From: Willy Tarreau <w@1wt.eu>
Date: Wed, 19 Aug 2009 09:14:11 +0000 (+0200)
Subject: [MEDIUM] remove TCP_CORK and make use of MSG_MORE instead
X-Git-Tag: v1.4-dev3~32
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6db06d3870ad4574414958574f1b5cf7a3f25997;p=thirdparty%2Fhaproxy.git

[MEDIUM] remove TCP_CORK and make use of MSG_MORE instead

send() supports the MSG_MORE flag on Linux, which does the same
as TCP_CORK except that we don't have to remove TCP_NODELAY before
and we don't need any syscall to set/remove it. This can save up
to 4 syscalls around a send() (two for setting it, two for removing
it), and it's much cleaner since it is not persistent. So make use
of it instead.
---

diff --git a/include/common/compat.h b/include/common/compat.h
index dec5d7d430..8ddb72db9e 100644
--- a/include/common/compat.h
+++ b/include/common/compat.h
@@ -66,6 +66,11 @@
 #define MSG_DONTWAIT	0
 #endif
 
+/* Only Linux defines MSG_MORE */
+#ifndef MSG_MORE
+#define MSG_MORE	0
+#endif
+
 #if defined(TPROXY) && defined(NETFILTER)
 #include <linux/types.h>
 #include <linux/netfilter_ipv6.h>
diff --git a/include/types/fd.h b/include/types/fd.h
index a50d076c37..3ab89feba8 100644
--- a/include/types/fd.h
+++ b/include/types/fd.h
@@ -63,8 +63,7 @@ enum {
  */
 #define FD_FL_TCP               0x0001       /* socket is TCP */
 #define FD_FL_TCP_NODELAY       0x0002
-#define FD_FL_TCP_CORK          0x0004
-#define FD_FL_TCP_NOLING        0x0008       /* lingering disabled */
+#define FD_FL_TCP_NOLING        0x0004       /* lingering disabled */
 
 /* info about one given fd */
 struct fdtab {
diff --git a/src/stream_sock.c b/src/stream_sock.c
index f563755edd..79426fb14b 100644
--- a/src/stream_sock.c
+++ b/src/stream_sock.c
@@ -585,28 +585,28 @@ static int stream_sock_write_loop(struct stream_interface *si, struct buffer *b)
 		if (max > b->send_max)
 			max = b->send_max;
 
-
-#if defined(TCP_CORK) && defined(SOL_TCP)
-		/*
-		 * Check if we want to cork output before sending. This typically occurs
-		 * when there are data left in the buffer, or when we reached the end of
-		 * buffer but we know we will close, so we try to merge the ongoing FIN
-		 * with the last data segment.
+		/* check if we want to inform the kernel that we're interested in
+		 * sending more data after this call. We want this if :
+		 *  - we're about to close after this last send and want to merge
+		 *    the ongoing FIN with the last segment.
+		 *  - we know we can't send everything at once and must get back
+		 *    here because of unaligned data
+		 * The test is arranged so that the most common case does only 2
+		 * tests.
 		 */
-		if ((fdtab[si->fd].flags & (FD_FL_TCP|FD_FL_TCP_NOLING|FD_FL_TCP_CORK)) == FD_FL_TCP) {
-			if (unlikely((b->send_max == b->l && 
-				      (b->flags & (BF_SHUTW|BF_SHUTW_NOW|BF_HIJACK|BF_WRITE_ENA|BF_SHUTR)) ==
-				      (BF_WRITE_ENA|BF_SHUTR)))) {
-				/* we have to unconditionally reset TCP_NODELAY for CORK */
-				setsockopt(si->fd, IPPROTO_TCP, TCP_NODELAY, (char *) &zero, sizeof(zero));
-				setsockopt(si->fd, SOL_TCP, TCP_CORK, (char *) &one, sizeof(one));
-				fdtab[si->fd].flags = (fdtab[si->fd].flags & ~FD_FL_TCP_NODELAY) | FD_FL_TCP_CORK;
-			}
-		}
-#endif
 
 		if (MSG_NOSIGNAL) {
-			ret = send(si->fd, b->w, max, MSG_DONTWAIT | MSG_NOSIGNAL);
+			unsigned int send_flag = MSG_DONTWAIT | MSG_NOSIGNAL;
+
+			if (MSG_MORE &&
+			    (((b->flags & (BF_SHUTW|BF_SHUTW_NOW|BF_HIJACK|BF_WRITE_ENA|BF_SHUTR)) == (BF_WRITE_ENA|BF_SHUTR) &&
+			      (max == b->l)) ||
+			     (max != b->l && max != b->send_max))
+			    && (fdtab[si->fd].flags & FD_FL_TCP)) {
+				send_flag |= MSG_MORE;
+			}
+
+			ret = send(si->fd, b->w, max, send_flag);
 		} else {
 			int skerr;
 			socklen_t lskerr = sizeof(skerr);
@@ -662,21 +662,6 @@ static int stream_sock_write_loop(struct stream_interface *si, struct buffer *b)
 		}
 	} /* while (1) */
 
-	/* check if we need to uncork the output, for instance when the
-	 * output buffer is empty but not shutr().
-	 */
-	if (unlikely((fdtab[si->fd].flags & (FD_FL_TCP|FD_FL_TCP_NODELAY)) == FD_FL_TCP && (b->flags & BF_EMPTY))) {
-		if ((b->flags & (BF_SHUTW|BF_SHUTW_NOW|BF_HIJACK|BF_WRITE_ENA|BF_SHUTR)) != (BF_WRITE_ENA|BF_SHUTR)) {
-#if defined(TCP_CORK) && defined(SOL_TCP)
-			if (fdtab[si->fd].flags & FD_FL_TCP_CORK)
-				setsockopt(si->fd, SOL_TCP, TCP_CORK, (char *) &zero, sizeof(zero));
-#endif
-			setsockopt(si->fd, IPPROTO_TCP, TCP_NODELAY, (char *) &one, sizeof(one));
-			fdtab[si->fd].flags = (fdtab[si->fd].flags & ~FD_FL_TCP_CORK) | FD_FL_TCP_NODELAY;
-		}
-	}
-
-
 	return retval;
 }