From 1239ed49cf56d19329c9bf951e92c34a5798445b Mon Sep 17 00:00:00 2001
From: Auston <amcrn@users.noreply.github.com>
Date: Thu, 14 Sep 2023 13:56:02 -0700
Subject: [PATCH] Update session.go

The `HostFilter` is not being used for the Control Connection (aka
the `controlConn`). This can be problematic, especially if the host
is being filtered due to it being in a bad state, as it can hold up
the creation of the Control Connection (and therefore the Session
itself) for quite some time.
---
 session.go | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/session.go b/session.go
index 0eac4cf0e..fcb068b49 100644
--- a/session.go
+++ b/session.go
@@ -198,6 +198,22 @@ func (s *Session) init() error {
 	}
 	s.ring.endpoints = hosts
 
+	// filter hosts at the onset to avoid using using filtered hosts in the control connection while
+	// discovering the protocol and/or connecting.
+	if s.cfg.HostFilter != nil {
+		newHosts := make([]*HostInfo, 0, len(hosts))
+		for _, host := range hosts {
+			if !s.cfg.filterHost(host) {
+				newHosts = append(newHosts, host)
+			}
+		}
+		if len(newHosts) > 0 {
+			hosts = newHosts
+		} else {
+			s.logger.Printf("gocql: hostfilter removed all hosts, defaulting to initial host list\n")
+		}
+	}
+
 	if !s.cfg.disableControlConn {
 		s.control = createControlConn(s)
 		if s.cfg.ProtoVersion == 0 {