From: Susant Sahani <susant@redhat.com>
Date: Mon, 28 Jul 2014 06:48:29 +0000 (+0530)
Subject: socket: add support for tcp nagle
X-Git-Tag: v216~125
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=commitdiff_plain;h=4427c3f43a87c2e0c784fda6be1b9715be820733;hp=e9e74f28d783a052dce7edfa94d7918bb591ba7a

socket: add support for tcp nagle

This patch adds support for TCP TCP_NODELAY socket option. This can be
configured via NoDelay conf parameter. TCP Nagle's algorithm works by
combining a number of small outgoing messages, and sending them all at
once.  This controls the TCP_NODELAY socket option.
---

diff --git a/man/systemd.socket.xml b/man/systemd.socket.xml
index 9c9af531e..352825f58 100644
--- a/man/systemd.socket.xml
+++ b/man/systemd.socket.xml
@@ -487,6 +487,17 @@
                                 <option>false</option>.</para></listitem>
                         </varlistentry>
 
+                        <varlistentry>
+                                <term><varname>NoDelay=</varname></term>
+                                <listitem><para>Takes a boolean
+                                argument. TCP Nagle's algorithm works by combining a number of
+                                small outgoing messages, and sending them all at once.
+                                This controls the TCP_NODELAY socket option (see
+                                <citerefentry><refentrytitle>tcp</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+                                Defaults to
+                                <option>false</option>.</para></listitem>
+                        </varlistentry>
+
                         <varlistentry>
                                 <term><varname>Priority=</varname></term>
                                 <listitem><para>Takes an integer
diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4
index d70f9eed3..f4acdda22 100644
--- a/src/core/load-fragment-gperf.gperf.m4
+++ b/src/core/load-fragment-gperf.gperf.m4
@@ -231,6 +231,7 @@ Socket.DirectoryMode,            config_parse_mode,                  0,
 Socket.Accept,                   config_parse_bool,                  0,                             offsetof(Socket, accept)
 Socket.MaxConnections,           config_parse_unsigned,              0,                             offsetof(Socket, max_connections)
 Socket.KeepAlive,                config_parse_bool,                  0,                             offsetof(Socket, keep_alive)
+Socket.NoDelay,                  config_parse_bool,                  0,                             offsetof(Socket, no_delay)
 Socket.Priority,                 config_parse_int,                   0,                             offsetof(Socket, priority)
 Socket.ReceiveBuffer,            config_parse_iec_size,              0,                             offsetof(Socket, receive_buffer)
 Socket.SendBuffer,               config_parse_iec_size,              0,                             offsetof(Socket, send_buffer)
diff --git a/src/core/socket.c b/src/core/socket.c
index 646887d80..5af15964f 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -480,6 +480,7 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) {
                 "%sSocketMode: %04o\n"
                 "%sDirectoryMode: %04o\n"
                 "%sKeepAlive: %s\n"
+                "%sNoDelay: %s\n"
                 "%sFreeBind: %s\n"
                 "%sTransparent: %s\n"
                 "%sBroadcast: %s\n"
@@ -494,6 +495,7 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) {
                 prefix, s->socket_mode,
                 prefix, s->directory_mode,
                 prefix, yes_no(s->keep_alive),
+                prefix, yes_no(s->no_delay),
                 prefix, yes_no(s->free_bind),
                 prefix, yes_no(s->transparent),
                 prefix, yes_no(s->broadcast),
@@ -790,6 +792,12 @@ static void socket_apply_socket_options(Socket *s, int fd) {
                         log_warning_unit(UNIT(s)->id, "SO_KEEPALIVE failed: %m");
         }
 
+        if (s->no_delay) {
+                int b = s->no_delay;
+                if (setsockopt(fd, SOL_TCP, TCP_NODELAY, &b, sizeof(b)) < 0)
+                        log_warning_unit(UNIT(s)->id, "TCP_NODELAY failed: %m");
+        }
+
         if (s->broadcast) {
                 int one = 1;
                 if (setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &one, sizeof(one)) < 0)
diff --git a/src/core/socket.h b/src/core/socket.h
index 814a3bfab..98396e732 100644
--- a/src/core/socket.h
+++ b/src/core/socket.h
@@ -134,6 +134,7 @@ struct Socket {
 
         /* Socket options */
         bool keep_alive;
+        bool no_delay;
         bool free_bind;
         bool transparent;
         bool broadcast;