mirror of
https://github.com/42wim/matterbridge.git
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542 lines
15 KiB
Go
542 lines
15 KiB
Go
// Package lumberjack provides a rolling logger.
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//
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// Note that this is v2.0 of lumberjack, and should be imported using gopkg.in
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// thusly:
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//
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// import "gopkg.in/natefinch/lumberjack.v2"
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//
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// The package name remains simply lumberjack, and the code resides at
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// https://github.com/natefinch/lumberjack under the v2.0 branch.
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//
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// Lumberjack is intended to be one part of a logging infrastructure.
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// It is not an all-in-one solution, but instead is a pluggable
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// component at the bottom of the logging stack that simply controls the files
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// to which logs are written.
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//
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// Lumberjack plays well with any logging package that can write to an
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// io.Writer, including the standard library's log package.
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//
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// Lumberjack assumes that only one process is writing to the output files.
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// Using the same lumberjack configuration from multiple processes on the same
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// machine will result in improper behavior.
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package lumberjack
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import (
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"compress/gzip"
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"path/filepath"
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"sort"
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"strings"
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"sync"
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"time"
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)
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const (
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backupTimeFormat = "2006-01-02T15-04-05.000"
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compressSuffix = ".gz"
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defaultMaxSize = 100
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)
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// ensure we always implement io.WriteCloser
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var _ io.WriteCloser = (*Logger)(nil)
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// Logger is an io.WriteCloser that writes to the specified filename.
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//
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// Logger opens or creates the logfile on first Write. If the file exists and
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// is less than MaxSize megabytes, lumberjack will open and append to that file.
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// If the file exists and its size is >= MaxSize megabytes, the file is renamed
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// by putting the current time in a timestamp in the name immediately before the
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// file's extension (or the end of the filename if there's no extension). A new
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// log file is then created using original filename.
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//
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// Whenever a write would cause the current log file exceed MaxSize megabytes,
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// the current file is closed, renamed, and a new log file created with the
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// original name. Thus, the filename you give Logger is always the "current" log
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// file.
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//
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// Backups use the log file name given to Logger, in the form
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// `name-timestamp.ext` where name is the filename without the extension,
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// timestamp is the time at which the log was rotated formatted with the
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// time.Time format of `2006-01-02T15-04-05.000` and the extension is the
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// original extension. For example, if your Logger.Filename is
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// `/var/log/foo/server.log`, a backup created at 6:30pm on Nov 11 2016 would
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// use the filename `/var/log/foo/server-2016-11-04T18-30-00.000.log`
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//
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// Cleaning Up Old Log Files
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//
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// Whenever a new logfile gets created, old log files may be deleted. The most
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// recent files according to the encoded timestamp will be retained, up to a
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// number equal to MaxBackups (or all of them if MaxBackups is 0). Any files
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// with an encoded timestamp older than MaxAge days are deleted, regardless of
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// MaxBackups. Note that the time encoded in the timestamp is the rotation
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// time, which may differ from the last time that file was written to.
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//
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// If MaxBackups and MaxAge are both 0, no old log files will be deleted.
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type Logger struct {
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// Filename is the file to write logs to. Backup log files will be retained
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// in the same directory. It uses <processname>-lumberjack.log in
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// os.TempDir() if empty.
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Filename string `json:"filename" yaml:"filename"`
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// MaxSize is the maximum size in megabytes of the log file before it gets
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// rotated. It defaults to 100 megabytes.
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MaxSize int `json:"maxsize" yaml:"maxsize"`
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// MaxAge is the maximum number of days to retain old log files based on the
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// timestamp encoded in their filename. Note that a day is defined as 24
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// hours and may not exactly correspond to calendar days due to daylight
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// savings, leap seconds, etc. The default is not to remove old log files
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// based on age.
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MaxAge int `json:"maxage" yaml:"maxage"`
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// MaxBackups is the maximum number of old log files to retain. The default
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// is to retain all old log files (though MaxAge may still cause them to get
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// deleted.)
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MaxBackups int `json:"maxbackups" yaml:"maxbackups"`
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// LocalTime determines if the time used for formatting the timestamps in
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// backup files is the computer's local time. The default is to use UTC
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// time.
