Handle SyncSession outliving the associated RealmCoordinator

realm · Aug 12, 2021 · a79de16 · a79de16
1 parent 01daf60
commit a79de16
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Showing 3 changed files with 29 additions and 5 deletions.
diff --git a/src/realm/object-store/impl/realm_coordinator.cpp b/src/realm/object-store/impl/realm_coordinator.cpp
@@ -95,6 +95,8 @@ void RealmCoordinator::create_sync_session()
         return;
 
     open_db();
+    if (m_sync_session)
+        return;
     m_sync_session = m_config.sync_config->user->sync_manager()->get_session(m_db, *m_config.sync_config);
 
     std::weak_ptr<RealmCoordinator> weak_self = shared_from_this();
@@ -418,6 +420,19 @@ void RealmCoordinator::open_db()
     if (m_db)
         return;
 
+    if (m_config.sync_config) {
+        // If we previously opened this Realm, we may have a lingering sync
+        // session which outlived its RealmCoordinator. If that happens we
+        // want to reuse it instead of creating a new DB.
+        auto existing_session = m_config.sync_config->user->sync_manager()->get_existing_session(m_config.path);
+        if (existing_session) {
+            m_sync_session = existing_session;
+            m_db = SyncSession::Internal::get_db(*existing_session);
+            m_sync_session->revive_if_needed();
+            return;
+        }
+    }
+
     bool server_synchronization_mode = m_config.sync_config || m_config.force_sync_history;
     try {
         if (m_config.immutable() && m_config.realm_data) {

diff --git a/src/realm/object-store/sync/sync_session.hpp b/src/realm/object-store/sync/sync_session.hpp
@@ -258,6 +258,11 @@ class SyncSession : public std::enable_shared_from_this<SyncSession> {
         {
             session.nonsync_transact_notify(version);
         }
+
+        static std::shared_ptr<DB> get_db(SyncSession& session)
+        {
+            return session.m_db;
+        }
     };
 
     // Expose some internal functionality to testing code.

diff --git a/test/object-store/sync/session/session.cpp b/test/object-store/sync/session/session.cpp
@@ -471,11 +471,15 @@ TEMPLATE_TEST_CASE("sync: stop policy behavior", "[sync]", RegularUser)
             });
         }
 
-        //        SECTION("transitions back to Active if the session is revived") {
-        //            auto session2 = sync_manager->get_session(config.path, *config.sync_config);
-        //            REQUIRE(session->state() == SyncSession::PublicState::Active);
-        //            REQUIRE(session2 == session);
-        //        }
+        SECTION("transitions back to Active if the session is revived") {
+            std::shared_ptr<SyncSession> session2;
+            {
+                auto realm = Realm::get_shared_realm(config);
+                session2 = user->sync_manager()->get_existing_session(config.path);
+            }
+            REQUIRE(session->state() == SyncSession::PublicState::Active);
+            REQUIRE(session2 == session);
+        }
 
         SECTION("transitions to Inactive if a fatal error occurs") {
             std::error_code code =