Golang使用lua脚本实现redis原子操作

127.0.0.1:6379> eval "return {'Hello, GrassInWind!'}" 0
1) "Hello, GrassInWind!"
127.0.0.1:6379> eval "return redis.call('set',KEYS[1],'bar')" 1 foo
OK

***@LAPTOP-V7V47H0L MINGW64 /d/study/code/lua
$ redis-cli.exe -a 123 --eval test.lua testkey , hello
hello

local key,value = KEYS[1],ARGV[1]
redis.log(redis.LOG_NOTICE, "key=", key, "value=", value)
redis.call('SET', key, value)
local a = redis.call('GET', key)
return a

127.0.0.1:6379> script load "return 'Hello GrassInWind'"
"c66be1d9b54b3182f8d8e12f8b01a4e5c7c4af5b"
127.0.0.1:6379> script exists "c66be1d9b54b3182f8d8e12f8b01a4e5c7c4af5b"
1) (integer) 1
127.0.0.1:6379> evalsha "c66be1d9b54b3182f8d8e12f8b01a4e5c7c4af5b" 0
"Hello GrassInWind"
127.0.0.1:6379> script flush
OK
127.0.0.1:6379> script exists "c66be1d9b54b3182f8d8e12f8b01a4e5c7c4af5b"
1) (integer) 0

-- redis zset operations
-- argv[capacity maxScore newMemberScore member]
-- 执行示例 redis-cli.exe --eval zsetop.lua mtest , 3 5 5 test1
-- 获取键和参数
local key,cap,maxSetScore,newMemberScore,member = KEYS[1],ARGV[1],ARGV[2],ARGV[3],ARGV[4]
redis.log(redis.LOG_NOTICE, "key=", key,",cap=", cap,",maxSetScore=", maxSetScore,",newMemberScore=", newMemberScore,",member=", member)
local len = redis.call('zcard', key);
-- len need not nil, otherwise will occur "attempt to compare nil with number"
if len then
 if tonumber(len) >= tonumber(cap)
 then
  local num = tonumber(len)-tonumber(cap)+1
  local list = redis.call('zrangebyscore',key,0,maxSetScore,'limit',0,num)
  redis.log(redis.LOG_NOTICE,"key=",key,"maxSetScore=",maxSetScore, "num=",num)
  for k,lowestScoreMember in pairs(list) do
   local lowestScore = redis.call('zscore', key,lowestScoreMember)
   redis.log(redis.LOG_NOTICE, "list: ", lowestScore, lowestScoreMember)
   if tonumber(newMemberScore) > tonumber(lowestScore)
   then
    local rank = redis.call('zrevrank',key,member)
    -- rank is nil indicate new member is not exist in set, need remove the lowest score member
    if not rank then
     local index = tonumber(len) - tonumber(cap);
     redis.call('zremrangebyrank',key, 0, index)
    end
    redis.call('zadd', key, newMemberScore, member);
    break
   end
  end
 else
  redis.call('zadd', key, newMemberScore, member);
 end
end

func init() {
 ...
 file, err := os.Open(zsetopFileName)
 if err != nil {
 panic("open"+zsetopFileName+" "+err.Error())
 }
 bytes,err := ioutil.ReadAll(file)
 if err != nil {
 panic(err.Error())
 }
 zsetopScript = utils.UnsafeBytesToString(bytes)
 logs.Debug(zsetopScript)
 lua =redis.NewScript(1,zsetopScript)
}
func ZaddWithCap(key,member string, score float32, maxScore, cap int) (reply interface{}, err error) {
 c := pool.Get()
 //Do optimistically evaluates the script using the EVALSHA command. If script not exist, will use eval command.
 reply, err= lua.Do(c,key,cap,maxScore,score,member)
 return
}

func (s *Script) Do(c Conn, keysAndArgs ...interface{}) (interface{}, error) {
 v, err := c.Do("EVALSHA", s.args(s.hash, keysAndArgs)...)
 if e, ok := err.(Error); ok && strings.HasPrefix(string(e), "NOSCRIPT ") {
 v, err = c.Do("EVAL", s.args(s.src, keysAndArgs)...)
 }
 return v, err
}

func UnsafeBytesToString(bytes []byte) string {
 hdr := &reflect.StringHeader{
 Data: uintptr(unsafe.Pointer(&bytes[0])),
 Len: len(bytes),
 }
 return *(*string)(unsafe.Pointer(hdr))
}

type SliceHeader struct {
 Data uintptr
 Len int
 Cap int
 } 
type StringHeader struct {
 Data uintptr
 Len int
 }