mirror of https://github.com/hashicorp/consul
138 lines
3.7 KiB
Go
138 lines
3.7 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package streaming implements encoder and decoder for streams
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// of runtime.Objects over io.Writer/Readers.
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package streaming
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import (
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"bytes"
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"fmt"
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"io"
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"k8s.io/apimachinery/pkg/runtime"
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"k8s.io/apimachinery/pkg/runtime/schema"
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)
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// Encoder is a runtime.Encoder on a stream.
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type Encoder interface {
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// Encode will write the provided object to the stream or return an error. It obeys the same
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// contract as runtime.VersionedEncoder.
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Encode(obj runtime.Object) error
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}
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// Decoder is a runtime.Decoder from a stream.
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type Decoder interface {
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// Decode will return io.EOF when no more objects are available.
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Decode(defaults *schema.GroupVersionKind, into runtime.Object) (runtime.Object, *schema.GroupVersionKind, error)
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// Close closes the underlying stream.
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Close() error
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}
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// Serializer is a factory for creating encoders and decoders that work over streams.
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type Serializer interface {
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NewEncoder(w io.Writer) Encoder
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NewDecoder(r io.ReadCloser) Decoder
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}
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type decoder struct {
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reader io.ReadCloser
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decoder runtime.Decoder
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buf []byte
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maxBytes int
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resetRead bool
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}
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// NewDecoder creates a streaming decoder that reads object chunks from r and decodes them with d.
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// The reader is expected to return ErrShortRead if the provided buffer is not large enough to read
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// an entire object.
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func NewDecoder(r io.ReadCloser, d runtime.Decoder) Decoder {
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return &decoder{
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reader: r,
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decoder: d,
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buf: make([]byte, 1024),
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maxBytes: 1024 * 1024,
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}
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}
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var ErrObjectTooLarge = fmt.Errorf("object to decode was longer than maximum allowed size")
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// Decode reads the next object from the stream and decodes it.
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func (d *decoder) Decode(defaults *schema.GroupVersionKind, into runtime.Object) (runtime.Object, *schema.GroupVersionKind, error) {
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base := 0
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for {
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n, err := d.reader.Read(d.buf[base:])
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if err == io.ErrShortBuffer {
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if n == 0 {
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return nil, nil, fmt.Errorf("got short buffer with n=0, base=%d, cap=%d", base, cap(d.buf))
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}
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if d.resetRead {
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continue
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}
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// double the buffer size up to maxBytes
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if len(d.buf) < d.maxBytes {
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base += n
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d.buf = append(d.buf, make([]byte, len(d.buf))...)
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continue
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}
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// must read the rest of the frame (until we stop getting ErrShortBuffer)
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d.resetRead = true
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base = 0
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return nil, nil, ErrObjectTooLarge
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}
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if err != nil {
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return nil, nil, err
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}
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if d.resetRead {
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// now that we have drained the large read, continue
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d.resetRead = false
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continue
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}
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base += n
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break
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}
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return d.decoder.Decode(d.buf[:base], defaults, into)
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}
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func (d *decoder) Close() error {
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return d.reader.Close()
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}
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type encoder struct {
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writer io.Writer
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encoder runtime.Encoder
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buf *bytes.Buffer
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}
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// NewEncoder returns a new streaming encoder.
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func NewEncoder(w io.Writer, e runtime.Encoder) Encoder {
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return &encoder{
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writer: w,
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encoder: e,
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buf: &bytes.Buffer{},
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}
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}
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// Encode writes the provided object to the nested writer.
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func (e *encoder) Encode(obj runtime.Object) error {
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if err := e.encoder.Encode(obj, e.buf); err != nil {
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return err
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}
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_, err := e.writer.Write(e.buf.Bytes())
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e.buf.Reset()
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return err
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}
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