Refactor link tracing code

CHANGELOG.md

@@ -15,12 +15,12 @@
 
 ### Fixed
 * <How do the end-user experience this issue? what was the impact?> ([#????](https://github.com/realm/realm-core/issues/????), since v?.?.?)
+* Prevent migrations to an embedded object type when there are incoming links from Mixed/TypedLink properties until we can support them. ([#5796](https://github.com/realm/realm-core/pull/5796))
 * Fixed undefined behaviour on queries involving a constant and an indexed column on some property types like UUID and Timestamp. ([#5753](https://github.com/realm/realm-core/issues/5753), since 12.5.0)
 * Fix all UBSan failures hit by tests. It is unclear if any of these manifested as visible bugs. ([PR #5665](https://github.com/realm/realm-core/pull/5665))
 * Fix sorting order for `realm_query_find_first` in the C API.([#5720](https://github.com/realm/realm-core/issues/5720))
 * Upload completion callbacks may have called before the download message that completed them was fully integrated. ([#4865](https://github.com/realm/realm-core/issues/4865)).
 
-
 ### Breaking changes
 * None.
 

Package.swift

@@ -75,6 +75,7 @@ let notSyncServerSources: [String] = [
  "realm/history.cpp",
  "realm/impl",
  "realm/index_string.cpp",
+ "realm/link_translator.cpp",
  "realm/list.cpp",
  "realm/mixed.cpp",
  "realm/node.cpp",

src/realm/CMakeLists.txt

@@ -41,6 +41,7 @@ set(REALM_SOURCES
  impl/simulated_failure.cpp
  impl/transact_log.cpp
  index_string.cpp
+ link_translator.cpp
  list.cpp
  node.cpp
  mixed.cpp

src/realm/link_translator.cpp

@@ -0,0 +1,94 @@
+/*************************************************************************
+ *
+ * Copyright 2022 Realm Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ **************************************************************************/
+
+#include "realm/link_translator.hpp"
+
+#include <realm/dictionary.hpp>
+#include <realm/list.hpp>
+#include <realm/set.hpp>
+
+namespace realm {
+
+LinkTranslator::LinkTranslator(Obj origin, ColKey origin_col_key)
+ : m_origin_obj(origin)
+ , m_origin_col_key(origin_col_key)
+{
+}
+
+void LinkTranslator::run()
+{
+ ColumnAttrMask attr = m_origin_col_key.get_attrs();
+ if (attr.test(col_attr_List)) {
+ if (m_origin_col_key.get_type() == col_type_LinkList) {
+ LnkLst link_list = m_origin_obj.get_linklist(m_origin_col_key);
+ on_list_of_links(link_list);
+ }
+ else if (m_origin_col_key.get_type() == col_type_Mixed) {
+ Lst<Mixed> list = m_origin_obj.get_list<Mixed>(m_origin_col_key);
+ on_list_of_mixed(list);
+ }
+ else if (m_origin_col_key.get_type() == col_type_TypedLink) {
+ Lst<ObjLink> list = m_origin_obj.get_list<ObjLink>(m_origin_col_key);
+ on_list_of_typedlink(list);
+ }
+ else {
+ throw std::runtime_error(
+ util::format("LinkTranslator unhandled list type: %1", m_origin_col_key.get_type()));
+ }
+ }
+ else if (attr.test(col_attr_Set)) {
+ if (m_origin_col_key.get_type() == col_type_Link) {
+ LnkSet set = m_origin_obj.get_linkset(m_origin_col_key);
+ on_set_of_links(set);
+ }
+ else if (m_origin_col_key.get_type() == col_type_Mixed) {
+ Set<Mixed> set = m_origin_obj.get_set<Mixed>(m_origin_col_key);
+ on_set_of_mixed(set);
+ }
+ else if (m_origin_col_key.get_type() == col_type_TypedLink) {
+ Set<ObjLink> set = m_origin_obj.get_set<ObjLink>(m_origin_col_key);
+ on_set_of_typedlink(set);
+ }
+ else {
+ throw std::runtime_error(
+ util::format("LinkTranslator unhandled set type: %1", m_origin_col_key.get_type()));
+ }
+ }
+ else if (attr.test(col_attr_Dictionary)) {
+ auto dict = m_origin_obj.get_dictionary(m_origin_col_key);
+ on_dictionary(dict);
+ }
+ else {
+ REALM_ASSERT_EX(!m_origin_col_key.is_collection(), m_origin_col_key);
+ if (m_origin_col_key.get_type() == col_type_Link) {
+ on_link_property(m_origin_col_key);
+ }
+ else if (m_origin_col_key.get_type() == col_type_Mixed) {
+ on_mixed_property(m_origin_col_key);
+ }
+ else if (m_origin_col_key.get_type() == col_type_TypedLink) {
+ on_typedlink_property(m_origin_col_key);
+ }
+ else {
+ throw std::runtime_error(
+ util::format("LinkTranslator unhandled property type: %1", m_origin_col_key.get_type()));
+ }
+ }
+}
+
+} // namespace realm

src/realm/link_translator.hpp

@@ -0,0 +1,47 @@
+/*************************************************************************
+ *
+ * Copyright 2022 Realm Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ **************************************************************************/
+
+#ifndef REALM_LINK_TRANSLATOR_HPP
+#define REALM_LINK_TRANSLATOR_HPP
+
+#include <realm/obj.hpp>
+
+namespace realm {
+
+struct LinkTranslator {
+ LinkTranslator(Obj origin, ColKey origin_col_key);
+ void run();
+ virtual void on_list_of_links(LnkLst list) = 0;
+ virtual void on_list_of_mixed(Lst<Mixed> list) = 0;
+ virtual void on_list_of_typedlink(Lst<ObjLink> list) = 0;
+ virtual void on_set_of_links(LnkSet set) = 0;
+ virtual void on_set_of_mixed(Set<Mixed> set) = 0;
+ virtual void on_set_of_typedlink(Set<ObjLink> set) = 0;
+ virtual void on_dictionary(Dictionary dict) = 0;
+ virtual void on_link_property(ColKey col) = 0;
+ virtual void on_mixed_property(ColKey col) = 0;
+ virtual void on_typedlink_property(ColKey col) = 0;
+
+protected:
+ Obj m_origin_obj;
+ ColKey m_origin_col_key;
+};
+
+} // namespace realm
+
+#endif // REALM_LINK_TRANSLATOR_HPP

src/realm/list.cpp

@@ -280,6 +280,8 @@ void Lst<ObjKey>::do_clear()
  target_obj.remove_one_backlink(backlink_col, m_obj.get_key()); // Throws
  size_t num_remaining = target_obj.get_backlink_count(*origin_table, m_col_key);
  if (num_remaining == 0) {
+ // embedded objects should only have one incoming link
+ REALM_ASSERT_EX(target_obj.get_backlink_count() == 0, target_obj.get_backlink_count());
  state.m_to_be_deleted.emplace_back(target_table_key, target_key);
  }
  }