MEDIUM: tcp: add explicit support for delayed ACK in connect()
Commit 24db47e0 tried to improve support for delayed ACK upon connect
but it was incomplete, because checks with the proxy protocol would
always enable polling for data receive and there was no way of
distinguishing data polling and delayed ack.
So we add a distinct delack flag to the connect() function so that
the caller decides whether or not to use a delayed ack regardless
of pending data (eg: when send-proxy is in use). Doing so covers all
combinations of { (check with data), (sendproxy), (smart-connect) }.
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index 2b8d148..fd9b03d 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -221,12 +221,13 @@
* bind addresses are still determined locally (due to the possible need of a
* source port). conn->target may point either to a valid server or to a backend,
* depending on conn->target. Only OBJ_TYPE_PROXY and OBJ_TYPE_SERVER are
- * supported. The <data> parameter indicates when non-zero that data will
- * immediately follow the connection and will tune the ACK behaviour after
- * the connect :
- * - 0 = always send it
- * - 1 = send it unless the backends has the tcp-smart-connect option
- * - 2 = never send it
+ * supported. The <data> parameter is a boolean indicating whether there are data
+ * waiting for being sent or not, in order to adjust data write polling and on
+ * some platforms, the ability to avoid an empty initial ACK. The <delack> argument
+ * allows the caller to force using a delayed ACK when establishing the connection :
+ * - 0 = no delayed ACK unless data are advertised and backend has tcp-smart-connect
+ * - 1 = delayed ACK if backend has tcp-smart-connect, regardless of data
+ * - 2 = delayed ACK regardless of backend options
*
* It can return one of :
* - SN_ERR_NONE if everything's OK
@@ -241,7 +242,7 @@
* it's invalid and the caller has nothing to do.
*/
-int tcp_connect_server(struct connection *conn, int data)
+int tcp_connect_server(struct connection *conn, int data, int delack)
{
int fd;
struct server *srv;
@@ -421,9 +422,9 @@
#if defined(TCP_QUICKACK)
/* disabling tcp quick ack now allows the first request to leave the
* machine with the first ACK. We only do this if there are pending
- * data in the buffer or if we plan to close after SYN/ACK (TCP checks).
+ * data in the buffer.
*/
- if (data == 2 || (data && (be->options2 & PR_O2_SMARTCON)))
+ if (delack == 2 || ((delack || data) && (be->options2 & PR_O2_SMARTCON)))
setsockopt(fd, IPPROTO_TCP, TCP_QUICKACK, &zero, sizeof(zero));
#endif