with_transaction to ignore nested transactions

Author: lukyanov

src/pgapp_worker.erl

@@ -111,9 +111,16 @@ handle_call({equery, Sql, Params}, _From,
     {reply, epgsql:equery(Conn, Sql, Params), State};
 handle_call({transaction, PoolName, Fun}, _From,
             #state{conn = Conn} = State) ->
-    put(?TX_CONNECTION_VAR(PoolName), Conn),
-    Result = epgsql:with_transaction(Conn, fun(_) -> Fun() end),
-    erase(?TX_CONNECTION_VAR(PoolName)),
+    Result = case get(?TX_CONNECTION_VAR(PoolName)) of
+        undefined ->
+            put(?TX_CONNECTION_VAR(PoolName), Conn),
+            Res = epgsql:with_transaction(Conn, fun(_) -> Fun() end),
+            erase(?TX_CONNECTION_VAR(PoolName)),
+            Res;
+        _ ->
+            % transaction is already in progress
+            Fun()
+    end,
     {reply, Result, State}.
 
 handle_cast(reconnect, State) ->