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educoder Redis安全与性能

老王420 2022-04-29 阅读 57
python

 第3关:Redis事务与流水线

#!/usr/bin/env python  
#-*- coding:utf-8 -*-
import time  
import redis
conn = redis.Redis()
# 将商品放到平台上  
def add_item_to_market(itemid, sellerid, price):  
    # 请在下面完成要求的功能  
    #********* Begin *********#  
    repertory = "inventory:" + sellerid  
    item = itemid + "." + sellerid  
    end = time.time() + 5  
    pipe = conn.pipeline()
    while time.time() < end:  
        try:  
            pipe.watch(repertory)  
            if not pipe.sismember(repertory, itemid):  
                pipe.unwatch()  
                return None  
            pipe.multi()  
            pipe.zadd("market", item, price)  
            pipe.srem(repertory, itemid)  
            pipe.execute()  
            return True  
        except redis.exceptions.WatchError:  
            pass  
    return False  
    #********* End *********#
# 购买商品  
def purchase(buyerid, itemid):  
    # 请在下面完成要求的功能  
    #********* Begin *********#  
    item, sellerid = itemid.split(".")  
    buyer = "users:" + buyerid  
    seller = "users:" + sellerid  
    repertory = "inventory:" + buyerid  
    end = time.time() + 10  
    pipe = conn.pipeline()
    while time.time() < end:  
        try:  
            pipe.watch("market", buyer)  
            price = pipe.zscore("market", itemid)  
            funds = int(pipe.hget(buyer, "funds"))  
            if funds < price:  
                pipe.unwatch()  
                return None
            pipe.multi()  
            pipe.hincrby(seller, "funds", int(price))  
            pipe.hincrby(buyer, "funds", int(-price))  
            pipe.sadd(repertory, item)  
            pipe.zrem("market", itemid)  
            pipe.execute()  
            return True  
        except redis.exceptions.WatchError:  
            pass  
    return False  
    #********* End *********#  
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