for %s' % key)
val = function()
cache.set(key, val, duration)
else:
log.debug('cache hit for %s' % key)
return val
def __iter__(self):
if self.iter_function is not None:
# This a RawQuerySet. Use the function passed into
# the class constructor.
iterator = self.iter_function
else:
# Otherwise, use super().__iter__.
iterator = super(CachingModelIterable, self).__iter__
if self.timeout == config.NO_CACHE:
# no cache, just iterate and return the results
for obj in iterator():
yield obj
return
# Try to fetch from the cache.
try:
query_key = self.query_key()
except query.EmptyResultSet:
return
cached = cache.get(query_key)
if cached is not None:
log.debug('cache hit: %s' % query_key)
for obj in cached:
obj.from_cache = True
yield obj
return
# Use the special FETCH_BY_ID iterator if configured.
if config.FETCH_BY_ID and hasattr(self.queryset, 'fetch_by_id'):
iterator = self.queryset.fetch_by_id
# No cached results. Do the database query, and cache it once we have
# all the objects.
to_cache = []
for obj in iterator():
obj.from_cache = False
to_cache.append(obj)
yield obj
if to_cache or config.CACHE_EMPTY_QUERYSETS:
self.cache_objects(to_cache, query_key)