Make streamed chunk size configurable

Defaults to a maximum of 1000000 bytes.

Also standardize the te_identity and te_chunked decoding functions.
Now they both try to read as much as possible (up to the limit),
making body reading much faster when not using chunked encoding.

3 files changed, 47 insertions, 33 deletions

diff --git a/guide/req.md b/guide/req.md
index e13d3a5..8fd854a 100644
--- a/guide/req.md
+++ b/guide/req.md
@@ -94,7 +94,8 @@ If you know the request contains a body, and that it is
 of appropriate size, then you can read it directly with
 either `body/1` or `body_qs/1`. Otherwise, you will want
 to stream it with `stream_body/1` and `skip_body/1`, with
-the streaming process optionally initialized using `init_stream/4`.
+the streaming process optionally initialized using `init_stream/4`
+or `init_stream/5`.
 
 Multipart request body
 ----------------------
diff --git a/src/cowboy_http.erl b/src/cowboy_http.erl
index 1d19838..57dac0b 100644
--- a/src/cowboy_http.erl
+++ b/src/cowboy_http.erl
@@ -853,7 +853,7 @@ authorization_basic_password(<<C, Rest/binary>>, Fun, Acc) ->
 %% @doc Decode a stream of chunks.
 -spec te_chunked(Bin, TransferState)
 	-> more | {more, non_neg_integer(), Bin, TransferState}
-	| {ok, Bin, TransferState} | {ok, Bin, Bin, TransferState}
+	| {ok, Bin, Bin, TransferState}
 	| {done, non_neg_integer(), Bin} | {error, badarg}
 	when Bin::binary(), TransferState::{non_neg_integer(), non_neg_integer()}.
 te_chunked(<< "0\r\n\r\n", Rest/binary >>, {0, Streamed}) ->
@@ -879,11 +879,13 @@ te_chunked(Data, {ChunkRem, Streamed}) ->
 
 %% @doc Decode an identity stream.
 -spec te_identity(Bin, TransferState)
-	-> {ok, Bin, TransferState} | {done, Bin, non_neg_integer(), Bin}
+	-> {more, non_neg_integer(), Bin, TransferState}
+	| {done, Bin, non_neg_integer(), Bin}
 	when Bin::binary(), TransferState::{non_neg_integer(), non_neg_integer()}.
 te_identity(Data, {Streamed, Total})
 		when Streamed + byte_size(Data) < Total ->
-	{ok, Data, {Streamed + byte_size(Data), Total}};
+	Streamed2 = Streamed + byte_size(Data),
+	{more, Total - Streamed2, Data, {Streamed2, Total}};
 te_identity(Data, {Streamed, Total}) ->
 	Size = Total - Streamed,
 	<< Data2:Size/binary, Rest/binary >> = Data,
diff --git a/src/cowboy_req.erl b/src/cowboy_req.erl
index c800595..93c8656 100644
--- a/src/cowboy_req.erl
+++ b/src/cowboy_req.erl
@@ -78,6 +78,7 @@
 -export([has_body/1]).
 -export([body_length/1]).
 -export([init_stream/4]).
+-export([init_stream/5]).
 -export([stream_body/1]).
 -export([skip_body/1]).
 -export([body/1]).
@@ -152,7 +153,8 @@
 	meta = [] :: [{atom(), any()}],
 
 	%% Request body.
-	body_state = waiting :: waiting | done | {stream, fun(), any(), fun()},
+	body_state = waiting :: waiting | done | {stream,
+		non_neg_integer(), non_neg_integer(), fun(), any(), fun()},
 	multipart = undefined :: undefined | {non_neg_integer(), fun()},
 	buffer = <<>> :: binary(),
 
@@ -587,6 +589,12 @@ 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
@@ -603,10 +611,11 @@ body_length(Req) ->
 %% Content encoding is generally used for compression.
 %%
 %% Standard encodings can be found in cowboy_http.
--spec init_stream(fun(), any(), fun(), Req) -> {ok, Req} when Req::req().
-init_stream(TransferDecode, TransferState, ContentDecode, Req) ->
+-spec init_stream(non_neg_integer(), fun(), any(), fun(), Req)
+	-> {ok, Req} when Req::req().
+init_stream(MaxLength, TransferDecode, TransferState, ContentDecode, Req) ->
 	{ok, Req#http_req{body_state=
-		{stream, TransferDecode, TransferState, ContentDecode}}}.
+		{stream, 0, MaxLength, TransferDecode, TransferState, ContentDecode}}}.
 
