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package autofile
import (
"os"
"os/signal"
"sync"
"syscall"
"time"
cmn "github.com/tendermint/tendermint/libs/common"
"github.com/tendermint/tendermint/libs/errors"
)
/* AutoFile usage
// Create/Append to ./autofile_test
af, err := OpenAutoFile("autofile_test")
if err != nil {
panic(err)
}
// Stream of writes.
// During this time, the file may be moved e.g. by logRotate.
for i := 0; i < 60; i++ {
af.Write([]byte(Fmt("LOOP(%v)", i)))
time.Sleep(time.Second)
}
// Close the AutoFile
err = af.Close()
if err != nil {
panic(err)
}
*/
const (
autoFileClosePeriod = 1000 * time.Millisecond
autoFilePerms = os.FileMode(0600)
)
// AutoFile automatically closes and re-opens file for writing. The file is
// automatically setup to close itself every 1s and upon receiving SIGHUP.
//
// This is useful for using a log file with the logrotate tool.
type AutoFile struct {
ID string
Path string
closeTicker *time.Ticker
closeTickerStopc chan struct{} // closed when closeTicker is stopped
hupc chan os.Signal
mtx sync.Mutex
file *os.File
}
// OpenAutoFile creates an AutoFile in the path (with random ID). If there is
// an error, it will be of type *PathError or *ErrPermissionsChanged (if file's
// permissions got changed (should be 0600)).
func OpenAutoFile(path string) (*AutoFile, error) {
af := &AutoFile{
ID: cmn.RandStr(12) + ":" + path,
Path: path,
closeTicker: time.NewTicker(autoFileClosePeriod),
closeTickerStopc: make(chan struct{}),
}
if err := af.openFile(); err != nil {
af.Close()
return nil, err
}
// Close file on SIGHUP.
af.hupc = make(chan os.Signal, 1)
signal.Notify(af.hupc, syscall.SIGHUP)
go func() {
for range af.hupc {
af.closeFile()
}
}()
go af.closeFileRoutine()
return af, nil
}
func (af *AutoFile) Close() error {
af.closeTicker.Stop()
close(af.closeTickerStopc)
if af.hupc != nil {
close(af.hupc)
}
return af.closeFile()
}
func (af *AutoFile) closeFileRoutine() {
for {
select {
case <-af.closeTicker.C:
af.closeFile()
case <-af.closeTickerStopc:
return
}
}
}
func (af *AutoFile) closeFile() (err error) {
af.mtx.Lock()
defer af.mtx.Unlock()
file := af.file
if file == nil {
return nil
}
af.file = nil
return file.Close()
}
func (af *AutoFile) Write(b []byte) (n int, err error) {
af.mtx.Lock()
defer af.mtx.Unlock()
if af.file == nil {
if err = af.openFile(); err != nil {
return
}
}
n, err = af.file.Write(b)
return
}
func (af *AutoFile) Sync() error {
af.mtx.Lock()
defer af.mtx.Unlock()
if af.file == nil {
if err := af.openFile(); err != nil {
return err
}
}
return af.file.Sync()
}
func (af *AutoFile) openFile() error {
file, err := os.OpenFile(af.Path, os.O_RDWR|os.O_CREATE|os.O_APPEND, autoFilePerms)
if err != nil {
return err
}
fileInfo, err := file.Stat()
if err != nil {
return err
}
if fileInfo.Mode() != autoFilePerms {
return errors.NewErrPermissionsChanged(file.Name(), fileInfo.Mode(), autoFilePerms)
}
af.file = file
return nil
}
func (af *AutoFile) Size() (int64, error) {
af.mtx.Lock()
defer af.mtx.Unlock()
if af.file == nil {
err := af.openFile()
if err != nil {
if err == os.ErrNotExist {
return 0, nil
}
return -1, err
}
}
stat, err := af.file.Stat()
if err != nil {
return -1, err
}
return stat.Size(), nil
}