(feat) Add auto-discovery in k8s | Adarsh

vendor/k8s.io/apimachinery/pkg/runtime/serializer/streaming/streaming.go

@@ -0,0 +1,137 @@
+/*
+Copyright 2015 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 streaming implements encoder and decoder for streams
+// of runtime.Objects over io.Writer/Readers.
+package streaming
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+// Encoder is a runtime.Encoder on a stream.
+type Encoder interface {
+	// Encode will write the provided object to the stream or return an error. It obeys the same
+	// contract as runtime.VersionedEncoder.
+	Encode(obj runtime.Object) error
+}
+
+// Decoder is a runtime.Decoder from a stream.
+type Decoder interface {
+	// Decode will return io.EOF when no more objects are available.
+	Decode(defaults *schema.GroupVersionKind, into runtime.Object) (runtime.Object, *schema.GroupVersionKind, error)
+	// Close closes the underlying stream.
+	Close() error
+}
+
+// Serializer is a factory for creating encoders and decoders that work over streams.
+type Serializer interface {
+	NewEncoder(w io.Writer) Encoder
+	NewDecoder(r io.ReadCloser) Decoder
+}
+
+type decoder struct {
+	reader    io.ReadCloser
+	decoder   runtime.Decoder
+	buf       []byte
+	maxBytes  int
+	resetRead bool
+}
+
+// NewDecoder creates a streaming decoder that reads object chunks from r and decodes them with d.
+// The reader is expected to return ErrShortRead if the provided buffer is not large enough to read
+// an entire object.
+func NewDecoder(r io.ReadCloser, d runtime.Decoder) Decoder {
+	return &decoder{
+		reader:   r,
+		decoder:  d,
+		buf:      make([]byte, 1024),
+		maxBytes: 16 * 1024 * 1024,
+	}
+}
+
+var ErrObjectTooLarge = fmt.Errorf("object to decode was longer than maximum allowed size")
+
+// Decode reads the next object from the stream and decodes it.
+func (d *decoder) Decode(defaults *schema.GroupVersionKind, into runtime.Object) (runtime.Object, *schema.GroupVersionKind, error) {
+	base := 0
+	for {
+		n, err := d.reader.Read(d.buf[base:])
+		if err == io.ErrShortBuffer {
+			if n == 0 {
+				return nil, nil, fmt.Errorf("got short buffer with n=0, base=%d, cap=%d", base, cap(d.buf))
+			}
+			if d.resetRead {
+				continue
+			}
+			// double the buffer size up to maxBytes
+			if len(d.buf) < d.maxBytes {
+				base += n
+				d.buf = append(d.buf, make([]byte, len(d.buf))...)
+				continue
+			}
+			// must read the rest of the frame (until we stop getting ErrShortBuffer)
+			d.resetRead = true
+			base = 0
+			return nil, nil, ErrObjectTooLarge
+		}
+		if err != nil {
+			return nil, nil, err
+		}
+		if d.resetRead {
+			// now that we have drained the large read, continue
+			d.resetRead = false
+			continue
+		}
+		base += n
+		break
+	}
+	return d.decoder.Decode(d.buf[:base], defaults, into)
+}
+
+func (d *decoder) Close() error {
+	return d.reader.Close()
+}
+
+type encoder struct {
+	writer  io.Writer
+	encoder runtime.Encoder
+	buf     *bytes.Buffer
+}
+
+// NewEncoder returns a new streaming encoder.
+func NewEncoder(w io.Writer, e runtime.Encoder) Encoder {
+	return &encoder{
+		writer:  w,
+		encoder: e,
+		buf:     &bytes.Buffer{},
+	}
+}
+
+// Encode writes the provided object to the nested writer.
+func (e *encoder) Encode(obj runtime.Object) error {
+	if err := e.encoder.Encode(obj, e.buf); err != nil {
+		return err
+	}
+	_, err := e.writer.Write(e.buf.Bytes())
+	e.buf.Reset()
+	return err
+}