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1 files changed, 54 insertions, 0 deletions

diff --git a/src/db/logic/db_access.erl b/src/db/logic/db_access.erl
new file mode 100644
index 0000000..f589ba8
--- /dev/null
+++ b/src/db/logic/db_access.erl
@@ -0,0 +1,54 @@
+-module(db_access).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% TYPES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% EXPORTS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+-export
+(
+   [
+      read/2,
+      insert/4,
+      query/1
+   ]
+).
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% LOCAL FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+get_value ([]) -> not_found;
+get_value ([Regval]) -> {ok, sh_db_item:get_value(Regval)}.
+
+read_transaction (DB, ID) ->
+   get_value(mnesia:read(DB, ID)).
+
+insert_transaction (DB, ID, Perm, Value) ->
+   StoredItem = sh_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 = sh_db_query:get_database(Query),
+   ID = sh_db_query:get_entry_id(Query),
+   [Item] = mnesia:read(DB, ID),
+   {ok, UpdatedItem} = sh_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]).