OpenResty连接Redis

        通常来说，对于OpenResty的应用多数都会用到Redis，用以减少回源次数，从而加速网站。话不多说，先上一个demo
        redis_iresty.lua

-- file name: resty/redis_iresty.lualocal 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 {} endendlocal _M = new_tab(0, 155)_M._VERSION = '0.01'local commands = {    "append",   "bgsave",       "blpop",        "brpoplpush",   "auth",         "bitcount",    "brpop",    "client",       "bgrewriteaof", "bitop",        "config",       "dbsize",    "debug",    "decr",         "del",          "discard",      "echo",         "eval",    "exec",     "expire",       "expireat",     "flushdb",      "get",          "getrange",    "getset",   "hexists",      "hget",         "hincrby",      "hincrbyfloat", "hlen",    "hmget",    "hset",         "hsetnx",       "incrby",       "keys",         "lastsave",    "llen",     "lpushx",       "lset",         "migrate",      "monitor",      "msetnx",    "persist",  "ping",         "pttl",         "publish",      "quit",         "randomkey",    "restore",  "rpop",         "rpushx",       "scan",         "sdiff",        "select",    "setex",    "shutdown",     "sismember",    "smembers",     "spop",         "sscan",    "strlen",   "sunionstore",  "ttl",          "type",         "watch",        "zcount",    "zrange",   "zrem",         "zrevrange",    "zscan",        "zscore",       "hmset",    "hvals",    "incrbyfloat",  "lindex",       "lpop",         "lrange",       "ltrim",    "move",     "multi",        "pexpire",      "psetex",       --[[ "punsubscribe", ]]    "rename",   "info",         "linsert",      "lpush",        "lrem",         "mget",    "mset",     "object",       "pexpireat",    "psubscribe",   "pubsub",       "renamenx",    "rpush",    "save",         "script",       "setbit",       "setrange",     "sinterstore",    "slowlog",  "sort",         "srem",         "sunion",       "time",         "rpoplpush",    "sadd",     "scard",        "sdiffstore",   "set",          "setnx",        "sinter",    "slaveof",  "smove",        "srandmember",  --[[ "subscribe",  ]]           "sync",    --[[ "unsubscribe", ]]      "zunionstore",  "evalsha",      "decrby",       "dump",    "exists",   "flushall",     "getbit",       "hdel",         "hgetall",      "hkeys",    "hscan",    "incr",         "zadd",         "zincrby",      "zrangebyscore","zrank",    "zremrangebyrank",          "zremrangebyscore",             "zrevrangebyscore",     "zrevrank", "unwatch",      "zcard",        "zinterstore" }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 falseend-- change connect address as you needfunction _M.connect_mod( self, redis )    redis:set_timeout(self.timeout)    return redis:connect("127.0.0.1", 6379)endfunction _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)endfunction _M.init_pipeline( self )    self._reqs = {}endfunction _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, errendfunction _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    local function do_read_func ( do_read )        if do_read == nil or do_read == true then            res, err = redis:read_reply()            if not res then                return nil, err            end            return res        end        redis:unsubscribe(channel)        self.set_keepalive_mod(redis)        return    end    return do_read_funcendlocal 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        return nil, err    end    if is_redis_null(result) then        result = nil    end    self.set_keepalive_mod(redis)    return result, errendfor i = 1, #commands do    local cmd = commands[i]    _M[cmd] =            function (self, ...)                return do_command(self, cmd, ...)            endend function _M.new(self, opts)    opts = opts or {}    local timeout = (opts.timeout and opts.timeout * 1000) or 1000  --1s    local db_index= opts.db_index or 0    return setmetatable({            timeout = timeout,            db_index = db_index,            _reqs = nil }, mt)endreturn _M

        上述代码片段摘自OpenResty 最佳实践，上面的模块是对resty.redis的包装。其中抽象了连接创建、认证及释放的过程，并且对外统一为池化操作。下面为一个调用的demo:

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

        这里调用的代码很简单，就不再多说了，下面说一下上面resty_iredis.lua的内容。
普通命令
        第一个调用的是new(opts)，入参是一个table，可以设置两个值，timeout和db索引值。（其他相关连接参数在工具内部，实际使用时可以抽出来配置文件）如timeout不设置，则默认超时为1s。
        在new的时候返回的是iresty对象本身，因此new上面对基本上所有的redis命令进行了重写。并最终由do_command方法去调用resty.redis的方法，实现了与原生resty.redis相同的API。
        还有一点需要提及的就是，上述API的封装是用到连接池的（虽然API中不能明显看出）。在new的时候并没有到连接池中获取连接，而是在具体的命令调用时（do_command方法中connect_mod）才去到cosocket连接池中去获取TCP连接的。cosocket中的连接池是以IP和端口号作为连接池的KEY，redis:connect(ip, port)才可以获取对应的TCP连接。
批量操作
        对于批量操作，上述工具里面主要包含两个接口：init_pipeline()和commit_pipeline()。当批量命令开始时，执行init_pipeline()，此时会初始化一个命令缓冲区_reqs，用以存储待执行的批量命令。最后调用_M:set_keepalive_mod中的redis:set_keepalive(60000, 1000)方法，用以释放连接到池中。若此时没有以此IP和端口号为KEY的连接池，则会创建一个大小为1000的连接池，最大存活时间为60s。
订阅服务
        对于订阅服务，调用代码请参见如下：

local red = redis:new({timeout=1000})local func = red:subscribe( "channel" )if not func then  return nilendwhile true do    local res, err = func()    if err then        func(false)    end... ...endreturn cbfunc

链接：http://moguhu.com/article/detail?articleId=20