Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame] | 1 | /* |
| 2 | Copyright 2015 The Kubernetes Authors. |
| 3 | |
| 4 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | you may not use this file except in compliance with the License. |
| 6 | You may obtain a copy of the License at |
| 7 | |
| 8 | http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | |
| 10 | Unless required by applicable law or agreed to in writing, software |
| 11 | distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | See the License for the specific language governing permissions and |
| 14 | limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | // Package streaming implements encoder and decoder for streams |
| 18 | // of runtime.Objects over io.Writer/Readers. |
| 19 | package streaming |
| 20 | |
| 21 | import ( |
| 22 | "bytes" |
| 23 | "fmt" |
| 24 | "io" |
| 25 | |
| 26 | "k8s.io/apimachinery/pkg/runtime" |
| 27 | "k8s.io/apimachinery/pkg/runtime/schema" |
| 28 | ) |
| 29 | |
| 30 | // Encoder is a runtime.Encoder on a stream. |
| 31 | type Encoder interface { |
| 32 | // Encode will write the provided object to the stream or return an error. It obeys the same |
| 33 | // contract as runtime.VersionedEncoder. |
| 34 | Encode(obj runtime.Object) error |
| 35 | } |
| 36 | |
| 37 | // Decoder is a runtime.Decoder from a stream. |
| 38 | type Decoder interface { |
| 39 | // Decode will return io.EOF when no more objects are available. |
| 40 | Decode(defaults *schema.GroupVersionKind, into runtime.Object) (runtime.Object, *schema.GroupVersionKind, error) |
| 41 | // Close closes the underlying stream. |
| 42 | Close() error |
| 43 | } |
| 44 | |
| 45 | // Serializer is a factory for creating encoders and decoders that work over streams. |
| 46 | type Serializer interface { |
| 47 | NewEncoder(w io.Writer) Encoder |
| 48 | NewDecoder(r io.ReadCloser) Decoder |
| 49 | } |
| 50 | |
| 51 | type decoder struct { |
| 52 | reader io.ReadCloser |
| 53 | decoder runtime.Decoder |
| 54 | buf []byte |
| 55 | maxBytes int |
| 56 | resetRead bool |
| 57 | } |
| 58 | |
| 59 | // NewDecoder creates a streaming decoder that reads object chunks from r and decodes them with d. |
| 60 | // The reader is expected to return ErrShortRead if the provided buffer is not large enough to read |
| 61 | // an entire object. |
| 62 | func NewDecoder(r io.ReadCloser, d runtime.Decoder) Decoder { |
| 63 | return &decoder{ |
| 64 | reader: r, |
| 65 | decoder: d, |
| 66 | buf: make([]byte, 1024), |
| 67 | maxBytes: 16 * 1024 * 1024, |
| 68 | } |
| 69 | } |
| 70 | |
| 71 | var ErrObjectTooLarge = fmt.Errorf("object to decode was longer than maximum allowed size") |
| 72 | |
| 73 | // Decode reads the next object from the stream and decodes it. |
| 74 | func (d *decoder) Decode(defaults *schema.GroupVersionKind, into runtime.Object) (runtime.Object, *schema.GroupVersionKind, error) { |
| 75 | base := 0 |
| 76 | for { |
| 77 | n, err := d.reader.Read(d.buf[base:]) |
| 78 | if err == io.ErrShortBuffer { |
| 79 | if n == 0 { |
| 80 | return nil, nil, fmt.Errorf("got short buffer with n=0, base=%d, cap=%d", base, cap(d.buf)) |
| 81 | } |
| 82 | if d.resetRead { |
| 83 | continue |
| 84 | } |
| 85 | // double the buffer size up to maxBytes |
| 86 | if len(d.buf) < d.maxBytes { |
| 87 | base += n |
| 88 | d.buf = append(d.buf, make([]byte, len(d.buf))...) |
| 89 | continue |
| 90 | } |
| 91 | // must read the rest of the frame (until we stop getting ErrShortBuffer) |
| 92 | d.resetRead = true |
| 93 | base = 0 |
| 94 | return nil, nil, ErrObjectTooLarge |
| 95 | } |
| 96 | if err != nil { |
| 97 | return nil, nil, err |
| 98 | } |
| 99 | if d.resetRead { |
| 100 | // now that we have drained the large read, continue |
| 101 | d.resetRead = false |
| 102 | continue |
| 103 | } |
| 104 | base += n |
| 105 | break |
| 106 | } |
| 107 | return d.decoder.Decode(d.buf[:base], defaults, into) |
| 108 | } |
| 109 | |
| 110 | func (d *decoder) Close() error { |
| 111 | return d.reader.Close() |
| 112 | } |
| 113 | |
| 114 | type encoder struct { |
| 115 | writer io.Writer |
| 116 | encoder runtime.Encoder |
| 117 | buf *bytes.Buffer |
| 118 | } |
| 119 | |
| 120 | // NewEncoder returns a new streaming encoder. |
| 121 | func NewEncoder(w io.Writer, e runtime.Encoder) Encoder { |
| 122 | return &encoder{ |
| 123 | writer: w, |
| 124 | encoder: e, |
| 125 | buf: &bytes.Buffer{}, |
| 126 | } |
| 127 | } |
| 128 | |
| 129 | // Encode writes the provided object to the nested writer. |
| 130 | func (e *encoder) Encode(obj runtime.Object) error { |
| 131 | if err := e.encoder.Encode(obj, e.buf); err != nil { |
| 132 | return err |
| 133 | } |
| 134 | _, err := e.writer.Write(e.buf.Bytes()) |
| 135 | e.buf.Reset() |
| 136 | return err |
| 137 | } |