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
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