def cache_results(self, results):
"""
Create invalidation signals for these results in the form of CacheBotSignals.
A CacheBotSignal stores a model and it's accessor path to self.queryset.model.
"""
# cache the results
invalidation_dict = {}
if results:
added_to_cache = cache.add(self.result_key, results, CACHE_SECONDS)
else:
added_to_cache = cache.add(self.result_key, None, CACHE_SECONDS)
if added_to_cache:
invalidation_dict.update(dict([(key,None) for key in self.get_invalidation_keys(results)]))
invalidation_dict.update(cache.get_many(invalidation_dict.keys()))
for child, negate in self.queryset._get_where_clause(self.queryset.query.where):
(table_alias, field_name, db_type), lookup_type, value_annotation, params = child
for model_class, accessor_path in self._get_join_paths(table_alias, field_name):
if model_class is None:
continue
if self._is_valid_flush_path(accessor_path):
cache_signals.register(model_class, accessor_path, lookup_type, negate=negate)
invalidation_key = get_invalidation_key(
model_class._meta.db_table,
accessor_path = accessor_path,
lookup_type = lookup_type,
negate = negate,
value = params, save=True)
invalidation_dict[invalidation_key] = None
join_to_tables = ifilter(lambda x: x[0] == model_class._meta.db_table, self.queryset.query.join_map.keys())
for join_tuple in join_to_tables:
if self._is_valid_flush_path(accessor_path):
model_class = self.queryset._get_model_class_from_table(join_tuple[1])
cache_signals.register(model_class, join_tuple[3], lookup_type, negate=negate)
invalidation_key = get_invalidation_key(
model_class._meta.db_table,
accessor_path = join_tuple[3],
lookup_type = lookup_type,
negate = negate,
value = params, save=True)
invalidation_dict[invalidation_key] = None
for flush_key, flush_list in invalidation_dict.iteritems():
# need to add and append to prevent race conditions
cache.add(flush_key, self.result_key, CACHE_SECONDS)
if flush_list is None or flush_key not in flush_list.split(','):
cache.append(flush_key, ',%s' % self.result_key)
def invalidate_cache(model_class, objects, **extra_keys):
"""
Flushes the cache of any cached objects associated with this instance.
Explicitly set a None value instead of just deleting so we don't have any race
conditions where:
Thread 1 -> Cache miss, get object from DB
Thread 2 -> Object saved, deleted from cache
Thread 1 -> Store (stale) object fetched from DB in cache
Five second should be more than enough time to prevent this from happening for
a web app.
"""
invalidation_dict = {}
accessor_set = cache_signals.get_global_signals(model_class)
for obj in objects:
for (accessor_path, lookup_type, negate) in accessor_set:
for value in get_values(obj, accessor_path):
invalidation_key = get_invalidation_key(
model_class._meta.db_table, accessor_path=accessor_path, negate=negate, value=value, save=False
)
invalidation_dict[invalidation_key] = None
invalidation_dict.update(cache.get_many(invalidation_dict.keys()))
cache_keys = set()
for obj_key, cache_key_list in invalidation_dict.iteritems():
if cache_key_list:
cache_keys.update(cache_key_list.split(","))
keys_to_invalidate = dict([(key, None) for key in chain(cache_keys, invalidation_dict.keys())])
keys_to_invalidate.update(extra_keys)
cache.set_many(keys_to_invalidate, 5)
cache.delete_many(keys_to_invalidate.keys())
def _register_signal(self, model_class, accessor_path, lookup_type, negate, params):
cache_signals.register(model_class, accessor_path, lookup_type, negate=negate)
return get_invalidation_key(
model_class._meta.db_table,
accessor_path = accessor_path,
lookup_type = lookup_type,
negate = negate,
value = params)
def _register_signal(self, model_class, accessor_path, lookup_type, negate, params):
cache_signals.register(model_class, accessor_path, lookup_type, negate=negate)
return get_invalidation_key(
model_class._meta.db_table,
accessor_path = accessor_path,
lookup_type = lookup_type,
negate = negate,
value = params)
def cache_results(self, results):
"""
Create invalidation signals for these results in the form of CacheBotSignals.
A CacheBotSignal stores a model and it's accessor path to self.queryset.model.
