drop in a logger

overlay/batch/multi_coalesce.go

@@ -3,6 +3,7 @@ package batch
 import (
 	"errors"
 	"io"
+	"log/slog"
 )
 
 // MultiCoalescer fans plaintext packets out to lane-specific batchers based
@@ -36,13 +37,13 @@ type MultiCoalescer struct {
 // opt out of TCP coalescing (e.g. when the queue can't do TSO); udpEnabled
 // likewise gates UDP coalescing (only enable when USO was negotiated).
 // Either lane disabled redirects its traffic into the passthrough lane.
-func NewMultiCoalescer(w io.Writer, tcpEnabled, udpEnabled bool) *MultiCoalescer {
+func NewMultiCoalescer(w io.Writer, l *slog.Logger, tcpEnabled, udpEnabled bool) *MultiCoalescer {
 	m := &MultiCoalescer{
 		pt:      NewPassthrough(w),
 		backing: make([]byte, 0, initialSlots*65535),
 	}
 	if tcpEnabled {
-		m.tcp = NewTCPCoalescer(w)
+		m.tcp = NewTCPCoalescer(w, l)
 	}
 	if udpEnabled {
 		m.udp = NewUDPCoalescer(w)

overlay/batch/multi_coalesce_test.go

@@ -2,6 +2,8 @@ package batch
 
 import (
 	"testing"
+
+	"github.com/slackhq/nebula/test"
 )
 
 // TestMultiCoalescerRoutesByProto confirms TCP/UDP/other land in the right
@@ -9,7 +11,7 @@ import (
 // else (ICMP here) falls through to plain Write.
 func TestMultiCoalescerRoutesByProto(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	m := NewMultiCoalescer(w, true, true)
+	m := NewMultiCoalescer(w, test.NewLogger(), true, true)
 
 	tcpPay := make([]byte, 1200)
 	udpPay := make([]byte, 1200)
@@ -51,7 +53,7 @@ func TestMultiCoalescerRoutesByProto(t *testing.T) {
 // the kernel via the passthrough lane rather than being lost.
 func TestMultiCoalescerDisabledUDPFallsThrough(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	m := NewMultiCoalescer(w, true, false) // TSO on, USO off
+	m := NewMultiCoalescer(w, test.NewLogger(), true, false) // TSO on, USO off
 
 	if err := m.Commit(buildUDPv4(1000, 53, make([]byte, 800))); err != nil {
 		t.Fatal(err)
@@ -73,7 +75,7 @@ func TestMultiCoalescerDisabledUDPFallsThrough(t *testing.T) {
 // TestMultiCoalescerDisabledTCPFallsThrough mirrors the TSO=off case.
 func TestMultiCoalescerDisabledTCPFallsThrough(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	m := NewMultiCoalescer(w, false, true) // TSO off, USO on
+	m := NewMultiCoalescer(w, test.NewLogger(), false, true) // TSO off, USO on
 
 	pay := make([]byte, 1200)
 	if err := m.Commit(buildTCPv4(1000, tcpAck, pay)); err != nil {

overlay/batch/tcp_coalesce.go

@@ -2,6 +2,7 @@ package batch
 
 import (
 	"bytes"
+	"context"
 	"encoding/binary"
 	"io"
 	"log/slog"
@@ -84,15 +85,17 @@ type TCPCoalescer struct {
 	pool     []*coalesceSlot // free list for reuse
 
