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

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

@@ -16,40 +16,91 @@ import (
 )
 
 const (
-	RedisKeyFormat = "higress:global_least_request_table:%s:%s"
-	RedisLua       = `local seed = KEYS[1]
+	RedisKeyFormat          = "higress:global_least_request_table:%s:%s"
+	RedisLastCleanKeyFormat = "higress:global_least_request_table:last_clean_time:%s:%s"
+	RedisLua                = `local seed = tonumber(KEYS[1])
 local hset_key = KEYS[2]
-local current_target = KEYS[3]
-local current_count = 0
+local last_clean_key = KEYS[3]
+local clean_interval = tonumber(KEYS[4])
+local current_target = KEYS[5]
+local healthy_count = tonumber(KEYS[6])
+local enable_detail_log = KEYS[7]
 
 math.randomseed(seed)
 
-local function randomBool()
-    return math.random() >= 0.5
-end
+-- 1. Selection
+local current_count = 0
+local same_count_hits = 0
 
-if redis.call('HEXISTS', hset_key, current_target) == 1 then
-    current_count = redis.call('HGET', hset_key, current_target)
-	for i = 4, #KEYS do
-		if redis.call('HEXISTS', hset_key, KEYS[i]) == 1 then
-			local count = redis.call('HGET', hset_key, KEYS[i])
-			if tonumber(count) < tonumber(current_count) then
-				current_target = KEYS[i]
-				current_count = count
-			elseif count == current_count and randomBool() then
-				current_target = KEYS[i]
-			end
-		end
-	end
+for i = 8, 8 + healthy_count - 1 do
+    local host = KEYS[i]
+    local count = 0
+    local val = redis.call('HGET', hset_key, host)
+    if val then
+        count = tonumber(val) or 0
+    end
+    
+    if same_count_hits == 0 or count < current_count then
+        current_target = host
+        current_count = count
+        same_count_hits = 1
+    elseif count == current_count then
+        same_count_hits = same_count_hits + 1
+        if math.random(same_count_hits) == 1 then
+            current_target = host
+        end
+    end
 end
 
 redis.call("HINCRBY", hset_key, current_target, 1)
+local new_count = redis.call("HGET", hset_key, current_target)
 
-return current_target`
+-- Collect host counts for logging
+local host_details = {}
+if enable_detail_log == "1" then
+    local fields = {}
+    for i = 8, #KEYS do
+        table.insert(fields, KEYS[i])
+    end
+    if #fields > 0 then
+        local values = redis.call('HMGET', hset_key, (table.unpack or unpack)(fields))
+        for i, val in ipairs(values) do
+            table.insert(host_details, fields[i])
+            table.insert(host_details, tostring(val or 0))
+        end
+    end
+end
+
+-- 2. Cleanup
+local current_time = math.floor(seed / 1000000)
+local last_clean_time = tonumber(redis.call('GET', last_clean_key) or 0)
+
+if current_time - last_clean_time >= clean_interval then
+    local all_keys = redis.call('HKEYS', hset_key)
+    if #all_keys > 0 then
+        -- Create a lookup table for current hosts (from index 8 onwards)
+        local current_hosts = {}
+        for i = 8, #KEYS do
+            current_hosts[KEYS[i]] = true
+        end
+        -- Remove keys not in current hosts
+        for _, host in ipairs(all_keys) do
+            if not current_hosts[host] then
+                redis.call('HDEL', hset_key, host)
+            end
+        end
+    end
+    redis.call('SET', last_clean_key, current_time)
+end
+
+return {current_target, new_count, host_details}`
 )
 
 type GlobalLeastRequestLoadBalancer struct {
-	redisClient wrapper.RedisClient
+	redisClient     wrapper.RedisClient
+	maxRequestCount int64
+	cleanInterval   int64 // seconds
+	enableDetailLog bool
 }
 
 func NewGlobalLeastRequestLoadBalancer(json gjson.Result) (GlobalLeastRequestLoadBalancer, error) {
@@ -72,6 +123,18 @@ func NewGlobalLeastRequestLoadBalancer(json gjson.Result) (GlobalLeastRequestLoa
 	}
 	// database default is 0
 	database := json.Get("database").Int()
+	lb.maxRequestCount = json.Get("maxRequestCount").Int()
+	lb.cleanInterval = json.Get("cleanInterval").Int()
+	if lb.cleanInterval == 0 {
+		lb.cleanInterval = 60 * 60 // default 60 minutes
+	} else {
+		lb.cleanInterval = lb.cleanInterval * 60 // convert minutes to seconds
+	}
+	lb.enableDetailLog = true
+	if val := json.Get("enableDetailLog"); val.Exists() {
+		lb.enableDetailLog = val.Bool()
+	}
+	log.Infof("redis client init, serviceFQDN: %s, servicePort: %d, timeout: %d, database: %d, maxRequestCount: %d, cleanInterval: %d minutes, enableDetailLog: %v", serviceFQDN, servicePort, timeout, database, lb.maxRequestCount, lb.cleanInterval/60, lb.enableDetailLog)
 	return lb, lb.redisClient.Init(username, password, int64(timeout), wrapper.WithDataBase(int(database)))
 }
 
