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聊聊golang的lumberjack
golang
序
本文主要研究一下golang的lumberjack
Logger
lumberjack.v2@v2.0.0/lumberjack.go
type Logger struct { // Filename is the file to write logs to. Backup log files will be retained // in the same directory. It uses <processname>-lumberjack.log in // os.TempDir() if empty. Filename string `json:"filename" yaml:"filename"` // MaxSize is the maximum size in megabytes of the log file before it gets // rotated. It defaults to 100 megabytes. MaxSize int `json:"maxsize" yaml:"maxsize"` // MaxAge is the maximum number of days to retain old log files based on the // timestamp encoded in their filename. Note that a day is defined as 24 // hours and may not exactly correspond to calendar days due to daylight // savings, leap seconds, etc. The default is not to remove old log files // based on age. MaxAge int `json:"maxage" yaml:"maxage"` // MaxBackups is the maximum number of old log files to retain. The default // is to retain all old log files (though MaxAge may still cause them to get // deleted.) MaxBackups int `json:"maxbackups" yaml:"maxbackups"` // LocalTime determines if the time used for formatting the timestamps in // backup files is the computer's local time. The default is to use UTC // time. LocalTime bool `json:"localtime" yaml:"localtime"` // Compress determines if the rotated log files should be compressed // using gzip. The default is not to perform compression. Compress bool `json:"compress" yaml:"compress"` size int64 file *os.File mu sync.Mutex millCh chan bool startMill sync.Once }
Logger定义了Filename、MaxSize(单个文件大小最大值,单位M
)、MaxAge(单位天
)、MaxBackups、LocalTime、Compress属性,另外还有私有属性size、file、sync.Mutex、millCh、startMill
Write
lumberjack.v2@v2.0.0/lumberjack.go
const ( backupTimeFormat = "2006-01-02T15-04-05.000" compressSuffix = ".gz" defaultMaxSize = 100 ) func (l *Logger) Write(p []byte) (n int, err error) { l.mu.Lock() defer l.mu.Unlock() writeLen := int64(len(p)) if writeLen > l.max() { return 0, fmt.Errorf( "write length %d exceeds maximum file size %d", writeLen, l.max(), ) } if l.file == nil { if err = l.openExistingOrNew(len(p)); err != nil { return 0, err } } if l.size+writeLen > l.max() { if err := l.rotate(); err != nil { return 0, err } } n, err = l.file.Write(p) l.size += int64(n) return n, err } func (l *Logger) max() int64 { if l.MaxSize == 0 { return int64(defaultMaxSize * megabyte) } return int64(l.MaxSize) * int64(megabyte) }
Write方法先判断要写入的长度是否超过l.max(),之后判断file是否为nil,如果为nil则执行l.openExistingOrNew;之后判断l.size+writeLen是否大于l.max(),如果大于则执行l.rotate(),否则执行l.file.Write(p),然后更新l.size
openExistingOrNew
lumberjack.v2@v2.0.0/lumberjack.go
func (l *Logger) openExistingOrNew(writeLen int) error { l.mill() filename := l.filename() info, err := os_Stat(filename) if os.IsNotExist(err) { return l.openNew() } if err != nil { return fmt.Errorf("error getting log file info: %s", err) } if info.Size()+int64(writeLen) >= l.max() { return l.rotate() } file, err := os.OpenFile(filename, os.O_APPEND|os.O_WRONLY, 0644) if err != nil { // if we fail to open the old log file for some reason, just ignore // it and open a new log file. return l.openNew() } l.file = file l.size = info.Size() return nil }
openExistingOrNew先执行mill方法,之后判断file是否存在,不存在则执行l.openNew();若文件大小与要写入的大小之和大于等于l.max(),执行l.rotate();否则执行os.OpenFile
millRunOnce
lumberjack.v2@v2.0.0/lumberjack.go