 	backing []byte
+	l       *slog.Logger
 }
 
-func NewTCPCoalescer(w io.Writer) *TCPCoalescer {
+func NewTCPCoalescer(w io.Writer, l *slog.Logger) *TCPCoalescer {
 	c := &TCPCoalescer{
 		plainW:    w,
 		slots:     make([]*coalesceSlot, 0, initialSlots),
 		openSlots: make(map[flowKey]*coalesceSlot, initialSlots),
 		pool:      make([]*coalesceSlot, 0, initialSlots),
 		backing:   make([]byte, 0, initialSlots*65535),
+		l:         l,
 	}
 	if gw, ok := tio.SupportsGSO(w, tio.GSOProtoTCP); ok {
 		c.gsoW = gw
@@ -488,22 +491,25 @@ func (c *TCPCoalescer) reorderForFlush() {
 				// the operator can quantify how often it happens; the data
 				// itself still emits in seq order, kernel TCP handles the
 				// gap via its OOO queue.
-				if prev.nextSeq != slotSeedSeq(s) {
-					logged = true
-					gap := int64(slotSeedSeq(s)) - int64(prev.nextSeq)
-					slog.Default().Warn("tcp coalesce: cross-slot seq gap",
-						"src", flowKeyAddr(s.fk, false),
-						"dst", flowKeyAddr(s.fk, true),
-						"sport", s.fk.sport,
-						"dport", s.fk.dport,
-						"prev_seed_seq", slotSeedSeq(prev),
-						"prev_next_seq", prev.nextSeq,
-						"this_seed_seq", slotSeedSeq(s),
-						"gap_bytes", gap,
-						"prev_seg_count", prev.numSeg,
-						"prev_total_pay", prev.totalPay,
-					)
+				if c.l.Enabled(context.Background(), slog.LevelDebug) {
+					if prev.nextSeq != slotSeedSeq(s) {
+						logged = true
+						gap := int64(slotSeedSeq(s)) - int64(prev.nextSeq)
+						c.l.Debug("tcp coalesce: cross-slot seq gap",
+							"src", flowKeyAddr(s.fk, false),
+							"dst", flowKeyAddr(s.fk, true),
+							"sport", s.fk.sport,
+							"dport", s.fk.dport,
+							"prev_seed_seq", slotSeedSeq(prev),
+							"prev_next_seq", prev.nextSeq,
+							"this_seed_seq", slotSeedSeq(s),
+							"gap_bytes", gap,
+							"prev_seg_count", prev.numSeg,
+							"prev_total_pay", prev.totalPay,
+						)
+					}
 				}
+
 				if canMergeSlots(prev, s) {
 					mergeSlots(prev, s)
 					c.release(s)
@@ -514,7 +520,7 @@ func (c *TCPCoalescer) reorderForFlush() {
 		out = append(out, s)
 	}
 	if logged {
-		slog.Default().Warn("==== end of batch ====")
+		c.l.Warn("==== end of batch ====")
 	}
 	c.slots = out
 }

overlay/batch/tcp_coalesce_bench_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/slackhq/nebula/overlay/tio"
+	"github.com/slackhq/nebula/test"
 )
 
 // nopTunWriter is a zero-alloc tio.GSOWriter for benchmarks. Discards
@@ -70,7 +71,7 @@ func buildICMPv4() []byte {
 // between batches, and reports per-packet cost.
 func runCommitBench(b *testing.B, pkts [][]byte, batchSize int) {
 	b.Helper()
-	c := NewTCPCoalescer(nopTunWriter{})
+	c := NewTCPCoalescer(nopTunWriter{}, test.NewLogger())
 	b.ReportAllocs()
 	b.SetBytes(int64(len(pkts[0])))
 	b.ResetTimer()
@@ -139,7 +140,7 @@ func BenchmarkCommitNonCoalesceableTCP(b *testing.B) {
 // is the bench that shows the savings of skipping the lane's re-parse.
 func runMultiCommitBench(b *testing.B, pkts [][]byte, batchSize int) {
 	b.Helper()
-	m := NewMultiCoalescer(nopTunWriter{}, true, true)
+	m := NewMultiCoalescer(nopTunWriter{}, test.NewLogger(), true, true)
 	b.ReportAllocs()
 	b.SetBytes(int64(len(pkts[0])))
 	b.ResetTimer()

overlay/batch/tcp_coalesce_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/slackhq/nebula/overlay/tio"
+	"github.com/slackhq/nebula/test"
 )
 
 // fakeTunWriter records plain Writes and WriteGSO calls without touching a
@@ -127,7 +128,7 @@ const (
 
 func TestCoalescerPassthroughWhenGSOUnavailable(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: false}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pkt := buildTCPv4(1000, tcpAck, []byte("hello"))
 	if err := c.Commit(pkt); err != nil {
 		t.Fatal(err)
@@ -146,7 +147,7 @@ func TestCoalescerPassthroughWhenGSOUnavailable(t *testing.T) {
 
 func TestCoalescerNonTCPPassthrough(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pkt := make([]byte, 28)
 	pkt[0] = 0x45
 	binary.BigEndian.PutUint16(pkt[2:4], 28)
@@ -166,7 +167,7 @@ func TestCoalescerNonTCPPassthrough(t *testing.T) {
 
 func TestCoalescerSeedThenFlushAlone(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pkt := buildTCPv4(1000, tcpAck, make([]byte, 1000))
 	if err := c.Commit(pkt); err != nil {
 		t.Fatal(err)
@@ -193,7 +194,7 @@ func TestCoalescerSeedThenFlushAlone(t *testing.T) {
 
 func TestCoalescerCoalescesAdjacentACKs(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	if err := c.Commit(buildTCPv4(1000, tcpAck, pay)); err != nil {
 		t.Fatal(err)
@@ -233,7 +234,7 @@ func TestCoalescerCoalescesAdjacentACKs(t *testing.T) {
 
