OpenResty调用redis

Redis是非常常见的缓存,在api服务器中当然少不了这个服务。Lua链接redis在没有封装之前还是略麻烦。

local redis = require "resty.redis"
local red = redis:new()

red:set_timeout(1000)

local ok, err = red:connect("127.0.0.1", 6379)

if not ok then
    ngx.say("failed to connect:", err)
    return
end

local count

count, err = red:get_reused_times()
if 0 == count then
    ok, err = red:auth("123456")
    if not ok then
        ngx.say("failed to auth", err)
        return
    end
elseif err then
    ngx.say("failed to read resued times.", err)
    return
end

ok, err = red:set("dog", "a animal")
if not ok then
    ngx.say("failed to set", err)
    return 
end

ngx.say("set result:", ok)

local ok, err = red:set_keepalive(10000, 100)
if not ok then
    ngx.say("filed to set keepalive:", err)
    return
end

调用这个文件的nginx配置就不贴了。显然,对于我们只是想要set一个dog变量来说,这个流程还是太复杂了,用过Laravel框架的都知道,它的门面系统非常强大,其中Redis就有对应的门面,使用的时候只需要调用Redis::Set()即可。

同样在Lua中也能封装这样的操作,而且可以使用连接池的方案,比php那种每次都得重新链接的方案能好不少(同样也会带来一些问题…)。

封装方案

这里就先不卖关子,从入口看会比较容易,最主要的就是do_command这个函数,它代理了所有的redis操作,代理的前提是载入模块的时候有个for循环,将所有的redis操作放入了模块的表中。比较容易理解,直接贴出来:

-- file name: resty/redis_iresty.lua
local redis_c = require "resty.redis"


local ok, new_tab = pcall(require, "table.new")
if not ok or type(new_tab) ~= "function" then
    new_tab = function (narr, nrec) return {} end
end


local _M = new_tab(0, 155)
_M._VERSION = '0.01'


local commands = {
    "append",            "auth",              "bgrewriteaof",
    "bgsave",            "bitcount",          "bitop",
    "blpop",             "brpop",
    "brpoplpush",        "client",            "config",
    "dbsize",
    "debug",             "decr",              "decrby",
    "del",               "discard",           "dump",
    "echo",
    "eval",              "exec",              "exists",
    "expire",            "expireat",          "flushall",
    "flushdb",           "get",               "getbit",
    "getrange",          "getset",            "hdel",
    "hexists",           "hget",              "hgetall",
    "hincrby",           "hincrbyfloat",      "hkeys",
    "hlen",
    "hmget",              "hmset",      "hscan",
    "hset",
    "hsetnx",            "hvals",             "incr",
    "incrby",            "incrbyfloat",       "info",
    "keys",
    "lastsave",          "lindex",            "linsert",
    "llen",              "lpop",              "lpush",
    "lpushx",            "lrange",            "lrem",
    "lset",              "ltrim",             "mget",
    "migrate",
    "monitor",           "move",              "mset",
    "msetnx",            "multi",             "object",
    "persist",           "pexpire",           "pexpireat",
    "ping",              "psetex",            "psubscribe",
    "pttl",
    "publish",      --[[ "punsubscribe", ]]   "pubsub",
    "quit",
    "randomkey",         "rename",            "renamenx",
    "restore",
    "rpop",              "rpoplpush",         "rpush",
    "rpushx",            "sadd",              "save",
    "scan",              "scard",             "script",
    "sdiff",             "sdiffstore",
    "select",            "set",               "setbit",
    "setex",             "setnx",             "setrange",
    "shutdown",          "sinter",            "sinterstore",
    "sismember",         "slaveof",           "slowlog",
    "smembers",          "smove",             "sort",
    "spop",              "srandmember",       "srem",
    "sscan",
    "strlen",       --[[ "subscribe",  ]]     "sunion",
    "sunionstore",       "sync",              "time",
    "ttl",
    "type",         --[[ "unsubscribe", ]]    "unwatch",
    "watch",             "zadd",              "zcard",
    "zcount",            "zincrby",           "zinterstore",
    "zrange",            "zrangebyscore",     "zrank",
    "zrem",              "zremrangebyrank",   "zremrangebyscore",
    "zrevrange",         "zrevrangebyscore",  "zrevrank",
    "zscan",
    "zscore",            "zunionstore",       "evalsha"
}


