From 210665e8a252faecf28ccebade999e734ab92582 Mon Sep 17 00:00:00 2001
From: Igor Slepchin
Date: Mon, 24 Sep 2018 22:44:03 -0400
Subject: Add nopush TCP socket option
This translates to TCP_CORK on Linux and TCP_NOPUSH on
BSD.
In effect, this acts as super-Nagle: no partial TCP segments
are sent out until this option is turned off. Once turned off,
all accumulated unsent data is sent out immediately. The latter
is *not* the case on OSX, hence the implementation ignores
"nopush" on OSX to reduce confusion.
---
erts/emulator/drivers/common/inet_drv.c | 30 ++++++++++++++++++++++++++++++
erts/preloaded/src/prim_inet.erl | 3 +++
lib/kernel/doc/src/inet.xml | 12 ++++++++++++
lib/kernel/src/inet_int.hrl | 1 +
lib/kernel/test/inet_sockopt_SUITE.erl | 9 +++++++--
5 files changed, 53 insertions(+), 2 deletions(-)
diff --git a/erts/emulator/drivers/common/inet_drv.c b/erts/emulator/drivers/common/inet_drv.c
index 7f20477363..c13ceb14ad 100644
--- a/erts/emulator/drivers/common/inet_drv.c
+++ b/erts/emulator/drivers/common/inet_drv.c
@@ -812,6 +812,7 @@ static size_t my_strnlen(const char *s, size_t maxlen)
#define INET_OPT_PKTOPTIONS 45 /* IP(V6)_PKTOPTIONS get ancillary data */
#define INET_OPT_TTL 46 /* IP_TTL */
#define INET_OPT_RECVTTL 47 /* IP_RECVTTL ancillary data */
+#define TCP_OPT_NOPUSH 48 /* super-Nagle, aka TCP_CORK */
/* SCTP options: a separate range, from 100: */
#define SCTP_OPT_RTOINFO 100
#define SCTP_OPT_ASSOCINFO 101
@@ -955,6 +956,12 @@ static size_t my_strnlen(const char *s, size_t maxlen)
#endif
+#if defined(TCP_CORK)
+#define INET_TCP_NOPUSH TCP_CORK
+#elif defined(TCP_NOPUSH) && !defined(__DARWIN__)
+#define INET_TCP_NOPUSH TCP_NOPUSH
+#endif
+
#define BIN_REALLOC_MARGIN(x) ((x)/4) /* 25% */
/* The general purpose sockaddr */
@@ -6532,6 +6539,19 @@ static int inet_set_opts(inet_descriptor* desc, char* ptr, int len)
(long)desc->port, desc->s, ival));
break;
+ case TCP_OPT_NOPUSH:
+#if defined(INET_TCP_NOPUSH)
+ proto = IPPROTO_TCP;
+ type = INET_TCP_NOPUSH;
+ DEBUGF(("inet_set_opts(%ld): s=%d, t=%d TCP_NOPUSH=%d\r\n",
+ (long)desc->port, desc->s, type, ival));
+ break;
+#else
+ /* inet_fill_opts always returns a value for this option,
+ * so we need to ignore it if not implemented, just in case */
+ continue;
+#endif
+
#if defined(HAVE_MULTICAST_SUPPORT) && defined(IPPROTO_IP)
case UDP_OPT_MULTICAST_TTL:
@@ -7693,6 +7713,16 @@ static ErlDrvSSizeT inet_fill_opts(inet_descriptor* desc,
proto = IPPROTO_TCP;
type = TCP_NODELAY;
break;
+ case TCP_OPT_NOPUSH:
+#if defined(INET_TCP_NOPUSH)
+ proto = IPPROTO_TCP;
+ type = INET_TCP_NOPUSH;
+ break;
+#else
+ *ptr++ = opt;
+ put_int32(0, ptr);
+ continue;
+#endif
#if defined(HAVE_MULTICAST_SUPPORT) && defined(IPPROTO_IP)
case UDP_OPT_MULTICAST_TTL:
diff --git a/erts/preloaded/src/prim_inet.erl b/erts/preloaded/src/prim_inet.erl
index 8169943dde..c98c7937b7 100644
--- a/erts/preloaded/src/prim_inet.erl
+++ b/erts/preloaded/src/prim_inet.erl
@@ -1275,6 +1275,7 @@ enc_opt(pktoptions) -> ?INET_OPT_PKTOPTIONS;
enc_opt(ttl) -> ?INET_OPT_TTL;
enc_opt(recvttl) -> ?INET_OPT_RECVTTL;
enc_opt(nodelay) -> ?TCP_OPT_NODELAY;
