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context.go
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context.go
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// Copyright © 2019 The Things Network Foundation, The Things Industries B.V.
//
// 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 events
import "context"
// ContextMarshaler interface for marshaling/unmarshaling contextual information
// to/from events.
type ContextMarshaler interface {
MarshalContext(context.Context) []byte
UnmarshalContext(context.Context, []byte) (context.Context, error)
}
var contextMarshalers = map[string]ContextMarshaler{}
// RegisterContextMarshaler registers a ContextMarshaler with the given name.
// This should only be called from init funcs.
func RegisterContextMarshaler(name string, m ContextMarshaler) {
contextMarshalers[name] = m
}
func unmarshalContext(ctx context.Context, data map[string][]byte) (context.Context, error) {
if ctx == nil {
ctx = context.Background()
}
var err error
for name, payload := range data {
m, ok := contextMarshalers[name]
if !ok {
continue
}
ctx, err = m.UnmarshalContext(ctx, payload)
if err != nil {
return nil, err
}
}
return ctx, nil
}
func marshalContext(ctx context.Context) (map[string][]byte, error) {
data := make(map[string][]byte, len(contextMarshalers))
for name, m := range contextMarshalers {
payload := m.MarshalContext(ctx)
if payload == nil {
continue
}
data[name] = payload
}
if len(data) == 0 {
return nil, nil
}
return data, nil
}