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-module(storage_access).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% TYPES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXPORTS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-export
(
[
read/2,
insert/4,
query/1
]
).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% LOCAL FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
get_value ([]) -> not_found;
get_value ([Regval]) -> {ok, db_item:get_value(Regval)}.
read_transaction (DB, ID) ->
get_value(mnesia:read(DB, ID)).
insert_transaction (DB, ID, Perm, Value) ->
StoredItem = 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.
query_transaction (Query) ->
DB = db_query:get_database(Query),
ID = db_query:get_entry_id(Query),
[Item] = mnesia:read(DB, ID),
{ok, UpdatedItem} = 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 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
read (DB, ID) ->
mnesia:transaction(fun read_transaction/2, [DB, ID]).
insert (DB, ID, Perm, Value) ->
mnesia:transaction(fun insert_transaction/4, [DB, ID, Perm, Value]).
query (Query) ->
mnesia:transaction(fun query_transaction/1, [Query]).
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