Add a simple rate limiter with a helper to use it in logging (#1915)

interface.go

@@ -24,6 +24,7 @@ import (
 	"github.com/slackhq/nebula/overlay"
 	"github.com/slackhq/nebula/overlay/batch"
 	"github.com/slackhq/nebula/overlay/tio"
+	"github.com/slackhq/nebula/ratelimit"
 	"github.com/slackhq/nebula/udp"
 )
 
@@ -124,6 +125,9 @@ type Interface struct {
 	batchers []*batch.MultiCoalescer
 	wg       sync.WaitGroup
 
+	udpTxErrLimiter      *ratelimit.Limiter // udp direct transmit error log limiter
+	udpRelayTxErrLimiter *ratelimit.Limiter // udp relay transmit error log limiter
+
 	// fatalErr holds the first unexpected reader error that caused shutdown.
 	// nil means "no fatal error" (yet)
 	fatalErr atomic.Pointer[error]
@@ -198,6 +202,15 @@ func NewInterface(ctx context.Context, c *InterfaceConfig) (*Interface, error) {
 		return nil, errors.New("no connection manager")
 	}
 
+	udpTxErrLimiter, err := ratelimit.New(1, time.Second)
+	if err != nil {
+		return nil, err
+	}
+	udpRelayTxErrLimiter, err := ratelimit.New(1, time.Second)
+	if err != nil {
+		return nil, err
+	}
+
 	if c.routines <= 1 {
 		c.PinThreads = false //pinning is not useful unless there's more than one tun reader
 	}
@@ -230,6 +243,8 @@ func NewInterface(ctx context.Context, c *InterfaceConfig) (*Interface, error) {
 		conntrackCacheTimeout: c.ConntrackCacheTimeout,
 		cpuAffinity:           c.CpuAffinity,
 		pinThreads:            c.PinThreads,
+		udpTxErrLimiter:       udpTxErrLimiter,
+		udpRelayTxErrLimiter:  udpRelayTxErrLimiter,
 
 		metricHandshakes: metrics.GetOrRegisterHistogram("handshakes", nil, metrics.NewExpDecaySample(1028, 0.015)),
 		metricTxDropped:  metrics.GetOrRegisterCounter("udp.tx.dropped", nil),