From: Timo Sirainen <timo.sirainen@open-xchange.com>
Date: Wed, 6 Nov 2019 12:39:25 +0000 (+0200)
Subject: lib: ostream-file - Set TCP_QUICKACK whenever uncorking
X-Git-Tag: 2.3.10~308
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=94ca934518b5ef17755ae47d914a0319c3256476;p=thirdparty%2Fdovecot%2Fcore.git

lib: ostream-file - Set TCP_QUICKACK whenever uncorking

This reduces latency in some situations.
---

diff --git a/src/lib/ostream-file-private.h b/src/lib/ostream-file-private.h
index bb0acb25df..2d58933559 100644
--- a/src/lib/ostream-file-private.h
+++ b/src/lib/ostream-file-private.h
@@ -25,6 +25,7 @@ struct file_ostream {
 	bool socket_cork_set:1;
 	bool no_socket_cork:1;
 	bool no_socket_nodelay:1;
+	bool no_socket_quickack:1;
 	bool no_sendfile:1;
 	bool autoclose_fd:1;
 };
diff --git a/src/lib/ostream-file.c b/src/lib/ostream-file.c
index 82bf729ac0..e3a85e2b4f 100644
--- a/src/lib/ostream-file.c
+++ b/src/lib/ostream-file.c
@@ -387,6 +387,12 @@ static void o_stream_file_cork(struct ostream_private *stream, bool set)
 			   output is sent outside corking it may get delayed. */
 			o_stream_tcp_flush_via_nodelay(fstream);
 		}
+		if (!set && !fstream->no_socket_quickack) {
+			/* Uncorking - disable delayed ACKs to reduce latency.
+			   Note that this needs to be set repeatedly. */
+			if (net_set_tcp_quickack(fstream->fd, TRUE) < 0)
+				fstream->no_socket_quickack = TRUE;
+		}
 		stream->corked = set;
 	}
 }
@@ -1026,6 +1032,7 @@ static void fstream_init_file(struct file_ostream *fstream)
 	if (S_ISREG(st.st_mode)) {
 		fstream->no_socket_cork = TRUE;
 		fstream->no_socket_nodelay = TRUE;
+		fstream->no_socket_quickack = TRUE;
 		fstream->file = TRUE;
 	}
 }
@@ -1056,10 +1063,12 @@ struct ostream * o_stream_create_fd_common(int fd, size_t max_buffer_size,
 			fstream->no_sendfile = TRUE;
 			fstream->no_socket_cork = TRUE;
 			fstream->no_socket_nodelay = TRUE;
+			fstream->no_socket_quickack = TRUE;
 		} else if (local_ip.family == 0) {
 			/* UNIX domain socket */
 			fstream->no_socket_cork = TRUE;
 			fstream->no_socket_nodelay = TRUE;
+			fstream->no_socket_quickack = TRUE;
 		}
 	}