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LocalTime bool `json:"localtime" yaml:"localtime"`
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// Compress determines if the rotated log files should be compressed
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// using gzip. The default is not to perform compression.
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Compress bool `json:"compress" yaml:"compress"`
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size int64
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file *os.File
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mu sync.Mutex
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millCh chan bool
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startMill sync.Once
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}
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var (
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// currentTime exists so it can be mocked out by tests.
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currentTime = time.Now
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// os_Stat exists so it can be mocked out by tests.
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os_Stat = os.Stat
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// megabyte is the conversion factor between MaxSize and bytes. It is a
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// variable so tests can mock it out and not need to write megabytes of data
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// to disk.
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megabyte = 1024 * 1024
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)
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// Write implements io.Writer. If a write would cause the log file to be larger
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// than MaxSize, the file is closed, renamed to include a timestamp of the
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// current time, and a new log file is created using the original log file name.
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// If the length of the write is greater than MaxSize, an error is returned.
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func (l *Logger) Write(p []byte) (n int, err error) {
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l.mu.Lock()
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defer l.mu.Unlock()
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writeLen := int64(len(p))
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if writeLen > l.max() {
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return 0, fmt.Errorf(
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"write length %d exceeds maximum file size %d", writeLen, l.max(),
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)
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}
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if l.file == nil {
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if err = l.openExistingOrNew(len(p)); err != nil {
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return 0, err
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}
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}
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if l.size+writeLen > l.max() {
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if err := l.rotate(); err != nil {
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return 0, err
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}
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}
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n, err = l.file.Write(p)
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l.size += int64(n)
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return n, err
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}
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// Close implements io.Closer, and closes the current logfile.
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func (l *Logger) Close() error {
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l.mu.Lock()
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defer l.mu.Unlock()
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return l.close()
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}
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// close closes the file if it is open.
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func (l *Logger) close() error {
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if l.file == nil {
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return nil
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}
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err := l.file.Close()
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l.file = nil
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return err
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}
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// Rotate causes Logger to close the existing log file and immediately create a
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// new one. This is a helper function for applications that want to initiate
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// rotations outside of the normal rotation rules, such as in response to
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// SIGHUP. After rotating, this initiates compression and removal of old log
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// files according to the configuration.
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func (l *Logger) Rotate() error {
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l.mu.Lock()
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defer l.mu.Unlock()
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return l.rotate()
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}
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// rotate closes the current file, moves it aside with a timestamp in the name,
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// (if it exists), opens a new file with the original filename, and then runs
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// post-rotation processing and removal.
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func (l *Logger) rotate() error {
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if err := l.close(); err != nil {
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return err
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}
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if err := l.openNew(); err != nil {
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return err
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}
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l.mill()
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return nil
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}
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// openNew opens a new log file for writing, moving any old log file out of the
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// way. This methods assumes the file has already been closed.
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func (l *Logger) openNew() error {
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err := os.MkdirAll(l.dir(), 0744)
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if err != nil {
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return fmt.Errorf("can't make directories for new logfile: %s", err)
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}
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name := l.filename()
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mode := os.FileMode(0644)
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info, err := os_Stat(name)
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if err == nil {
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// Copy the mode off the old logfile.
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mode = info.Mode()
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// move the existing file
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newname := backupName(name, l.LocalTime)
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if err := os.Rename(name, newname); err != nil {
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return fmt.Errorf("can't rename log file: %s", err)
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}
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// this is a no-op anywhere but linux
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if err := chown(name, info); err != nil {
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return err
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}
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}
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// we use truncate here because this should only get called when we've moved
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// the file ourselves. if someone else creates the file in the meantime,
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// just wipe out the contents.
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f, err := os.OpenFile(name, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, mode)
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if err != nil {
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return fmt.Errorf("can't open new logfile: %s", err)
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}
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l.file = f
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l.size = 0
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return nil
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}
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// backupName creates a new filename from the given name, inserting a timestamp
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// between the filename and the extension, using the local time if requested
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// (otherwise UTC).
