def push_objects(cls, key, obj, queryset):
conn = RedisClient.get_connection()
if not conn.exists(key):
cls._load_object_to_cache(key, queryset)
return
serialized_data = DjangoModelSerializer.serialize(obj)
conn.lpush(key, serialized_data)
def push_object(cls, key, obj, queryset):
conn = RedisClient.get_connection()
if not conn.exists(key):
cls._load_objects_to_cache(key, queryset)
return
serialized_data = DjangoModelSerializer.serialize(obj)
conn.lpush(key, serialized_data)
conn.ltrim(key, 0, settings.REDIS_LIST_LENGTH_LIMIT - 1)
def push_object(cls, key, obj, queryset):
conn = RedisClient.get_connection()
if not conn.exists(key):
# if key doesn't exist in cache, read from db
# don't use push single object to cache
cls._load_objects_to_cache(key, queryset)
return
serialized_data = DjangoModelSerializer.serialize(obj)
conn.lpush(key, serialized_data)
conn.ltrim(key, 0, settings.REDIS_LIST_LENGTH_LIMIT - 1)
def _load_objects_to_cache(cls, key, objects):
conn = RedisClient.get_connection()
serialized_list = []
for obj in objects:
serialized_data = DjangoModelSerializer.serialize(obj)
serialized_list.append(serialized_data)
if serialized_list:
conn.rpush(key, *serialized_list)
conn.expire(key, settings.REDIS_KEY_EXPIRE_TIME)
def test_cache_tweet_in_redis(self):
tweet = self.create_tweet(self.linghu)
conn = RedisClient.get_connection()
serialized_data = DjangoModelSerializer.serialize(tweet)
conn.set(f'tweet:{tweet.id}', serialized_data)
data = conn.get(f'tweet:not_exists')
self.assertEqual(data, None)
data = conn.get(f'tweet:{tweet.id}')
cached_tweet = DjangoModelSerializer.deserialize(data)
self.assertEqual(tweet, cached_tweet)
def test_cache_tweet_in_redis(self):
tweet = self.tweets[0]
conn = RedisClient.get_connection()
serialized_data = DjangoModelSerializer.serialize(tweet)
conn.set(f'tweet:{tweet.id}', serialized_data)
data=conn.get('tweet:bogus')
self.assertEqual(data, None)
data = conn.get(f'tweet:{tweet.id}')
cached_tweet = DjangoModelSerializer.deserialize(data)
self.assertEqual(cached_tweet, tweet)
def push_object(cls, key, obj, queryset):
queryset = queryset[:settings.REDIS_LIST_LENGTH_LIMIT]
conn = RedisClient.get_connection()
if not conn.exists(key):
# 如果key不存在，直接从数据库里面load
# 就不走单个push的方式加到cache里面了
cls._load_objects_to_cache(key, queryset)
return
serialized_data = DjangoModelSerializer.serialize(obj)
conn.lpush(key, serialized_data)
conn.ltrim(key, 0, settings.REDIS_LIST_LENGTH_LIMIT - 1)
def _load_objects_to_cache(cls, key, objects):
conn = RedisClient.get_connection()
serialized_list = []
# 最多只 cache REDIS_LIST_LENGTH_LIMIT 那么多个 objects
# 超过这个限制的 objects，就去数据库里读取。一般这个限制会比较大，比如 1000
# 因此翻页翻到 1000 的用户访问量会比较少，从数据库读取也不是大问题
for obj in objects[:settings.REDIS_LIST_LENGTH_LIMIT]:
serialized_data = DjangoModelSerializer.serialize(obj)
serialized_list.append(serialized_data)
if serialized_list:
conn.rpush(key, *serialized_list)
conn.expire(key, settings.REDIS_KEY_EXPIRE_TIME)
def _load_objects_to_cache(cls, key, objects):
conn = RedisClient.get_connection()
serialized_list = []
# allowing to cache at most REDIS_LIST_LENGTH_LIMIT number of objects
# when exceeding the limit, fetch data in DB instead
# since the limit if often large, it's a edge case for user to read that many number of items directly
for obj in objects[:settings.REDIS_LIST_LENGTH_LIMIT]:
serialized_data = DjangoModelSerializer.serialize(obj)
serialized_list.append(serialized_data)
if serialized_list:
conn.rpush(key, *serialized_list)
conn.expire(key, settings.REDIS_KEY_EXPIRE_TIME)
def _load_objects_to_cache(cls, key, objects):
conn = RedisClient.get_connection()
serialized_list = []
for obj in objects[:settings.REDIS_LIST_LENGTH_LIMIT]:
# it can only read REDIS_LIST_LENGTH_LIMIT number of objects
# if the number of objects is over the limitation, read from db
# usually, the limitation number is big, such as 1000
# due to user normally not page down more than 1000 objects,
# it is rarely need to read data from db
serialized_data = DjangoModelSerializer.serialize(obj)
serialized_list.append(serialized_data)
if serialized_list:
conn.rpush(key, *serialized_list)
conn.expire(key, settings.REDIS_KEY_EXPIRE_TIME)