Python中Redis连接池的正确使用方法

Question

foo.py和bar.py这两个不同的模块应该如何从Redis连接池中获取连接？换句话说，我们应该如何构建应用程序？

我相信我们的目标是为所有模块提供一个连接池，以便从中获取连接。

Q1：在我的示例中，两个模块是否从同一个连接池中获取连接？

Q2：是否可以在RedisClient.py创建RedisClient实例，然后将该实例导入其他2个模块？还是有更好的办法？

Q3：延迟加载conn实例变量真的​​有用吗？

RedisClient.py

import redis

class RedisClient(object):

    def __init__(self):
        self.pool = redis.ConnectionPool(host = HOST, port = PORT, password = PASSWORD)

    @property
    def conn(self):
        if not hasattr(self, '_conn'):
            self.getConnection()
        return self._conn

    def getConnection(self):
        self._conn = redis.Redis(connection_pool = self.pool)

redisClient = RedisClient()

foo.py

from RedisClient import redisClient

species = 'lion'
key = 'zoo:{0}'.format(species)
data = redisClient.conn.hmget(key, 'age', 'weight')
print(data)

bar.py

from RedisClient import redisClient

print(redisClient.conn.ping())

---

还是这样更好？

RedisClient.py

import redis

class RedisClient(object):

    def __init__(self):
        self.pool = redis.ConnectionPool(host = HOST, port = PORT, password = PASSWORD)

    def getConnection(self):
        return redis.Redis(connection_pool = self.pool)

redisClient = RedisClient()

foo.py

from RedisClient import redisClient

species = 'lion'
key = 'zoo:{0}'.format(species)
data = redisClient.getConnection().hmget(key, 'age', 'weight')
print(data)

bar.py

from RedisClient import redisClient

print(redisClient.getConnection().ping())

Answer 1

A1：是的，它们使用相同的连接池。

A2：这不是一个好习惯。因为您无法控制此实例的初始化。另一种方法是使用单例。

import redis


class Singleton(type):
    """
    An metaclass for singleton purpose. Every singleton class should inherit from this class by 'metaclass=Singleton'.
    """
    _instances = {}

    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
        return cls._instances[cls]


class RedisClient(object):

    def __init__(self):
        self.pool = redis.ConnectionPool(host = HOST, port = PORT, password = PASSWORD)

    @property
    def conn(self):
        if not hasattr(self, '_conn'):
            self.getConnection()
        return self._conn

    def getConnection(self):
        self._conn = redis.Redis(connection_pool = self.pool)

那么RedisClient 将是一个单例类。不管你调用多少次client = RedisClient()，你都会得到相同的对象。

所以你可以像这样使用它：

from RedisClient import RedisClient

client = RedisClient()
species = 'lion'
key = 'zoo:{0}'.format(species)
data = client.conn.hmget(key, 'age', 'weight')
print(data)

而您第一次调用client = RedisClient() 时实际上会初始化这个实例。

或者您可能希望根据不同的参数获取不同的实例：

class Singleton(type):
    """
    An metaclass for singleton purpose. Every singleton class should inherit from this class by 'metaclass=Singleton'.
    """
    _instances = {}

    def __call__(cls, *args, **kwargs):
        key = (args, tuple(sorted(kwargs.items())))
        if cls not in cls._instances:
            cls._instances[cls] = {}
        if key not in cls._instances[cls]:
            cls._instances[cls][key] = super(Singleton, cls).__call__(*args, **kwargs)
        return cls._instances[cls][key]