Decrease a relay buffer size for MIPS devices

mtglib/internal/relay/pool_settings_mips.go

@@ -0,0 +1,13 @@
+//go:build mips || mipsle
+
+package relay
+
+import "github.com/9seconds/mtg/v2/mtglib/internal/tls"
+
+const (
+	// MIPS is quite short in resources, and usually it means that it will run
+	// on Microtiks, OpenWRT-based routers or similar hardware. I think it worth
+	// to sacrifice a number of read syscalls (read, CPU load) to shrink
+	// limited RAM resources.
+	bufPoolSize = tls.MaxRecordPayloadSize / 2
+)

mtglib/internal/relay/pool_settings_other.go

@@ -0,0 +1,9 @@
+//go:build !mips && !mipsle
+
+package relay
+
+import "github.com/9seconds/mtg/v2/mtglib/internal/tls"
+
+const (
+	bufPoolSize = tls.MaxRecordPayloadSize
+)

mtglib/internal/relay/pools.go

@@ -0,0 +1,18 @@
+package relay
+
+import "sync"
+
+var bufPool = sync.Pool{
+	New: func() any {
+		b := make([]byte, bufPoolSize)
+		return &b
+	},
+}
+
+func acquireBuffer() *[]byte {
+	return bufPool.Get().(*[]byte)
+}
+
+func releaseBuffer(p *[]byte) {
+	bufPool.Put(p)
+}

mtglib/internal/relay/relay.go

@@ -4,19 +4,10 @@ import (
 	"context"
 	"errors"
 	"io"
-	"sync"
 
 	"github.com/9seconds/mtg/v2/essentials"
-	"github.com/9seconds/mtg/v2/mtglib/internal/tls"
 )
 
-var bufPool = sync.Pool{
-	New: func() any {
-		b := make([]byte, tls.MaxRecordPayloadSize)
-		return &b
-	},
-}
-
 func Relay(ctx context.Context, log Logger, telegramConn, clientConn essentials.Conn) {
 	defer telegramConn.Close() //nolint: errcheck
 	defer clientConn.Close()   //nolint: errcheck
@@ -44,13 +35,13 @@ func Relay(ctx context.Context, log Logger, telegramConn, clientConn essentials.
 }
 
 func pump(log Logger, src, dst essentials.Conn, direction string) {
-	bp := bufPool.Get().(*[]byte)
-	defer bufPool.Put(bp)
+	buf := acquireBuffer()
+	defer releaseBuffer(buf)
 
 	defer src.CloseRead()  //nolint: errcheck
 	defer dst.CloseWrite() //nolint: errcheck
 
-	n, err := io.CopyBuffer(src, dst, *bp)
+	n, err := io.CopyBuffer(src, dst, *buf)
 
 	switch {
 	case err == nil: