From 260eee8bff62ddf05b62455188039b801bb153c0 Mon Sep 17 00:00:00 2001
From: levlam <levlam@telegram.org>
Date: Mon, 10 May 2021 01:59:35 +0300
Subject: [PATCH] Avoid upgrade of read transaction to a write transaction.

---
 td/telegram/MessagesManager.cpp | 14 ++++++++------
 td/telegram/StickersManager.cpp |  5 +++--
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/td/telegram/MessagesManager.cpp b/td/telegram/MessagesManager.cpp
index 5c3cdb9ba..750f33ba9 100644
--- a/td/telegram/MessagesManager.cpp
+++ b/td/telegram/MessagesManager.cpp
@@ -27108,8 +27108,9 @@ MessagesManager::MessageNotificationGroup MessagesManager::get_message_notificat
     d = get_dialog(it->second);
     CHECK(d != nullptr);
   } else if (G()->parameters().use_message_db) {
-    G()->td_db()->get_dialog_db_sync()->begin_transaction().ensure();
-    auto r_value = G()->td_db()->get_dialog_db_sync()->get_notification_group(group_id);
+    auto *dialog_db = G()->td_db()->get_dialog_db_sync();
+    dialog_db->begin_transaction().ensure();  // read transaction
+    auto r_value = dialog_db->get_notification_group(group_id);
     if (r_value.is_ok()) {
       VLOG(notifications) << "Loaded " << r_value.ok() << " from database by " << group_id;
       d = get_dialog_force(r_value.ok().dialog_id, "get_message_notification_group_force");
@@ -27117,7 +27118,7 @@ MessagesManager::MessageNotificationGroup MessagesManager::get_message_notificat
       CHECK(r_value.error().message() == "Not found");
       VLOG(notifications) << "Failed to load " << group_id << " from database";
     }
-    G()->td_db()->get_dialog_db_sync()->commit_transaction().ensure();
+    dialog_db->commit_transaction().ensure();
   }
 
   if (d == nullptr) {
@@ -27403,9 +27404,10 @@ vector<NotificationGroupKey> MessagesManager::get_message_notification_group_key
   VLOG(notifications) << "Trying to load " << limit << " message notification groups from database from "
                       << from_group_key;
 
-  G()->td_db()->get_dialog_db_sync()->begin_transaction().ensure();
+  auto *dialog_db = G()->td_db()->get_dialog_db_sync();
+  dialog_db->begin_transaction().ensure();  // read transaction
   Result<vector<NotificationGroupKey>> r_notification_group_keys =
-      G()->td_db()->get_dialog_db_sync()->get_notification_groups_by_last_notification_date(from_group_key, limit);
+      dialog_db->get_notification_groups_by_last_notification_date(from_group_key, limit);
   r_notification_group_keys.ensure();
   auto group_keys = r_notification_group_keys.move_as_ok();
 
@@ -27424,7 +27426,7 @@ vector<NotificationGroupKey> MessagesManager::get_message_notification_group_key
     VLOG(notifications) << "Loaded " << group_key << " from database";
     result.push_back(group_key);
   }
-  G()->td_db()->get_dialog_db_sync()->commit_transaction().ensure();
+  dialog_db->commit_transaction().ensure();
   return result;
 }
 
diff --git a/td/telegram/StickersManager.cpp b/td/telegram/StickersManager.cpp
index 05151d843..122323af3 100644
--- a/td/telegram/StickersManager.cpp
+++ b/td/telegram/StickersManager.cpp
@@ -6415,6 +6415,9 @@ void StickersManager::on_get_emoji_keywords_difference(
   version = keywords->version_;
   auto *pmc = G()->td_db()->get_sqlite_sync_pmc();
   pmc->begin_transaction().ensure();
+  // set must be the first operation to start a write transaction
+  pmc->set(get_emoji_language_code_version_database_key(language_code), to_string(version));
+  pmc->set(get_emoji_language_code_last_difference_time_database_key(language_code), to_string(G()->unix_time()));
   for (auto &keyword_ptr : keywords->keywords_) {
     switch (keyword_ptr->get_id()) {
       case telegram_api::emojiKeyword::ID: {
@@ -6467,8 +6470,6 @@ void StickersManager::on_get_emoji_keywords_difference(
         UNREACHABLE();
     }
   }
-  pmc->set(get_emoji_language_code_version_database_key(language_code), to_string(version));
-  pmc->set(get_emoji_language_code_last_difference_time_database_key(language_code), to_string(G()->unix_time()));
   pmc->commit_transaction().ensure();
   emoji_language_code_versions_[language_code] = version;
   emoji_language_code_last_difference_times_[language_code] = static_cast<int32>(Time::now_cached());