企业级 分布式 限流 方案.zip

## 分布式限流实现案例 ## ### 技术栈 * Java * Redis * Lua ### 测试脚本 [LimiterOperationTest](com.github.bakerzhu.LimiterOperationTest) ### 核心Lua脚本 ```lua --- 判断source_str 中是否contains sub_str --- @param source_str --- @param sub_str local function contains(source_str , sub_str) local start_pos,end_pos = string.find(source_str,sub_str); if start_pos == nil then return false end local source_str_len = string.len(source_str) local s = string.sub(source_str,end_pos,end_pos) if source_str_len == end_pos then return true; elseif string.sub(source_str,end_pos + 1,end_pos + 1) == "," then return true; end return false; end --- 获取令牌 --- 返回码 --- 0 没有令牌桶配置 --- -1 表示取令牌失败，也就是桶里没有令牌 --- 1 表示取令牌成功 --- @param key 令牌的唯一标识 --- @param permits 请求令牌数量 --- @param curr_mill_second 当前毫秒数 --- @param context 使用令牌的应用标识 local function acquire(key , permits , curr_mill_second , context) local rate_limit_info = redis.pcall("HMGET" , key , "last_mill_second","curr_permits","max_permits","rate","apps") local last_mill_second = rate_limit_info[1] local curr_permits = tonumber(rate_limit_info[2]) local max_permits = tonumber(rate_limit_info[3]) local rate = rate_limit_info[4] local apps = rate_limit_info[5] -- 标识没有配置令牌桶 if type(apps) == 'boolean' or apps == nil or not contains(apps , context) then return 0 end local local_curr_permits = curr_permits --- 令牌桶刚刚创建，上一次获取令牌的毫秒数为空 --- 根据和上一次向桶里添加令牌的时间和当前时间差，触发式往桶里添加令牌，并且更新上一次向桶里添加令牌的时间 --- 如果向桶里添加的令牌数不足一个，则不更新上一次向桶里添加令牌的时间 if (type(last_mill_second) ~= 'boolean' and last_mill_second ~= nil) then local reverse_permits = math.floor(((curr_mill_second - last_mill_second)/1000) * rate) local expect_curr_permits = reverse_permits + curr_permits; local_curr_permits = math.min(expect_curr_permits,max_permits) --- 大于0表示不是第一次获取令牌，也没有向桶里添加令牌 if (reverse_permits > 0) then redis.pcall("HSET",key, "last_mill_second" , curr_mill_second) end else redis.pcall("HSET" , key, "last_mill_second" , curr_mill_second) end local result = -1 if (local_curr_permits - permits >=0) then result = 1 redis.pcall("HSET" , key , "curr_permits" , local_curr_permits - permits) else redis.pcall("HSET" , key , "curr_permits" , local_curr_permits) end return result end --- 初始化令牌桶配置 --- @param key 令牌的唯一标识 --- @param max_permits 桶大小 --- @param rate 向桶里添加令牌的速率 --- @param apps 可以使用令牌桶的应用列表，应用之前用逗号分隔 local function init(key, max_permits, rate , apps) local rate_limit_info = redis.pcall("HMGET",key,"last_mill_second","curr_permits","max_permits","rate","apps") local org_max_permits = tonumber(rate_limit_info[3]) local org_rate = rate_limit_info[4] local org_apps = rate_limit_info[5] if (org_max_permits == nil) or (apps ~= org_apps or rate ~= org_rate or max_permits ~= org_max_permits) then redis.pcall("HMSET", key , "max_permits" , max_permits , "rate" , rate , "curr_permits" , max_permits , "apps" , apps) end return 1 end --- 删除令牌桶 local function delete(key) redis.pcall("DEL",key) return 1 end local key = KEYS[1] local method = ARGV[1] if method == 'acquire' then return acquire(key,KEYS[2],KEYS[3],KEYS[4]) elseif method == 'init' then return init(key,KEYS[2],KEYS[3],KEYS[4]) elseif method == 'delete' then return delete(key) end ```