Release retired document sources outside the cache lock

internal/atspi/adapter_tree_test.go

@@ -683,3 +683,67 @@ func TestCaptureFailsFastWhileProviderHung(t *testing.T) {
 		t.Fatalf("hung placement error = %v, want ErrProviderHung", err)
 	}
 }
+
+func TestDocumentSlotReleaseAllowsReentrantInvalidation(t *testing.T) {
+	for _, orphaned := range []bool{false, true} {
+		t.Run(fmt.Sprintf("orphaned=%v", orphaned), func(t *testing.T) {
+			adapter := New()
+			oldRoot := testID("/old")
+			newRoot := testID("/new")
+			oldTree, err := NewAccessibleTree(oldRoot, []TreeNode{{Snapshot: Snapshot{BusName: oldRoot.BusName, Path: oldRoot.Path}}})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if orphaned {
+				adapter.nativeDocument = documentSourceKeys(adapter.nativeDocument, oldRoot)
+			} else {
+				adapter.documentSlotRoot = testID("/active")
+				adapter.documentTree = oldTree
+				adapter.stashedDocumentIDs = []ObjectID{oldRoot, testID("/second"), testID("/third")}
+				adapter.stashedDocuments = map[ObjectID]stashedDocument{oldRoot: {tree: oldTree}}
+			}
+			releases := 0
+			adapter.rotateDocumentSlotsAndRelease(newRoot, func(retired stashedDocument) {
+				releases++
+				if !adapter.treeMutex.TryLock() {
+					t.Fatal("native disposal would deadlock reentrant defunct invalidation")
+				}
+				adapter.treeMutex.Unlock()
+				if adapter.documentSlotRoot != newRoot || adapter.documentTree != nil {
+					t.Fatal("disposal observed partially rotated slots")
+				}
+				if _, retained := adapter.stashedDocuments[oldRoot]; retained {
+					t.Fatal("disposed document still retained")
+				}
+				adapter.invalidateTreeEvent(DefunctStateEvent, 1, oldRoot, ObjectID{})
+			})
+			if releases != 1 {
+				t.Fatalf("released %d documents, want 1", releases)
+			}
+		})
+	}
+}
+
+func BenchmarkDocumentSlotEviction(b *testing.B) {
+	adapter := New()
+	roots := make([]ObjectID, maxStashedDocuments+2)
+	trees := make([]*AccessibleTree, len(roots))
+	for i := range roots {
+		roots[i] = testID(fmt.Sprintf("/doc%d", i))
+		var err error
+		trees[i], err = NewAccessibleTree(roots[i], []TreeNode{{Snapshot: Snapshot{BusName: roots[i].BusName, Path: roots[i].Path}}})
+		if err != nil {
+			b.Fatal(err)
+		}
+	}
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		index := i % len(roots)
+		adapter.rotateDocumentSlots(roots[index])
+		if adapter.documentTree != nil {
+			b.Fatal("expected evicted document to need recapture")
+		}
+		adapter.documentTree = trees[index]
+	}
+}