e0ebcf4216
The codec factory should support two distinct interfaces - negotiating for a serializer with a client, vs reading or writing data to a storage form (etcd, disk, etc). Make the EncodeForVersion and DecodeToVersion methods only take Encoder and Decoder, and slight refactoring elsewhere. In the storage factory, use a content type to control what serializer to pick, and use the universal deserializer. This ensures that storage can read JSON (which might be from older objects) while only writing protobuf. Add exceptions for those resources that may not be able to write to protobuf (specifically third party resources, but potentially others in the future).
128 lines
3.4 KiB
Go
128 lines
3.4 KiB
Go
/*
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Copyright 2014 The Kubernetes Authors All rights reserved.
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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 recognizer
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import (
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"bufio"
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"bytes"
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"fmt"
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"io"
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"k8s.io/kubernetes/pkg/api/unversioned"
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"k8s.io/kubernetes/pkg/runtime"
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)
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type RecognizingDecoder interface {
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runtime.Decoder
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// RecognizesData should return true if the input provided in the provided reader
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// belongs to this decoder, or an error if the data could not be read or is ambiguous.
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// Unknown is true if the data could not be determined to match the decoder type.
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// Decoders should assume that they can read as much of peek as they need (as the caller
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// provides) and may return unknown if the data provided is not sufficient to make a
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// a determination. When peek returns EOF that may mean the end of the input or the
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// end of buffered input - recognizers should return the best guess at that time.
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RecognizesData(peek io.Reader) (ok, unknown bool, err error)
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}
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// NewDecoder creates a decoder that will attempt multiple decoders in an order defined
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// by:
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//
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// 1. The decoder implements RecognizingDecoder and identifies the data
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// 2. All other decoders, and any decoder that returned true for unknown.
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//
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// The order passed to the constructor is preserved within those priorities.
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func NewDecoder(decoders ...runtime.Decoder) runtime.Decoder {
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return &decoder{
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decoders: decoders,
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}
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}
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type decoder struct {
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decoders []runtime.Decoder
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}
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var _ RecognizingDecoder = &decoder{}
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func (d *decoder) RecognizesData(peek io.Reader) (bool, bool, error) {
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var (
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lastErr error
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anyUnknown bool
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)
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data, _ := bufio.NewReaderSize(peek, 1024).Peek(1024)
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for _, r := range d.decoders {
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switch t := r.(type) {
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case RecognizingDecoder:
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ok, unknown, err := t.RecognizesData(bytes.NewBuffer(data))
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if err != nil {
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lastErr = err
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continue
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}
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anyUnknown = anyUnknown || unknown
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if !ok {
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continue
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}
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return true, false, nil
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}
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}
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return false, anyUnknown, lastErr
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}
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func (d *decoder) Decode(data []byte, gvk *unversioned.GroupVersionKind, into runtime.Object) (runtime.Object, *unversioned.GroupVersionKind, error) {
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var (
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lastErr error
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skipped []runtime.Decoder
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)
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// try recognizers, record any decoders we need to give a chance later
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for _, r := range d.decoders {
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switch t := r.(type) {
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case RecognizingDecoder:
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buf := bytes.NewBuffer(data)
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ok, unknown, err := t.RecognizesData(buf)
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if err != nil {
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lastErr = err
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continue
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}
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if unknown {
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skipped = append(skipped, t)
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continue
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}
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if !ok {
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continue
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}
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return r.Decode(data, gvk, into)
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default:
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skipped = append(skipped, t)
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}
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}
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// try recognizers that returned unknown or didn't recognize their data
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for _, r := range skipped {
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out, actual, err := r.Decode(data, gvk, into)
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if err != nil {
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lastErr = err
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continue
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}
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return out, actual, nil
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}
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if lastErr == nil {
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lastErr = fmt.Errorf("no serialization format matched the provided data")
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}
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return nil, nil, lastErr
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}
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