broken checkpt

overlay/batch/coalesce_core.go

@@ -147,44 +147,3 @@ func mergeECNIntoSeed(seedHdr, pktHdr []byte, isV6 bool) {
 		seedHdr[1] |= pktHdr[1] & 0x03
 	}
 }
-
-// Arena is an injectable byte-slab that hands out non-overlapping borrowed
-// slices via Reserve and releases them in bulk via Reset. Coalescers take
-// an *Arena at construction so the caller controls the slab lifetime and
-// can share one slab across multiple coalescers (MultiCoalescer hands the
-// same *Arena to every lane so the lanes don't carry their own backings).
-//
-// Reserve borrows; the slice is valid until the next Reset. The slab grows
-// (by allocating a fresh, larger backing array) if a Reserve doesn't fit;
-// pre-size the arena via NewArena to avoid that path on the hot path.
-type Arena struct {
-	buf []byte
-}
-
-// NewArena returns an Arena with a pre-allocated backing of the given
-// capacity. Pass 0 if you don't intend to call Reserve (e.g. a test that
-// only feeds the coalescer pre-made []byte packets via Commit).
-func NewArena(capacity int) *Arena {
-	return &Arena{buf: make([]byte, 0, capacity)}
-}
-
-// Reserve hands out a non-overlapping sz-byte slice from the arena. If the
-// request doesn't fit the current backing, a fresh, larger backing is
-// allocated; already-borrowed slices reference the old backing and remain
-// valid until Reset.
-func (a *Arena) Reserve(sz int) []byte {
-	if len(a.buf)+sz > cap(a.buf) {
-		newCap := max(cap(a.buf)*2, sz)
-		a.buf = make([]byte, 0, newCap)
-	}
-	start := len(a.buf)
-	a.buf = a.buf[:start+sz]
-	return a.buf[start : start+sz : start+sz]
-}
-
-// Reset releases every slice handed out since the last Reset. Callers must
-// not use any previously-borrowed slice after this returns. The underlying
-// backing array is retained so subsequent Reserves don't re-allocate.
-func (a *Arena) Reset() {
-	a.buf = a.buf[:0]
-}

overlay/batch/multi_coalesce.go

@@ -2,8 +2,10 @@ package batch
 
 import (
 	"errors"
-	"io"
 	"log/slog"
+
+	"github.com/slackhq/nebula/overlay/tio"
+	"github.com/slackhq/nebula/util"
 )
 
 // MultiCoalescer fans plaintext packets out to lane-specific batchers based
@@ -35,7 +37,7 @@ type MultiCoalescer struct {
 	// sequentially and never Reserves in between, so a later lane's
 	// slots stay readable across an earlier lane's Reset (the underlying
 	// bytes are still alive — Reset only re-slices len to 0).
-	arena *Arena
+	arena *util.Arena
 }
 
 // DefaultMultiArenaCap is the recommended arena capacity for a Multi-lane
@@ -49,9 +51,9 @@ const DefaultMultiArenaCap = initialSlots * 65535
 // Either lane disabled redirects its traffic into the passthrough lane.
 // arena is the single backing slab shared across every lane; the caller
 // pre-sizes it via NewArena so the hot path never allocates.
-func NewMultiCoalescer(w io.Writer, l *slog.Logger, arena *Arena, tcpEnabled, udpEnabled bool) *MultiCoalescer {
+func NewMultiCoalescer(w tio.Queue, l *slog.Logger, arena *util.Arena, tcpEnabled, udpEnabled bool) *MultiCoalescer {
 	m := &MultiCoalescer{
-		pt:    NewPassthrough(w, arena),
+		pt:    NewPassthrough(w, initialSlots, arena),
 		arena: arena,
 	}
 	if tcpEnabled {

overlay/batch/passthrough.go

@@ -4,6 +4,7 @@ import (
 	"io"
 
 	"github.com/slackhq/nebula/udp"
+	"github.com/slackhq/nebula/util"
 )
 
 // Passthrough is a RxBatcher that doesn't batch anything, it just accumulates and then sends packets.
@@ -11,7 +12,7 @@ type Passthrough struct {
 	out   io.Writer
 	slots [][]byte
 	// arena is injected; see TCPCoalescer.arena for the contract.
-	arena  *Arena
+	arena  *util.Arena
 	cursor int
 }
 
@@ -21,7 +22,7 @@ const passthroughBaseNumSlots = 128
 // standalone Passthrough batcher: 128 slots × udp.MTU ≈ 1.1 MiB.
 const DefaultPassthroughArenaCap = passthroughBaseNumSlots * udp.MTU
 
-func NewPassthrough(w io.Writer, slots int, arena *Arena) *Passthrough {
+func NewPassthrough(w io.Writer, slots int, arena *util.Arena) *Passthrough {
 	return &Passthrough{
 		out:   w,
 		slots: make([][]byte, 0, slots),

overlay/batch/tcp_coalesce.go

@@ -10,6 +10,8 @@ import (
 	"slices"
 
