feat: migrate lua script to lua file (#4069)

core/limit/tokenlimit.go

@@ -2,6 +2,7 @@ package limit
 
 import (
 	"context"
+	_ "embed"
 	"errors"
 	"fmt"
 	"strconv"
@@ -20,37 +21,12 @@ const (
 	pingInterval    = time.Millisecond * 100
 )
 
-// to be compatible with aliyun redis, we cannot use `local key = KEYS[1]` to reuse the key
-// KEYS[1] as tokens_key
-// KEYS[2] as timestamp_key
-var script = redis.NewScript(`local rate = tonumber(ARGV[1])
-local capacity = tonumber(ARGV[2])
-local now = tonumber(ARGV[3])
-local requested = tonumber(ARGV[4])
-local fill_time = capacity/rate
-local ttl = math.floor(fill_time*2)
-local last_tokens = tonumber(redis.call("get", KEYS[1]))
-if last_tokens == nil then
-    last_tokens = capacity
-end
+var (
+	//go:embed tokenscript.lua
+	tokenScript string
 
-local last_refreshed = tonumber(redis.call("get", KEYS[2]))
-if last_refreshed == nil then
-    last_refreshed = 0
-end
-
-local delta = math.max(0, now-last_refreshed)
-local filled_tokens = math.min(capacity, last_tokens+(delta*rate))
-local allowed = filled_tokens >= requested
-local new_tokens = filled_tokens
-if allowed then
-    new_tokens = filled_tokens - requested
-end
-
-redis.call("setex", KEYS[1], ttl, new_tokens)
-redis.call("setex", KEYS[2], ttl, now)
-
-return allowed`)
+	scriptToken = redis.NewScript(tokenScript)
+)
 
 // A TokenLimiter controls how frequently events are allowed to happen with in one second.
 type TokenLimiter struct {
@@ -112,7 +88,7 @@ func (lim *TokenLimiter) reserveN(ctx context.Context, now time.Time, n int) boo
 	}
 
 	resp, err := lim.store.ScriptRunCtx(ctx,
-		script,
+		scriptToken,
 		[]string{
 			lim.tokenKey,
 			lim.timestampKey,