 %% @doc Stream the request's body.
 %%
@@ -635,8 +644,9 @@ 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, fun cowboy_http:te_chunked/2, {0, 0},
-				 fun cowboy_http:ce_identity/1}});
+				{stream, 0, 1000000,
+					fun cowboy_http:te_chunked/2, {0, 0},
+					fun cowboy_http:ce_identity/1}});
 		{ok, [<<"identity">>], Req2} ->
 			{Length, Req3} = body_length(Req2),
 			case Length of
@@ -644,24 +654,26 @@ stream_body(Req=#http_req{body_state=waiting,
 					{done, Req3#http_req{body_state=done}};
 				Length ->
 					stream_body(Req3#http_req{body_state=
-						{stream, fun cowboy_http:te_identity/2, {0, Length},
-						 fun cowboy_http:ce_identity/1}})
+						{stream, Length, 1000000,
+							fun cowboy_http:te_identity/2, {0, Length},
+							fun cowboy_http:ce_identity/1}})
 			end
 	end;
-stream_body(Req=#http_req{buffer=Buffer, body_state={stream, _, _, _}})
+stream_body(Req=#http_req{body_state=done}) ->
+	{done, Req};
+stream_body(Req=#http_req{buffer=Buffer})
 		when Buffer =/= <<>> ->
 	transfer_decode(Buffer, Req#http_req{buffer= <<>>});
-stream_body(Req=#http_req{body_state={stream, _, _, _}}) ->
-	stream_body_recv(0, Req);
-stream_body(Req=#http_req{body_state=done}) ->
-	{done, Req}.
+stream_body(Req) ->
+	stream_body_recv(Req).
 
--spec stream_body_recv(non_neg_integer(), Req)
+-spec stream_body_recv(Req)
 	-> {ok, binary(), Req} | {error, atom()} when Req::req().
-stream_body_recv(Length, Req=#http_req{
-		transport=Transport, socket=Socket, buffer=Buffer}) ->
+stream_body_recv(Req=#http_req{
+		transport=Transport, socket=Socket, buffer=Buffer,
+		body_state={stream, Length, MaxLength, _, _, _}}) ->
 	%% @todo Allow configuring the timeout.
-	case Transport:recv(Socket, Length, 5000) of
+	case Transport:recv(Socket, min(Length, MaxLength), 5000) of
 		{ok, Data} -> transfer_decode(<< Buffer/binary, Data/binary >>,
 			Req#http_req{buffer= <<>>});
 		{error, Reason} -> {error, Reason}
@@ -669,22 +681,21 @@ stream_body_recv(Length, 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, TransferDecode, TransferState, ContentDecode}}) ->
+transfer_decode(Data, Req=#http_req{body_state={stream, _, MaxLength,
+		TransferDecode, TransferState, ContentDecode}}) ->
 	case TransferDecode(Data, TransferState) of
-		{ok, Data2, TransferState2} ->
-			content_decode(ContentDecode, Data2, Req#http_req{body_state=
-				{stream, TransferDecode, TransferState2, ContentDecode}});
 		{ok, Data2, Rest, TransferState2} ->
-			content_decode(ContentDecode, Data2, Req#http_req{
-				buffer=Rest, body_state=
-				{stream, TransferDecode, TransferState2, ContentDecode}});
+			content_decode(ContentDecode, Data2,
+				Req#http_req{buffer=Rest, body_state={stream, 0, MaxLength,
+				TransferDecode, TransferState2, ContentDecode}});
 		%% @todo {header(s) for chunked
 		more ->
-			stream_body_recv(0, Req#http_req{buffer=Data});
-		{more, Length, Rest, TransferState2} ->
-			stream_body_recv(Length, Req#http_req{buffer=Rest, body_state=
-				{stream, TransferDecode, TransferState2, ContentDecode}});
+			stream_body_recv(Req#http_req{buffer=Data, body_state={stream,
+				0, MaxLength, TransferDecode, TransferState, ContentDecode}});
+		{more, Length, Data2, TransferState2} ->
+			content_decode(ContentDecode, Data2,
+				Req#http_req{body_state={stream, Length, MaxLength,
+				TransferDecode, TransferState2, ContentDecode}});
 		{done, Length, Rest} ->
 			Req2 = transfer_decode_done(Length, Rest, Req),
 			{done, Req2};