Various fixes for container streaming.

Signed-off-by: Lantao Liu <lantaol@google.com>

pkg/ioutil/read_closer.go

@@ -0,0 +1,54 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package ioutil
+
+import (
+	"io"
+	"sync"
+)
+
+// writeCloseInformer wraps a reader with a close function.
+type wrapReadCloser struct {
+	// TODO(random-liu): Evaluate whether the lock introduces
+	// performance regression.
+	sync.RWMutex
+	r      io.Reader
+	closed bool
+}
+
+// NewWrapReadCloser creates a wrapReadCloser from a reader.
+func NewWrapReadCloser(r io.Reader) io.ReadCloser {
+	return &wrapReadCloser{r: r}
+}
+
+// Read reads up to len(p) bytes into p.
+func (w *wrapReadCloser) Read(p []byte) (int, error) {
+	w.RLock()
+	defer w.RUnlock()
+	if w.closed {
+		return 0, io.EOF
+	}
+	return w.r.Read(p)
+}
+
+// Close closes read closer.
+func (w *wrapReadCloser) Close() error {
+	w.Lock()
+	defer w.Unlock()
+	w.closed = true
+	return nil
+}

pkg/ioutil/read_closer_test.go

@@ -0,0 +1,47 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package ioutil
+
+import (
+	"bytes"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestWrapReadCloser(t *testing.T) {
+	buf := bytes.NewBufferString("abc")
+
+	rc := NewWrapReadCloser(buf)
+	dst := make([]byte, 1)
+	n, err := rc.Read(dst)
+	assert.Equal(t, 1, n)
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("a"), dst)
+
+	n, err = rc.Read(dst)
+	assert.Equal(t, 1, n)
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("b"), dst)
+
+	rc.Close()
+	n, err = rc.Read(dst)
+	assert.Equal(t, 0, n)
+	assert.Equal(t, io.EOF, err)
+	assert.Equal(t, []byte("b"), dst)
+}