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logger.go
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logger.go
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// Copyright (c) Contributors to the Apptainer project, established as
// Apptainer a Series of LF Projects LLC.
// For website terms of use, trademark policy, privacy policy and other
// project policies see https://lfprojects.org/policies
// Copyright (c) 2018, Sylabs Inc. All rights reserved.
// This software is licensed under a 3-clause BSD license. Please consult the
// LICENSE.md file distributed with the sources of this project regarding your
// rights to use or distribute this software.
package instance
import (
"bufio"
"bytes"
"fmt"
"io"
"os"
"strings"
"sync"
"syscall"
"time"
)
const (
// BasicLogFormat represents basic log format.
BasicLogFormat = "basic"
// KubernetesLogFormat represents kubernetes log format.
KubernetesLogFormat = "kubernetes"
// JSONLogFormat represents JSON log format.
JSONLogFormat = "json"
)
// LogFormatter implements a log formatter.
type LogFormatter func(stream string, data string) string
func kubernetesLogFormatter(stream, data string) string {
return fmt.Sprintf("%s %s F %s\n", time.Now().Format(time.RFC3339Nano), stream, data)
}
func jsonLogFormatter(stream, data string) string {
return fmt.Sprintf("{\"time\":\"%s\",\"stream\":\"%s\",\"log\":\"%s\"}\n", time.Now().Format(time.RFC3339Nano), stream, data)
}
func basicLogFormatter(stream, data string) string {
if stream != "" {
return fmt.Sprintf("%s %s %s\n", time.Now().Format(time.RFC3339Nano), stream, data)
}
return fmt.Sprintf("%s %s\n", time.Now().Format(time.RFC3339Nano), data)
}
type closer func()
// LogFormats contains supported log format by default.
var LogFormats = map[string]LogFormatter{
BasicLogFormat: basicLogFormatter,
KubernetesLogFormat: kubernetesLogFormatter,
JSONLogFormat: jsonLogFormatter,
}
// Logger defines a file logger.
type Logger struct {
fm sync.Mutex // protect file
file *os.File
formatter LogFormatter
cm sync.Mutex // protect closers array
closers []closer
}
// NewLogger instantiates a new logger with formatter and return it.
func NewLogger(logPath string, formatter LogFormatter) (*Logger, error) {
logger := &Logger{
formatter: formatter,
closers: make([]closer, 0),
}
if logger.formatter == nil {
logger.formatter = basicLogFormatter
}
if err := logger.openFile(logPath); err != nil {
return nil, err
}
return logger, nil
}
func (l *Logger) openFile(path string) (err error) {
oldmask := syscall.Umask(0)
defer syscall.Umask(oldmask)
l.file, err = os.OpenFile(path, os.O_CREATE|os.O_RDWR|os.O_APPEND, 0o640)
return err
}
func (l *Logger) scanOutput(data []byte, atEOF bool) (advance int, token []byte, err error) {
if atEOF && len(data) == 0 {
return 0, nil, nil
}
if i := bytes.IndexByte(data, '\n'); i >= 0 {
return i + 1, data[0 : i+1], nil
}
if atEOF {
return len(data), data, nil
}
return 0, nil, nil
}
// NewWriter create a new pipe pair for corresponding stream.
func (l *Logger) NewWriter(stream string, dropCRNL bool) (*io.PipeWriter, error) {
l.cm.Lock()
defer l.cm.Unlock()
// means Close has been called and logger is not usable
if l.closers == nil {
return nil, fmt.Errorf("logger has been closed")
}
reader, writer := io.Pipe()
closer := l.scan(stream, reader, writer, dropCRNL)
l.closers = append(l.closers, closer)
return writer, nil
}
func (l *Logger) scan(stream string, pr *io.PipeReader, pw *io.PipeWriter, dropCRNL bool) closer {
r := strings.NewReplacer("\r", "\\r", "\n", "\\n")
scanner := bufio.NewScanner(pr)
if !dropCRNL {
scanner.Split(l.scanOutput)
}
wg := new(sync.WaitGroup)
wg.Add(1)
go func() {
for scanner.Scan() {
// this section is locked to ensure that log file is
// not being written while ReOpenFile is called
l.fm.Lock()
// means ReOpenFile has failed proceed with cleanup
if l.file == nil {
l.fm.Unlock()
break
}
if !dropCRNL {
fmt.Fprint(l.file, l.formatter(stream, r.Replace(scanner.Text())))
} else {
fmt.Fprint(l.file, l.formatter(stream, scanner.Text()))
}
l.fm.Unlock()
}
pr.Close()
wg.Done()
}()
// closer function
return func() {
pw.Close()
wg.Wait()
}
}
func (l *Logger) endScans() {
// closer will terminate scan goroutines spawned with NewWriter
// by closing pipe write end
l.cm.Lock()
defer l.cm.Unlock()
for _, closer := range l.closers {
closer()
}
l.closers = nil
}
// Close closes all pipe pairs created with NewWriter and also closes
// log file descriptor.
func (l *Logger) Close() {
l.endScans()
l.fm.Lock()
l.file.Sync()
l.file.Close()
l.fm.Unlock()
}
// ReOpenFile closes and re-open log file (eg: log rotation).
func (l *Logger) ReOpenFile() error {
l.fm.Lock()
filename := l.file.Name()
l.file.Sync()
l.file.Close()
err := l.openFile(filename)
l.fm.Unlock()
if err != nil {
// logger is not usable anymore, proceed with cleanup
l.endScans()
}
return err
}