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-module(db_access).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% TYPES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXPORTS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-export
(
[
read/2,
insert/4,
query/1
]
).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% LOCAL FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-spec get_value (list(shr_db_item:type())) -> ({'ok', any()} | 'not_found').
get_value ([]) -> not_found;
get_value ([Regval]) -> {ok, shr_db_item:get_value(Regval)}.
-spec read_transaction (atom(), any()) -> ({'ok', any()} | 'not_found').
read_transaction (DB, ID) ->
get_value(mnesia:read(DB, ID)).
-spec insert_transaction
(
atom(),
any(),
shr_db_user:permission(),
any()
)
-> 'ok'.
insert_transaction (DB, ID, Perm, Value) ->
StoredItem = shr_db_item:new(ID, Perm, Value),
% FIXME: handle return value, mnesia:write -> (transaction abort | ok).
% FIXME: is this an atomic OP? Is the lock freed afterwards?
mnesia:write(DB, StoredItem, sticky_write),
ok.
-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())
-> ({'aborted', any()} | {'atomic', ({'ok', any()} | 'not_found')}).
read (DB, ID) ->
mnesia:transaction(fun read_transaction/2, [DB, ID]).
-spec insert (atom(), any(), shr_db_user:permission(), any())
-> ({'aborted', any()} | {'atomic', 'ok'}).
insert (DB, ID, Perm, Value) ->
mnesia:transaction(fun insert_transaction/4, [DB, ID, Perm, Value]).
-spec query (shr_db_query:type()) -> ({'aborted', any()} | {'atomic', 'ok'}).
query (Query) ->
mnesia:transaction(fun query_transaction/1, [Query]).
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