Observatory: Clear removed outbounds (#5876)

* fix: prune stale observatory status

* More readable

Refactor observer to clear removed outbounds instead of updating status. Introduced slices package for improved outbound checking.

---------

Co-authored-by: 风扇滑翔翼 <Fangliding.fshxy@outlook.com>

app/observatory/observer.go

@@ -5,6 +5,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"slices"
 	"sort"
 	"sync"
 	"time"
@@ -70,7 +71,7 @@ func (o *Observer) background() {
 
 		outbounds := hs.Select(o.config.SubjectSelector)
 
-		o.updateStatus(outbounds)
+		o.clearRemovedOutbounds(outbounds)
 
 		sleepTime := time.Second * 10
 		if o.config.ProbeInterval != 0 {
@@ -111,11 +112,19 @@ func (o *Observer) background() {
 	}
 }
 
-func (o *Observer) updateStatus(outbounds []string) {
+func (o *Observer) clearRemovedOutbounds(outbounds []string) {
 	o.statusLock.Lock()
 	defer o.statusLock.Unlock()
-	// TODO should remove old inbound that is removed
-	_ = outbounds
+	if len(o.status) == 0 {
+		return
+	}
+	var pruned []*OutboundStatus
+	for _, status := range o.status {
+		if slices.Contains(outbounds, status.OutboundTag) {
+			pruned = append(pruned, status)
+		}
+	}
+	o.status = pruned
 }
 
 func (o *Observer) probe(outbound string) ProbeResult {

app/observatory/observer_test.go

@@ -0,0 +1,64 @@
+package observatory
+
+import "testing"
+
+func TestObserverUpdateStatusPrunesStaleOutbounds(t *testing.T) {
+	observer := &Observer{
+		status: []*OutboundStatus{
+			{
+				OutboundTag:     "keep",
+				Alive:           true,
+				Delay:           42,
+				LastErrorReason: "",
+				LastSeenTime:    111,
+				LastTryTime:     222,
+			},
+			{
+				OutboundTag:     "drop",
+				Alive:           false,
+				Delay:           99999999,
+				LastErrorReason: "probe failed",
+				LastSeenTime:    333,
+				LastTryTime:     444,
+			},
+		},
+	}
+
+	observer.clearRemovedOutbounds([]string{"keep"})
+
+	if len(observer.status) != 1 {
+		t.Fatalf("expected 1 status after pruning, got %d", len(observer.status))
+	}
+
+	got := observer.status[0]
+	if got.OutboundTag != "keep" {
+		t.Fatalf("expected remaining status for keep, got %q", got.OutboundTag)
+	}
+	if !got.Alive {
+		t.Fatal("expected remaining status to preserve Alive field")
+	}
+	if got.Delay != 42 {
+		t.Fatalf("expected remaining status to preserve Delay, got %d", got.Delay)
+	}
+	if got.LastSeenTime != 111 {
+		t.Fatalf("expected remaining status to preserve LastSeenTime, got %d", got.LastSeenTime)
+	}
+	if got.LastTryTime != 222 {
+		t.Fatalf("expected remaining status to preserve LastTryTime, got %d", got.LastTryTime)
+	}
+}
+
+func TestObserverUpdateStatusClearsWhenNoOutboundsRemain(t *testing.T) {
+	observer := &Observer{
+		status: []*OutboundStatus{
+			{OutboundTag: "drop-1"},
+			{OutboundTag: "drop-2"},
+		},
+	}
+
+	observer.clearRemovedOutbounds(nil)
+
+	if len(observer.status) != 0 {
+		t.Fatalf("expected all statuses to be removed, got %d", len(observer.status))
+	}
+}