Replace init_stream/5 with stream_body/2

This allows us to change the max chunk length on a per chunk basis
instead of for the whole stream. It's also much easier to use this
way even if we don't want to change the chunk size.

guide/req.md

@@ -104,9 +104,9 @@ and `body_qs/2` will return `{error, badlength}`. If the request
 contains chunked body, `body/1`, `body/2`, `body_qs/1`
 and `body_qs/2` will return `{error, chunked}`.
 If you get either of the above two errors, you will want to
-handle the body of the request using `stream_body/1` and
-`skip_body/1`, with the streaming process optionally
-initialized using `init_stream/4` or `init_stream/5`.
+handle the body of the request using `stream_body/1`,
+`stream_body/2` and `skip_body/1`, with the streaming process
+optionally initialized using `init_stream/4`.
 
 Multipart request body
 ----------------------

src/cowboy_req.erl

@@ -78,8 +78,8 @@
 -export([has_body/1]).
 -export([body_length/1]).
 -export([init_stream/4]).
--export([init_stream/5]).
 -export([stream_body/1]).
+-export([stream_body/2]).
 -export([skip_body/1]).
 -export([body/1]).
 -export([body/2]).
@@ -155,8 +155,8 @@
 	meta = [] :: [{atom(), any()}],
 
 	%% Request body.
-	body_state = waiting :: waiting | done | {stream,
-		non_neg_integer(), non_neg_integer(), fun(), any(), fun()},
+	body_state = waiting :: waiting | done
+		| {stream, non_neg_integer(), fun(), any(), fun()},
 	multipart = undefined :: undefined | {non_neg_integer(), fun()},
 	buffer = <<>> :: binary(),
 
@@ -591,17 +591,11 @@ body_length(Req) ->
 			{undefined, Req2}
 	end.
 
-%% @equiv init_stream(1000000, TransferDecode, TransferState, ContentDecode, Req)
--spec init_stream(fun(), any(), fun(), Req)
-	-> {ok, Req} when Req::req().
-init_stream(TransferDecode, TransferState, ContentDecode, Req) ->
-	init_stream(1000000, TransferDecode, TransferState, ContentDecode, Req).
-
 %% @doc Initialize body streaming and set custom decoding functions.
 %%
 %% Calling this function is optional. It should only be used if you
 %% need to override the default behavior of Cowboy. Otherwise you
-%% should call stream_body/1 directly.
+%% should call stream_body/{1,2} directly.
 %%
 %% Two decodings happen. First a decoding function is applied to the
 %% transferred data, and then another is applied to the actual content.
@@ -613,27 +607,36 @@ init_stream(TransferDecode, TransferState, ContentDecode, Req) ->
 %% Content encoding is generally used for compression.
 %%
 %% Standard encodings can be found in cowboy_http.
--spec init_stream(non_neg_integer(), fun(), any(), fun(), Req)
+-spec init_stream(fun(), any(), fun(), Req)
 	-> {ok, Req} when Req::req().
-init_stream(MaxLength, TransferDecode, TransferState, ContentDecode, Req) ->
+init_stream(TransferDecode, TransferState, ContentDecode, Req) ->
 	{ok, Req#http_req{body_state=
-		{stream, 0, MaxLength, TransferDecode, TransferState, ContentDecode}}}.
+		{stream, 0, TransferDecode, TransferState, ContentDecode}}}.
+
+%% @equiv stream_body(Req, 1000000)
+-spec stream_body(Req) -> {ok, binary(), Req}
+	| {done, Req} | {error, atom()} when Req::req().
+stream_body(Req) ->
+	stream_body(Req, 1000000).
 
