realm · michael-wb · Apr 29, 2023 · Apr 27, 2023 · Apr 27, 2023 · Apr 28, 2023
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,7 +2,7 @@
 
 ### Enhancements
 * <New feature description> (PR [#????](https://github.com/realm/realm-core/pull/????))
-* None.
+* PBS to FLX Migration for migrating a client app that uses partition based sync to use flexible sync under the hood if the server has been migrated to flexible sync. ([#6554](https://github.com/realm/realm-core/issues/6554))
 
 ### Fixed
 * <How do the end-user experience this issue? what was the impact?> ([#????](https://github.com/realm/realm-core/issues/????), since v?.?.?)
@@ -17,7 +17,7 @@
 -----------
 
 ### Internals
-* None.
+* Bump the sync protocol version to v8 ([PR #6549](https://github.com/realm/realm-core/pull/6549))
 
 ----------------------------------------------
 

diff --git a/evergreen/config.yml b/evergreen/config.yml
@@ -115,10 +115,6 @@ functions:
           set_cmake_var realm_vars REALM_TEST_LOGGING BOOL On
           set_cmake_var realm_vars REALM_TEST_LOGGING_LEVEL STRING "debug"
 
-          if [ -n "${enable_sync_v8|}" ]; then
-              set_cmake_var realm_vars REALM_SYNC_PROTOCOL_V8 BOOL On
-          fi
-
           GENERATOR="${cmake_generator}"
           if [ -z "${cmake_generator|}" ]; then
               GENERATOR="Ninja Multi-Config"
@@ -634,7 +630,7 @@ tasks:
                 export DEVELOPER_DIR="${xcode_developer_dir}"
             fi
 
-            ./evergreen/install_baas.sh -w ./baas-work-dir -b cfda5c63e6910091853d3fb1085dcf45396279bb 2>&1 | tee install_baas_output.log
+            ./evergreen/install_baas.sh -w ./baas-work-dir -b 4da4c3b3e9083ea834522bdf67a2e129fd701d86 2>&1 | tee install_baas_output.log
         fi
 
   - command: shell.exec
@@ -923,25 +919,6 @@ buildvariants:
     - ubuntu2004-large
   - name: long-running-tests
 
-- name: ubuntu2004-asan-sync-v8
-  display_name: "Ubuntu 20.04 x86_64 SyncV8 (Clang 11 ASAN)"
-  run_on: ubuntu2004-small
-  expansions:
-    clang_url: "https://s3.amazonaws.com/static.realm.io/evergreen-assets/clang%2Bllvm-11.0.0-x86_64-linux-gnu-ubuntu-20.04.tar.xz"
-    cmake_url: "https://s3.amazonaws.com/static.realm.io/evergreen-assets/cmake-3.20.3-linux-x86_64.tar.gz"
-    cmake_bindir: "./cmake_binaries/bin"
-    fetch_missing_dependencies: On
-    run_tests_against_baas: On
-    enable_asan: On
-    enable_sync_v8: On
-    c_compiler: "./clang_binaries/bin/clang"
-    cxx_compiler: "./clang_binaries/bin/clang++"
-    llvm_symbolizer: "./clang_binaries/bin/llvm-symbolizer"
-  tasks:
-  - name: object-store-tests-v8
-    distros:
-    - ubuntu2004-large
-
 - name: ubuntu2004-tsan
   display_name: "Ubuntu 20.04 x86_64 (Clang 11 TSAN)"
   run_on: ubuntu2004-small

diff --git a/src/realm/sync/noinst/protocol_codec.cpp b/src/realm/sync/noinst/protocol_codec.cpp
@@ -26,9 +26,10 @@ void ClientProtocol::make_flx_bind_message(int protocol_version, OutputBuffer& o
                                            const nlohmann::json& json_data, const std::string& signed_user_token,
                                            bool need_client_file_ident, bool is_subserver)
 {
+    static_cast<void>(protocol_version);
     std::string json_data_stg;
     // Protocol version v8 and above accepts stringified json_data for the first data argument
-    if (protocol_version >= 8 && !json_data.empty()) {
+    if (!json_data.empty()) {
         json_data_stg = json_data.dump();
     }
 

