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Merge pull request #1290 from timstclair/tail

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Cleanup tail util from #1264
This commit is contained in:
Tim St. Clair 2016-05-18 14:46:50 -07:00
commit 18e56007c1
1 changed files with 18 additions and 28 deletions
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36
utils/tail/tail.go
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@ -27,16 +27,10 @@ import (
"golang.org/x/exp/inotify" "golang.org/x/exp/inotify"
) )
const (
readerStateOpening = 1 << iota
readerStateOpened
readerStateError
)
type Tail struct { type Tail struct {
reader *bufio.Reader reader *bufio.Reader
readerState int readerErr error
readerLock sync.Mutex readerLock sync.RWMutex
filename string filename string
file *os.File file *os.File
stop chan bool stop chan bool
@ -57,20 +51,16 @@ func NewTail(filename string) (*Tail, error) {
if err != nil { if err != nil {
return nil, fmt.Errorf("inotify init failed on %s: %v", t.filename, err) return nil, fmt.Errorf("inotify init failed on %s: %v", t.filename, err)
} }
t.readerState = readerStateOpening
go t.watchLoop() go t.watchLoop()
return t, nil return t, nil
} }
// Read implements the io.Reader interface for Tail // Read implements the io.Reader interface for Tail
func (t *Tail) Read(p []byte) (int, error) { func (t *Tail) Read(p []byte) (int, error) {
t.readerLock.Lock() t.readerLock.RLock()
defer t.readerLock.Unlock() defer t.readerLock.RUnlock()
if t.reader == nil { if t.reader == nil || t.readerErr != nil {
if t.readerState == readerStateOpening { return 0, t.readerErr
return 0, nil
}
return 0, fmt.Errorf("can't open log file %s", t.filename)
} }
return t.reader.Read(p) return t.reader.Read(p)
} }
@ -100,27 +90,30 @@ func (t *Tail) fileChanged() error {
} }
} }
func (t *Tail) attemptOpen() (err error) { func (t *Tail) attemptOpen() error {
t.readerLock.Lock() t.readerLock.Lock()
defer t.readerLock.Unlock() defer t.readerLock.Unlock()
t.reader = nil
t.readerErr = nil
for attempt := 1; attempt <= maxOpenAttempts; attempt++ { for attempt := 1; attempt <= maxOpenAttempts; attempt++ {
glog.V(4).Infof("Opening %s (attempt %d of %d)", t.filename, attempt, maxOpenAttempts) glog.V(4).Infof("Opening %s (attempt %d of %d)", t.filename, attempt, maxOpenAttempts)
var err error
t.file, err = os.Open(t.filename) t.file, err = os.Open(t.filename)
if err == nil { if err == nil {
// TODO: not interested in old events? // TODO: not interested in old events?
//t.file.Seek(0, os.SEEK_END) //t.file.Seek(0, os.SEEK_END)
t.reader = bufio.NewReader(t.file) t.reader = bufio.NewReader(t.file)
t.readerState = readerStateOpened
return nil return nil
} }
select { select {
case <-time.After(retryOpenInterval): case <-time.After(retryOpenInterval):
case <-t.stop: case <-t.stop:
t.readerState = readerStateError t.readerErr = io.EOF
return fmt.Errorf("watch was cancelled") return fmt.Errorf("watch was cancelled")
} }
} }
t.readerState = readerStateError err := fmt.Errorf("can't open log file %s", t.filename)
t.readerErr = err
return err return err
} }
@ -150,8 +143,5 @@ func (t *Tail) watchFile() error {
return err return err
} }
glog.V(4).Infof("Log file %s moved/deleted", t.filename) glog.V(4).Infof("Log file %s moved/deleted", t.filename)
t.readerLock.Lock()
defer t.readerLock.Unlock()
t.readerState = readerStateOpening
return nil return nil
} }