@@ -100,9 +163,11 @@ func (lb GlobalLeastRequestLoadBalancer) HandleHttpRequestBody(ctx wrapper.HttpC
 		ctx.SetContext("error", true)
 		return types.ActionContinue
 	}
+	allHostMap := make(map[string]struct{})
 	// Only healthy host can be selected
 	healthyHostArray := []string{}
 	for _, hostInfo := range hostInfos {
+		allHostMap[hostInfo[0]] = struct{}{}
 		if gjson.Get(hostInfo[1], "health_status").String() == "Healthy" {
 			healthyHostArray = append(healthyHostArray, hostInfo[0])
 		}
@@ -113,10 +178,37 @@ func (lb GlobalLeastRequestLoadBalancer) HandleHttpRequestBody(ctx wrapper.HttpC
 	}
 	randomIndex := rand.Intn(len(healthyHostArray))
 	hostSelected := healthyHostArray[randomIndex]
-	keys := []interface{}{time.Now().UnixMicro(), fmt.Sprintf(RedisKeyFormat, routeName, clusterName), hostSelected}
+
+	// KEYS structure: [seed, hset_key, last_clean_key, clean_interval, host_selected, healthy_count, ...healthy_hosts, enableDetailLog, ...unhealthy_hosts]
+	keys := []interface{}{
+		time.Now().UnixMicro(),
+		fmt.Sprintf(RedisKeyFormat, routeName, clusterName),
+		fmt.Sprintf(RedisLastCleanKeyFormat, routeName, clusterName),
+		lb.cleanInterval,
+		hostSelected,
+		len(healthyHostArray),
+		"0",
+	}
+	if lb.enableDetailLog {
+		keys[6] = "1"
+	}
 	for _, v := range healthyHostArray {
 		keys = append(keys, v)
 	}
+	// Append unhealthy hosts (those in allHostMap but not in healthyHostArray)
+	for host := range allHostMap {
+		isHealthy := false
+		for _, hh := range healthyHostArray {
+			if host == hh {
+				isHealthy = true
+				break
+			}
+		}
+		if !isHealthy {
+			keys = append(keys, host)
+		}
+	}
+
 	err = lb.redisClient.Eval(RedisLua, len(keys), keys, []interface{}{}, func(response resp.Value) {
 		if err := response.Error(); err != nil {
 			log.Errorf("HGetAll failed: %+v", err)
@@ -124,17 +216,54 @@ func (lb GlobalLeastRequestLoadBalancer) HandleHttpRequestBody(ctx wrapper.HttpC
 			proxywasm.ResumeHttpRequest()
 			return
 		}
-		hostSelected = response.String()
+		valArray := response.Array()
+		if len(valArray) < 2 {
+			log.Errorf("redis eval lua result format error, expect at least [host, count], got: %+v", valArray)
+			ctx.SetContext("error", true)
+			proxywasm.ResumeHttpRequest()
+			return
+		}
+		hostSelected = valArray[0].String()
+		currentCount := valArray[1].Integer()
+
+		// detail log
+		if lb.enableDetailLog && len(valArray) >= 3 {
+			detailLogStr := "host and count: "
+			details := valArray[2].Array()
+			for i := 0; i+1 < len(details); i += 2 {
+				h := details[i].String()
+				c := details[i+1].String()
+				detailLogStr += fmt.Sprintf("{%s: %s}, ", h, c)
+			}
+			log.Debugf("host_selected: %s + 1, %s", hostSelected, detailLogStr)
+		}
+
+		// check rate limit
+		if !lb.checkRateLimit(hostSelected, int64(currentCount), ctx, routeName, clusterName) {
+			ctx.SetContext("error", true)
+			log.Warnf("host_selected: %s, current_count: %d, exceed max request limit %d", hostSelected, currentCount, lb.maxRequestCount)
+			// return 429
+			proxywasm.SendHttpResponse(429, [][2]string{}, []byte("Exceeded maximum request limit from ai-load-balancer."), -1)
+			ctx.DontReadResponseBody()
+			return
+		}
+
 		if err := proxywasm.SetUpstreamOverrideHost([]byte(hostSelected)); err != nil {
 			ctx.SetContext("error", true)
 			log.Errorf("override upstream host failed, fallback to default lb policy, error informations: %+v", err)
+			proxywasm.ResumeHttpRequest()
+			return
 		}
+
 		log.Debugf("host_selected: %s", hostSelected)
+
+		// finally resume the request
 		ctx.SetContext("host_selected", hostSelected)
 		proxywasm.ResumeHttpRequest()
 	})
 	if err != nil {
 		ctx.SetContext("error", true)
+		log.Errorf("redis eval failed, fallback to default lb policy, error informations: %+v", err)
 		return types.ActionContinue
 	}
 	return types.ActionPause
@@ -161,7 +290,10 @@ func (lb GlobalLeastRequestLoadBalancer) HandleHttpStreamDone(ctx wrapper.HttpCo
 		if host_selected == "" {
 			log.Errorf("get host_selected failed")
 		} else {
-			lb.redisClient.HIncrBy(fmt.Sprintf(RedisKeyFormat, routeName, clusterName), host_selected, -1, nil)
+			err := lb.redisClient.HIncrBy(fmt.Sprintf(RedisKeyFormat, routeName, clusterName), host_selected, -1, nil)
+			if err != nil {
+				log.Errorf("host_selected: %s - 1, failed to update count from redis: %v", host_selected, err)
+			}
 		}
 	}
 }

