add undocumented tuning variables, they might change

Signed-off-by: Kristoffer Dalby <[email protected]>

hscontrol/poll.go

@@ -18,7 +18,6 @@ import (
 	"github.com/rs/zerolog/log"
 	xslices "golang.org/x/exp/slices"
 	"gorm.io/gorm"
-	"tailscale.com/envknob"
 	"tailscale.com/tailcfg"
 )
 
@@ -65,12 +64,7 @@ func (h *Headscale) newMapSession(
 	// Use a buffered channel in case a node is not fully ready
 	// to receive a message to make sure we dont block the entire
 	// notifier.
-	// 12 is arbitrarily chosen.
-	chanSize := 3000
-	if size, ok := envknob.LookupInt("HEADSCALE_TUNING_POLL_QUEUE_SIZE"); ok {
-		chanSize = size
-	}
-	updateChan := make(chan types.StateUpdate, chanSize)
+	updateChan := make(chan types.StateUpdate, h.cfg.Tuning.NodeMapSessionBufferedChanSize)
 
 	return &mapSession{
 		h:      h,

hscontrol/types/config.go

@@ -69,6 +69,8 @@ type Config struct {
 	CLI CLIConfig
 
 	ACL ACLConfig
+
+	Tuning Tuning
 }
 
 type SqliteConfig struct {
@@ -161,6 +163,11 @@ type LogConfig struct {
 	Level  zerolog.Level
 }
 
+type Tuning struct {
+	BatchChangeDelay               time.Duration
+	NodeMapSessionBufferedChanSize int
+}
+
 func LoadConfig(path string, isFile bool) error {
 	if isFile {
 		viper.SetConfigFile(path)
@@ -220,6 +227,9 @@ func LoadConfig(path string, isFile bool) error {
 
 	viper.SetDefault("node_update_check_interval", "10s")
 
+	viper.SetDefault("tuning.batch_change_delay", "800ms")
+	viper.SetDefault("tuning.node_mapsession_buffered_chan_size", 30)
+
 	if IsCLIConfigured() {
 		return nil
 	}
@@ -719,6 +729,12 @@ func GetHeadscaleConfig() (*Config, error) {
 		},
 
 		Log: GetLogConfig(),
+
+		// TODO(kradalby): Document these settings when more stable
+		Tuning: Tuning{
+			BatchChangeDelay:               viper.GetDuration("tuning.batch_change_delay"),
+			NodeMapSessionBufferedChanSize: viper.GetInt("tuning.node_mapsession_buffered_chan_size"),
+		},
 	}, nil
 }