Fix nil segment caused panic in handleSignal (#13990)

Signed-off-by: NCongqi Xia <congqi.xia@zilliz.com>

internal/datacoord/compaction_trigger.go

@@ -269,6 +269,10 @@ func (t *compactionTrigger) handleSignal(signal *compactionSignal) {
 	}
 
 	segment := t.meta.GetSegment(signal.segmentID)
+	if segment == nil {
+		log.Warn("segment in compaction signal not found in meta", zap.Int64("segmentID", signal.segmentID))
+		return
+	}
 	singleCompactionPlan, err := t.singleCompaction(segment, signal.isForce, signal)
 	if err != nil {
 		log.Warn("failed to do single compaction", zap.Int64("segmentID", segment.ID), zap.Error(err))

internal/datacoord/compaction_trigger_test.go

@@ -1103,3 +1103,14 @@ func Test_newCompactionTrigger(t *testing.T) {
 		})
 	}
 }
+
+func Test_handleSignal(t *testing.T) {
+
+	got := newCompactionTrigger(&meta{segments: NewSegmentsInfo()}, &compactionPlanHandler{}, newMockAllocator())
+	signal := &compactionSignal{
+		segmentID: 1,
+	}
+	assert.NotPanics(t, func() {
+		got.handleSignal(signal)
+	})
+}