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/compress.go b/vendor/github.com/Shopify/sarama/compress.go
new file mode 100644
index 0000000..94b716e
--- /dev/null
+++ b/vendor/github.com/Shopify/sarama/compress.go
@@ -0,0 +1,75 @@
+package sarama
+
+import (
+	"bytes"
+	"compress/gzip"
+	"fmt"
+	"sync"
+
+	"github.com/eapache/go-xerial-snappy"
+	"github.com/pierrec/lz4"
+)
+
+var (
+	lz4WriterPool = sync.Pool{
+		New: func() interface{} {
+			return lz4.NewWriter(nil)
+		},
+	}
+
+	gzipWriterPool = sync.Pool{
+		New: func() interface{} {
+			return gzip.NewWriter(nil)
+		},
+	}
+)
+
+func compress(cc CompressionCodec, level int, data []byte) ([]byte, error) {
+	switch cc {
+	case CompressionNone:
+		return data, nil
+	case CompressionGZIP:
+		var (
+			err    error
+			buf    bytes.Buffer
+			writer *gzip.Writer
+		)
+		if level != CompressionLevelDefault {
+			writer, err = gzip.NewWriterLevel(&buf, level)
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			writer = gzipWriterPool.Get().(*gzip.Writer)
+			defer gzipWriterPool.Put(writer)
+			writer.Reset(&buf)
+		}
+		if _, err := writer.Write(data); err != nil {
+			return nil, err
+		}
+		if err := writer.Close(); err != nil {
+			return nil, err
+		}
+		return buf.Bytes(), nil
+	case CompressionSnappy:
+		return snappy.Encode(data), nil
+	case CompressionLZ4:
+		writer := lz4WriterPool.Get().(*lz4.Writer)
+		defer lz4WriterPool.Put(writer)
+
+		var buf bytes.Buffer
+		writer.Reset(&buf)
+
+		if _, err := writer.Write(data); err != nil {
+			return nil, err
+		}
+		if err := writer.Close(); err != nil {
+			return nil, err
+		}
+		return buf.Bytes(), nil
+	case CompressionZSTD:
+		return zstdCompressLevel(nil, data, level)
+	default:
+		return nil, PacketEncodingError{fmt.Sprintf("unsupported compression codec (%d)", cc)}
+	}
+}