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func backupName(name string, local bool) string {
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dir := filepath.Dir(name)
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filename := filepath.Base(name)
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ext := filepath.Ext(filename)
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prefix := filename[:len(filename)-len(ext)]
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t := currentTime()
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if !local {
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t = t.UTC()
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}
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timestamp := t.Format(backupTimeFormat)
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return filepath.Join(dir, fmt.Sprintf("%s-%s%s", prefix, timestamp, ext))
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}
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// openExistingOrNew opens the logfile if it exists and if the current write
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// would not put it over MaxSize. If there is no such file or the write would
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// put it over the MaxSize, a new file is created.
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func (l *Logger) openExistingOrNew(writeLen int) error {
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l.mill()
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filename := l.filename()
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info, err := os_Stat(filename)
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if os.IsNotExist(err) {
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return l.openNew()
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}
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if err != nil {
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return fmt.Errorf("error getting log file info: %s", err)
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}
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if info.Size()+int64(writeLen) >= l.max() {
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return l.rotate()
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}
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file, err := os.OpenFile(filename, os.O_APPEND|os.O_WRONLY, 0644)
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if err != nil {
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// if we fail to open the old log file for some reason, just ignore
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// it and open a new log file.
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return l.openNew()
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}
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l.file = file
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l.size = info.Size()
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return nil
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}
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// genFilename generates the name of the logfile from the current time.
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func (l *Logger) filename() string {
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if l.Filename != "" {
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return l.Filename
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}
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name := filepath.Base(os.Args[0]) + "-lumberjack.log"
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return filepath.Join(os.TempDir(), name)
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}
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// millRunOnce performs compression and removal of stale log files.
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// Log files are compressed if enabled via configuration and old log
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// files are removed, keeping at most l.MaxBackups files, as long as
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// none of them are older than MaxAge.
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func (l *Logger) millRunOnce() error {
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if l.MaxBackups == 0 && l.MaxAge == 0 && !l.Compress {
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return nil
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}
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files, err := l.oldLogFiles()
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if err != nil {
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return err
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}
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var compress, remove []logInfo
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if l.MaxBackups > 0 && l.MaxBackups < len(files) {
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preserved := make(map[string]bool)
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var remaining []logInfo
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for _, f := range files {
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// Only count the uncompressed log file or the
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// compressed log file, not both.
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fn := f.Name()
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if strings.HasSuffix(fn, compressSuffix) {
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fn = fn[:len(fn)-len(compressSuffix)]
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}
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preserved[fn] = true
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if len(preserved) > l.MaxBackups {
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remove = append(remove, f)
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} else {
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remaining = append(remaining, f)
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}
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}
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files = remaining
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}
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if l.MaxAge > 0 {
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diff := time.Duration(int64(24*time.Hour) * int64(l.MaxAge))
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cutoff := currentTime().Add(-1 * diff)
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var remaining []logInfo
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for _, f := range files {
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if f.timestamp.Before(cutoff) {
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remove = append(remove, f)
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} else {
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remaining = append(remaining, f)
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}
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}
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files = remaining
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}
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if l.Compress {
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for _, f := range files {
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if !strings.HasSuffix(f.Name(), compressSuffix) {
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compress = append(compress, f)
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}
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}
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}
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for _, f := range remove {
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errRemove := os.Remove(filepath.Join(l.dir(), f.Name()))
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if err == nil && errRemove != nil {
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err = errRemove
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}
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}
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for _, f := range compress {
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fn := filepath.Join(l.dir(), f.Name())
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errCompress := compressLogFile(fn, fn+compressSuffix)
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if err == nil && errCompress != nil {
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err = errCompress
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}
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}
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return err
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}
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// millRun runs in a goroutine to manage post-rotation compression and removal
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// of old log files.
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func (l *Logger) millRun() {
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for _ = range l.millCh {
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// what am I going to do, log this?
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_ = l.millRunOnce()
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}
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}
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// mill performs post-rotation compression and removal of stale log files,
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// starting the mill goroutine if necessary.
