Adding upstream version 1.2.0.

Signed-off-by: Daniel Baumann <daniel@debian.org>

spill.go

@@ -0,0 +1,41 @@
+package buffer
+
+import (
+	"encoding/gob"
+	"io"
+	"io/ioutil"
+	"math"
+)
+
+type spill struct {
+	Buffer
+	Spiller io.Writer
+}
+
+// NewSpill returns a Buffer which writes data to w when there's an error
+// writing to buf. Such as when buf is full, or the disk is full, etc.
+func NewSpill(buf Buffer, w io.Writer) Buffer {
+	if w == nil {
+		w = ioutil.Discard
+	}
+	return &spill{
+		Buffer:  buf,
+		Spiller: w,
+	}
+}
+
+func (buf *spill) Cap() int64 {
+	return math.MaxInt64
+}
+
+func (buf *spill) Write(p []byte) (n int, err error) {
+	if n, err = buf.Buffer.Write(p); err != nil {
+		m, err := buf.Spiller.Write(p[n:])
+		return m + n, err
+	}
+	return len(p), nil
+}
+
+func init() {
+	gob.Register(&spill{})
+}