plugins/wasm-go/extensions/ai-load-balancer/global_least_request/lb_script_test.lua

@@ -0,0 +1,220 @@
+-- Mocking Redis environment
+local redis_data = {
+    hset = {},
+    kv = {}
+}
+
+local redis = {
+    call = function(cmd, ...)
+        local args = {...}
+        if cmd == "HGET" then
+            local key, field = args[1], args[2]
+            return redis_data.hset[field]
+        elseif cmd == "HSET" then
+            local key, field, val = args[1], args[2], args[3]
+            redis_data.hset[field] = val
+        elseif cmd == "HINCRBY" then
+            local key, field, increment = args[1], args[2], args[3]
+            local val = tonumber(redis_data.hset[field] or 0)
+            redis_data.hset[field] = tostring(val + increment)
+            return redis_data.hset[field]
+        elseif cmd == "HKEYS" then
+            local keys = {}
+            for k, _ in pairs(redis_data.hset) do
+                table.insert(keys, k)
+            end
+            return keys
+        elseif cmd == "HDEL" then
+            local key, field = args[1], args[2]
+            redis_data.hset[field] = nil
+        elseif cmd == "GET" then
+            return redis_data.kv[args[1]]
+        elseif cmd == "HMGET" then
+            local key = args[1]
+            local res = {}
+            for i = 2, #args do
+                table.insert(res, redis_data.hset[args[i]])
+            end
+            return res
+        elseif cmd == "SET" then
+            redis_data.kv[args[1]] = args[2]
+        end
+    end
+}
+
+-- The actual logic from lb_policy.go
+local function run_lb_logic(KEYS)
+    local seed = tonumber(KEYS[1])
+    local hset_key = KEYS[2]
+    local last_clean_key = KEYS[3]
+    local clean_interval = tonumber(KEYS[4])
+    local current_target = KEYS[5]
+    local healthy_count = tonumber(KEYS[6])
+    local enable_detail_log = KEYS[7]
+
+    math.randomseed(seed)
+
+    -- 1. Selection
+    local current_count = 0
+    local same_count_hits = 0
+
+    for i = 8, 8 + healthy_count - 1 do
+        local host = KEYS[i]
+        local count = 0
+        local val = redis.call('HGET', hset_key, host)
+        if val then
+            count = tonumber(val) or 0
+        end
+        
+        if same_count_hits == 0 or count < current_count then
+            current_target = host
+            current_count = count
+            same_count_hits = 1
+        elseif count == current_count then
+            same_count_hits = same_count_hits + 1
+            if math.random(same_count_hits) == 1 then
+                current_target = host
+            end
+        end
+    end
+
+    redis.call("HINCRBY", hset_key, current_target, 1)
+    local new_count = redis.call("HGET", hset_key, current_target)
+
+    -- Collect host counts for logging
+    local host_details = {}
+    if enable_detail_log == "1" then
+        local fields = {}
+        for i = 8, #KEYS do
+            table.insert(fields, KEYS[i])
+        end
+        if #fields > 0 then
+            local values = redis.call('HMGET', hset_key, (table.unpack or unpack)(fields))
+            for i, val in ipairs(values) do
+                table.insert(host_details, fields[i])
+                table.insert(host_details, tostring(val or 0))
+            end
+        end
+    end
+
+    -- 2. Cleanup
+    local current_time = math.floor(seed / 1000000)
+    local last_clean_time = tonumber(redis.call('GET', last_clean_key) or 0)
+
+    if current_time - last_clean_time >= clean_interval then
+        local all_keys = redis.call('HKEYS', hset_key)
+        if #all_keys > 0 then
+            -- Create a lookup table for current hosts (from index 8 onwards)
+            local current_hosts = {}
+            for i = 8, #KEYS do
+                current_hosts[KEYS[i]] = true
+            end
+            -- Remove keys not in current hosts
