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// Copyright 2018 The gVisor 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 log
import (
"encoding/json"
"fmt"
"time"
)
type jsonLog struct {
Msg string `json:"msg"`
Level Level `json:"level"`
Time time.Time `json:"time"`
}
// MarshalJSON implements json.Marshaler.MarashalJSON.
func (lv Level) MarshalJSON() ([]byte, error) {
switch lv {
case Warning:
return []byte(`"warning"`), nil
case Info:
return []byte(`"info"`), nil
case Debug:
return []byte(`"debug"`), nil
default:
return nil, fmt.Errorf("unknown level %v", lv)
}
}
// UnmarshalJSON implements json.Unmarshaler.UnmarshalJSON. It can unmarshal
// from both string names and integers.
func (lv *Level) UnmarshalJSON(b []byte) error {
switch s := string(b); s {
case "0", `"warning"`:
*lv = Warning
case "1", `"info"`:
*lv = Info
case "2", `"debug"`:
*lv = Debug
default:
return fmt.Errorf("unknown level %q", s)
}
return nil
}
// JSONEmitter logs messages in json format.
type JSONEmitter struct {
Writer
}
// Emit implements Emitter.Emit.
func (e JSONEmitter) Emit(_ int, level Level, timestamp time.Time, format string, v ...interface{}) {
j := jsonLog{
Msg: fmt.Sprintf(format, v...),
Level: level,
Time: timestamp,
}
b, err := json.Marshal(j)
if err != nil {
panic(err)
}
e.Writer.Write(b)
}
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