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-module(db_access).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% TYPES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXPORTS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-export
(
[
read/3,
insert/5,
query/1
]
).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% LOCAL FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-spec query_transaction (shr_db_query:type()) -> 'ok'.
query_transaction (Query) ->
DB = shr_db_query:get_database(Query),
ID = shr_db_query:get_entry_id(Query),
[Item] = mnesia:read(DB, ID),
{ok, UpdatedItem} = shr_db_query:apply_to(Query, Item),
% FIXME: handle return value, mnesia:write -> (transaction abort | ok).
% FIXME: is this an atomic OP? Is the lock freed afterwards?
mnesia:write(DB, UpdatedItem, sticky_write),
ok.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXPORTED FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-spec read
(
atom(),
any(),
shr_db_user:user()
)
-> ({'aborted', any()} | {'atomic', ({'ok', any()} | 'not_found')}).
read (DB, ID, Cred) ->
case mnesia:transaction(fun mnesia:read/2, [DB, ID]) of
{'atomic', []} -> {'atomic', 'not_found'};
{'atomic', [Item]} ->
true =
shr_db_user:can_access
(
shr_db_item:get_write_permission(Item),
Cred
),
{'atomic', {ok, shr_db_item:get_value(Item)}};
Other -> {'aborted', Other}
end.
-spec insert
(
atom(),
any(),
shr_db_user:permission(),
shr_db_user:permission(),
any())
-> ({'aborted', any()} | {'atomic', 'ok'}).
insert (DB, ID, ReadPerm, WritePerm, Value) ->
Item = shr_db_item:new(ID, ReadPerm, WritePerm, Value),
mnesia:transaction(fun mnesia:write/3, [DB, Item, sticky_write]).
-spec query (shr_db_query:type()) -> ({'aborted', any()} | {'atomic', 'ok'}).
query (Query) ->
mnesia:transaction(fun query_transaction/1, [Query]).
|
