vendor update for CSI 0.3.0

vendor/google.golang.org/grpc/encoding/gzip/gzip.go

@@ -23,6 +23,7 @@ package gzip
 
 import (
 	"compress/gzip"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"sync"
@@ -46,6 +47,26 @@ type writer struct {
 	pool *sync.Pool
 }
 
+// SetLevel updates the registered gzip compressor to use the compression level specified (gzip.HuffmanOnly is not supported).
+// NOTE: this function must only be called during initialization time (i.e. in an init() function),
+// and is not thread-safe.
+//
+// The error returned will be nil if the specified level is valid.
+func SetLevel(level int) error {
+	if level < gzip.DefaultCompression || level > gzip.BestCompression {
+		return fmt.Errorf("grpc: invalid gzip compression level: %d", level)
+	}
+	c := encoding.GetCompressor(Name).(*compressor)
+	c.poolCompressor.New = func() interface{} {
+		w, err := gzip.NewWriterLevel(ioutil.Discard, level)
+		if err != nil {
+			panic(err)
+		}
+		return &writer{Writer: w, pool: &c.poolCompressor}
+	}
+	return nil
+}
+
 func (c *compressor) Compress(w io.Writer) (io.WriteCloser, error) {
 	z := c.poolCompressor.Get().(*writer)
 	z.Writer.Reset(w)