From fbfec873f6026b858c3604d74d88470ce45f4296 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lo=C3=AFc=20Hoguin?= <essen@ninenines.eu>
Date: Thu, 15 Nov 2018 10:11:36 +0100
Subject: Add a compress_buffering option to cowboy_compress_h

Also changes the behavior to disable buffering by default, so
that the default works in all cases, including server-sent events.
---
 src/cowboy_compress_h.erl | 20 ++++++++++++++------
 src/cowboy_http.erl       |  1 +
 src/cowboy_http2.erl      |  1 +
 3 files changed, 16 insertions(+), 6 deletions(-)

(limited to 'src')

diff --git a/src/cowboy_compress_h.erl b/src/cowboy_compress_h.erl
index ed81db6..bd3df42 100644
--- a/src/cowboy_compress_h.erl
+++ b/src/cowboy_compress_h.erl
@@ -25,7 +25,8 @@
 	next :: any(),
 	threshold :: non_neg_integer() | undefined,
 	compress = undefined :: undefined | gzip,
-	deflate = undefined :: undefined | zlib:zstream()
+	deflate = undefined :: undefined | zlib:zstream(),
+	deflate_flush = sync :: none | sync
 }).
 
 -spec init(cowboy_stream:streamid(), cowboy_req:req(), cowboy:opts())
@@ -33,8 +34,14 @@
 init(StreamID, Req, Opts) ->
 	State0 = check_req(Req),
 	CompressThreshold = maps:get(compress_threshold, Opts, 300),
+	DeflateFlush = case maps:get(compress_buffering, Opts, false) of
+		false -> sync;
+		true -> none
+	end,
 	{Commands0, Next} = cowboy_stream:init(StreamID, Req, Opts),
-	fold(Commands0, State0#state{next=Next, threshold=CompressThreshold}).
+	fold(Commands0, State0#state{next=Next,
+		threshold=CompressThreshold,
+		deflate_flush=DeflateFlush}).
 
 -spec data(cowboy_stream:streamid(), cowboy_stream:fin(), cowboy_req:resp_body(), State)
 	-> {cowboy_stream:commands(), State} when State::#state{}.
@@ -176,9 +183,10 @@ gzip_headers({headers, Status, Headers0}, State) ->
 %% includes a checksum at the end of the stream. We have
 %% to read the file in memory, making this not suitable for
 %% large files.
-gzip_data({data, nofin, Sendfile={sendfile, _, _, _}}, State=#state{deflate=Z}) ->
+gzip_data({data, nofin, Sendfile={sendfile, _, _, _}},
+		State=#state{deflate=Z, deflate_flush=Flush}) ->
 	{ok, Data0} = read_file(Sendfile),
-	Data = zlib:deflate(Z, Data0),
+	Data = zlib:deflate(Z, Data0, Flush),
 	{{data, nofin, Data}, State};
 gzip_data({data, fin, Sendfile={sendfile, _, _, _}}, State=#state{deflate=Z}) ->
 	{ok, Data0} = read_file(Sendfile),
@@ -186,8 +194,8 @@ gzip_data({data, fin, Sendfile={sendfile, _, _, _}}, State=#state{deflate=Z}) ->
 	zlib:deflateEnd(Z),
 	zlib:close(Z),
 	{{data, fin, Data}, State#state{deflate=undefined}};
-gzip_data({data, nofin, Data0}, State=#state{deflate=Z}) ->
-	Data = zlib:deflate(Z, Data0),
+gzip_data({data, nofin, Data0}, State=#state{deflate=Z, deflate_flush=Flush}) ->
+	Data = zlib:deflate(Z, Data0, Flush),
 	{{data, nofin, Data}, State};
 gzip_data({data, fin, Data0}, State=#state{deflate=Z}) ->
 	Data = zlib:deflate(Z, Data0, finish),
diff --git a/src/cowboy_http.erl b/src/cowboy_http.erl
index 56a4af8..9a10790 100644
--- a/src/cowboy_http.erl
+++ b/src/cowboy_http.erl
@@ -25,6 +25,7 @@
 -export([system_code_change/4]).
 
 -type opts() :: #{
+	compress_buffering => boolean(),
 	compress_threshold => non_neg_integer(),
 	connection_type => worker | supervisor,
 	env => cowboy_middleware:env(),
diff --git a/src/cowboy_http2.erl b/src/cowboy_http2.erl
index fc1a3a0..3397241 100644
--- a/src/cowboy_http2.erl
+++ b/src/cowboy_http2.erl
@@ -27,6 +27,7 @@
 -export([system_code_change/4]).
 
 -type opts() :: #{
+	compress_buffering => boolean(),
 	compress_threshold => non_neg_integer(),
 	connection_type => worker | supervisor,
 	enable_connect_protocol => boolean(),
-- 
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