diff --git a/src/realm/sync/protocol.hpp b/src/realm/sync/protocol.hpp
@@ -44,29 +44,19 @@ namespace sync {
 //
 constexpr int get_current_protocol_version() noexcept
 {
-#ifdef REALM_SYNC_PROTOCOL_V8
+    // Also update the current protocol version test in flx_sync.cpp when
+    // updating this value
     return 8;
-#else
-    return 7;
-#endif // REALM_SYNC_PROTOCOL_V8
 }
 
 constexpr std::string_view get_pbs_websocket_protocol_prefix() noexcept
 {
-#ifdef REALM_SYNC_PROTOCOL_V8
     return "com.mongodb.realm-sync#";
-#else
-    return "com.mongodb.realm-sync/";
-#endif // REALM_SYNC_PROTOCOL_V8
 }
 
 constexpr std::string_view get_flx_websocket_protocol_prefix() noexcept
 {
-#ifdef REALM_SYNC_PROTOCOL_V8
     return "com.mongodb.realm-query-sync#";
-#else
-    return "com.mongodb.realm-query-sync/";
-#endif // REALM_SYNC_PROTOCOL_V8
 }
 
 enum class SyncServerMode { PBS, FLX };

diff --git a/test/object-store/CMakeLists.txt b/test/object-store/CMakeLists.txt
@@ -94,7 +94,6 @@ add_bundled_test(ObjectStoreTests)
 if(REALM_ENABLE_SYNC)
     target_link_libraries(ObjectStoreTests SyncServer)
     option(REALM_ENABLE_AUTH_TESTS "" OFF)
-    option(REALM_SYNC_PROTOCOL_V8 "" OFF)
     if(REALM_ENABLE_AUTH_TESTS)
         if(NOT REALM_MONGODB_ENDPOINT)
             message(FATAL_ERROR "REALM_MONGODB_ENDPOINT must be set when specifying REALM_ENABLE_AUTH_TESTS.")
@@ -108,9 +107,6 @@ if(REALM_ENABLE_SYNC)
         find_package(CURL REQUIRED)
         target_link_libraries(ObjectStoreTests CURL::libcurl)
     endif()
-    if(REALM_SYNC_PROTOCOL_V8)
-        target_compile_definitions(ObjectStoreTests PRIVATE REALM_SYNC_PROTOCOL_V8=1)
-    endif()
 endif()
 
 if(REALM_TEST_LOGGING)

diff --git a/test/object-store/sync/flx_migration.cpp b/test/object-store/sync/flx_migration.cpp
@@ -13,7 +13,6 @@
 #include <catch2/catch_all.hpp>
 #include <chrono>
 
-
 #if REALM_ENABLE_SYNC
 #if REALM_ENABLE_AUTH_TESTS
 
@@ -40,7 +39,7 @@ static void trigger_server_migration(const AppSession& app_session, MigrationMod
         else
             return "FLX->PBS Server rollback";
     }();
-    const int duration = 300; // 5 minutes, for now, since it sometimes takes longet than 90 seconds
+    const int duration = 480; // 8 minutes, for now, since it sometimes takes longer than 300 seconds
     try {
         timed_sleeping_wait_for(
             [&] {
@@ -240,8 +239,6 @@ TEST_CASE("Test server migration and rollback", "[flx][migration]") {
     }
 }
 
-#ifdef REALM_SYNC_PROTOCOL_V8
-
 TEST_CASE("Test client migration and rollback", "[flx][migration]") {
     std::shared_ptr<util::Logger> logger_ptr =
         std::make_shared<util::StderrLogger>(realm::util::Logger::Level::TEST_LOGGING_LEVEL);
@@ -319,32 +316,32 @@ TEST_CASE("Test client migration and rollback with recovery", "[flx][migration]"
     // Primary key of the object to recover
     auto obj_id = ObjectId::gen();
 
+    // Keep this realm around for after the revert to PBS
+    auto outer_realm = Realm::get_shared_realm(config);
+    REQUIRE(!wait_for_upload(*outer_realm));
+    REQUIRE(!wait_for_download(*outer_realm));
+
     // Wait to upload the data
     {
-        auto realm = Realm::get_shared_realm(config);
-
-        REQUIRE(!wait_for_upload(*realm));
-        REQUIRE(!wait_for_download(*realm));
-
-        auto table = realm->read_group().get_table("class_Object");
+        auto table = outer_realm->read_group().get_table("class_Object");
         REQUIRE(table->size() == 5);
 