 func TestCoalescerRejectsSeqGap(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	if err := c.Commit(buildTCPv4(1000, tcpAck, pay)); err != nil {
 		t.Fatal(err)
@@ -252,7 +253,7 @@ func TestCoalescerRejectsSeqGap(t *testing.T) {
 
 func TestCoalescerRejectsFlagMismatch(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	if err := c.Commit(buildTCPv4(1000, tcpAck, pay)); err != nil {
 		t.Fatal(err)
@@ -273,7 +274,7 @@ func TestCoalescerRejectsFlagMismatch(t *testing.T) {
 
 func TestCoalescerRejectsFIN(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	fin := buildTCPv4(1000, tcpAck|tcpFin, []byte("x"))
 	if err := c.Commit(fin); err != nil {
 		t.Fatal(err)
@@ -289,7 +290,7 @@ func TestCoalescerRejectsFIN(t *testing.T) {
 
 func TestCoalescerShortLastSegmentClosesChain(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	full := make([]byte, 1200)
 	half := make([]byte, 500)
 	if err := c.Commit(buildTCPv4(1000, tcpAck, full)); err != nil {
@@ -324,7 +325,7 @@ func TestCoalescerShortLastSegmentClosesChain(t *testing.T) {
 
 func TestCoalescerPSHFinalizesChain(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	if err := c.Commit(buildTCPv4(1000, tcpAck, pay)); err != nil {
 		t.Fatal(err)
@@ -354,7 +355,7 @@ func TestCoalescerPSHFinalizesChain(t *testing.T) {
 // coalescer drops it the sender's push signal never reaches the receiver.
 func TestCoalescerPropagatesPSHFromAppended(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	// Seed has no PSH; second segment carries PSH and seals the chain.
 	if err := c.Commit(buildTCPv4(1000, tcpAck, pay)); err != nil {
@@ -382,7 +383,7 @@ func TestCoalescerPropagatesPSHFromAppended(t *testing.T) {
 
 func TestCoalescerRejectsDifferentFlow(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	p1 := buildTCPv4(1000, tcpAck, pay)
 	p2 := buildTCPv4(2200, tcpAck, pay)
@@ -404,7 +405,7 @@ func TestCoalescerRejectsDifferentFlow(t *testing.T) {
 
 func TestCoalescerRejectsIPOptions(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 500)
 	pkt := buildTCPv4(1000, tcpAck, pay)
 	// Bump IHL to 6 to simulate 4 bytes of IP options. Don't actually add
@@ -424,7 +425,7 @@ func TestCoalescerRejectsIPOptions(t *testing.T) {
 