local mt = { __index = _M }


local function is_redis_null( res )
    if type(res) == "table" then
        for k,v in pairs(res) do
            if v ~= ngx.null then
                return false
            end
        end
        return true
    elseif res == ngx.null then
        return true
    elseif res == nil then
        return true
    end

    return false
end


-- change connect address as you need
function _M.connect_mod( self, redis )
    redis:set_timeout(self.timeout)
    return redis:connect("127.0.0.1", 6379)
end


function _M.set_keepalive_mod( redis )
    -- put it into the connection pool of size 100, with 60 seconds max idle time
    return redis:set_keepalive(60000, 1000)
end


function _M.init_pipeline( self )
    self._reqs = {}
end


function _M.commit_pipeline( self )
    local reqs = self._reqs

    if nil == reqs or 0 == #reqs then
        return {}, "no pipeline"
    else
        self._reqs = nil
    end

    local redis, err = redis_c:new()
    if not redis then
        return nil, err
    end

    local ok, err = self:connect_mod(redis)
    if not ok then
        return {}, err
    end

    redis:init_pipeline()
    for _, vals in ipairs(reqs) do
        local fun = redis[vals[1]]
        table.remove(vals , 1)

        fun(redis, unpack(vals))
    end

    local results, err = redis:commit_pipeline()
    if not results or err then
        return {}, err
    end

    if is_redis_null(results) then
        results = {}
        ngx.log(ngx.WARN, "is null")
    end
    -- table.remove (results , 1)

    self.set_keepalive_mod(redis)

    for i,value in ipairs(results) do
        if is_redis_null(value) then
            results[i] = nil
        end
    end

    return results, err
end


function _M.subscribe( self, channel )
    local redis, err = redis_c:new()
    if not redis then
        return nil, err
    end

    local ok, err = self:connect_mod(redis)
    if not ok or err then
        return nil, err
    end

    local res, err = redis:subscribe(channel)
    if not res then
        return nil, err
    end

    res, err = redis:read_reply()
    if not res then
        return nil, err
    end

    redis:unsubscribe(channel)
    self.set_keepalive_mod(redis)

    return res, err
end


local function do_command(self, cmd, ... )
    if self._reqs then
        table.insert(self._reqs, {cmd, ...})
        return
    end

    local redis, err = redis_c:new()
    if not redis then
        return nil, err
    end

    local ok, err = self:connect_mod(redis)
    if not ok or err then
        return nil, err
    end

    local fun = redis[cmd]
    local result, err = fun(redis, ...)
    if not result or err then
        -- ngx.log(ngx.ERR, "pipeline result:", result, " err:", err)
        return nil, err
    end

    if is_redis_null(result) then
        result = nil
    end

    self.set_keepalive_mod(redis)

    return result, err
end


for i = 1, #commands do
    local cmd = commands[i]
    _M[cmd] =
            function (self, ...)
                return do_command(self, cmd, ...)
            end
end


function _M.new(self, opts)
    opts = opts or {}
    local timeout = (opts.timeout and opts.timeout * 1000) or 1000
    local db_index= opts.db_index or 0

    return setmetatable({
            timeout = timeout,
            db_index = db_index,
            _reqs = nil }, mt)
end


return _M

有了这段库之后,我们就不必理会细节了,只管调用就好:

local redis = require "resty.redis_iresty"
local red = redis:new()

local ok, err = red:set("dog", "an animal")
if not ok then
    ngx.say("failed to set dog: ", err)
    return
end

ngx.say("set result: ", ok)

使用封装之后的代码会简洁很多,阅读起来也没有任何困难。