Add container attach support.

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

pkg/ioutil/write_closer.go

@@ -0,0 +1,68 @@
+/*
+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"
+
+// writeCloseInformer wraps passed in write closer with a close channel.
+// Caller could wait on the close channel for the write closer to be
+// closed.
+type writeCloseInformer struct {
+	close chan struct{}
+	wc    io.WriteCloser
+}
+
+// NewWriteCloseInformer creates the writeCloseInformer from a write closer.
+func NewWriteCloseInformer(wc io.WriteCloser) (io.WriteCloser, <-chan struct{}) {
+	close := make(chan struct{})
+	return &writeCloseInformer{
+		close: close,
+		wc:    wc,
+	}, close
+}
+
+// Write passes through the data into the internal write closer.
+func (w *writeCloseInformer) Write(p []byte) (int, error) {
+	return w.wc.Write(p)
+}
+
+// Close closes the internal write closer and inform the close channel.
+func (w *writeCloseInformer) Close() error {
+	err := w.wc.Close()
+	close(w.close)
+	return err
+}
+
+// nopWriteCloser wraps passed in writer with a nop close function.
+type nopWriteCloser struct {
+	w io.Writer
+}
+
+// NewNopWriteCloser creates the nopWriteCloser from a writer.
+func NewNopWriteCloser(w io.Writer) io.WriteCloser {
+	return &nopWriteCloser{w: w}
+}
+
+// Write passes through the data into the internal writer.
+func (n *nopWriteCloser) Write(p []byte) (int, error) {
+	return n.w.Write(p)
+}
+
+// Close is a nop close function.
+func (n *nopWriteCloser) Close() error {
+	return nil
+}

pkg/ioutil/write_closer_test.go

@@ -0,0 +1,49 @@
+/*
+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 (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestWriteCloseInformer(t *testing.T) {
+	original := &writeCloser{}
+	wci, close := NewWriteCloseInformer(original)
+	data := "test"
+
+	n, err := wci.Write([]byte(data))
+	assert.Equal(t, len(data), n)
+	assert.Equal(t, data, original.buf.String())
+	assert.NoError(t, err)
+
+	select {
+	case <-close:
+		assert.Fail(t, "write closer closed")
+	default:
+	}
+
+	wci.Close()
+	assert.True(t, original.closed)
+
+	select {
+	case <-close:
+	default:
+		assert.Fail(t, "write closer not closed")
+	}
+}

pkg/ioutil/writer_group.go

@@ -0,0 +1,103 @@
+/*
+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 (
+	"errors"
+	"io"
+	"sync"
+
+	"github.com/golang/glog"
+)
+
+// WriterGroup is a group of writers. Writer could be dynamically
+// added and removed.
+type WriterGroup struct {
+	mu      sync.Mutex
+	writers map[string]io.WriteCloser
+	closed  bool
+}
+
+var _ io.Writer = &WriterGroup{}
+
+// NewWriterGroup creates an empty writer group.
+func NewWriterGroup() *WriterGroup {
+	return &WriterGroup{
+		writers: make(map[string]io.WriteCloser),
+	}
+}
+
+// Add adds a writer into the group, returns an error when writer
+// group is closed.
+func (g *WriterGroup) Add(key string, w io.WriteCloser) error {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	if g.closed {
+		return errors.New("wait group closed")
+	}
+	g.writers[key] = w
+	return nil
+}
+
+// Remove removes a writer from the group.
+func (g *WriterGroup) Remove(key string) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	w, ok := g.writers[key]
+	if !ok {
+		return
+	}
+	w.Close()
+	delete(g.writers, key)
+}
+
+// Write writes data into each writer. If a writer returns error,
+// it will be closed and removed from the writer group. It returns
+// error if writer group is empty.
+func (g *WriterGroup) Write(p []byte) (int, error) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	for k, w := range g.writers {
+		n, err := w.Write(p)
+		if err != nil {
+			glog.Errorf("Writer %q write error: %v", k, err)
+		} else if len(p) != n {
+			glog.Errorf("Writer %q short write error", k)
+		} else {
+			continue
+		}
+		// The writer is closed or in bad state, remove it.
+		w.Close()
+		delete(g.writers, k)
+	}
+	if len(g.writers) == 0 {
+		return 0, errors.New("writer group is empty")
+	}
+	return len(p), nil
+}
+
+// Close closes the writer group. Write or Add will return error
+// after closed.
+func (g *WriterGroup) Close() {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	for _, w := range g.writers {
+		w.Close()
+	}
+	g.writers = nil
+	g.closed = true
+}

pkg/ioutil/writer_group_test.go

@@ -0,0 +1,94 @@
+/*
+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"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type writeCloser struct {
+	buf    bytes.Buffer
+	closed bool
+}
+
+func (wc *writeCloser) Write(p []byte) (int, error) {
+	return wc.buf.Write(p)
+}
+
+func (wc *writeCloser) Close() error {
+	wc.closed = true
+	return nil
+}
+
+func TestEmptyWriterGroup(t *testing.T) {
+	wg := NewWriterGroup()
+	_, err := wg.Write([]byte("test"))
+	assert.Error(t, err)
+}
+
+func TestClosedWriterGroup(t *testing.T) {
+	wg := NewWriterGroup()
+	wc := &writeCloser{}
+	key, data := "test key", "test data"
+
+	err := wg.Add(key, wc)
+	assert.NoError(t, err)
+
+	n, err := wg.Write([]byte(data))
+	assert.Equal(t, len(data), n)
+	assert.Equal(t, data, wc.buf.String())
+	assert.NoError(t, err)
+
+	wg.Close()
+	assert.True(t, wc.closed)
+
+	err = wg.Add(key, &writeCloser{})
+	assert.Error(t, err)
+
+	_, err = wg.Write([]byte(data))
+	assert.Error(t, err)
+}
+
+func TestAddRemoveWriter(t *testing.T) {
+	wg := NewWriterGroup()
+	wc1, wc2 := &writeCloser{}, &writeCloser{}
+	key1, key2 := "test key 1", "test key 2"
+
+	err := wg.Add(key1, wc1)
+	assert.NoError(t, err)
+	_, err = wg.Write([]byte("test data 1"))
+	assert.NoError(t, err)
+	assert.Equal(t, "test data 1", wc1.buf.String())
+
+	err = wg.Add(key2, wc2)
+	assert.NoError(t, err)
+	_, err = wg.Write([]byte("test data 2"))
+	assert.NoError(t, err)
+	assert.Equal(t, "test data 1test data 2", wc1.buf.String())
+	assert.Equal(t, "test data 2", wc2.buf.String())
+
+	wg.Remove(key1)
+	_, err = wg.Write([]byte("test data 3"))
+	assert.NoError(t, err)
+	assert.Equal(t, "test data 1test data 2", wc1.buf.String())
+	assert.Equal(t, "test data 2test data 3", wc2.buf.String())
+
+	wg.Close()
+}