WIP migrate table encoding

test/mnesia_rocksdb_migration_SUITE.erl

@@ -16,6 +16,9 @@
          manual_migration/1
        , migrate_with_encoding_change/1
        , auto_migration/1
+       , online_encoding_migration/1
+       , online_encoding_migration_restart/1
+       , online_encoding_migration_interrupt/1
         ]).
 
 -include_lib("common_test/include/ct.hrl").
@@ -31,7 +34,10 @@ all() ->
 groups() ->
     [
      {all_tests, [sequence], [ manual_migration
-                             , migrate_with_encoding_change ]}
+                             , migrate_with_encoding_change
+                             , online_encoding_migration
+                             , online_encoding_migration_restart
+                             , online_encoding_migration_interrupt ]}
     ].
 
 init_per_suite(Config) ->
@@ -125,6 +131,113 @@ migrate_with_encoding_change(_Config) ->
 auto_migration(_Config) ->
     ok.
 
+%% Online encoding migration: term keys -> sext keys while dual-writing.
+online_encoding_migration(_Config) ->
+    ok = create_tab(enc, [{attributes, [k, v]}]),
+    %% Default set encoding is {term, {value, term}} for 2-attr tables.
+    lists:foreach(
+      fun(I) ->
+              mrdb:insert(enc, {enc, I, I * 10})
+      end, lists:seq(1, 50)),
+    50 = length(mrdb:select(enc, [{'_', [], ['$_']}])),
+    Ref0 = mrdb:get_ref(enc),
+    ct:log("Before migration ref: ~p", [maps:with([encoding, type, semantics], Ref0)]),
+    {term, _} = maps:get(encoding, Ref0),
+    %% Concurrent writes during migration
+    ok = mnesia_rocksdb_admin:migrate_encoding(
+           rdb, enc, {sext, {value, term}}),
+    %% Dual-write should be active
+    #{migration := _} = mrdb:get_ref(enc),
+    mrdb:insert(enc, {enc, 100, 1000}),
+    mrdb:delete(enc, 5),
+    %% Wait for copy_done
+    ok = wait_copy_done(enc, 50),
+    ct:log("Status after copy: ~p", [mnesia_rocksdb_admin:migration_status(enc)]),
+    ok = mnesia_rocksdb_admin:finalize_migration(rdb, enc),
+    Ref1 = mrdb:get_ref(enc),
+    ct:log("After finalize ref: ~p", [maps:with([encoding, type], Ref1)]),
+    {sext, _} = maps:get(encoding, Ref1),
+    false = maps:is_key(migration, Ref1),
+    Objs = lists:sort(mrdb:select(enc, [{'_', [], ['$_']}])),
+    %% 50 - 1 deleted + 1 inserted = 50
+    50 = length(Objs),
+    false = lists:keymember(5, 2, Objs),
+    true = lists:keymember(100, 2, Objs),
+    {enc, 100, 1000} = lists:keyfind(100, 2, Objs),
+    %% sext-encoded key is readable via rdb_get
+    {ok, _} = mrdb:rdb_get(Ref1, sext:encode(100), []),
+    ok.
+
+wait_copy_done(_Tab, 0) ->
+    {error, timeout};
+wait_copy_done(Tab, N) ->
+    case mnesia_rocksdb_admin:migration_status(Tab) of
+        #{phase := copy_done} ->
+            ok;
+        _ ->
+            timer:sleep(50),
+            wait_copy_done(Tab, N - 1)
+    end.
+
+%% Complete migration, restart mnesia, verify encoding + data survive.
+online_encoding_migration_restart(_Config) ->
+    ok = create_tab(enc_r, [{attributes, [k, v]}]),
+    [mrdb:insert(enc_r, {enc_r, I, I * 3}) || I <- lists:seq(1, 30)],
+    ok = mnesia_rocksdb_admin:migrate_encoding(
+           rdb, enc_r, {sext, {value, term}}),
+    ok = wait_copy_done(enc_r, 100),
+    ok = mnesia_rocksdb_admin:finalize_migration(rdb, enc_r),
+    {sext, _} = maps:get(encoding, mrdb:get_ref(enc_r)),
+    Before = lists:sort(mrdb:select(enc_r, [{'_', [], ['$_']}])),
+    30 = length(Before),
+    %% Close and reopen DB (same VM: stop/start mnesia + wait for tables).
+    stopped = mnesia:stop(),
+    ok = mnesia:start(),
+    ok = mnesia:wait_for_tables([enc_r], 10000),
+    Ref = mrdb:get_ref(enc_r),
+    ct:log("After restart ref: ~p",
+           [maps:with([encoding, cf_gen, type], Ref)]),
+    {sext, _} = maps:get(encoding, Ref),
+    false = maps:is_key(migration, Ref),
+    After = lists:sort(mrdb:select(enc_r, [{'_', [], ['$_']}])),
+    Before = After,
+    {ok, _} = mrdb:rdb_get(Ref, sext:encode(1), []),
+    ok.
+
+%% Stop mid-migration (after dual-write is up), reopen, finish copy + finalize.
+online_encoding_migration_interrupt(_Config) ->
+    ok = create_tab(enc_i, [{attributes, [k, v]}]),
+    [mrdb:insert(enc_i, {enc_i, I, I}) || I <- lists:seq(1, 100)],
+    ok = mnesia_rocksdb_admin:migrate_encoding(
+           rdb, enc_i, {sext, {value, term}}),
+    %% Dual-write active; do not wait for copy_done — interrupt promptly.
+    #{migration := _} = mrdb:get_ref(enc_i),
+    mrdb:insert(enc_i, {enc_i, 200, 200}),
+    mrdb:delete(enc_i, 10),
+    stopped = mnesia:stop(),
+    ok = mnesia:start(),
+    ok = mnesia:wait_for_tables([enc_i], 10000),
+    %% Migration should be re-armed (dual-write) or already copy_done.
+    case mnesia_rocksdb_admin:migration_status(enc_i) of
+        #{phase := Phase} when Phase =:= copying; Phase =:= copy_done ->
+            ok;
+        Other ->
+            ct:fail({expected_migration_after_restart, Other})
+    end,
+    %% Writes during resumed dual-write
+    mrdb:insert(enc_i, {enc_i, 201, 201}),
+    ok = wait_copy_done(enc_i, 200),
+    ok = mnesia_rocksdb_admin:finalize_migration(rdb, enc_i),
+    {sext, _} = maps:get(encoding, mrdb:get_ref(enc_i)),
+    false = maps:is_key(migration, mrdb:get_ref(enc_i)),
+    Objs = lists:sort(mrdb:select(enc_i, [{'_', [], ['$_']}])),
+    false = lists:keymember(10, 2, Objs),
+    true = lists:keymember(200, 2, Objs),
+    true = lists:keymember(201, 2, Objs),
+    %% 100 - 1 delete + 2 inserts = 101
+    101 = length(Objs),
+    ok.
+
 ok({ok, Value}) -> Value.
 
 tr_opts() ->