fix golint issues in core/iox (#488)

core/iox/bufferpool.go

@@ -5,11 +5,13 @@ import (
 	"sync"
 )
 
+// A BufferPool is a pool to buffer bytes.Buffer objects.
 type BufferPool struct {
 	capability int
 	pool       *sync.Pool
 }
 
+// NewBufferPool returns a BufferPool.
 func NewBufferPool(capability int) *BufferPool {
 	return &BufferPool{
 		capability: capability,
@@ -21,12 +23,14 @@ func NewBufferPool(capability int) *BufferPool {
 	}
 }
 
+// Get returns a bytes.Buffer object from bp.
 func (bp *BufferPool) Get() *bytes.Buffer {
 	buf := bp.pool.Get().(*bytes.Buffer)
 	buf.Reset()
 	return buf
 }
 
+// Put returns buf into bp.
 func (bp *BufferPool) Put(buf *bytes.Buffer) {
 	if buf.Cap() < bp.capability {
 		bp.pool.Put(buf)