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package loggerutils // import "github.com/docker/docker/daemon/logger/loggerutils"
import (
"io"
"os"
"time"
"github.com/docker/docker/daemon/logger"
"github.com/docker/docker/pkg/filenotify"
"github.com/fsnotify/fsnotify"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
)
var errRetry = errors.New("retry")
var errDone = errors.New("done")
type follow struct {
file *os.File
dec Decoder
fileWatcher filenotify.FileWatcher
logWatcher *logger.LogWatcher
notifyRotate, notifyEvict chan interface{}
oldSize int64
retries int
}
func (fl *follow) handleRotate() error {
name := fl.file.Name()
fl.file.Close()
fl.fileWatcher.Remove(name)
// retry when the file doesn't exist
var err error
for retries := 0; retries <= 5; retries++ {
f, err := open(name)
if err == nil || !os.IsNotExist(err) {
fl.file = f
break
}
}
if err != nil {
return err
}
if err := fl.fileWatcher.Add(name); err != nil {
return err
}
fl.dec.Reset(fl.file)
return nil
}
func (fl *follow) handleMustClose(evictErr error) {
fl.file.Close()
fl.dec.Close()
fl.logWatcher.Err <- errors.Wrap(evictErr, "log reader evicted due to errors")
logrus.WithField("file", fl.file.Name()).Error("Log reader notified that it must re-open log file, some log data may not be streamed to the client.")
}
func (fl *follow) waitRead() error {
select {
case e := <-fl.notifyEvict:
if e != nil {
err := e.(error)
fl.handleMustClose(err)
}
return errDone
case e := <-fl.fileWatcher.Events():
switch e.Op {
case fsnotify.Write:
fl.dec.Reset(fl.file)
return nil
case fsnotify.Rename, fsnotify.Remove:
select {
case <-fl.notifyRotate:
case <-fl.logWatcher.WatchProducerGone():
return errDone
case <-fl.logWatcher.WatchConsumerGone():
return errDone
}
if err := fl.handleRotate(); err != nil {
return err
}
return nil
}
return errRetry
case err := <-fl.fileWatcher.Errors():
logrus.Debugf("logger got error watching file: %v", err)
// Something happened, let's try and stay alive and create a new watcher
if fl.retries <= 5 {
fl.fileWatcher.Close()
fl.fileWatcher, err = watchFile(fl.file.Name())
if err != nil {
return err
}
fl.retries++
return errRetry
}
return err
case <-fl.logWatcher.WatchProducerGone():
return errDone
case <-fl.logWatcher.WatchConsumerGone():
return errDone
}
}
func (fl *follow) handleDecodeErr(err error) error {
if !errors.Is(err, io.EOF) {
return err
}
// Handle special case (#39235): max-file=1 and file was truncated
st, stErr := fl.file.Stat()
if stErr == nil {
size := st.Size()
defer func() { fl.oldSize = size }()
if size < fl.oldSize { // truncated
fl.file.Seek(0, 0)
fl.dec.Reset(fl.file)
return nil
}
} else {
logrus.WithError(stErr).Warn("logger: stat error")
}
for {
err := fl.waitRead()
if err == nil {
break
}
if err == errRetry {
continue
}
return err
}
return nil
}
func (fl *follow) mainLoop(since, until time.Time) {
for {
select {
case err := <-fl.notifyEvict:
if err != nil {
fl.handleMustClose(err.(error))
}
return
default:
}
msg, err := fl.dec.Decode()
if err != nil {
if err := fl.handleDecodeErr(err); err != nil {
if err == errDone {
return
}
// we got an unrecoverable error, so return
fl.logWatcher.Err <- err
return
}
// ready to try again
continue
}
fl.retries = 0 // reset retries since we've succeeded
if !since.IsZero() && msg.Timestamp.Before(since) {
continue
}
if !until.IsZero() && msg.Timestamp.After(until) {
return
}
// send the message, unless the consumer is gone
select {
case e := <-fl.notifyEvict:
if e != nil {
err := e.(error)
logrus.WithError(err).Debug("Reader evicted while sending log message")
fl.logWatcher.Err <- err
}
return
case fl.logWatcher.Msg <- msg:
case <-fl.logWatcher.WatchConsumerGone():
return
}
}
}
func followLogs(f *os.File, logWatcher *logger.LogWatcher, notifyRotate, notifyEvict chan interface{}, dec Decoder, since, until time.Time) {
dec.Reset(f)
name := f.Name()
fileWatcher, err := watchFile(name)
if err != nil {
logWatcher.Err <- err
return
}
defer func() {
f.Close()
dec.Close()
fileWatcher.Close()
}()
fl := &follow{
file: f,
oldSize: -1,
logWatcher: logWatcher,
fileWatcher: fileWatcher,
notifyRotate: notifyRotate,
notifyEvict: notifyEvict,
dec: dec,
}
fl.mainLoop(since, until)
}
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