func (l *Logger) mill() { l.startMill.Do(func() { l.millCh = make(chan bool, 1) go l.millRun() }) select { case l.millCh <- true: default: } } func (l *Logger) millRun() { for _ = range l.millCh { // what am I going to do, log this? _ = l.millRunOnce() } } func (l *Logger) millRunOnce() error { if l.MaxBackups == 0 && l.MaxAge == 0 && !l.Compress { return nil } files, err := l.oldLogFiles() if err != nil { return err } var compress, remove []logInfo if l.MaxBackups > 0 && l.MaxBackups < len(files) { preserved := make(map[string]bool) var remaining []logInfo for _, f := range files { // Only count the uncompressed log file or the // compressed log file, not both. fn := f.Name() if strings.HasSuffix(fn, compressSuffix) { fn = fn[:len(fn)-len(compressSuffix)] } preserved[fn] = true if len(preserved) > l.MaxBackups { remove = append(remove, f) } else { remaining = append(remaining, f) } } files = remaining } if l.MaxAge > 0 { diff := time.Duration(int64(24*time.Hour) * int64(l.MaxAge)) cutoff := currentTime().Add(-1 * diff) var remaining []logInfo for _, f := range files { if f.timestamp.Before(cutoff) { remove = append(remove, f) } else { remaining = append(remaining, f) } } files = remaining } if l.Compress { for _, f := range files { if !strings.HasSuffix(f.Name(), compressSuffix) { compress = append(compress, f) } } } for _, f := range remove { errRemove := os.Remove(filepath.Join(l.dir(), f.Name())) if err == nil && errRemove != nil { err = errRemove } } for _, f := range compress { fn := filepath.Join(l.dir(), f.Name()) errCompress := compressLogFile(fn, fn+compressSuffix) if err == nil && errCompress != nil { err = errCompress } } return err }
millRunOnce通过l.oldLogFiles()获取files,然后对于配置了MaxBackups且该值小于旧文件个数时计算要remove的文件,更新files;若l.MaxAge大于0则再根据日期计算要remove的文件,更新files;若l.Compress为true则计算需要compress的文件;之后遍历remove移除文件,遍历compress执行压缩
oldLogFiles
lumberjack.v2@v2.0.0/lumberjack.go
func (l *Logger) oldLogFiles() ([]logInfo, error) { files, err := ioutil.ReadDir(l.dir()) if err != nil { return nil, fmt.Errorf("can't read log file directory: %s", err) } logFiles := []logInfo{} prefix, ext := l.prefixAndExt() for _, f := range files { if f.IsDir() { continue } if t, err := l.timeFromName(f.Name(), prefix, ext); err == nil { logFiles = append(logFiles, logInfo{t, f}) continue } if t, err := l.timeFromName(f.Name(), prefix, ext+compressSuffix); err == nil { logFiles = append(logFiles, logInfo{t, f}) continue } // error parsing means that the suffix at the end was not generated // by lumberjack, and therefore it's not a backup file. } sort.Sort(byFormatTime(logFiles)) return logFiles, nil } func (l *Logger) prefixAndExt() (prefix, ext string) { filename := filepath.Base(l.filename()) ext = filepath.Ext(filename) prefix = filename[:len(filename)-len(ext)] + "-" return prefix, ext } func (l *Logger) timeFromName(filename, prefix, ext string) (time.Time, error) { if !strings.HasPrefix(filename, prefix) { return time.Time{}, errors.New("mismatched prefix") } if !strings.HasSuffix(filename, ext) { return time.Time{}, errors.New("mismatched extension") } ts := filename[len(prefix) : len(filename)-len(ext)] return time.Parse(backupTimeFormat, ts) } type byFormatTime []logInfo func (b byFormatTime) Less(i, j int) bool { return b[i].timestamp.After(b[j].timestamp) } func (b byFormatTime) Swap(i, j int) { b[i], b[j] = b[j], b[i] } func (b byFormatTime) Len() int { return len(b) }
oldLogFiles读取当前目录的文件,然后通过byFormatTime排序,即按时间降序排列
rotate
lumberjack.v2@v2.0.0/lumberjack.go
