[#3] signature: Add buffer pool

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

util/signature/buffer.go

@@ -0,0 +1,29 @@
+package signature
+
+import "sync"
+
+const poolSliceMaxSize = 64 * 1024
+
+var buffersPool = sync.Pool{
+	New: func() any {
+		return make([]byte, 0)
+	},
+}
+
+func newBufferFromPool(size int) []byte {
+	result := buffersPool.Get().([]byte)
+	if cap(result) < size {
+		result = make([]byte, size)
+	} else {
+		result = result[:size]
+	}
+	return result
+}
+
+func returnBufferToPool(buf []byte) {
+	if cap(buf) > poolSliceMaxSize {
+		return
+	}
+	buf = buf[:0]
+	buffersPool.Put(buf)
+}