From a724a3c62bca11f033e4d6d8bbc7cead4b0f97af Mon Sep 17 00:00:00 2001
From: Roman Kredentser <shareed2k@gmail.com>
Date: Thu, 1 Apr 2021 14:00:00 +0300
Subject: [PATCH] change after @shamil cr

---
 algorithm/gcra/gcra_lua.go | 64 --------------------------------------
 algorithm/model.go         | 15 +--------
 limit.go                   | 14 ++++-----
 limiter.go                 | 29 +++++++----------
 4 files changed, 18 insertions(+), 104 deletions(-)
 delete mode 100644 algorithm/gcra/gcra_lua.go

diff --git a/algorithm/gcra/gcra_lua.go b/algorithm/gcra/gcra_lua.go
deleted file mode 100644
index 7214468..0000000
--- a/algorithm/gcra/gcra_lua.go
+++ /dev/null
@@ -1,64 +0,0 @@
-package gcra
-
-import "github.com/go-redis/redis/v8"
-
-// Copyright (c) 2017 Pavel Pravosud
-// https://github.com/rwz/redis-gcra/blob/master/vendor/perform_gcra_ratelimit.lua
-var script = redis.NewScript(`
--- this script has side-effects, so it requires replicate commands mode
-redis.replicate_commands()
-
-local rate_limit_key = KEYS[1]
-local burst = ARGV[1]
-local rate = ARGV[2]
-local period = ARGV[3]
-local cost = ARGV[4]
-
-local emission_interval = period / rate
-local increment = emission_interval * cost
-local burst_offset = emission_interval * burst
-local now = redis.call("TIME")
-
--- redis returns time as an array containing two integers: seconds of the epoch
--- time (10 digits) and microseconds (6 digits). for convenience we need to
--- convert them to a floating point number. the resulting number is 16 digits,
--- bordering on the limits of a 64-bit double-precision floating point number.
--- adjust the epoch to be relative to Jan 1, 2017 00:00:00 GMT to avoid floating
--- point problems. this approach is good until "now" is 2,483,228,799 (Wed, 09
--- Sep 2048 01:46:39 GMT), when the adjusted value is 16 digits.
-local jan_1_2017 = 1483228800
-now = (now[1] - jan_1_2017) + (now[2] / 1000000)
-
-local tat = redis.call("GET", rate_limit_key)
-
-if not tat then
-  tat = now
-else
-  tat = tonumber(tat)
-end
-
-local new_tat = math.max(tat, now) + increment
-
-local allow_at = new_tat - burst_offset
-local diff = now - allow_at
-
-local limited
-local retry_after
-local reset_after
-
-local remaining = math.floor(diff / emission_interval + 0.5) -- poor man's round
-
-if remaining < 0 then
-  limited = 1
-  remaining = 0
-  reset_after = tat - now
-  retry_after = diff * -1
-else
-  limited = 0
-  reset_after = new_tat - now
-  redis.call("SET", rate_limit_key, new_tat, "EX", math.ceil(reset_after))
-  retry_after = -1
-end
-
-return {limited, remaining, tostring(retry_after), tostring(reset_after)}
-`)
diff --git a/algorithm/model.go b/algorithm/model.go
index ef6064d..39c90c3 100644
--- a/algorithm/model.go
+++ b/algorithm/model.go
@@ -2,15 +2,12 @@ package algorithm
 
 import (
 	"context"
-	"fmt"
 	"time"
 
 	"github.com/go-redis/redis/v8"
 )
 
-var (
-	Registry []*RegInfo
-)
+var Registry []*RegInfo
 
 type (
 	Limit interface {
@@ -79,13 +76,3 @@ type (
 func Register(info *RegInfo) {
 	Registry = append(Registry, info)
 }
-
-func Find(name string) (*RegInfo, error) {
-	for _, item := range Registry {
-		if item.Name == name {
-			return item, nil
-		}
-	}
-
-	return nil, fmt.Errorf("didn't find algorithm called %q", name)
-}
diff --git a/limit.go b/limit.go
index 813fb98..2743d9b 100644
--- a/limit.go
+++ b/limit.go
@@ -2,14 +2,12 @@ package go_redis_ratelimit
 
 import "time"
 
-type (
-	Limit struct {
-		Algorithm string
-		Burst     int64
-		Rate      int64
-		Period    time.Duration
-	}
-)
+type Limit struct {
+	Algorithm string
+	Burst     int64
+	Rate      int64
+	Period    time.Duration
+}
 
 func (l *Limit) GetAlgorithm() string {
 	return l.Algorithm
diff --git a/limiter.go b/limiter.go
index e2ddadf..baff76f 100644
--- a/limiter.go
+++ b/limiter.go
@@ -6,38 +6,31 @@ import (
 	"github.com/go-redis/redis/v8"
 
 	"github.com/bringg/go_redis_ratelimit/algorithm"
-
 	_ "github.com/bringg/go_redis_ratelimit/algorithm/all"
 )
 
-const (
-	DefaultPrefix = "limiter"
-)
-
-var (
-	algorithmPool map[string]algorithm.Algorithm
-)
+const DefaultPrefix = "limiter"
 
-type (
-	// Limiter controls how frequently events are allowed to happen.
-	Limiter struct {
-		Prefix string
-	}
-)
+// Limiter controls how frequently events are allowed to happen.
+type Limiter struct {
+	Prefix     string
+	algorithms map[string]algorithm.Algorithm
+}
 
 // NewLimiter returns a new Limiter.
 func NewLimiter(rdb *redis.Client) (*Limiter, error) {
-	algorithmPool = make(map[string]algorithm.Algorithm, len(algorithm.Registry))
+	algorithms := make(map[string]algorithm.Algorithm, len(algorithm.Registry))
 
 	var err error
 	for _, info := range algorithm.Registry {
-		if algorithmPool[info.Name], err = info.NewAlgorithm(rdb); err != nil {
+		if algorithms[info.Name], err = info.NewAlgorithm(rdb); err != nil {
 			return nil, err
 		}
 	}
 
 	return &Limiter{
-		Prefix: DefaultPrefix,
+		Prefix:     DefaultPrefix,
+		algorithms: algorithms,
 	}, nil
 }
 
@@ -54,7 +47,7 @@ func (l *Limiter) Allow(key string, limit *Limit) (*algorithm.Result, error) {
 }
 
 func (l *Limiter) findAlgorithm(name string) (algorithm.Algorithm, error) {
-	if algo, ok := algorithmPool[name]; ok {
+	if algo, ok := l.algorithms[name]; ok {
 		return algo, nil
 	}