From 2b8ba962b80a98c62413c59a189fadacb1985176 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B8rgen=20Edelbo?= <jorgen.edelbo@mongodb.com>
Date: Thu, 19 Oct 2023 13:29:42 +0200
Subject: [PATCH] Optimize further by dropping ttl on ephemeral objects

---
 src/realm/db.cpp    | 10 +++-------
 src/realm/group.hpp | 14 +-------------
 src/realm/table.cpp | 12 +++++-------
 3 files changed, 9 insertions(+), 27 deletions(-)

diff --git a/src/realm/db.cpp b/src/realm/db.cpp
index 77b35f8f498..cfc53ec54ae 100644
--- a/src/realm/db.cpp
+++ b/src/realm/db.cpp
@@ -2412,15 +2412,11 @@ Replication::version_type DB::do_commit(Transaction& transaction, bool commit_to
     version_type new_version = current_version + 1;
 
     if (!transaction.m_objects_to_delete.empty()) {
-        std::map<TableKey, std::vector<ObjKey>> table_object_map;
-        for (auto it : transaction.m_objects_to_delete) {
-            // Checking ttl would go here
-            table_object_map[it.table_key].push_back(it.obj_key);
+        for (auto& [table_key, obj_keys] : transaction.m_objects_to_delete) {
+            sort(obj_keys.begin(), obj_keys.end());
+            transaction.get_table_unchecked(table_key)->batch_erase_objects(obj_keys);
         }
         transaction.m_objects_to_delete.clear();
-        for (auto& item : table_object_map) {
-            transaction.get_table_unchecked(item.first)->batch_erase_objects(item.second);
-        }
     }
     if (Replication* repl = get_replication()) {
         // If Replication::prepare_commit() fails, then the entire transaction
diff --git a/src/realm/group.hpp b/src/realm/group.hpp
index 0501742aed6..3b7e1ed8b7e 100644
--- a/src/realm/group.hpp
+++ b/src/realm/group.hpp
@@ -538,18 +538,6 @@ class Group : public ArrayParent {
 private:
     static constexpr StringData g_class_name_prefix = "class_";
 
-    struct ToDeleteRef {
-        ToDeleteRef(TableKey tk, ObjKey k)
-            : table_key(tk)
-            , obj_key(k)
-            , ttl(std::chrono::steady_clock::now())
-        {
-        }
-        TableKey table_key;
-        ObjKey obj_key;
-        std::chrono::steady_clock::time_point ttl;
-    };
-
     // nullptr, if we're sharing an allocator provided during initialization
     std::unique_ptr<SlabAlloc> m_local_alloc;
     // in-use allocator. If local, then equal to m_local_alloc.
@@ -614,7 +602,7 @@ class Group : public ArrayParent {
 
     util::UniqueFunction<void(const CascadeNotification&)> m_notify_handler;
     util::UniqueFunction<void()> m_schema_change_handler;
-    std::vector<ToDeleteRef> m_objects_to_delete;
+    std::map<TableKey, std::vector<ObjKey>> m_objects_to_delete;
 
     Group(SlabAlloc* alloc) noexcept;
     void init_array_parents() noexcept;
diff --git a/src/realm/table.cpp b/src/realm/table.cpp
index 0f1fbed31ae..73afcec9230 100644
--- a/src/realm/table.cpp
+++ b/src/realm/table.cpp
@@ -3056,7 +3056,7 @@ Obj Table::create_object_with_primary_key(const Mixed& primary_key, FieldValues&
         }
     }
     if (is_asymmetric() && repl && repl->get_history_type() == Replication::HistoryType::hist_SyncClient) {
-        get_parent_group()->m_objects_to_delete.emplace_back(this->m_key, ret.get_key());
+        get_parent_group()->m_objects_to_delete[this->m_key].emplace_back(ret.get_key());
     }
     return ret;
 }
@@ -3391,12 +3391,10 @@ void Table::remove_object(ObjKey key)
 
     if (is_asymmetric()) {
         REALM_ASSERT(g);
-        auto it = std::find_if(g->m_objects_to_delete.begin(), g->m_objects_to_delete.end(),
-                               [&](const Group::ToDeleteRef& item) {
-                                   return item.table_key == m_key && item.obj_key == key;
-                               });
-        if (it != g->m_objects_to_delete.end()) {
-            g->m_objects_to_delete.erase(it);
+        auto& obj_keys = g->m_objects_to_delete[m_key];
+        auto it = std::find(obj_keys.begin(), obj_keys.end(), key);
+        if (it != obj_keys.end()) {
+            obj_keys.erase(it);
         }
     }