"""
# cache the results
if not self.invalidation_only:
cache.set(self.result_key, results, CACHE_SECONDS)
invalidation_dict = {}
for child, negate in self.queryset._get_where_clause(self.queryset.query.where):
(table_alias, field_name, db_type), lookup_type, value_annotation, params = child
for model_class, accessor_path in self._get_join_paths(table_alias, field_name):
if self._is_valid_flush_path(accessor_path):
cache_signals.register(model_class, accessor_path, lookup_type, negate=negate)
invalidation_key = get_invalidation_key(
model_class._meta.db_table,
accessor_path = accessor_path,
lookup_type = lookup_type,
negate = negate,
value = params, save=True)
invalidation_dict[invalidation_key] = None
join_to_tables = ifilter(lambda x: x[0] == model_class._meta.db_table, self.queryset.query.join_map.keys())
for join_tuple in join_to_tables:
if self._is_valid_flush_path(accessor_path):
model_class = self.queryset._get_model_class_from_table(join_tuple[1])
cache_signals.register(model_class, join_tuple[3], lookup_type, negate=negate)
invalidation_key = get_invalidation_key(
model_class._meta.db_table,
accessor_path = join_tuple[3],
lookup_type = lookup_type,
negate = negate,
value = params, save=True)
invalidation_dict[invalidation_key] = None
invalidation_dict.update(dict([(key,None) for key in self.get_invalidation_keys(results)]))
invalidation_dict.update(cache.get_many(invalidation_dict.keys()))
for flush_key, flush_list in invalidation_dict.iteritems():
if flush_list is None:
invalidation_dict[flush_key] = set([self.result_key])
else:
invalidation_dict[flush_key].add(self.result_key)
cache.set_many(invalidation_dict, CACHE_SECONDS)
def invalidate_cache(model_class, objects, **extra_keys):
"""
Flushes the cache of any cached objects associated with this instance.
Explicitly set a None value instead of just deleting so we don't have any race
conditions where:
Thread 1 -> Cache miss, get object from DB
Thread 2 -> Object saved, deleted from cache
Thread 1 -> Store (stale) object fetched from DB in cache
Five second should be more than enough time to prevent this from happening for
a web app.
"""
invalidation_dict = {}
accessor_set = cache_signals.get_global_signals(model_class)
for obj in objects:
for (accessor_path, lookup_type, negate) in accessor_set:
if lookup_type != 'exact' or negate:
invalidation_key = get_invalidation_key(
model_class._meta.db_table,
accessor_path=accessor_path,
negate=negate,
value='')
invalidation_dict[invalidation_key] = None
else:
for value in get_values(obj, accessor_path):
invalidation_key = get_invalidation_key(
model_class._meta.db_table,
accessor_path=accessor_path,
negate=negate,
value=value)
invalidation_dict[invalidation_key] = None
if invalidation_dict:
invalidation_dict.update(cache.get_many(invalidation_dict.keys()))
cache_keys = set()
for obj_key, cache_key_list in invalidation_dict.iteritems():
if cache_key_list:
cache_keys.update(cache_key_list.split(','))
if cache_keys:
cache.set_many(dict([(key, None) for key in cache_keys]),
conf.CACHE_INVALIDATION_TIMEOUT)
invalidation_dict.update(extra_keys)
cache.delete_many(invalidation_dict.keys())
def get_invalidation_keys(self, results):
"""
Iterates through a list of results, and returns an invalidation key for each result. If the
query spans multiple tables, also return invalidation keys of any related rows.
"""
related_fields = self.queryset._related_fields
for obj in results:
for field, model_class in related_fields.iteritems():
pk_name = model_class._meta.pk.attname
cache_signals.register(model_class, pk_name, 'exact')
for value in get_values(obj, field):
invalidation_key = get_invalidation_key(
model_class._meta.db_table,
accessor_path = pk_name,
value = value)
yield invalidation_key
def get_invalidation_keys(self, results):
"""
Iterates through a list of results, and returns an invalidation key for each result. If the
query spans multiple tables, also return invalidation keys of any related rows.
"""
related_fields = self.queryset._related_fields
for obj in results:
for field, model_class in related_fields.iteritems():
pk_name = model_class._meta.pk.attname
cache_signals.register(model_class, pk_name, 'exact')
for value in get_values(obj, field):
invalidation_key = get_invalidation_key(
model_class._meta.db_table,
accessor_path = pk_name,
value = value)
yield invalidation_key
