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-rw-r--r--lib/mnesia/src/mnesia_schema.erl206
1 files changed, 195 insertions, 11 deletions
diff --git a/lib/mnesia/src/mnesia_schema.erl b/lib/mnesia/src/mnesia_schema.erl
index 76a9dbf26c..1aebd8f762 100644
--- a/lib/mnesia/src/mnesia_schema.erl
+++ b/lib/mnesia/src/mnesia_schema.erl
@@ -29,6 +29,11 @@
-module(mnesia_schema).
-export([
+ add_backend_type/2,
+ do_add_backend_type/2,
+ delete_backend_type/1,
+ do_delete_backend_type/1,
+ backend_types/0,
add_snmp/2,
add_table_copy/3,
add_table_index/2,
@@ -55,11 +60,12 @@
dump_tables/1,
ensure_no_schema/1,
get_create_list/1,
- get_initial_schema/2,
+ get_initial_schema/3,
get_table_properties/1,
info/0,
info/1,
init/1,
+ init_backends/0,
insert_cstruct/3,
is_remote_member/1,
list2cs/1,
@@ -143,7 +149,24 @@ init(IgnoreFallback) ->
set({schema, where_to_read}, node()),
set({schema, load_node}, node()),
set({schema, load_reason}, initial),
- mnesia_controller:add_active_replica(schema, node()).
+ mnesia_controller:add_active_replica(schema, node()),
+ init_backends().
+
+
+init_backends() ->
+ Backends = lists:foldl(fun({Alias, Mod}, Acc) ->
+ orddict:append(Mod, Alias, Acc)
+ end, orddict:new(), get_ext_types()),
+ [init_backend(Mod, Aliases) || {Mod, Aliases} <- Backends],
+ ok.
+
+init_backend(Mod, [_|_] = Aliases) ->
+ case Mod:init_backend() of
+ ok ->
+ Mod:add_aliases(Aliases);
+ Error ->
+ mnesia:abort({backend_init_error, Error})
+ end.
exit_on_error({error, Reason}) ->
exit(Reason);
@@ -525,9 +548,14 @@ do_read_disc_schema(Fname, Keep) ->
Res.
get_initial_schema(SchemaStorage, Nodes) ->
+ get_initial_schema(SchemaStorage, Nodes, []).
+
+get_initial_schema(SchemaStorage, Nodes, Properties) -> %
+ UserProps = initial_schema_properties(Properties),
Cs = #cstruct{name = schema,
record_name = schema,
- attributes = [table, cstruct]},
+ attributes = [table, cstruct],
+ user_properties = UserProps},
Cs2 =
case SchemaStorage of
ram_copies -> Cs#cstruct{ram_copies = Nodes};
@@ -535,6 +563,30 @@ get_initial_schema(SchemaStorage, Nodes) ->
end,
cs2list(Cs2).
+initial_schema_properties(Props0) ->
+ DefaultProps = remove_duplicates(mnesia_monitor:get_env(schema)),
+ Props = lists:foldl(
+ fun({K,V}, Acc) ->
+ lists:keystore(K, 1, Acc, {K,V})
+ end, DefaultProps, remove_duplicates(Props0)),
+ initial_schema_properties_(Props).
+
+initial_schema_properties_([{backend_types, Types}|Props]) ->
+ lists:foreach(fun({Name, Module}) ->
+ verify_backend_type(Name, Module)
+ end, Types),
+ [{mnesia_backend_types, Types}|initial_schema_properties_(Props)];
+initial_schema_properties_([P|_Props]) ->
+ mnesia:abort({bad_schema_property, P});
+initial_schema_properties_([]) ->
+ [].
+
+remove_duplicates([{K,_} = H|T]) ->
+ [H | remove_duplicates([X || {K1,_} = X <- T,
+ K1 =/= K])];
+remove_duplicates([]) ->
+ [].
+
read_cstructs_from_disc() ->
%% Assumptions:
%% - local schema lock in global
@@ -783,6 +835,25 @@ pick(Tab, Key, List, Default) ->
mnesia:abort({bad_type, Tab, BadArg})
end.
+get_ext_types() ->
+ get_schema_user_property(mnesia_backend_types).
+
+get_schema_user_property(Key) ->
+ Tab = schema,
+ %% Must work reliably both within transactions and outside of transactions
+ Res = case get(mnesia_activity_state) of
+ undefined ->
+ dirty_read_table_property(Tab, Key);
+ _ ->
+ do_read_table_property(Tab, Key)
+ end,
+ case Res of
+ undefined ->
+ [];
+ {_, Types} ->
+ Types
+ end.