+            for _, host in ipairs(all_keys) do
+                if not current_hosts[host] then
+                    redis.call('HDEL', hset_key, host)
+                end
+            end
+        end
+        redis.call('SET', last_clean_key, current_time)
+    end
+
+    return {current_target, new_count, host_details}
+end
+
+-- --- Test 1: Load Balancing Distribution ---
+print("--- Test 1: Load Balancing Distribution ---")
+local hosts = {"host1", "host2", "host3", "host4", "host5"}
+local iterations = 100000
+local results = {}
+for _, h in ipairs(hosts) do results[h] = 0 end
+
+-- Reset redis
+redis_data.hset = {}
+for _, h in ipairs(hosts) do redis_data.hset[h] = "0" end
+
+print(string.format("Running %d iterations with %d hosts (all counts started at 0)...", iterations, #hosts))
+
+for i = 1, iterations do
+    local initial_host = hosts[math.random(#hosts)]
+    -- KEYS structure: [seed, hset_key, last_clean_key, clean_interval, host_selected, healthy_count, enable_detail_log, ...healthy_hosts]
+    local keys = {i * 1000000, "table_key", "clean_key", 3600, initial_host, #hosts, "1"}
+    for _, h in ipairs(hosts) do table.insert(keys, h) end
+    
+    local res = run_lb_logic(keys)
+    local selected = res[1]
+    results[selected] = results[selected] + 1
+end
+
+for _, h in ipairs(hosts) do
+    local percentage = (results[h] / iterations) * 100
+    print(string.format("%s: %6d (%.2f%%)", h, results[h], percentage))
+end
+
+-- --- Test 2: IP Cleanup Logic ---
+print("\n--- Test 2: IP Cleanup Logic ---")
+
+local function test_cleanup()
+    redis_data.hset = {
+        ["host1"] = "10",
+        ["host2"] = "5",
+        ["old_ip_1"] = "1",
+        ["old_ip_2"] = "1",
+    }
+    redis_data.kv["clean_key"] = "1000" -- Last cleaned at 1000s
+    
+    local current_hosts = {"host1", "host2"}
+    local current_time_ms = 1000 * 1000000 + 500 * 1000000 -- 1500s (interval is 300s, let's say)
+    local clean_interval = 300
+    
+    print("Initial Redis IPs:", table.concat((function() local res={} for k,_ in pairs(redis_data.hset) do table.insert(res, k) end return res end)(), ", "))
+    
+    -- Run logic (seed is microtime)
+    local keys = {current_time_ms, "table_key", "clean_key", clean_interval, "host1", #current_hosts, "1"}
+    for _, h in ipairs(current_hosts) do table.insert(keys, h) end
+    
+    run_lb_logic(keys)
+    
+    print("After Cleanup Redis IPs:", table.concat((function() local res={} for k,_ in pairs(redis_data.hset) do table.insert(res, k) end table.sort(res) return res end)(), ", "))
+    
+    local exists_old1 = redis_data.hset["old_ip_1"] ~= nil
+    local exists_old2 = redis_data.hset["old_ip_2"] ~= nil
+    
+    if not exists_old1 and not exists_old2 then
+        print("Success: Outdated IPs removed.")
+    else
+        print("Failure: Outdated IPs still exist.")
+    end
+    
+    print("New last_clean_time:", redis_data.kv["clean_key"])
+end
+
+test_cleanup()
+
+-- --- Test 3: No Cleanup if Interval Not Reached ---
+print("\n--- Test 3: No Cleanup if Interval Not Reached ---")
+
+local function test_no_cleanup()
+    redis_data.hset = {
+        ["host1"] = "10",
+        ["old_ip_1"] = "1",
+    }
+    redis_data.kv["clean_key"] = "1000"
+    
+    local current_hosts = {"host1"}
+    local current_time_ms = 1000 * 1000000 + 100 * 1000000 -- 1100s (interval 300s, not reached)
+    local clean_interval = 300
+    
+    local keys = {current_time_ms, "table_key", "clean_key", clean_interval, "host1", #current_hosts, "0"}
+    for _, h in ipairs(current_hosts) do table.insert(keys, h) end
+    
+    run_lb_logic(keys)
+    
+    if redis_data.hset["old_ip_1"] then
+        print("Success: Cleanup not triggered as expected.")
+    else
+        print("Failure: Cleanup triggered unexpectedly.")
+    end
+end
+
+test_no_cleanup()

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
+}