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fs: update ChangeNotifier interface

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This introduces a channel to the ChangeNotify function, which can be
used to update the poll-interval and cleanly exit the polling function.
This commit is contained in:
Fabian Möller 2018-08-25 21:28:57 +02:00
parent 96ce49ec4e
commit 1eec59e091
7 changed files with 103 additions and 53 deletions
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74
backend/drive/drive.go
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@ -1660,25 +1660,50 @@ func (f *Fs) DirMove(src fs.Fs, srcRemote, dstRemote string) error {
// Automatically restarts itself in case of unexpected behaviour of the remote.
//
// Close the returned channel to stop being notified.
func (f *Fs) ChangeNotify(notifyFunc func(string, fs.EntryType), pollInterval time.Duration) chan bool {
quit := make(chan bool)
func (f *Fs) ChangeNotify(notifyFunc func(string, fs.EntryType), pollIntervalChan <-chan time.Duration) {
go func() {
select {
case <-quit:
return
default:
for {
f.changeNotifyRunner(notifyFunc, pollInterval)
fs.Debugf(f, "Notify listener service ran into issues, restarting shortly.")
time.Sleep(pollInterval)
// get the StartPageToken early so all changes from now on get processed
startPageToken, err := f.changeNotifyStartPageToken()
if err != nil {
fs.Infof(f, "Failed to get StartPageToken: %s", err)
}
var ticker *time.Ticker
var tickerC <-chan time.Time
for {
select {
case pollInterval, ok := <-pollIntervalChan:
if !ok {
if ticker != nil {
ticker.Stop()
}
return
}
if ticker != nil {
ticker.Stop()
ticker, tickerC = nil, nil
}
if pollInterval != 0 {
ticker = time.NewTicker(pollInterval)
tickerC = ticker.C
}
case <-tickerC:
if startPageToken == "" {
startPageToken, err = f.changeNotifyStartPageToken()
if err != nil {
fs.Infof(f, "Failed to get StartPageToken: %s", err)
continue
}
}
fs.Debugf(f, "Checking for changes on remote")
startPageToken, err = f.changeNotifyRunner(notifyFunc, startPageToken)
if err != nil {
fs.Infof(f, "Change notify listener failure: %s", err)
}
}
}
}()
return quit
}
func (f *Fs) changeNotifyRunner(notifyFunc func(string, fs.EntryType), pollInterval time.Duration) {
var err error
func (f *Fs) changeNotifyStartPageToken() (pageToken string, err error) {
var startPageToken *drive.StartPageToken
err = f.pacer.Call(func() (bool, error) {
startPageToken, err = f.svc.Changes.GetStartPageToken().
@ -1687,13 +1712,14 @@ func (f *Fs) changeNotifyRunner(notifyFunc func(string, fs.EntryType), pollInter
return shouldRetry(err)
})
if err != nil {
fs.Debugf(f, "Failed to get StartPageToken: %v", err)
return
}
pageToken := startPageToken.StartPageToken
return startPageToken.StartPageToken, nil
}
func (f *Fs) changeNotifyRunner(notifyFunc func(string, fs.EntryType), startPageToken string) (newStartPageToken string, err error) {
pageToken := startPageToken
for {
fs.Debugf(f, "Checking for changes on remote")
var changeList *drive.ChangeList
err = f.pacer.Call(func() (bool, error) {
@ -1711,7 +1737,6 @@ func (f *Fs) changeNotifyRunner(notifyFunc func(string, fs.EntryType), pollInter
return shouldRetry(err)
})
if err != nil {
fs.Debugf(f, "Failed to get Changes: %v", err)
return
}
@ -1763,15 +1788,12 @@ func (f *Fs) changeNotifyRunner(notifyFunc func(string, fs.EntryType), pollInter
notifyFunc(entry.path, entry.entryType)
}
if changeList.NewStartPageToken != "" {
pageToken = changeList.NewStartPageToken
fs.Debugf(f, "All changes were processed. Waiting for more.")
time.Sleep(pollInterval)
} else if changeList.NextPageToken != "" {
switch {
case changeList.NewStartPageToken != "":
return changeList.NewStartPageToken, nil
case changeList.NextPageToken != "":
pageToken = changeList.NextPageToken
fs.Debugf(f, "There are more changes pending, checking now.")
} else {
fs.Debugf(f, "Did not get any page token, something went wrong! %+v", changeList)
default:
return
}
}