+
%% Convert attribute name to integer if neccessary
attr_tab_to_pos(_Tab, Pos) when is_integer(Pos) ->
Pos;
@@ -1039,6 +1110,103 @@ check_active([{badrpc, Reason} | _Replies], Expl, Tab) ->
check_active([], _Expl, _Tab) ->
ok.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Function for definining an external backend type
+
+add_backend_type(Name, Module) ->
+ case schema_transaction(fun() -> do_add_backend_type(Name, Module) end) of
+ {atomic, NeedsInit} ->
+ case NeedsInit of
+ true ->
+ Module:init_backend();
+ false ->
+ ignore
+ end,
+ Module:add_aliases([Name]),
+ {atomic, ok};
+ Other ->
+ Other
+ end.
+
+do_add_backend_type(Name, Module) ->
+ verify_backend_type(Name, Module),
+ Types = case do_read_table_property(schema, mnesia_backend_types) of
+ undefined ->
+ [];
+ {_, Ts} ->
+ case lists:keymember(Name, 1, Ts) of
+ true ->
+ mnesia:abort({backend_type_already_exists, Name});
+ false ->
+ Ts
+ end
+ end,
+ ModuleRegistered = lists:keymember(Module, 2, Types),
+ do_write_table_property(schema, {mnesia_backend_types,
+ [{Name, Module}|Types]}),
+ ModuleRegistered.
+
+delete_backend_type(Name) ->
+ schema_transaction(fun() -> do_delete_backend_type(Name) end).
+
+do_delete_backend_type(Name) ->
+ case do_read_table_property(schema, mnesia_backend_types) of
+ undefined ->
+ [];
+ {_, Ts} ->
+ case lists:keyfind(Name, 1, Ts) of
+ {_, Mod} ->
+ case using_backend_type(Name, Mod) of
+ [_|_] = Tabs ->
+ mnesia:abort({backend_in_use, {Name, Tabs}});
+ [] ->
+ do_write_table_property(
+ schema, {mnesia_backend_types,
+ lists:keydelete(Name, 1, Ts)})
+ end;
+ false ->
+ mnesia:abort({no_such_backend, Name})
+ end
+ end.
+
+using_backend_type(Name, Mod) ->
+ Ext = ets:select(mnesia_gvar,
+ [{ {{'$1',external_copies},'$2'}, [], [{{'$1','$2'}}] }]),
+ Entry = {Name, Mod},
+ [T || {T,C} <- Ext,
+ lists:keymember(Entry, 1, C)].
+
+verify_backend_type(Name, Module) ->
+ case legal_backend_name(Name) of
+ false ->
+ mnesia:abort({bad_type, {backend_type,Name,Module}});
+ true ->
+ ok
+ end,
+ ExpectedExports = mnesia_backend_type:behaviour_info(callbacks),
+ Exports = try Module:module_info(exports)
+ catch
+ error:_ ->
+ mnesia:abort({undef_backend, Module})
+ end,
+ case ExpectedExports -- Exports of
+ [] ->
+ ok;
+ _Other ->
+ io:fwrite(user, "Missing backend_type exports: ~p~n", [_Other]),
+ mnesia:abort({bad_type, {backend_type,Name,Module}})
+ end.
+
+legal_backend_name(Name) ->
+ is_atom(Name) andalso
+ (not lists:member(Name, record_info(fields, cstruct))).
+
+%% Used e.g. by mnesia:system_info(backend_types).
+backend_types() ->
+ [ram_copies, disc_copies, disc_only_copies |
+ [T || {T,_} <- get_ext_types()]].
+
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Here's the real interface function to create a table
@@ -1711,22 +1879,38 @@ do_read_table_property(Tab, Key) ->
{_, _, Ts} = TidTs,
Store = Ts#tidstore.store,
Props = ets:foldl(
- fun({op, create_table, [{name, T}|Opts]}, _Acc)
- when T==Tab ->
+ fun({op, announce_im_running,_,Opts,_,_}, _Acc) when Tab==schema ->
+ find_props(Opts);
+ ({op, create_table, [{name, T}|Opts]}, _Acc)
+ when T==Tab ->
find_props(Opts);
({op, Op, [{name,T}|Opts], _Prop}, _Acc)
- when T==Tab, Op==write_property; Op==delete_property ->
+ when T==Tab, Op==write_property;
+ T==Tab, Op==delete_property ->
find_props(Opts);
({op, delete_table, [{name,T}|_]}, _Acc)
when T==Tab ->
[];
(_Other, Acc) ->
Acc
- end, [], Store),
- case lists:keysearch(Key, 1, Props) of
- {value, Property} ->
- Property;
- false ->
+ end, undefined, Store),
+ case Props of
+ undefined ->
+ get_tid_ts_and_lock(Tab, read),
+ dirty_read_table_property(Tab, Key);
+ _ when is_list(Props) ->
+ case lists:keyfind(Key, 1, Props) of
+ false ->
+ undefined;
+ Other ->
+ Other
+ end
+ end.
+
+dirty_read_table_property(Tab, Key) ->
+ try ets:lookup_element(mnesia_gvar, {Tab,user_property,Key}, 2)
+ catch
+ error:_ ->
undefined
end.
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-19 07:35:44 +0000