feat: 添加过载保护、背压和熔断机制

internal/task/task.go

@@ -19,6 +19,7 @@ const (
 	StateCompleted TaskState = "COMPLETED"
 	StateFailed    TaskState = "FAILED"
 	StateCancelled TaskState = "CANCELLED"
+	StateTimedOut  TaskState = "TIMED_OUT"
 )
 
 // TaskPriority levels (P0 highest, P4 lowest).
@@ -53,6 +54,10 @@ type Task struct {
 	OutputTokens int
 	NodeID       string
 	Degraded     bool
+	QueueMs      int
+	FirstTokenMs int
+	InferenceMs  int
+	TotalMs      int
 	cancelCh     chan struct{}
 	cancelOnce   sync.Once
 	mu           sync.RWMutex
@@ -76,12 +81,13 @@ func NewTask(id, requestID, appID, tenantID, logicalModel string, priority TaskP
 
 // AllowedTransitions defines valid state transitions.
 var allowedTransitions = map[TaskState][]TaskState{
-	StateQueued:    {StateRunning, StateFailed, StateCancelled},
-	StateRunning:   {StateStreaming, StateCompleted, StateFailed, StateCancelled},
-	StateStreaming: {StateCompleted, StateFailed, StateCancelled},
+	StateQueued:    {StateRunning, StateFailed, StateCancelled, StateTimedOut},
+	StateRunning:   {StateStreaming, StateCompleted, StateFailed, StateCancelled, StateTimedOut},
+	StateStreaming: {StateCompleted, StateFailed, StateCancelled, StateTimedOut},
 	StateCompleted: {},
 	StateFailed:    {},
 	StateCancelled: {},
+	StateTimedOut:  {},
 }
 
 // Transition changes the task state if the transition is valid.
@@ -112,7 +118,7 @@ func (t *Task) Transition(to TaskState) error {
 	switch to {
 	case StateRunning:
 		t.StartedAt = &now
-	case StateCompleted, StateFailed, StateCancelled:
+	case StateCompleted, StateFailed, StateCancelled, StateTimedOut:
 		t.CompletedAt = &now
 	}
 
@@ -129,7 +135,7 @@ func (t *Task) Cancel(reason string) error {
 	t.mu.Lock()
 	defer t.mu.Unlock()
 
-	if t.State == StateCompleted || t.State == StateFailed || t.State == StateCancelled {
+	if t.State == StateCompleted || t.State == StateFailed || t.State == StateCancelled || t.State == StateTimedOut {
 		return errors.New("task already in terminal state")
 	}
 
@@ -165,7 +171,7 @@ func (t *Task) GetState() TaskState {
 // IsTerminal returns true if the task is in a terminal state.
 func (t *Task) IsTerminal() bool {
 	s := t.GetState()
-	return s == StateCompleted || s == StateFailed || s == StateCancelled
+	return s == StateCompleted || s == StateFailed || s == StateCancelled || s == StateTimedOut
 }
 
 // StateMachineLogger logs state transitions.