Add a REST example that streams its response

examples/rest_stream_response/src/toppage_handler.erl

@@ -0,0 +1,42 @@
+%% Feel free to use, reuse and abuse the code in this file.
+
+%% @doc Streaming handler.
+-module(toppage_handler).
+
+-export([init/3]).
+-export([rest_init/2]).
+-export([content_types_provided/2]).
+-export([streaming_csv/2]).
+
+init(_Transport, _Req, _Table) ->
+	{upgrade, protocol, cowboy_rest}.
+
+rest_init(Req, Table) ->
+	{ok, Req, Table}.
+
+content_types_provided(Req, State) ->
+	{[
+		{{<<"text">>, <<"csv">>, []}, streaming_csv}
+	], Req, State}.
+
+streaming_csv(Req, Table) ->
+	{N, Req1} = cowboy_req:binding(v1, Req, 1),
+	MS = [{{'$1', '$2', '$3'}, [{'==', '$2', N}], ['$$']}],
+
+	{{stream, result_streamer(Table, MS)}, Req1, Table}.
+
+result_streamer(Table, MS) ->
+	fun (Socket, Transport) ->
+			send_records(Socket, Transport, ets:select(Table, MS, 1))
+	end.
+
+send_records(Socket, Transport, {[Rec], Cont}) ->
+	timer:sleep(500),
+	send_line(Socket, Transport, Rec),
+	send_records(Socket, Transport, ets:select(Cont));
+send_records(_Socket, _Transport, '$end_of_table') ->
+	ok.
+
+send_line(Socket, Transport, [Key, V1, V2]) ->
+	Transport:send(Socket,
+		[Key, $,, integer_to_list(V1), $,, integer_to_list(V2), $\r, $\n]).