From: Vsevolod Stakhov <vsevolod@rspamd.com>
Date: Wed, 8 Oct 2025 09:54:56 +0000 (+0100)
Subject: [Minor] Fuzzy TCP: enable TCP_NODELAY for reduced latency
X-Git-Tag: 3.14.0~84^2~4
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c4999f8d625d8e8e898a7675addcb4a8c41ed804;p=thirdparty%2Frspamd.git

[Minor] Fuzzy TCP: enable TCP_NODELAY for reduced latency

Disables Nagle's algorithm on fuzzy TCP connections to minimize latency
for request-response traffic patterns. This prevents small packets from
being buffered, which is optimal for the fuzzy check protocol.
---

diff --git a/src/plugins/fuzzy_check.c b/src/plugins/fuzzy_check.c
index aad5ae3436..d11339feb9 100644
--- a/src/plugins/fuzzy_check.c
+++ b/src/plugins/fuzzy_check.c
@@ -643,6 +643,18 @@ fuzzy_tcp_connect_async(struct fuzzy_rule *rule,
 		return NULL;
 	}
 
+	/* Set TCP_NODELAY to disable Nagle's algorithm - reduces latency for request-response traffic */
+#ifdef TCP_NODELAY
+	{
+		int nodelay = 1;
+		if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &nodelay, sizeof(nodelay)) == -1) {
+			msg_warn_task("fuzzy_tcp: cannot set TCP_NODELAY for %s: %s",
+						  rspamd_inet_address_to_string_pretty(addr),
+						  strerror(errno));
+		}
+	}
+#endif
+
 	/* Create connection structure */
 	conn = fuzzy_tcp_connection_new(rule, task->event_loop);
 	conn->fd = fd;