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func (l *Logger) mill() {
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l.startMill.Do(func() {
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l.millCh = make(chan bool, 1)
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go l.millRun()
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})
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select {
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case l.millCh <- true:
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default:
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}
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}
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// oldLogFiles returns the list of backup log files stored in the same
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// directory as the current log file, sorted by ModTime
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func (l *Logger) oldLogFiles() ([]logInfo, error) {
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files, err := ioutil.ReadDir(l.dir())
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if err != nil {
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return nil, fmt.Errorf("can't read log file directory: %s", err)
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}
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logFiles := []logInfo{}
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prefix, ext := l.prefixAndExt()
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for _, f := range files {
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if f.IsDir() {
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continue
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}
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if t, err := l.timeFromName(f.Name(), prefix, ext); err == nil {
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logFiles = append(logFiles, logInfo{t, f})
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continue
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}
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if t, err := l.timeFromName(f.Name(), prefix, ext+compressSuffix); err == nil {
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logFiles = append(logFiles, logInfo{t, f})
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continue
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}
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// error parsing means that the suffix at the end was not generated
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// by lumberjack, and therefore it's not a backup file.
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}
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sort.Sort(byFormatTime(logFiles))
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return logFiles, nil
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}
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// timeFromName extracts the formatted time from the filename by stripping off
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// the filename's prefix and extension. This prevents someone's filename from
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// confusing time.parse.
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func (l *Logger) timeFromName(filename, prefix, ext string) (time.Time, error) {
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if !strings.HasPrefix(filename, prefix) {
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return time.Time{}, errors.New("mismatched prefix")
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}
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if !strings.HasSuffix(filename, ext) {
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return time.Time{}, errors.New("mismatched extension")
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}
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ts := filename[len(prefix) : len(filename)-len(ext)]
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return time.Parse(backupTimeFormat, ts)
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}
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// max returns the maximum size in bytes of log files before rolling.
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func (l *Logger) max() int64 {
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if l.MaxSize == 0 {
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return int64(defaultMaxSize * megabyte)
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}
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return int64(l.MaxSize) * int64(megabyte)
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}
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// dir returns the directory for the current filename.
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func (l *Logger) dir() string {
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return filepath.Dir(l.filename())
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}
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// prefixAndExt returns the filename part and extension part from the Logger's
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// filename.
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func (l *Logger) prefixAndExt() (prefix, ext string) {
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filename := filepath.Base(l.filename())
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ext = filepath.Ext(filename)
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prefix = filename[:len(filename)-len(ext)] + "-"
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return prefix, ext
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}
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// compressLogFile compresses the given log file, removing the
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// uncompressed log file if successful.
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func compressLogFile(src, dst string) (err error) {
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f, err := os.Open(src)
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if err != nil {
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return fmt.Errorf("failed to open log file: %v", err)
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}
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defer f.Close()
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fi, err := os_Stat(src)
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if err != nil {
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return fmt.Errorf("failed to stat log file: %v", err)
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}
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if err := chown(dst, fi); err != nil {
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return fmt.Errorf("failed to chown compressed log file: %v", err)
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}
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// If this file already exists, we presume it was created by
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// a previous attempt to compress the log file.
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gzf, err := os.OpenFile(dst, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, fi.Mode())
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if err != nil {
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return fmt.Errorf("failed to open compressed log file: %v", err)
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}
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defer gzf.Close()
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gz := gzip.NewWriter(gzf)
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defer func() {
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if err != nil {
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os.Remove(dst)
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err = fmt.Errorf("failed to compress log file: %v", err)
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}
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}()
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if _, err := io.Copy(gz, f); err != nil {
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return err
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}
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if err := gz.Close(); err != nil {
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return err
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}
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if err := gzf.Close(); err != nil {
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return err
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}
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if err := f.Close(); err != nil {
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return err
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}
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if err := os.Remove(src); err != nil {
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return err
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}
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return nil
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}
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// logInfo is a convenience struct to return the filename and its embedded
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// timestamp.
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type logInfo struct {
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timestamp time.Time
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|
os.FileInfo
|
|
}
|
|
|
|
// byFormatTime sorts by newest time formatted in the name.
|
|
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)
|
|
}
|