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Merge pull request #10993 from SergeTupchiy/improve_mnesia_backup_import 

fix(emqx_mgmt_data_backup): avoid writing temporary Mnesia backup file
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SergeTupchiy 2023-06-12 17:26:26 +03:00 committed by GitHub
parent 8ba5a54f2e 2aad6671ac
commit 5ef19ecf58
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 15 additions and 20 deletions
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35
apps/emqx_management/src/emqx_mgmt_data_backup.erl
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@ -382,15 +382,17 @@ import_mnesia_tab(BackupDir, TabName, Opts) ->
end.
restore_mnesia_tab(BackupDir, MnesiaBackupFileName, TabName, Opts) ->
BackupNameToImport = MnesiaBackupFileName ++ "_for_import",
Prepared =
Validated =
catch mnesia:traverse_backup(
MnesiaBackupFileName, BackupNameToImport, fun backup_converter/2, 0
MnesiaBackupFileName, mnesia_backup, dummy, read_only, fun validate_mnesia_backup/2, 0
),
try
case Prepared of
case Validated of
{ok, _} ->
Restored = mnesia:restore(BackupNameToImport, [{default_op, keep_tables}]),
%% As we use keep_tables option, we don't need to modify 'copies' (nodes)
%% in a backup file before restoring it, as `mnsia:restore/2` will ignore
%% backed-up schema and keep the current table schema unchanged
Restored = mnesia:restore(MnesiaBackupFileName, [{default_op, keep_tables}]),
case Restored of
{atomic, [TabName]} ->
ok;
@ -416,30 +418,23 @@ restore_mnesia_tab(BackupDir, MnesiaBackupFileName, TabName, Opts) ->
end
after
%% Cleanup files as soon as they are not needed any more for more efficient disk usage
_ = file:delete(BackupNameToImport),
_ = file:delete(MnesiaBackupFileName)
end.
backup_converter({schema, Tab, CreateList}, Acc) ->
check_rec_attributes(Tab, CreateList),
{[{schema, Tab, lists:map(fun convert_copies/1, CreateList)}], Acc};
backup_converter(Other, Acc) ->
{[Other], Acc}.
check_rec_attributes(Tab, CreateList) ->
%% NOTE: if backup file is valid, we keep traversing it, though we only need to validate schema.
%% Looks like there is no clean way to abort traversal without triggering any error reporting,
%% `mnesia_bup:read_schema/2` is an option but its direct usage should also be avoided...
validate_mnesia_backup({schema, Tab, CreateList} = Schema, Acc) ->
ImportAttributes = proplists:get_value(attributes, CreateList),
Attributes = mnesia:table_info(Tab, attributes),
case ImportAttributes =/= Attributes of
true ->
throw({error, different_table_schema});
false ->
ok
end.
convert_copies({K, [_ | _]}) when K == ram_copies; K == disc_copies; K == disc_only_copies ->
{K, [node()]};
convert_copies(Other) ->
Other.
{[Schema], Acc}
end;
validate_mnesia_backup(Other, Acc) ->
{[Other], Acc}.
extract_backup(BackupFileName) ->
BackupDir = root_backup_dir(),