From 8b5add5301808a449f8b58f466cd3b85a2e72546 Mon Sep 17 00:00:00 2001
From: Arceliar <Arceliar@users.noreply.github.com>
Date: Sun, 21 May 2023 12:38:16 -0500
Subject: [PATCH] reduce allocations (also pulls in updated ironwood to do the
 same)

---
 go.mod           |  2 +-
 go.sum           |  4 ++--
 src/core/core.go |  6 ++++--
 src/core/pool.go | 17 +++++++++++++++++
 4 files changed, 24 insertions(+), 5 deletions(-)
 create mode 100644 src/core/pool.go

diff --git a/go.mod b/go.mod
index 4fd73400..6811e98a 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module github.com/yggdrasil-network/yggdrasil-go
 go 1.19
 
 require (
-	github.com/Arceliar/ironwood v0.0.0-20230515022317-31b976732ebe
+	github.com/Arceliar/ironwood v0.0.0-20230521173602-97ee6b09b8e0
 	github.com/Arceliar/phony v0.0.0-20220903101357-530938a4b13d
 	github.com/cheggaaa/pb/v3 v3.0.8
 	github.com/gologme/log v1.2.0
diff --git a/go.sum b/go.sum
index ed5f7448..6eff958e 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,5 @@
-github.com/Arceliar/ironwood v0.0.0-20230515022317-31b976732ebe h1:u69sr6Y9jqu6sk43Yyt+izLnLGgqCw3OYh2HU+jYUBw=
-github.com/Arceliar/ironwood v0.0.0-20230515022317-31b976732ebe/go.mod h1:MIfrhR4b+U6gurd5pln622Zwaf2kzpIvXcnvRZMvlRI=
+github.com/Arceliar/ironwood v0.0.0-20230521173602-97ee6b09b8e0 h1:u0BeMjhq0+jU+zaL6zlaBo9Z5KuG26bMtm+XM2e6dSQ=
+github.com/Arceliar/ironwood v0.0.0-20230521173602-97ee6b09b8e0/go.mod h1:5x7fWW0mshe9WQ1lvSMmmHBYC3BeHH9gpwW5tz7cbfw=
 github.com/Arceliar/phony v0.0.0-20220903101357-530938a4b13d h1:UK9fsWbWqwIQkMCz1CP+v5pGbsGoWAw6g4AyvMpm1EM=
 github.com/Arceliar/phony v0.0.0-20220903101357-530938a4b13d/go.mod h1:BCnxhRf47C/dy/e/D2pmB8NkB3dQVIrkD98b220rx5Q=
 github.com/VividCortex/ewma v1.1.1/go.mod h1:2Tkkvm3sRDVXaiyucHiACn4cqf7DpdyLvmxzcbUokwA=
diff --git a/src/core/core.go b/src/core/core.go
index 748b7381..dfc18704 100644
--- a/src/core/core.go
+++ b/src/core/core.go
@@ -183,7 +183,8 @@ func (c *Core) MTU() uint64 {
 }
 
 func (c *Core) ReadFrom(p []byte) (n int, from net.Addr, err error) {
-	buf := make([]byte, c.PacketConn.MTU())
+	buf := allocBytes(int(c.PacketConn.MTU()))
+	defer freeBytes(buf)
 	for {
 		bs := buf
 		n, from, err = c.PacketConn.ReadFrom(bs)
@@ -217,7 +218,8 @@ func (c *Core) ReadFrom(p []byte) (n int, from net.Addr, err error) {
 }
 
 func (c *Core) WriteTo(p []byte, addr net.Addr) (n int, err error) {
-	buf := make([]byte, 0, 65535)
+	buf := allocBytes(0)
+	defer freeBytes(buf)
 	buf = append(buf, typeSessionTraffic)
 	buf = append(buf, p...)
 	n, err = c.PacketConn.WriteTo(buf, addr)
diff --git a/src/core/pool.go b/src/core/pool.go
new file mode 100644
index 00000000..63c6253b
--- /dev/null
+++ b/src/core/pool.go
@@ -0,0 +1,17 @@
+package core
+
+import "sync"
+
+var bytePool = sync.Pool{New: func() interface{} { return []byte(nil) }}
+
+func allocBytes(size int) []byte {
+	bs := bytePool.Get().([]byte)
+	if cap(bs) < size {
+		bs = make([]byte, size)
+	}
+	return bs[:size]
+}
+
+func freeBytes(bs []byte) {
+	bytePool.Put(bs[:0])
+}