Use buffer pool for proxy copying data

Signed-off-by: Philip Laine <philip.laine@gmail.com>

internal/buffer/buffer.go

@@ -0,0 +1,25 @@
+package buffer
+
+import "sync"
+
+type BufferPool struct {
+	pool *sync.Pool
+}
+
+func NewBufferPool() *BufferPool {
+	return &BufferPool{
+		pool: &sync.Pool{
+			New: func() interface{} {
+				return make([]byte, 32*1024)
+			},
+		},
+	}
+}
+
+func (p *BufferPool) Get() []byte {
+	return p.pool.Get().([]byte)
+}
+
+func (p *BufferPool) Put(b []byte) {
+	p.pool.Put(b)
+}

internal/buffer/buffer_test.go

@@ -0,0 +1,16 @@
+package buffer
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestBufferPool(t *testing.T) {
+	t.Parallel()
+
+	bufferPool := NewBufferPool()
+	b := bufferPool.Get()
+	require.Len(t, b, 32*1024)
+	bufferPool.Put(b)
+}

pkg/registry/registry.go

@@ -16,6 +16,7 @@ import (
 
 	"github.com/go-logr/logr"
 
+	"github.com/spegel-org/spegel/internal/buffer"
 	"github.com/spegel-org/spegel/internal/mux"
 	"github.com/spegel-org/spegel/pkg/metrics"
 	"github.com/spegel-org/spegel/pkg/oci"
@@ -37,6 +38,7 @@ type Registry struct {
 	resolveRetries   int
 	resolveTimeout   time.Duration
 	resolveLatestTag bool
+	bufferPool       *buffer.BufferPool
 }
 
 type Option func(*Registry)
@@ -90,6 +92,7 @@ func NewRegistry(ociClient oci.Client, router routing.Router, opts ...Option) *R
 		resolveRetries:   3,
 		resolveTimeout:   20 * time.Millisecond,
 		resolveLatestTag: true,
+		bufferPool:       buffer.NewBufferPool(),
 	}
 	for _, opt := range opts {
 		opt(r)
@@ -280,6 +283,7 @@ func (r *Registry) handleMirror(rw mux.ResponseWriter, req *http.Request, ref re
 				Host:   ipAddr.String(),
 			}
 			proxy := httputil.NewSingleHostReverseProxy(u)
+			proxy.BufferPool = r.bufferPool
 			proxy.Transport = r.transport
 			proxy.ErrorHandler = func(_ http.ResponseWriter, _ *http.Request, err error) {
 				log.Error(err, "request to mirror failed", "attempt", mirrorAttempts)