-        // Close the sync session and make a change. This will be recovered by the migration.
-        realm->sync_session()->force_close();
-        realm->begin_transaction();
-        realm->read_group()
+        // Pause the sync session and make a change.
+        // This will be recovered when it is resumed after the migration.
+        outer_realm->sync_session()->pause();
+        outer_realm->begin_transaction();
+        outer_realm->read_group()
             .get_table("class_Object")
             ->create_object_with_primary_key(obj_id)
             .set("string_field", "partition-set-during-sync-upload");
-        realm->commit_transaction();
+        outer_realm->commit_transaction();
     }
 
     // Migrate to FLX
     trigger_server_migration(session.app_session(), MigrateToFLX, logger_ptr);
 
-    // Keep this realm around for after the revert to PBS
-    auto outer_realm = Realm::get_shared_realm(config);
-
+    // Resume the session and verify the additional object was uploaded after the migration
+    outer_realm->sync_session()->resume();
     REQUIRE(!wait_for_upload(*outer_realm));
     REQUIRE(!wait_for_download(*outer_realm));
 
@@ -363,11 +360,11 @@ TEST_CASE("Test client migration and rollback with recovery", "[flx][migration]"
         auto object_table = outer_realm->read_group().get_table("class_Object");
         auto pending_object = object_table->get_object_with_primary_key(obj_id);
         REQUIRE(pending_object.get<String>("string_field") == "partition-set-during-sync-upload");
-
-        // Close the session and create a dummy subscription with a notification to verify it has been cancelled
-        outer_realm->sync_session()->pause();
     }
 
+    // Pause the sync session so a pending subscription and object can be created
+    // before processing the rollback
+    outer_realm->sync_session()->pause();
     util::Future<sync::SubscriptionSet::State> new_subs_future = [&] {
         auto sub_store = outer_realm->sync_session()->get_flx_subscription_store();
         auto mut_subs = sub_store->get_active().make_mutable_copy();
@@ -379,13 +376,6 @@ TEST_CASE("Test client migration and rollback with recovery", "[flx][migration]"
         return new_subs.get_state_change_notification(sync::SubscriptionSet::State::Complete);
     }();
 
-    // Wait for the object to be written to Atlas/MongoDB before rollback, otherwise it may be lost
-    reset_utils::wait_for_object_to_persist_to_atlas(session.app()->current_user(), session.app_session(), "Object",
-                                                     {{"_id", obj_id}});
-
-    //  Roll back to PBS
-    trigger_server_migration(session.app_session(), RollbackToPBS, logger_ptr);
-
     // Add a local object while the session is paused. This will be recovered when connecting after the rollback.
     {
         outer_realm->begin_transaction();
@@ -396,6 +386,13 @@ TEST_CASE("Test client migration and rollback with recovery", "[flx][migration]"
         outer_realm->commit_transaction();
     }
 
+    // Wait for the object to be written to Atlas/MongoDB before rollback, otherwise it may be lost
+    reset_utils::wait_for_object_to_persist_to_atlas(session.app()->current_user(), session.app_session(), "Object",
+                                                     {{"_id", obj_id}});
+
+    //  Roll back to PBS
+    trigger_server_migration(session.app_session(), RollbackToPBS, logger_ptr);
+
     // Connect after rolling back to PBS
     outer_realm->sync_session()->resume();
     REQUIRE(!wait_for_upload(*outer_realm));
@@ -419,21 +416,17 @@ TEST_CASE("Test client migration and rollback with recovery", "[flx][migration]"
         REALM_ASSERT(result.get_value() == sync::SubscriptionSet::State::Superseded);
     }
 
-    outer_realm.reset();
-
-    //  Migrate back to FLX
+    //  Migrate back to FLX - and keep the realm session open
     trigger_server_migration(session.app_session(), MigrateToFLX, logger_ptr);
 
