From 549555f14d04324c739e88f900f246b878fc461a Mon Sep 17 00:00:00 2001 From: Ulf Wiger Date: Tue, 10 Nov 2015 15:28:51 +0100 Subject: mnesia_ext: Create schema functionality Add ext to table/system information Add add_backend_type --- lib/mnesia/src/mnesia_schema.erl | 206 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 195 insertions(+), 11 deletions(-) (limited to 'lib/mnesia/src/mnesia_schema.erl') 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. -- cgit v1.2.3