Add cowboy_http_req:set_resp_body_fun/3.

test/http_handler_stream_body.erl

@@ -0,0 +1,24 @@
+%% Feel free to use, reuse and abuse the code in this file.
+
+-module(http_handler_stream_body).
+-behaviour(cowboy_http_handler).
+-export([init/3, handle/2, terminate/2]).
+
+-record(state, {headers, body, reply}).
+
+init({_Transport, http}, Req, Opts) ->
+	Headers = proplists:get_value(headers, Opts, []),
+	Body = proplists:get_value(body, Opts, "http_handler_stream_body"),
+	Reply = proplists:get_value(reply, Opts),
+	{ok, Req, #state{headers=Headers, body=Body, reply=Reply}}.
+
+handle(Req, State=#state{headers=_Headers, body=Body, reply=set_resp}) ->
+	{ok, Transport, Socket} = cowboy_http_req:transport(Req),
+	SFun = fun() -> Transport:send(Socket, Body), sent end,
+	SLen = iolist_size(Body),
+	{ok, Req2} = cowboy_http_req:set_resp_body_fun(SLen, SFun, Req),
+	{ok, Req3} = cowboy_http_req:reply(200, Req2),
+	{ok, Req3, State}.
+
+terminate(_Req, _State) ->
+	ok.