 	"github.com/slackhq/nebula/overlay/tio"
+	"github.com/slackhq/nebula/util"
+	"github.com/slackhq/nebula/wire"
 )
 
 // ipProtoTCP is the IANA protocol number for TCP. Hardcoded instead of
@@ -88,11 +90,11 @@ type TCPCoalescer struct {
 	// and tells it to release them via Reset on Flush. When wrapped in
 	// MultiCoalescer the same *Arena is shared with the other lanes so
 	// there's exactly one backing slab per Multi instance.
-	arena *Arena
+	arena *util.Arena
 	l     *slog.Logger
 }
 
-func NewTCPCoalescer(w io.Writer, l *slog.Logger, arena *Arena) *TCPCoalescer {
+func NewTCPCoalescer(w tio.Queue, l *slog.Logger, arena *util.Arena) *TCPCoalescer {
 	c := &TCPCoalescer{
 		plainW:    w,
 		slots:     make([]*coalesceSlot, 0, initialSlots),
@@ -101,7 +103,7 @@ func NewTCPCoalescer(w io.Writer, l *slog.Logger, arena *Arena) *TCPCoalescer {
 		arena:     arena,
 		l:         l,
 	}
-	if gw, ok := tio.SupportsGSO(w, tio.GSOProtoTCP); ok {
+	if gw, ok := tio.SupportsGSO(w, wire.GSOProtoTCP); ok {
 		c.gsoW = gw
 	}
 	return c
@@ -419,7 +421,7 @@ func (c *TCPCoalescer) flushSlot(s *coalesceSlot) error {
 	tcsum := s.ipHdrLen + 16
 	binary.BigEndian.PutUint16(hdr[tcsum:tcsum+2], foldOnceNoInvert(psum))
 
-	return c.gsoW.WriteGSO(hdr[:s.ipHdrLen], hdr[s.ipHdrLen:], s.payIovs, tio.GSOProtoTCP)
+	return c.gsoW.WriteGSO(hdr[:s.ipHdrLen], hdr[s.ipHdrLen:], s.payIovs, wire.GSOProtoTCP)
 }
 
 // headersMatch compares two IP+TCP header prefixes for byte-for-byte

overlay/batch/udp_coalesce.go

@@ -5,6 +5,8 @@ import (
 	"io"
 
 	"github.com/slackhq/nebula/overlay/tio"
+	"github.com/slackhq/nebula/util"
+	"github.com/slackhq/nebula/wire"
 )
 
 // ipProtoUDP is the IANA protocol number for UDP.
@@ -67,7 +69,7 @@ type UDPCoalescer struct {
 	pool      []*udpSlot
 
 	// arena is injected; see TCPCoalescer.arena for the contract.
-	arena *Arena
+	arena *util.Arena
 }
 
 // NewUDPCoalescer wraps w. The caller is responsible for only constructing
@@ -75,7 +77,7 @@ type UDPCoalescer struct {
 // the kernel may reject GSO_UDP_L4 writes. If w does not implement
 // tio.GSOWriter at all (single-packet Queue), the coalescer degrades to
 // plain Writes — same defensive shape as the TCP coalescer.
-func NewUDPCoalescer(w io.Writer, arena *Arena) *UDPCoalescer {
+func NewUDPCoalescer(w tio.Queue, arena *util.Arena) *UDPCoalescer {
 	c := &UDPCoalescer{
 		plainW:    w,
 		slots:     make([]*udpSlot, 0, initialSlots),
@@ -83,7 +85,7 @@ func NewUDPCoalescer(w io.Writer, arena *Arena) *UDPCoalescer {
 		pool:      make([]*udpSlot, 0, initialSlots),
 		arena:     arena,
 	}
-	if gw, ok := tio.SupportsGSO(w, tio.GSOProtoUDP); ok {
+	if gw, ok := tio.SupportsGSO(w, wire.GSOProtoUDP); ok {
 		c.gsoW = gw
 	}
 	return c
@@ -313,7 +315,7 @@ func (c *UDPCoalescer) flushSlot(s *udpSlot) error {
 	udpCsumOff := s.ipHdrLen + 6
 	binary.BigEndian.PutUint16(hdr[udpCsumOff:udpCsumOff+2], foldOnceNoInvert(psum))
 
-	return c.gsoW.WriteGSO(hdr[:s.ipHdrLen], hdr[s.ipHdrLen:], s.payIovs, tio.GSOProtoUDP)
+	return c.gsoW.WriteGSO(hdr[:s.ipHdrLen], hdr[s.ipHdrLen:], s.payIovs, wire.GSOProtoUDP)
 }
 
 // udpHeadersMatch compares two IP+UDP header prefixes for byte-equality on