Python DBUtils 连接池对象 (PooledDB)

数据处理用到 mysql, 需要在多进程中的多线程中使用 mysql 的连接

实现:

使用 DBUtils 中的 PooledDB 类来实现.
自己写一个类, 继承 PooledDB 类, 这样就能使用到 PooledDB 中的其它常用的方法.
使用单例模式, 确保整个应用服务中只有一个连接池对象.
使用: 可以定义全局变量初始化连接池对象, 在别的地方获取mysql连接使用.

demo:

# coding: utf-8
import pymysql
import functools
from seemmo.common.time_func import now_time, today
from conf.config import DB_HOST, DB_PORT, DB_USER, DB_NAME, DB_CHARSET
from pymysql.cursors import DictCursor
from DBUtils.PooledDB import PooledDB

# 获取加密的mysql密码
from seemmo.common.utils import get_pwd
DB_PASSWD = get_pwd("mysql_pwd")


class MysqlPool(PooledDB):
    __instance = None
    __pool = None

    def __new__(cls, *args, **kwargs):
        if not cls.__instance:
            # cls.__instance = object.__new__(cls)
            cls.__instance = super().__new__(cls)
        return cls.__instance

    def __init__(self):
        """创建链接池"""
        PooledDB.__init__(self, pymysql, maxconnections=50, mincached=0, maxcached=0, maxshared=0, blocking=True,
                          host=DB_HOST, port=DB_PORT, user=DB_USER, password=DB_PASSWD, database=DB_NAME,
                          charset=DB_CHARSET, cursorclass=DictCursor)

    def conn(self):
        _conn = self.connection()
        return _conn

使用 (装饰器) :

# 创建连接池对象
mysql_pool = MysqlPool()


# mysql 闭包环境
def db_wrap(method):
    @functools.wraps(method)
    def _wrapper(*args, **kwargs):
        conn = mysql_pool.conn()
        cursor = conn.cursor()
        try:
            conn.begin()
            retval = method(cursor, *args, **kwargs)
            conn.commit()
        except Exception as e:
            conn.rollback()
            raise e
        finally:
            cursor.close()
            conn.close()
        return retval
    return _wrapper


@db_wrap
def create_table(cursor, sql):
    ret = cursor.execute(sql)
    return ret


@db_wrap
def query_by_index(cursor, table_name, start_index, next_index):
    """
    根据 index 范围查询违法记录
    :param cursor: 数据库操作游标
    :param table_name: 需要操作的表名称
    :param start_index: 开始 index
    :param next_index:  截止 index
    :return: 查询结果
    """
    sql = """select * from {} where id > {} and id <= {}""".format(table_name, start_index, next_index)
    cursor.execute(sql)
    res = cursor.fetchall()
    return res

ending ~

来源：https://www.cnblogs.com/kaichenkai/p/11851597.html

标签

连接池

python