feat: tune websocket hub backpressure

internal/config/config.go

@@ -10,31 +10,39 @@ import (
 )
 
 type Config struct {
-	HTTPAddr             string
-	MySQLDSN             string
-	MaxOpen              int
-	MaxIdle              int
-	MetricsAddr          string
-	WorkflowTickInterval time.Duration // WorkflowTickInterval Weave 持久化推进扫描间隔，范围100ms–1m。
-	ScheduleTickInterval time.Duration // ScheduleTickInterval 计划扫描间隔，范围100ms–1m。
-	RecoveryTickInterval time.Duration // RecoveryTickInterval 执行租约恢复扫描间隔，范围100ms–1m。
-	RuntimeBatchLimit    int           // RuntimeBatchLimit 每个后台批次的候选上限，范围1–100。
-	ShutdownTimeout      time.Duration // ShutdownTimeout 优雅排空和关闭窗口，范围1s–5m。
+	HTTPAddr              string
+	MySQLDSN              string
+	MaxOpen               int
+	MaxIdle               int
+	MetricsAddr           string
+	WorkflowTickInterval  time.Duration // WorkflowTickInterval Weave 持久化推进扫描间隔，范围100ms–1m。
+	ScheduleTickInterval  time.Duration // ScheduleTickInterval 计划扫描间隔，范围100ms–1m。
+	RecoveryTickInterval  time.Duration // RecoveryTickInterval 执行租约恢复扫描间隔，范围100ms–1m。
+	RuntimeBatchLimit     int           // RuntimeBatchLimit 每个后台批次的候选上限，范围1–100。
+	ShutdownTimeout       time.Duration // ShutdownTimeout 优雅排空和关闭窗口，范围1s–5m。
+	WorkerConnectionLimit int           // WorkerConnectionLimit 单节点 Worker WebSocket 连接上限，范围1–4096。
+	EventConnectionLimit  int           // EventConnectionLimit 单节点 Event WebSocket 连接上限，范围1–4096。
+	DispatchWorkers       int           // DispatchWorkers 单个 Hub 并发执行数据库领取调用的协程数，范围1–256。
+	DispatchCapacity      int           // DispatchCapacity 单个 Hub 领取调用的有界内存排队槽位，范围1–65536。
 }
 
 func Load() (Config, error) { return FromEnv(os.Getenv) }
 func FromEnv(get func(string) string) (Config, error) {
 	c := Config{
-		HTTPAddr:             get("ORBIT_HTTP_ADDR"),
-		MySQLDSN:             get("ORBIT_MYSQL_DSN"),
-		MaxOpen:              20,
-		MaxIdle:              5,
-		MetricsAddr:          get("ORBIT_METRICS_ADDR"),
-		WorkflowTickInterval: time.Second,
-		ScheduleTickInterval: time.Second,
-		RecoveryTickInterval: 2 * time.Second,
-		RuntimeBatchLimit:    100,
-		ShutdownTimeout:      10 * time.Second,
+		HTTPAddr:              get("ORBIT_HTTP_ADDR"),
+		MySQLDSN:              get("ORBIT_MYSQL_DSN"),
+		MaxOpen:               20,
+		MaxIdle:               5,
+		MetricsAddr:           get("ORBIT_METRICS_ADDR"),
+		WorkflowTickInterval:  time.Second,
+		ScheduleTickInterval:  time.Second,
+		RecoveryTickInterval:  2 * time.Second,
+		RuntimeBatchLimit:     100,
+		ShutdownTimeout:       10 * time.Second,
+		WorkerConnectionLimit: 128,
+		EventConnectionLimit:  128,
+		DispatchWorkers:       4,
+		DispatchCapacity:      128,
 	}
 	if c.HTTPAddr == "" {
 		c.HTTPAddr = "127.0.0.1:8080"
@@ -86,6 +94,25 @@ func FromEnv(get func(string) string) (Config, error) {
 		}
 		c.ShutdownTimeout = d
 	}
+	for _, field := range []struct {
+		name string
+		dst  *int
+		min  int
+		max  int
+	}{
+		{"ORBIT_WORKER_CONNECTION_LIMIT", &c.WorkerConnectionLimit, 1, 4096},
+		{"ORBIT_EVENT_CONNECTION_LIMIT", &c.EventConnectionLimit, 1, 4096},
+		{"ORBIT_DISPATCH_WORKERS", &c.DispatchWorkers, 1, 256},
+		{"ORBIT_DISPATCH_CAPACITY", &c.DispatchCapacity, 1, 65536},
+	} {
+		if raw := get(field.name); raw != "" {
+			n, err := strconv.Atoi(raw)
+			if err != nil || n < field.min || n > field.max {
+				return Config{}, fmt.Errorf("%s must be an integer from %d to %d", field.name, field.min, field.max)
+			}
+			*field.dst = n
+		}
+	}
 	if c.MetricsAddr != "" {
 		_, port, err := net.SplitHostPort(c.MetricsAddr)
 		n, parseErr := strconv.Atoi(port)