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file_rotator.go
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file_rotator.go
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package logp
import (
"fmt"
"os"
"path/filepath"
"strconv"
"strings"
)
const RotatorMaxFiles = 1024
const DefaultKeepFiles = 7
const DefaultRotateEveryBytes = 10 * 1024 * 1024
type FileRotator struct {
Path string
Name string
RotateEveryBytes *uint64
KeepFiles *int
current *os.File
currentSize uint64
}
func (rotator *FileRotator) CreateDirectory() error {
fileinfo, err := os.Stat(rotator.Path)
if err == nil {
if !fileinfo.IsDir() {
return fmt.Errorf("%s exists but it's not a directory", rotator.Path)
}
}
if os.IsNotExist(err) {
err = os.MkdirAll(rotator.Path, 0750)
if err != nil {
return err
}
}
return nil
}
func (rotator *FileRotator) CheckIfConfigSane() error {
if len(rotator.Name) == 0 {
return fmt.Errorf("File logging requires a name for the file names")
}
if rotator.KeepFiles == nil {
rotator.KeepFiles = new(int)
*rotator.KeepFiles = DefaultKeepFiles
}
if rotator.RotateEveryBytes == nil {
rotator.RotateEveryBytes = new(uint64)
*rotator.RotateEveryBytes = DefaultRotateEveryBytes
}
if *rotator.KeepFiles < 2 || *rotator.KeepFiles >= RotatorMaxFiles {
return fmt.Errorf("The number of files to keep should be between 2 and %d", RotatorMaxFiles-1)
}
return nil
}
func (rotator *FileRotator) WriteLine(line []byte) error {
if rotator.shouldRotate() {
err := rotator.Rotate()
if err != nil {
return err
}
}
line = append(line, '\n')
_, err := rotator.current.Write(line)
if err != nil {
return err
}
rotator.currentSize += uint64(len(line))
return nil
}
func (rotator *FileRotator) shouldRotate() bool {
if rotator.current == nil {
return true
}
if rotator.currentSize >= *rotator.RotateEveryBytes {
return true
}
return false
}
func (rotator *FileRotator) FilePath(fileNo int) string {
if fileNo == 0 {
return filepath.Join(rotator.Path, rotator.Name)
}
filename := strings.Join([]string{rotator.Name, strconv.Itoa(fileNo)}, ".")
return filepath.Join(rotator.Path, filename)
}
func (rotator *FileRotator) FileExists(fileNo int) bool {
path := rotator.FilePath(fileNo)
_, err := os.Stat(path)
if os.IsNotExist(err) {
return false
}
return true
}
func (rotator *FileRotator) Rotate() error {
if rotator.current != nil {
if err := rotator.current.Close(); err != nil {
return err
}
}
// delete any extra files, normally we shouldn't have any
for fileNo := *rotator.KeepFiles; fileNo < RotatorMaxFiles; fileNo++ {
if rotator.FileExists(fileNo) {
perr := os.Remove(rotator.FilePath(fileNo))
if perr != nil {
return perr
}
}
}
// shift all files from last to first
for fileNo := *rotator.KeepFiles - 1; fileNo >= 0; fileNo-- {
if !rotator.FileExists(fileNo) {
// file doesn't exist, don't rotate
continue
}
path := rotator.FilePath(fileNo)
if rotator.FileExists(fileNo + 1) {
// next file exists, something is strange
return fmt.Errorf("File %s exists, when rotating would overwrite it", rotator.FilePath(fileNo+1))
}
err := os.Rename(path, rotator.FilePath(fileNo+1))
if err != nil {
return err
}
}
// create the new file
path := rotator.FilePath(0)
current, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
return err
}
rotator.current = current
rotator.currentSize = 0
// delete the extra file, ignore errors here
path = rotator.FilePath(*rotator.KeepFiles)
os.Remove(path)
return nil
}