 %% @doc Stream the request's body.
 %%
 %% This is the most low level function to read the request body.
 %%
-%% In most cases, if they weren't defined before using stream_body/4,
+%% In most cases, if they weren't defined before using init_stream/4,
 %% this function will guess which transfer and content encodings were
 %% used for building the request body, and configure the decoding
 %% functions that will be used when streaming.
 %%
 %% It then starts streaming the body, returning {ok, Data, Req}
 %% for each streamed part, and {done, Req} when it's finished streaming.
--spec stream_body(Req) -> {ok, binary(), Req}
+%%
+%% You can limit the size of the chunks being returned by using the
+%% second argument which is the size in bytes. It defaults to 1000000 bytes.
+-spec stream_body(Req, non_neg_integer()) -> {ok, binary(), Req}
 	| {done, Req} | {error, atom()} when Req::req().
-stream_body(Req=#http_req{body_state=waiting,
-		version=Version, transport=Transport, socket=Socket}) ->
+stream_body(Req=#http_req{body_state=waiting, version=Version,
+		transport=Transport, socket=Socket}, MaxLength) ->
 	{ok, ExpectHeader, Req1} = parse_header(<<"expect">>, Req),
 	case ExpectHeader of
 		[<<"100-continue">>] ->
@@ -646,34 +649,36 @@ stream_body(Req=#http_req{body_state=waiting,
 	case parse_header(<<"transfer-encoding">>, Req1) of
 		{ok, [<<"chunked">>], Req2} ->
 			stream_body(Req2#http_req{body_state=
-				{stream, 0, 1000000,
+				{stream, 0,
 					fun cowboy_http:te_chunked/2, {0, 0},
-					fun cowboy_http:ce_identity/1}});
+					fun cowboy_http:ce_identity/1}},
+				MaxLength);
 		{ok, [<<"identity">>], Req2} ->
 			{Length, Req3} = body_length(Req2),
 			case Length of
 				0 ->
 					{done, Req3#http_req{body_state=done}};
 				Length ->
 					stream_body(Req3#http_req{body_state=
-						{stream, Length, 1000000,
+						{stream, Length,
 							fun cowboy_http:te_identity/2, {0, Length},
-							fun cowboy_http:ce_identity/1}})
+							fun cowboy_http:ce_identity/1}},
+						MaxLength)
 			end
 	end;
-stream_body(Req=#http_req{body_state=done}) ->
+stream_body(Req=#http_req{body_state=done}, _) ->
 	{done, Req};
-stream_body(Req=#http_req{buffer=Buffer})
+stream_body(Req=#http_req{buffer=Buffer}, _)
 		when Buffer =/= <<>> ->
 	transfer_decode(Buffer, Req#http_req{buffer= <<>>});
-stream_body(Req) ->
-	stream_body_recv(Req).
+stream_body(Req, MaxLength) ->
+	stream_body_recv(Req, MaxLength).
 
--spec stream_body_recv(Req)
+-spec stream_body_recv(Req, non_neg_integer())
 	-> {ok, binary(), Req} | {error, atom()} when Req::req().
 stream_body_recv(Req=#http_req{
 		transport=Transport, socket=Socket, buffer=Buffer,
-		body_state={stream, Length, MaxLength, _, _, _}}) ->
+		body_state={stream, Length, _, _, _}}, MaxLength) ->
 	%% @todo Allow configuring the timeout.
 	case Transport:recv(Socket, min(Length, MaxLength), 5000) of
 		{ok, Data} -> transfer_decode(<< Buffer/binary, Data/binary >>,
@@ -683,20 +688,20 @@ stream_body_recv(Req=#http_req{
 
 -spec transfer_decode(binary(), Req)
 	-> {ok, binary(), Req} | {error, atom()} when Req::req().
-transfer_decode(Data, Req=#http_req{body_state={stream, _, MaxLength,
+transfer_decode(Data, Req=#http_req{body_state={stream, _,
 		TransferDecode, TransferState, ContentDecode}}) ->
 	case TransferDecode(Data, TransferState) of
 		{ok, Data2, Rest, TransferState2} ->
 			content_decode(ContentDecode, Data2,
-				Req#http_req{buffer=Rest, body_state={stream, 0, MaxLength,
+				Req#http_req{buffer=Rest, body_state={stream, 0,
 				TransferDecode, TransferState2, ContentDecode}});
 		%% @todo {header(s) for chunked
 		more ->
 			stream_body_recv(Req#http_req{buffer=Data, body_state={stream,
-				0, MaxLength, TransferDecode, TransferState, ContentDecode}});
+				0, TransferDecode, TransferState, ContentDecode}}, 0);
 		{more, Length, Data2, TransferState2} ->
 			content_decode(ContentDecode, Data2,
-				Req#http_req{body_state={stream, Length, MaxLength,
+				Req#http_req{body_state={stream, Length,
 				TransferDecode, TransferState2, ContentDecode}});
 		{done, Length, Rest} ->
 			Req2 = transfer_decode_done(Length, Rest, Req),