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// Copyright 2016 Google Inc. All rights reserved.
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file.
// +build !appengine
package internal
import (
"encoding/json"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"strings"
"sync"
"time"
)
// jsonLogger writes logs in the JSON format required for Flex Logging. It can
// be used concurrently.
type jsonLogger struct {
mu sync.Mutex
enc *json.Encoder
}
type logLine struct {
Message string `json:"message"`
Timestamp logTimestamp `json:"timestamp"`
Severity string `json:"severity"`
TraceID string `json:"traceId,omitempty"`
}
type logTimestamp struct {
Seconds int64 `json:"seconds"`
Nanos int `json:"nanos"`
}
var (
logger *jsonLogger
loggerOnce sync.Once
logPath = "/var/log/app_engine/app.json"
stderrLogger = newJSONLogger(os.Stderr)
testLogger = newJSONLogger(ioutil.Discard)
levels = map[int64]string{
0: "DEBUG",
1: "INFO",
2: "WARNING",
3: "ERROR",
4: "CRITICAL",
}
)
func globalLogger() *jsonLogger {
loggerOnce.Do(func() {
f, err := os.OpenFile(logPath, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0666)
if err != nil {
log.Printf("failed to open/create log file, logging to stderr: %v", err)
logger = stderrLogger
return
}
logger = newJSONLogger(f)
})
return logger
}
func logf(ctx *context, level int64, format string, args ...interface{}) {
s := strings.TrimSpace(fmt.Sprintf(format, args...))
now := time.Now()
trace := ctx.req.Header.Get(traceHeader)
if i := strings.Index(trace, "/"); i > -1 {
trace = trace[:i]
}
line := &logLine{
Message: s,
Timestamp: logTimestamp{
Seconds: now.Unix(),
Nanos: now.Nanosecond(),
},
Severity: levels[level],
TraceID: trace,
}
if err := ctx.logger.emit(line); err != nil {
log.Printf("failed to write log line to file: %v", err)
}
log.Print(levels[level] + ": " + s)
}
func newJSONLogger(w io.Writer) *jsonLogger {
return &jsonLogger{
enc: json.NewEncoder(w),
}
}
func (l *jsonLogger) emit(line *logLine) error {
l.mu.Lock()
defer l.mu.Unlock()
return l.enc.Encode(line)
}
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