forked from lestrrat-go/file-rotatelogs
/
rotatelogs.go
230 lines (192 loc) · 4.18 KB
/
rotatelogs.go
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/*
Port of File-RotateLogs from Perl (https://metacpan.org/release/File-RotateLogs)
*/
package rotatelogs
import (
"fmt"
"os"
"path/filepath"
"regexp"
"strings"
"time"
"bitbucket.org/tebeka/strftime"
)
type RotateLogs struct {
LogFile string
LinkName string
RotationTime time.Duration
MaxAge time.Duration
Offset time.Duration
curFn string
outFh *os.File
logfilePattern string
sem chan struct{}
}
/* CurrentTime is only used for testing. Normally it's the time.Now()
* function
*/
var CurrentTime = time.Now
func NewRotateLogs(logfile string) *RotateLogs {
return &RotateLogs{
LogFile: logfile,
LinkName: "",
RotationTime: 86400 * time.Second,
MaxAge: 0,
Offset: 0,
curFn: "",
outFh: nil,
logfilePattern: "",
sem: make(chan struct{}, 1),
}
}
func (rl *RotateLogs) GenFilename() (string, error) {
now := CurrentTime()
diff := time.Duration(now.Add(rl.Offset).UnixNano()) % rl.RotationTime
t := now.Add(time.Duration(-1 * diff))
str, err := strftime.Format(rl.LogFile, t)
if err != nil {
return "", err
}
return str, err
}
func (rl *RotateLogs) Write(p []byte) (n int, err error) {
// Guard against concurrent writes
rl.sem <- struct{}{}
defer func() { <-rl.sem }()
// This filename contains the name of the "NEW" filename
// to log to, which may be newer than rl.currentFilename
filename, err := rl.GenFilename()
if err != nil {
return 0, err
}
var out *os.File
if filename == rl.curFn { // Match!
out = rl.outFh // use old one
}
isNew := false
if out == nil {
isNew = true
_, err := os.Stat(filename)
if err == nil {
if rl.LinkName != "" {
_, err = os.Lstat(rl.LinkName)
if err == nil {
isNew = false
}
}
}
fh, err := os.OpenFile(filename, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
if err != nil {
return 0, fmt.Errorf("error: Failed to open file %s: %s", rl.LogFile, err)
}
out = fh
if isNew {
rl.Rotate(filename)
}
}
n, err = out.Write(p)
if rl.outFh == nil {
rl.outFh = out
} else if isNew {
rl.outFh.Close()
rl.outFh = out
}
rl.curFn = filename
return n, err
}
func (rl *RotateLogs) CurrentFileName() string {
return rl.curFn
}
var patternConversionRegexps = []*regexp.Regexp{
regexp.MustCompile(`%[%+A-Za-z]`),
regexp.MustCompile(`\*+`),
}
func (rl *RotateLogs) LogFilePattern() string {
if rl.logfilePattern == "" {
lf := rl.LogFile
for _, re := range patternConversionRegexps {
lf = re.ReplaceAllString(lf, "*")
}
rl.logfilePattern = lf
}
return rl.logfilePattern
}
func (rl *RotateLogs) Rotate(filename string) error {
lockfn := fmt.Sprintf("%s_lock", filename)
fh, err := os.OpenFile(lockfn, os.O_CREATE|os.O_EXCL, 0644)
if err != nil {
// Can't lock, just return
return err
}
goneToBackground := false
guard := func() {
fh.Close()
os.Remove(lockfn)
}
defer func() {
if !goneToBackground {
guard()
}
}()
if rl.LinkName != "" {
linkTarget := filename
if !filepath.IsAbs(rl.LinkName) {
linkTarget, err = filepath.Rel(filepath.Dir(rl.LinkName), filename)
if err != nil {
return err
}
}
tmpLinkName := fmt.Sprintf("%s_symlink", filename)
err = os.Symlink(linkTarget, tmpLinkName)
if err != nil {
return err
}
err = os.Rename(tmpLinkName, rl.LinkName)
if err != nil {
return err
}
}
if rl.MaxAge <= 0 {
return nil
}
pattern := rl.LogFilePattern()
matches, err := filepath.Glob(pattern)
if err != nil {
return err
}
cutoff := CurrentTime().Add(-1 * rl.MaxAge)
var toUnlink []string
for _, path := range matches {
// Ignore lock files
if strings.HasSuffix(path, "_lock") || strings.HasSuffix(path, "_symlink") {
continue
}
fi, err := os.Stat(path)
if err != nil {
continue
}
if fi.ModTime().After(cutoff) {
continue
}
toUnlink = append(toUnlink, path)
}
if len(toUnlink) <= 0 {
return nil
}
goneToBackground = true
go func() {
defer guard()
// unlink files on a separate goroutine
for _, path := range toUnlink {
os.Remove(path)
}
}()
return nil
}
func (rl *RotateLogs) Close() error {
if rl.outFh != nil {
rl.outFh.Close()
rl.outFh = nil
}
return nil
}