From 2a9aacbacbbadc05042597831bb0da1363425d4b Mon Sep 17 00:00:00 2001
From: Zibi Braniecki <zbraniecki@mozilla.com>
Date: Thu, 23 May 2019 19:01:35 +0000
Subject: [PATCH] Bug 1546432 - Add roots management to Mutations. r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D31337

--HG--
extra : moz-landing-system : lando
---
 intl/l10n/DocumentL10n.cpp | 44 +++++++++++++++++++++++++++++++++++---
 intl/l10n/DocumentL10n.h   | 14 ++++++++++++
 2 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/intl/l10n/DocumentL10n.cpp b/intl/l10n/DocumentL10n.cpp
index 0e1d1b417673..5fdb6415ca18 100644
--- a/intl/l10n/DocumentL10n.cpp
+++ b/intl/l10n/DocumentL10n.cpp
@@ -63,6 +63,7 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(DocumentL10n)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mDOMLocalization)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mContentSink)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mReady)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mRoots)
   NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(DocumentL10n)
@@ -71,6 +72,7 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(DocumentL10n)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mDOMLocalization)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mContentSink)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mReady)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mRoots)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(DocumentL10n)
 
@@ -102,8 +104,8 @@ DocumentL10n::~DocumentL10n() {
 
 void DocumentL10n::DisconnectMutations() {
   if (mMutations) {
-    mDocument->RemoveMutationObserver(mMutations);
     mMutations->Disconnect();
+    DisconnectRoots();
   }
 }
 
@@ -645,7 +647,7 @@ void DocumentL10n::TriggerInitialDocumentTranslation() {
 
   GetTranslatables(*elem, elements, rv);
 
-  mMutations->ConnectRoot(elem);
+  ConnectRoot(elem);
 
   RefPtr<Promise> promise = TranslateElements(elements, rv);
   if (!promise) {
@@ -676,7 +678,6 @@ void DocumentL10n::InitialDocumentTranslationCompleted() {
     mContentSink->InitialDocumentTranslationCompleted();
     mContentSink = nullptr;
   }
-  mDocument->AddMutationObserverUnlessExists(mMutations);
 }
 
 Promise* DocumentL10n::Ready() { return mReady; }
@@ -687,6 +688,43 @@ void DocumentL10n::OnChange() {
   }
 }
 
+void DocumentL10n::ConnectRoot(nsINode* aNode) {
+  nsCOMPtr<nsIGlobalObject> global = aNode->GetOwnerGlobal();
+  if (!global) {
+    return;
+  }
+
+#ifdef DEBUG
+  for (auto iter = mRoots.ConstIter(); !iter.Done(); iter.Next()) {
+    nsINode* root = iter.Get()->GetKey();
+
+    MOZ_ASSERT(
+        root != aNode && !root->Contains(aNode) && !aNode->Contains(root),
+        "Cannot add a root that overlaps with existing root.");
+  }
+#endif
+
+  mRoots.PutEntry(aNode);
+
+  aNode->AddMutationObserverUnlessExists(mMutations);
+}
+
+void DocumentL10n::DisconnectRoot(nsINode* aNode) {
+  if (mRoots.Contains(aNode)) {
+    aNode->RemoveMutationObserver(mMutations);
+    mRoots.RemoveEntry(aNode);
+  }
+}
+
+void DocumentL10n::DisconnectRoots() {
+  for (auto iter = mRoots.ConstIter(); !iter.Done(); iter.Next()) {
+    nsRefPtrHashKey<nsINode>* elem = iter.Get();
+
+    elem->GetKey()->RemoveMutationObserver(mMutations);
+  }
+  mRoots.Clear();
+}
+
 void DocumentL10n::SetRootInfo(Element* aElement) {
   nsAutoCString primaryLocale;
   LocaleService::GetInstance()->GetAppLocaleAsBCP47(primaryLocale);
diff --git a/intl/l10n/DocumentL10n.h b/intl/l10n/DocumentL10n.h
index 888818a45700..50b7e3ef914b 100644
--- a/intl/l10n/DocumentL10n.h
+++ b/intl/l10n/DocumentL10n.h
@@ -85,6 +85,7 @@ class DocumentL10n final : public nsIObserver,
   nsCOMPtr<mozIDOMLocalization> mDOMLocalization;
   nsCOMPtr<nsIContentSink> mContentSink;
   RefPtr<l10n::Mutations> mMutations;
+  nsTHashtable<nsRefPtrHashKey<nsINode>> mRoots;
 
   already_AddRefed<Promise> MaybeWrapPromise(Promise* aPromise);
   void RegisterObservers();
@@ -142,6 +143,18 @@ class DocumentL10n final : public nsIObserver,
 
   Promise* Ready();
 
+  /**
+   * Add node to nodes observed for localization
+   * related changes.
+   */
+  void ConnectRoot(nsINode* aNode);
+
+  /**
+   * Remove node from nodes observed for localization
+   * related changes.
+   */
+  void DisconnectRoot(nsINode* aNode);
+
   void TriggerInitialDocumentTranslation();
 
   void InitialDocumentTranslationCompleted();
@@ -150,6 +163,7 @@ class DocumentL10n final : public nsIObserver,
 
   void OnChange();
  protected:
+  void DisconnectRoots();
 };
 
 }  // namespace dom