feat(ai-load-balancer): enhance global least request load balancer (#3255)

plugins/wasm-go/extensions/ai-load-balancer/global_least_request/rate_limit.go

@@ -0,0 +1,24 @@
+package global_least_request
+
+import (
+	"fmt"
+
+	"github.com/higress-group/wasm-go/pkg/wrapper"
+)
+
+func (lb GlobalLeastRequestLoadBalancer) checkRateLimit(hostSelected string, currentCount int64, ctx wrapper.HttpContext, routeName string, clusterName string) bool {
+	// 如果没有配置最大请求数，直接通过
+	if lb.maxRequestCount <= 0 {
+		return true
+	}
+
+	// 如果当前请求数大于最大请求数，则限流
+	// 注意：Lua脚本已经加了1，所以这里比较的是加1后的值
+	if currentCount > lb.maxRequestCount {
+		// 恢复 Redis 计数
+		lb.redisClient.HIncrBy(fmt.Sprintf(RedisKeyFormat, routeName, clusterName), hostSelected, -1, nil)
+		return false
+	}
+
+	return true
+}