一步步使用Redis红包，轻松就能迎来福利（redis红包怎么使用）

一步步使用Redis红包，轻松就能迎来福利

随着互联网技术的迅速发展，红包已经成为中国新年传统文化的重要组成部分。然而，近年来，不仅是春节，各种活动、营销活动中也大量出现了红包元素。在程序开发领域，电商、社交等应用也将红包作为互动方式，提高用户粘性。此时，Redis红包的出现就显得尤为重要。Redis红包集合了分布式锁、列表、哈希表等功能，使红包功能更强大，更灵活。本文将着重介绍如何使用Redis实现红包功能。

一、分布式锁

分布式锁能够保证Redis的并发访问安全，常用的分布式锁有三种：

1.基于Redis的SETNX命令实现分布式锁：

“`python

def acquire_lock(conn, lockname, acquire_timeout=10):

“分布式锁，用法类似于Python的上下文管理器”

# 锁的Value值

identifier = str(uuid.uuid4())

# 锁的名称

lockname = ‘lock:’ + lockname

# 锁超时时间

lock_timeout = acquire_timeout

# 等待锁的时间

lock_wt_time = 0.001

while lock_timeout >= 0:

if conn.setnx(lockname, identifier):

return identifier

elif not conn.ttl(lockname):

conn.expire(lockname, 30)

time.sleep(lock_wt_time)

lock_timeout -= lock_wt_time

return False

def release_lock(conn, lockname, identifier):

“通过标识符来释放锁”

lockname = ‘lock:’ + lockname

with conn.pipeline() as pipe:

while True:

try:

pipe.watch(lockname)

if pipe.get(lockname) == identifier:

pipe.multi()

pipe.delete(lockname)

pipe.execute()

return True

pipe.unwatch()

break

except redis.exceptions.WatchError:

pass

return False


2.基于Red锁（独立锁）实现分布式锁：

```python
def acquire_red_lock(conn, lockname, acquire_timeout=10, lock_timeout=10):
    "基于Red锁实现分布式锁"
    identifier = str(uuid.uuid4())
    # 锁的名称
    lockname = 'lock:' + lockname
    lock_timeout = int(lock_timeout)
    lock_try_time = acquire_timeout / 3
    while lock_try_time >= 0:
        # 创建Red锁
        locks = []
        for _ in range(5):
            lock_key = lockname + ':' + str(uuid.uuid4())
            redis_lock = RedLock(lock_key, retry_times=3, retry_delay=100)
            locks.append(redis_lock)

        # 获取Red锁
        try:
            if RedLock.acquire(locks, timeout=lock_timeout):
                return identifier
        except Exception as e:
            print(e)
        # 释放Red锁
        for lock in locks:
            lock.release()

        # 循环等待
        time.sleep(0.001)
        lock_try_time -= 0.001
    return False
def release_red_lock(conn, lockname, identifier):
    "释放Red锁"
    lockname = 'lock:' + lockname
    with conn.pipeline() as pipe:
        while True:
            try:
                pipe.watch(lockname)
                if pipe.get(lockname) == identifier:
                    pipe.multi()
                    pipe.delete(lockname)
                    pipe.execute()
                    return True
                pipe.unwatch()
                break
            except redis.exceptions.WatchError:
                pass
    return False

3.基于Lua脚本实现分布式锁：

“`python

lock_script = “””

local identifier = ARGV[1]

local lockname = KEYS[1]

redis.call(“SETNX”, lockname, identifier)

if redis.call(“GET”, lockname) == identifier then

redis.call(“EXPIRE”, lockname, 30)

return 1

end

“””

def acquire_lua_lock(conn, lockname, acquire_timeout=10):

“基于Lua脚本实现分布式锁，建议在Redis2.8.0及以上版本使用”

# 锁的Value值

identifier = str(uuid.uuid4())

# 锁的名称

lockname = ‘lock:’ + lockname

lock_timeout = acquire_timeout

# 等待锁的时间

lock_wt_time = 0.001

while lock_timeout >= 0:

result = conn.eval(lock_script, 1, lockname, identifier)

if result:

return identifier

time.sleep(lock_wt_time)

lock_timeout -= lock_wt_time

return False

def release_lua_lock(conn, lockname, identifier):

“释放Lua脚本锁”

lockname = ‘lock:’ + lockname

with conn.pipeline() as pipe:

while True:

try:

pipe.watch(lockname)

if pipe.get(lockname) == identifier:

pipe.multi()

pipe.delete(lockname)

pipe.execute()

return True

pipe.unwatch()

break

except redis.exceptions.WatchError:

pass

return False


二、Redis的列表数据结构

Redis的列表数据结构是基于链表实现的。所以，可以利用Redis的列表数据结构来实现红包。下面是基于Redis列表数据结构的红包生成函数：

```python
def set_redbag_total(conn, red_packet_id, total_amount):
    "设置红包"
    key = 'redbag:' + red_packet_id
    with conn.pipeline() as pipe:
        while True:
            try:
                pipe.watch(key)
                # 获取剩余金额，查询红包是否可以修改
                remning_amount = pipe.lindex(key, 0)
                remning_amount = int(remning_amount) if remning_amount else 0
                if remning_amount 
                    pipe.unwatch()
                    return False
                # 设置总金额与剩余金额
                total_amount_str = str(total_amount)
                pipe.multi()
                pipe.lset(key, 0, total_amount_str)
                pipe.lpush(key, total_amount_str)
                pipe.execute()
                return True
            except redis.exceptions.WatchError:
                pass
    return False
def add_redbag_amount(conn, red_packet_id, sender, amount):
    "添加红包金额"
    sender_id = 'user:' + sender
    redbag_id = 'redbag:' + red_packet_id
    with conn.pipeline() as pipe:
        while True:
            try:
                pipe.watch(redbag_id, sender_id)
                # 判断红包是否已被抢完
                remning_amount = pipe.lindex(redbag_id, 0)
                remning_amount = int(remning_amount) if remning_amount else 0
                if remning_amount 
                    pipe.unwatch()
                    return False
                # 判断用户是否已经抢过该红包
                if pipe.sismember(sender_id, red_packet_id):
                    pipe.unwatch()
                    return False
                # 执行事务
                pipe.multi()
                pipe.sadd(sender_id, red_packet_id)
                remning_amount -= amount
                pipe.lset(redbag_id, 0, remning_amount)
                pipe.rpush(redbag_id, amount)
                pipe.execute()
                return True
            except redis.exceptions.WatchError:
                pass
    return False

def get_redbag(conn, red_packet_id, receiver):
    "抢红包"
    sender_id = 'user:' + receiver
    redbag_id = 'redbag:' + red_packet_id
    with conn.pipeline() as pipe:
        while True:
            try:
                # 添加分布式锁，避免并发访问
                identifier = acquire_redis_lock(pipe, red_packet_id)
                if identifier:
                    # 判断红包是否已经抢完
                    remning_amount = pipe.lindex(redbag_id, 0)
                    remning_amount = int(remning_amount) if remning_amount else 0
                    if remning_amount 
                        pipe.unwatch()
                        return False
                    # 判断用户是否已经抢过该红包
                    if pipe.sismember(sender_id, red_packet_id):
                        pipe.unwatch()
                        return False
                    # 抢红包
                    amount = pipe.rpop(redbag_id)
                    # 如果红包已经被抢完，那么删除该红包
                    if not amount:
                        pipe.multi()
                        pipe.del(redbag_id, sender_id)
                        pipe.execute()
                        break
                    # 把红包金额加入用户账户
                    amount = int(amount)
                    pipe.multi()
                    pipe.sadd