Release retired document sources outside the cache lock

internal/atspi/adapter.go

@@ -489,11 +489,30 @@ func (adapter *Adapter) retainedDocumentRoot(id ObjectID) ObjectID {
 // calls this on the GLib thread once the capture root is known, before
 // preparing the incremental-refresh cache.
 func (adapter *Adapter) rotateDocumentSlots(root ObjectID) {
+	adapter.rotateDocumentSlotsAndRelease(root, releaseDocumentSources)
+}
+
+func releaseDocumentSources(document stashedDocument) {
+	for _, source := range document.sources {
+		C.g_object_unref(C.gpointer(source))
+	}
+}
+
+// libatspi disposal synchronously emits defunct events. Publish the new slots
+// and unlock before releasing references, so reentrant invalidation sees a
+// consistent cache and can acquire treeMutex.
+func (adapter *Adapter) rotateDocumentSlotsAndRelease(root ObjectID, release func(stashedDocument)) {
 	if !root.Valid() {
 		return
 	}
+	var retired []stashedDocument
 	adapter.treeMutex.Lock()
-	defer adapter.treeMutex.Unlock()
+	defer func() {
+		adapter.treeMutex.Unlock()
+		for _, document := range retired {
+			release(document)
+		}
+	}()
 	if root == adapter.documentSlotRoot {
 		return
 	}
@@ -509,14 +528,12 @@ func (adapter *Adapter) rotateDocumentSlots(root ObjectID) {
 	}
 	if adapter.documentSlotRoot.Valid() &&
 		(adapter.documentTree != nil || adapter.documentTextTree != nil) {
-		adapter.stashDocumentLocked(adapter.documentSlotRoot, stashedDocument{
+		retired = adapter.stashDocumentLocked(adapter.documentSlotRoot, stashedDocument{
 			tree: adapter.documentTree, textTree: adapter.documentTextTree,
 			sources: adapter.nativeDocument,
 		})
-	} else {
-		for _, source := range adapter.nativeDocument {
-			C.g_object_unref(C.gpointer(source))
-		}
+	} else if len(adapter.nativeDocument) != 0 {
+		retired = append(retired, stashedDocument{sources: adapter.nativeDocument})
 	}
 	adapter.documentTree = stashed.tree
 	adapter.documentTextTree = stashed.textTree
@@ -524,14 +541,13 @@ func (adapter *Adapter) rotateDocumentSlots(root ObjectID) {
 	adapter.documentSlotRoot = root
 }
 
-func (adapter *Adapter) stashDocumentLocked(root ObjectID, document stashedDocument) {
+func (adapter *Adapter) stashDocumentLocked(root ObjectID, document stashedDocument) []stashedDocument {
+	var retired []stashedDocument
 	if adapter.stashedDocuments == nil {
 		adapter.stashedDocuments = make(map[ObjectID]stashedDocument)
 	}
 	if old, ok := adapter.stashedDocuments[root]; ok {
-		for _, source := range old.sources {
-			C.g_object_unref(C.gpointer(source))
-		}
+		retired = append(retired, old)
 		for index, id := range adapter.stashedDocumentIDs {
 			if id == root {
 				adapter.stashedDocumentIDs = append(adapter.stashedDocumentIDs[:index], adapter.stashedDocumentIDs[index+1:]...)
@@ -543,12 +559,11 @@ func (adapter *Adapter) stashDocumentLocked(root ObjectID, document stashedDocum
 	adapter.stashedDocumentIDs = append(adapter.stashedDocumentIDs, root)
 	for len(adapter.stashedDocumentIDs) > maxStashedDocuments {
 		oldest := adapter.stashedDocumentIDs[0]
-		for _, source := range adapter.stashedDocuments[oldest].sources {
-			C.g_object_unref(C.gpointer(source))
-		}
+		retired = append(retired, adapter.stashedDocuments[oldest])
 		delete(adapter.stashedDocuments, oldest)
 		adapter.stashedDocumentIDs = adapter.stashedDocumentIDs[1:]
 	}
+	return retired
 }
 
 // clearStashedDocuments releases every stashed document's native sources.