+enc_opt(nopush) -> ?TCP_OPT_NOPUSH;
enc_opt(multicast_if) -> ?UDP_OPT_MULTICAST_IF;
enc_opt(multicast_ttl) -> ?UDP_OPT_MULTICAST_TTL;
enc_opt(multicast_loop) -> ?UDP_OPT_MULTICAST_LOOP;
@@ -1336,6 +1337,7 @@ dec_opt(?INET_OPT_PRIORITY) -> priority;
dec_opt(?INET_OPT_TOS) -> tos;
dec_opt(?INET_OPT_TCLASS) -> tclass;
dec_opt(?TCP_OPT_NODELAY) -> nodelay;
+dec_opt(?TCP_OPT_NOPUSH) -> nopush;
dec_opt(?INET_OPT_RECVTOS) -> recvtos;
dec_opt(?INET_OPT_RECVTCLASS) -> recvtclass;
dec_opt(?INET_OPT_PKTOPTIONS) -> pktoptions;
@@ -1422,6 +1424,7 @@ type_opt_1(pktoptions) -> opts;
type_opt_1(ttl) -> int;
type_opt_1(recvttl) -> bool;
type_opt_1(nodelay) -> bool;
+type_opt_1(nopush) -> bool;
type_opt_1(ipv6_v6only) -> bool;
%% multicast
type_opt_1(multicast_ttl) -> int;
diff --git a/lib/kernel/doc/src/inet.xml b/lib/kernel/doc/src/inet.xml
index ed775d67eb..9fc361a234 100644
--- a/lib/kernel/doc/src/inet.xml
+++ b/lib/kernel/doc/src/inet.xml
@@ -1039,6 +1039,18 @@ setcap cap_sys_admin,cap_sys_ptrace,cap_dac_read_search+epi beam.smp
is turned on for the socket, which means that also small
amounts of data are sent immediately.
+ {nopush, Boolean}(TCP/IP sockets)
+ -
+
This translates to TCP_NOPUSH on BSD and
+ to TCP_CORK on Linux.
+ If Boolean == true, the corresponding option
+ is turned on for the socket, which means that small
+ amounts of data are accumulated until a full MSS-worth
+ of data is available or this option is turned off.
+ Note that while TCP_NOPUSH socket option is available on OSX, its semantics
+ is very different (e.g., unsetting it does not cause immediate send
+ of accumulated data). Hence, nopush option is intentionally ignored on OSX.
+
{packet, PacketType}(TCP/IP sockets)
-
Defines the type of packets to use for a socket.
diff --git a/lib/kernel/src/inet_int.hrl b/lib/kernel/src/inet_int.hrl
index c8e09d18ad..f6525d7261 100644
--- a/lib/kernel/src/inet_int.hrl
+++ b/lib/kernel/src/inet_int.hrl
@@ -162,6 +162,7 @@
-define(INET_OPT_PKTOPTIONS, 45).
-define(INET_OPT_TTL, 46).
-define(INET_OPT_RECVTTL, 47).
+-define(TCP_OPT_NOPUSH, 48).
% Specific SCTP options: separate range:
-define(SCTP_OPT_RTOINFO, 100).
-define(SCTP_OPT_ASSOCINFO, 101).
diff --git a/lib/kernel/test/inet_sockopt_SUITE.erl b/lib/kernel/test/inet_sockopt_SUITE.erl
index ada9c2689c..27ff74e309 100644
--- a/lib/kernel/test/inet_sockopt_SUITE.erl
+++ b/lib/kernel/test/inet_sockopt_SUITE.erl
@@ -110,9 +110,14 @@ simple(Config) when is_list(Config) ->
{S1,S2} = create_socketpair(Opt, Opt),
{ok,Opt} = inet:getopts(S1,OptTags),
{ok,Opt} = inet:getopts(S2,OptTags),
- COpt = [{X,case X of nodelay -> false;_ -> Y end} || {X,Y} <- Opt],
+ NoPushOpt = case os:type() of
+ {unix, Osname} when Osname =:= linux; Osname =:= freebsd -> {nopush, true};
+ {_,_} -> {nopush, false}
+ end,
+ COpt = [{X,case X of nodelay -> false;_ -> Y end} || {X,Y} <- [NoPushOpt|Opt]],
+ COptTags = [X || {X,_} <- COpt],
inet:setopts(S1,COpt),
- {ok,COpt} = inet:getopts(S1,OptTags),
+ {ok,COpt} = inet:getopts(S1,COptTags),
{ok,Opt} = inet:getopts(S2,OptTags),
gen_tcp:close(S1),
gen_tcp:close(S2),
--
cgit v1.2.3