+    REQUIRE(!wait_for_upload(*outer_realm));
+    REQUIRE(!wait_for_download(*outer_realm));
+
     // Verify data has been sync'ed and there is only 1 subscription for the Object table
     {
-        auto realm = Realm::get_shared_realm(config);
-
-        REQUIRE(!wait_for_upload(*realm));
-        REQUIRE(!wait_for_download(*realm));
-
-        auto table = realm->read_group().get_table("class_Object");
+        auto table = outer_realm->read_group().get_table("class_Object");
         REQUIRE(table->size() == 7);
-        auto sync_session = realm->sync_session();
+        auto sync_session = outer_realm->sync_session();
         REQUIRE(sync_session);
         auto sub_store = sync_session->get_flx_subscription_store();
         REQUIRE(sub_store);
@@ -442,16 +435,14 @@ TEST_CASE("Test client migration and rollback with recovery", "[flx][migration]"
         REQUIRE(active_subs.find("flx_migrated_Object"));
     }
 
-    // Roll back to PBS once again
+    // Roll back to PBS once again - and keep the realm session open
     trigger_server_migration(session.app_session(), RollbackToPBS, logger_ptr);
 
-    {
-        auto realm = Realm::get_shared_realm(config);
-
-        REQUIRE(!wait_for_upload(*realm));
-        REQUIRE(!wait_for_download(*realm));
+    REQUIRE(!wait_for_upload(*outer_realm));
+    REQUIRE(!wait_for_download(*outer_realm));
 
-        auto table = realm->read_group().get_table("class_Object");
+    {
+        auto table = outer_realm->read_group().get_table("class_Object");
         REQUIRE(table->size() == 7);
     }
 }
@@ -786,13 +777,5 @@ TEST_CASE("New table is synced after migration", "[flx][migration]") {
     }
 }
 
-TEST_CASE("Validate protocol v8 features", "[flx][migration]") {
-    REQUIRE(sync::get_current_protocol_version() >= 8);
-    REQUIRE("com.mongodb.realm-sync#" == sync::get_pbs_websocket_protocol_prefix());
-    REQUIRE("com.mongodb.realm-query-sync#" == sync::get_flx_websocket_protocol_prefix());
-}
-
-#endif // REALM_SYNC_PROTOCOL_V8
-
 #endif // REALM_ENABLE_AUTH_TESTS
 #endif // REALM_ENABLE_SYNC
diff --git a/test/object-store/sync/flx_sync.cpp b/test/object-store/sync/flx_sync.cpp
@@ -1588,6 +1588,15 @@ TEST_CASE("flx: writes work without waiting for sync", "[sync][flx][app]") {
     });
 }
 
+TEST_CASE("flx: verify PBS/FLX websocket protocol number and prefixes", "[sync][flx]") {
+    // Update the expected value whenever the protocol version is updated - this ensures
+    // that the current protocol version does not change unexpectedly.
+    REQUIRE(8 == sync::get_current_protocol_version());
+    // This was updated in Protocol V8 to use '#' instead of '/' to support the Web SDK
+    REQUIRE("com.mongodb.realm-sync#" == sync::get_pbs_websocket_protocol_prefix());
+    REQUIRE("com.mongodb.realm-query-sync#" == sync::get_flx_websocket_protocol_prefix());
+}
+
 TEST_CASE("flx: subscriptions persist after closing/reopening", "[sync][flx][app]") {
     FLXSyncTestHarness harness("flx_bad_query");
     SyncTestFile config(harness.app()->current_user(), harness.schema(), SyncConfig::FLXSyncEnabled{});

diff --git a/test/test_sync_protocol_codec.cpp b/test/test_sync_protocol_codec.cpp
@@ -61,11 +61,6 @@ TEST(Protocol_Codec_Bind_FLX)
     json_data["valA"] = 123;
     json_data["valB"] = "something";
 
-    out.reset();
-    expected_out_string = "bind 234888 0 6 0 1\ntoken1";
-    protocol.make_flx_bind_message(7, out, 234888, json_data, "token1", false, true);
-    compare_out_string(expected_out_string, out, test_context);
-
     out.reset();
     expected_out_string = "bind 345888 0 6 1 0\ntoken2";
     protocol.make_flx_bind_message(8, out, 345888, {}, "token2", true, false);