WIP [VOL-2811] - Incorporate preliminary onu-adapter-go code into opencord repo

- reason "discovery-mibsync-complete" reached (via full MibUpload only, received data won't be stored yet)
- first review comments of patchset #4 considered
 (please have a look into our inline-comments in Gerrit to know more about the current state)
- no refactoring done yet

Change-Id: Iac47817f8ce4bd28dd8132f530b0570d57ae99b8
Signed-off-by: Holger Hildebrandt <holger.hildebrandt@adtran.com>
diff --git a/vendor/github.com/Shopify/sarama/decompress.go b/vendor/github.com/Shopify/sarama/decompress.go
new file mode 100644
index 0000000..eaccbfc
--- /dev/null
+++ b/vendor/github.com/Shopify/sarama/decompress.go
@@ -0,0 +1,63 @@
+package sarama
+
+import (
+	"bytes"
+	"compress/gzip"
+	"fmt"
+	"io/ioutil"
+	"sync"
+
+	"github.com/eapache/go-xerial-snappy"
+	"github.com/pierrec/lz4"
+)
+
+var (
+	lz4ReaderPool = sync.Pool{
+		New: func() interface{} {
+			return lz4.NewReader(nil)
+		},
+	}
+
+	gzipReaderPool sync.Pool
+)
+
+func decompress(cc CompressionCodec, data []byte) ([]byte, error) {
+	switch cc {
+	case CompressionNone:
+		return data, nil
+	case CompressionGZIP:
+		var (
+			err        error
+			reader     *gzip.Reader
+			readerIntf = gzipReaderPool.Get()
+		)
+		if readerIntf != nil {
+			reader = readerIntf.(*gzip.Reader)
+		} else {
+			reader, err = gzip.NewReader(bytes.NewReader(data))
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		defer gzipReaderPool.Put(reader)
+
+		if err := reader.Reset(bytes.NewReader(data)); err != nil {
+			return nil, err
+		}
+
+		return ioutil.ReadAll(reader)
+	case CompressionSnappy:
+		return snappy.Decode(data)
+	case CompressionLZ4:
+		reader := lz4ReaderPool.Get().(*lz4.Reader)
+		defer lz4ReaderPool.Put(reader)
+
+		reader.Reset(bytes.NewReader(data))
+		return ioutil.ReadAll(reader)
+	case CompressionZSTD:
+		return zstdDecompress(nil, data)
+	default:
+		return nil, PacketDecodingError{fmt.Sprintf("invalid compression specified (%d)", cc)}
+	}
+}