 func TestCoalescerCapBySegments(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 512)
 	seq := uint32(1000)
 	for i := 0; i < tcpCoalesceMaxSegs+5; i++ {
@@ -448,7 +449,7 @@ func TestCoalescerCapBySegments(t *testing.T) {
 // flows coalesce independently in a single Flush.
 func TestCoalescerMultipleFlowsInSameBatch(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 
 	// Flow A: sport 1000. Flow B: sport 3000.
@@ -505,7 +506,7 @@ func TestCoalescerMultipleFlowsInSameBatch(t *testing.T) {
 // writing passthrough packets synchronously.
 func TestCoalescerPreservesArrivalOrder(t *testing.T) {
 	w := &orderedFakeWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	// Sequence: coalesceable TCP, ICMP (passthrough), coalesceable TCP on
 	// a different flow. Expected emit order: gso(X), plain(ICMP), gso(Y).
 	pay := make([]byte, 1200)
@@ -573,7 +574,7 @@ func stringSliceEq(a, b []string) bool {
 // packet (SYN) mid-flow only flushes its own flow, not others.
 func TestCoalescerInterleavedFlowsPreserveOrdering(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 
 	// Flow A two segments.
@@ -678,7 +679,7 @@ func buildTCPv6(tcLow byte, seq uint32, flags byte, payload []byte) []byte {
 // retains ECE on the wire.
 func TestCoalescerCoalescesEceFlow(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	flags := byte(tcpAck | tcpEce)
 	if err := c.Commit(buildTCPv4(1000, flags, pay)); err != nil {
@@ -707,7 +708,7 @@ func TestCoalescerCoalescesEceFlow(t *testing.T) {
 // in-flow segment seeds a new slot rather than extending the prior burst.
 func TestCoalescerCwrSealsFlow(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	if err := c.Commit(buildTCPv4(1000, tcpAck, pay)); err != nil {
 		t.Fatal(err)
@@ -740,7 +741,7 @@ func TestCoalescerCwrSealsFlow(t *testing.T) {
 // a CE-echoing window or none.
 func TestCoalescerEceMismatchReseeds(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	if err := c.Commit(buildTCPv4(1000, tcpAck|tcpEce, pay)); err != nil {
 		t.Fatal(err)
@@ -765,7 +766,7 @@ func TestCoalescerEceMismatchReseeds(t *testing.T) {
 // CE-marked packet still coalesces, and the merged superpacket carries CE.
 func TestCoalescerMergesCEMark(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	if err := c.Commit(buildTCPv4WithToS(ecnECT0, 1000, tcpAck, pay)); err != nil {
 		t.Fatal(err)
@@ -796,7 +797,7 @@ func TestCoalescerMergesCEMark(t *testing.T) {
 // headersMatch did not also relax DSCP — different DSCP must still split.
 func TestCoalescerDscpMismatchReseeds(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	// Same ECN (Not-ECT), different DSCP (0x10 vs 0x20 in upper 6 bits).
 	tosA := byte(0x10<<2) | ecnNotECT
@@ -819,7 +820,7 @@ func TestCoalescerDscpMismatchReseeds(t *testing.T) {
 // TestCoalescerCoalescesEceFlow.
 func TestCoalescerIPv6CoalescesEceFlow(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	flags := byte(tcpAck | tcpEce)
 	if err := c.Commit(buildTCPv6(0, 1000, flags, pay)); err != nil {
@@ -850,7 +851,7 @@ func TestCoalescerIPv6CoalescesEceFlow(t *testing.T) {
 // seen had the wire never reordered.
 func TestCoalescerSortsReorderedSeedsAndMerges(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	// Arrival order: seq 1000, 3400, 2200. The 3400 seeds a separate slot
 	// because 3400 != nextSeq=2200, then 2200 fails to extend the 3400 slot
@@ -886,7 +887,7 @@ func TestCoalescerSortsReorderedSeedsAndMerges(t *testing.T) {
 // without any cross-flow contamination.
 func TestCoalescerSortAcrossFlowsMergesEachIndependently(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	// Flow A (sport 1000) seq 100, 1300; flow B (sport 3000) seq 500, 1700.
 	// Arrival: A.1300, B.1700, A.100, B.500 — every flow reordered.
@@ -937,7 +938,7 @@ func TestCoalescerSortAcrossFlowsMergesEachIndependently(t *testing.T) {
 // boundary by an arbitrary number of segments.
 func TestCoalescerSortKeepsPSHBoundary(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	// Seq 1000 (no PSH) + 2200 (PSH) → seal one slot with PSH set.
 	// Seq 3400 (no PSH) is contiguous to 3400 from seq 2200+1200; without
@@ -965,7 +966,7 @@ func TestCoalescerSortKeepsPSHBoundary(t *testing.T) {
 // is sorted/merged independently.
 func TestCoalescerSortKeepsPassthroughBarrier(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	// First two segments seed S1 (then a 3400 reorder seeds S2).
 	if err := c.Commit(buildTCPv4(1000, tcpAck, pay)); err != nil {
@@ -998,7 +999,7 @@ func TestCoalescerSortKeepsPassthroughBarrier(t *testing.T) {
 // TestCoalescerMergesCEMark. ECN bits live in TC[1:0] = byte 1 mask 0x30.
 func TestCoalescerIPv6MergesCEMark(t *testing.T) {
 	w := &fakeTunWriter{gsoEnabled: true}
-	c := NewTCPCoalescer(w)
+	c := NewTCPCoalescer(w, test.NewLogger())
 	pay := make([]byte, 1200)
 	// tcLow is the low 4 bits of TC; ECN occupies the bottom 2 of those.
 	if err := c.Commit(buildTCPv6(ecnECT0, 1000, tcpAck, pay)); err != nil {

overlay/batch/tx_batch.go

@@ -22,13 +22,14 @@ type SendBatch struct {
 	backing []byte
 }
 
-func NewSendBatch(out batchWriter, batchCap, slotCap int) *SendBatch {
+// NewSendBatch makes a SendBatch with batchCap slots and an arenaSize byte buffer for slices to back those slots
+func NewSendBatch(out batchWriter, batchCap, arenaSize int) *SendBatch {
 	return &SendBatch{
 		out:     out,
 		bufs:    make([][]byte, 0, batchCap),
 		dsts:    make([]netip.AddrPort, 0, batchCap),
 		ecns:    make([]byte, 0, batchCap),
-		backing: make([]byte, 0, batchCap*slotCap),
+		backing: make([]byte, 0, arenaSize),
 	}
 }