func (l *Logger) rotate() error { if err := l.close(); err != nil { return err } if err := l.openNew(); err != nil { return err } l.mill() return nil } func (l *Logger) close() error { if l.file == nil { return nil } err := l.file.Close() l.file = nil return err } func (l *Logger) openNew() error { err := os.MkdirAll(l.dir(), 0744) if err != nil { return fmt.Errorf("can't make directories for new logfile: %s", err) } name := l.filename() mode := os.FileMode(0644) info, err := os_Stat(name) if err == nil { // Copy the mode off the old logfile. mode = info.Mode() // move the existing file newname := backupName(name, l.LocalTime) if err := os.Rename(name, newname); err != nil { return fmt.Errorf("can't rename log file: %s", err) } // this is a no-op anywhere but linux if err := chown(name, info); err != nil { return err } } // we use truncate here because this should only get called when we've moved // the file ourselves. if someone else creates the file in the meantime, // just wipe out the contents. f, err := os.OpenFile(name, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, mode) if err != nil { return fmt.Errorf("can't open new logfile: %s", err) } l.file = f l.size = 0 return nil } func backupName(name string, local bool) string { dir := filepath.Dir(name) filename := filepath.Base(name) ext := filepath.Ext(filename) prefix := filename[:len(filename)-len(ext)] t := currentTime() if !local { t = t.UTC() } timestamp := t.Format(backupTimeFormat) return filepath.Join(dir, fmt.Sprintf("%s-%s%s", prefix, timestamp, ext)) }
rotate方法会close当前文件,然后openNew新文件,最后执行l.mill();openNew方法先通过backupName计算要备份的文件名,然后执行Rename,将当前文件重命名为备份文件名,然后执行chown,最后执行os.OpenFile打开新文件
小结
Logger定义了Filename、MaxSize(单个文件大小最大值,单位M
)、MaxAge(单位天
)、MaxBackups、LocalTime、Compress属性;Write方法先判断要写入的长度是否超过l.max(),之后判断file是否为nil,如果为nil则执行l.openExistingOrNew;之后判断l.size+writeLen是否大于l.max(),如果大于则执行l.rotate(),否则执行l.file.Write(p),然后更新l.size。
doc
- lumberjack
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目录
序
本文主要研究一下golang的lumberjack
Logger
lumberjack.v2@v2.0.0/lumberjack.go
type Logger struct { // Filename is the file to write logs to. Backup log files will be retained // in the same directory. It uses <processname>-lumberjack.log in // os.TempDir() if empty. Filename string `json:"filename" yaml:"filename"` // MaxSize is the maximum size in megabytes of the log file before it gets // rotated. It defaults to 100 megabytes. MaxSize int `json:"maxsize" yaml:"maxsize"` // MaxAge is the maximum number of days to retain old log files based on the // timestamp encoded in their filename. Note that a day is defined as 24 // hours and may not exactly correspond to calendar days due to daylight // savings, leap seconds, etc. The default is not to remove old log files // based on age. MaxAge int `json:"maxage" yaml:"maxage"` // MaxBackups is the maximum number of old log files to retain. The default // is to retain all old log files (though MaxAge may still cause them to get // deleted.) MaxBackups int `json:"maxbackups" yaml:"maxbackups"` // LocalTime determines if the time used for formatting the timestamps in // backup files is the computer's local time. The default is to use UTC // time. LocalTime bool `json:"localtime" yaml:"localtime"` // Compress determines if the rotated log files should be compressed // using gzip. The default is not to perform compression. Compress bool `json:"compress" yaml:"compress"` size int64 file *os.File mu sync.Mutex millCh chan bool startMill sync.Once }
Logger定义了Filename、MaxSize(单个文件大小最大值,单位M
)、MaxAge(单位天
)、MaxBackups、LocalTime、Compress属性,另外还有私有属性size、file、sync.Mutex、millCh、startMill
Write
lumberjack.v2@v2.0.0/lumberjack.go
