From dc16b979e7cc6a0ebaa3c6478433fd5bf4b4d100 Mon Sep 17 00:00:00 2001
From: hayzam <hayzam@difuse.io>
Date: Tue, 12 May 2026 13:31:19 +0000
Subject: [PATCH] engine, io: more caching + optimizations

---
 engine/engine.go       | 47 ++++++++++++++++++++++++++++++------------
 engine/mac_resolver.go |  8 ++-----
 2 files changed, 36 insertions(+), 19 deletions(-)

diff --git a/engine/engine.go b/engine/engine.go
index 8bf7ff8..ccd8dfe 100644
--- a/engine/engine.go
+++ b/engine/engine.go
@@ -4,6 +4,8 @@ import (
 	"context"
 	"encoding/binary"
 	"runtime"
+	"sync"
+	"sync/atomic"
 
 	"git.difuse.io/Difuse/Mellaris/io"
 	"git.difuse.io/Difuse/Mellaris/ruleset"
@@ -14,10 +16,17 @@ import (
 
 var _ Engine = (*engine)(nil)
 
+type verdictEntry struct {
+	Verdict io.Verdict
+	Gen     int64
+}
+
 type engine struct {
-	logger  Logger
-	io      io.PacketIO
-	workers []*worker
+	logger      Logger
+	io          io.PacketIO
+	workers     []*worker
+	verdicts    sync.Map     // streamID(uint32) → verdictEntry
+	verdictsGen atomic.Int64 // incremented on ruleset update
 }
 
 func NewEngine(config Config) (Engine, error) {
@@ -43,14 +52,17 @@ func NewEngine(config Config) (Engine, error) {
 			return nil, err
 		}
 	}
-	return &engine{
+	e := &engine{
 		logger:  config.Logger,
 		io:      config.IO,
 		workers: workers,
-	}, nil
+	}
+	return e, nil
 }
 
 func (e *engine) UpdateRuleset(r ruleset.Ruleset) error {
+	e.verdictsGen.Add(1)
+	e.verdicts = sync.Map{}
 	for _, w := range e.workers {
 		if err := w.UpdateRuleset(r); err != nil {
 			return err
@@ -61,14 +73,12 @@ func (e *engine) UpdateRuleset(r ruleset.Ruleset) error {
 
 func (e *engine) Run(ctx context.Context) error {
 	ioCtx, ioCancel := context.WithCancel(ctx)
-	defer ioCancel() // Stop workers & IO
+	defer ioCancel()
 
-	// Start workers
 	for _, w := range e.workers {
 		go w.Run(ioCtx)
 	}
 
-	// Register IO callback
 	errChan := make(chan error, 1)
 	err := e.io.Register(ioCtx, func(p io.Packet, err error) bool {
 		if err != nil {
@@ -81,7 +91,6 @@ func (e *engine) Run(ctx context.Context) error {
 		return err
 	}
 
-	// Block until IO errors or context is cancelled
 	select {
 	case err := <-errChan:
 		return err
@@ -90,23 +99,35 @@ func (e *engine) Run(ctx context.Context) error {
 	}
 }
 
-// dispatch dispatches a packet to a worker.
 func (e *engine) dispatch(p io.Packet) bool {
+	streamID := p.StreamID()
+
+	if v, ok := e.verdicts.Load(streamID); ok {
+		entry := v.(verdictEntry)
+		if entry.Gen == e.verdictsGen.Load() {
+			_ = e.io.SetVerdict(p, entry.Verdict, nil)
+			return true
+		}
+	}
+
 	data := p.Data()
 	layerType, srcMAC, dstMAC, ok := classifyPacket(data)
 	if !ok {
-		// Unsupported network layer
 		_ = e.io.SetVerdict(p, io.VerdictAcceptStream, nil)
 		return true
 	}
-	index := p.StreamID() % uint32(len(e.workers))
+	gen := e.verdictsGen.Load()
+	index := streamID % uint32(len(e.workers))
 	e.workers[index].Feed(&workerPacket{
-		StreamID:  p.StreamID(),
+		StreamID:  streamID,
 		Data:      data,
 		LayerType: layerType,
 		SrcMAC:    srcMAC,
 		DstMAC:    dstMAC,
 		SetVerdict: func(v io.Verdict, b []byte) error {
+			if v == io.VerdictAcceptStream || v == io.VerdictDropStream {
+				e.verdicts.Store(streamID, verdictEntry{Verdict: v, Gen: gen})
+			}
 			return e.io.SetVerdict(p, v, b)
 		},
 	})
diff --git a/engine/mac_resolver.go b/engine/mac_resolver.go
index a1eecd8..91fefd7 100644
--- a/engine/mac_resolver.go
+++ b/engine/mac_resolver.go
@@ -343,17 +343,13 @@ func lookupNeighborMACNetlink(target net.IP) (net.HardwareAddr, bool) {
 func readIPv6NeighCommand() map[string]net.HardwareAddr {
 	commands := [][]string{
 		{"ip", "-6", "neigh", "show"},
-		{"/sbin/ip", "-6", "neigh", "show"},
-		{"/usr/sbin/ip", "-6", "neigh", "show"},
-		{"busybox", "ip", "-6", "neigh", "show"},
-		{"/bin/busybox", "ip", "-6", "neigh", "show"},
 	}
+	m := make(map[string]net.HardwareAddr)
 	for _, cmd := range commands {
 		out, err := exec.Command(cmd[0], cmd[1:]...).Output()
 		if err != nil || len(out) == 0 {
 			continue
 		}
-		m := make(map[string]net.HardwareAddr)
 		for _, line := range strings.Split(string(out), "\n") {
 			ip, mac, ok := parseNeighborLine(line)
 			if !ok {
@@ -365,7 +361,7 @@ func readIPv6NeighCommand() map[string]net.HardwareAddr {
 			return m
 		}
 	}
-	return map[string]net.HardwareAddr{}
+	return m
 }
 
 func parseNeighborLine(line string) (string, net.HardwareAddr, bool) {