const ( backupTimeFormat = "2006-01-02T15-04-05.000" compressSuffix = ".gz" defaultMaxSize = 100 ) func (l *Logger) Write(p []byte) (n int, err error) { l.mu.Lock() defer l.mu.Unlock() writeLen := int64(len(p)) if writeLen > l.max() { return 0, fmt.Errorf( "write length %d exceeds maximum file size %d", writeLen, l.max(), ) } if l.file == nil { if err = l.openExistingOrNew(len(p)); err != nil { return 0, err } } if l.size+writeLen > l.max() { if err := l.rotate(); err != nil { return 0, err } } n, err = l.file.Write(p) l.size += int64(n) return n, err } func (l *Logger) max() int64 { if l.MaxSize == 0 { return int64(defaultMaxSize * megabyte) } return int64(l.MaxSize) * int64(megabyte) }
Write方法先判断要写入的长度是否超过l.max(),之后判断file是否为nil,如果为nil则执行l.openExistingOrNew;之后判断l.size+writeLen是否大于l.max(),如果大于则执行l.rotate(),否则执行l.file.Write(p),然后更新l.size
openExistingOrNew
lumberjack.v2@v2.0.0/lumberjack.go
func (l *Logger) openExistingOrNew(writeLen int) error { l.mill() filename := l.filename() info, err := os_Stat(filename) if os.IsNotExist(err) { return l.openNew() } if err != nil { return fmt.Errorf("error getting log file info: %s", err) } if info.Size()+int64(writeLen) >= l.max() { return l.rotate() } file, err := os.OpenFile(filename, os.O_APPEND|os.O_WRONLY, 0644) if err != nil { // if we fail to open the old log file for some reason, just ignore // it and open a new log file. return l.openNew() } l.file = file l.size = info.Size() return nil }
openExistingOrNew先执行mill方法,之后判断file是否存在,不存在则执行l.openNew();若文件大小与要写入的大小之和大于等于l.max(),执行l.rotate();否则执行os.OpenFile
millRunOnce
lumberjack.v2@v2.0.0/lumberjack.go
func (l *Logger) mill() { l.startMill.Do(func() { l.millCh = make(chan bool, 1) go l.millRun() }) select { case l.millCh <- true: default: } } func (l *Logger) millRun() { for _ = range l.millCh { // what am I going to do, log this? _ = l.millRunOnce() } } func (l *Logger) millRunOnce() error { if l.MaxBackups == 0 && l.MaxAge == 0 && !l.Compress { return nil } files, err := l.oldLogFiles() if err != nil { return err } var compress, remove []logInfo if l.MaxBackups > 0 && l.MaxBackups < len(files) { preserved := make(map[string]bool) var remaining []logInfo for _, f := range files { // Only count the uncompressed log file or the // compressed log file, not both. fn := f.Name() if strings.HasSuffix(fn, compressSuffix) { fn = fn[:len(fn)-len(compressSuffix)] } preserved[fn] = true if len(preserved) > l.MaxBackups { remove = append(remove, f) } else { remaining = append(remaining, f) } } files = remaining } if l.MaxAge > 0 { diff := time.Duration(int64(24*time.Hour) * int64(l.MaxAge)) cutoff := currentTime().Add(-1 * diff) var remaining []logInfo for _, f := range files { if f.timestamp.Before(cutoff) { remove = append(remove, f) } else { remaining = append(remaining, f) } } files = remaining } if l.Compress { for _, f := range files { if !strings.HasSuffix(f.Name(), compressSuffix) { compress = append(compress, f) } } } for _, f := range remove { errRemove := os.Remove(filepath.Join(l.dir(), f.Name())) if err == nil && errRemove != nil { err = errRemove } } for _, f := range compress { fn := filepath.Join(l.dir(), f.Name()) errCompress := compressLogFile(fn, fn+compressSuffix) if err == nil && errCompress != nil { err = errCompress } } return err }
millRunOnce通过l.oldLogFiles()获取files,然后对于配置了MaxBackups且该值小于旧文件个数时计算要remove的文件,更新files;若l.MaxAge大于0则再根据日期计算要remove的文件,更新files;若l.Compress为true则计算需要compress的文件;之后遍历remove移除文件,遍历compress执行压缩
oldLogFiles
lumberjack.v2@v2.0.0/lumberjack.go
func (l *Logger) oldLogFiles() ([]logInfo, error) { files, err := ioutil.ReadDir(l.dir()) if err != nil { return nil, fmt.Errorf("can't read log file directory: %s", err) } logFiles := []logInfo{} prefix, ext := l.prefixAndExt() for _, f := range files { if f.IsDir() { continue } if t, err := l.timeFromName(f.Name(), prefix, ext); err == nil { logFiles = append(logFiles, logInfo{t, f}) continue } if t, err := l.timeFromName(f.Name(), prefix, ext+compressSuffix); err == nil { logFiles = append(logFiles, logInfo{t, f}) continue } // error parsing means that the suffix at the end was not generated // by lumberjack, and therefore it's not a backup file. } sort.Sort(byFormatTime(logFiles)) return logFiles, nil } func (l *Logger) prefixAndExt() (prefix, ext string) { filename := filepath.Base(l.filename()) ext = filepath.Ext(filename) prefix = filename[:len(filename)-len(ext)] + "-" return prefix, ext } func (l *Logger) timeFromName(filename, prefix, ext string) (time.Time, error) { if !strings.HasPrefix(filename, prefix) { return time.Time{}, errors.New("mismatched prefix") } if !strings.HasSuffix(filename, ext) { return time.Time{}, errors.New("mismatched extension") } ts := filename[len(prefix) : len(filename)-len(ext)] return time.Parse(backupTimeFormat, ts) } type byFormatTime []logInfo func (b byFormatTime) Less(i, j int) bool { return b[i].timestamp.After(b[j].timestamp) } func (b byFormatTime) Swap(i, j int) { b[i], b[j] = b[j], b[i] } func (b byFormatTime) Len() int { return len(b) }
oldLogFiles读取当前目录的文件,然后通过byFormatTime排序,即按时间降序排列
rotate
lumberjack.v2@v2.0.0/lumberjack.go
func (l *Logger) rotate() error { if err := l.close(); err != nil { return err } if err := l.openNew(); err != nil { return err } l.mill() return nil } func (l *Logger) close() error { if l.file == nil { return nil } err := l.file.Close() l.file = nil return err } func (l *Logger) openNew() error { err := os.MkdirAll(l.dir(), 0744) if err != nil { return fmt.Errorf("can't make directories for new logfile: %s", err) } name := l.filename() mode := os.FileMode(0644) info, err := os_Stat(name) if err == nil { // Copy the mode off the old logfile. mode = info.Mode() // move the existing file newname := backupName(name, l.LocalTime) if err := os.Rename(name, newname); err != nil { return fmt.Errorf("can't rename log file: %s", err) } // this is a no-op anywhere but linux if err := chown(name, info); err != nil { return err } } // we use truncate here because this should only get called when we've moved // the file ourselves. if someone else creates the file in the meantime, // just wipe out the contents. f, err := os.OpenFile(name, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, mode) if err != nil { return fmt.Errorf("can't open new logfile: %s", err) } l.file = f l.size = 0 return nil } func backupName(name string, local bool) string { dir := filepath.Dir(name) filename := filepath.Base(name) ext := filepath.Ext(filename) prefix := filename[:len(filename)-len(ext)] t := currentTime() if !local { t = t.UTC() } timestamp := t.Format(backupTimeFormat) return filepath.Join(dir, fmt.Sprintf("%s-%s%s", prefix, timestamp, ext)) }
rotate方法会close当前文件,然后openNew新文件,最后执行l.mill();openNew方法先通过backupName计算要备份的文件名,然后执行Rename,将当前文件重命名为备份文件名,然后执行chown,最后执行os.OpenFile打开新文件
小结
Logger定义了Filename、MaxSize(单个文件大小最大值,单位M
)、MaxAge(单位天
)、MaxBackups、LocalTime、Compress属性;Write方法先判断要写入的长度是否超过l.max(),之后判断file是否为nil,如果为nil则执行l.openExistingOrNew;之后判断l.size+writeLen是否大于l.max(),如果大于则执行l.rotate(),否则执行l.file.Write(p),然后更新l.size。
doc
- lumberjack
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