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lib/fs, lib/model: Add error channel to Watch to avoid panics (fixes #5697) (#5734)

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* lib/fs, lib/model: Add error channel to Watch to avoid panics (fixes #5697)

* forgot unsupported watch

* and more non(-standard)-unixy fixes

* and windows test

* review
This commit is contained in:
Simon Frei
2019-05-25 21:08:26 +02:00
committed by Audrius Butkevicius
parent 9e6db72535
commit 486230768e
12 changed files with 158 additions and 105 deletions
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107
lib/model/folder.go
View File

@@ -173,9 +173,6 @@ func (f *folder) Serve() {
pullFailTimer.Reset(pause)
}
// The reason for running the scanner from within the puller is that
// this is the easiest way to make sure we are not doing both at the
// same time.
case <-f.scanTimer.C:
l.Debugln(f, "Scanning subdirectories")
f.scanTimerFired()
@@ -611,53 +608,91 @@ func (f *folder) startWatch() {
f.watchChan = make(chan []string)
f.watchCancel = cancel
f.watchMut.Unlock()
go f.startWatchAsync(ctx)
go f.monitorWatch(ctx)
}
// startWatchAsync tries to start the filesystem watching and retries every minute on failure.
// It is a convenience function that should not be used except in startWatch.
func (f *folder) startWatchAsync(ctx context.Context) {
timer := time.NewTimer(0)
// monitorWatch starts the filesystem watching and retries every minute on failure.
// It should not be used except in startWatch.
func (f *folder) monitorWatch(ctx context.Context) {
failTimer := time.NewTimer(0)
aggrCtx, aggrCancel := context.WithCancel(ctx)
var err error
var eventChan <-chan fs.Event
var errChan <-chan error
warnedOutside := false
for {
select {
case <-timer.C:
eventChan, err := f.Filesystem().Watch(".", f.ignores, ctx, f.IgnorePerms)
f.watchMut.Lock()
prevErr := f.watchErr
f.watchErr = err
f.watchMut.Unlock()
if err != prevErr {
data := map[string]interface{}{
"folder": f.ID,
}
if prevErr != nil {
data["from"] = prevErr.Error()
}
if err != nil {
data["to"] = err.Error()
}
events.Default.Log(events.FolderWatchStateChanged, data)
}
case <-failTimer.C:
eventChan, errChan, err = f.Filesystem().Watch(".", f.ignores, ctx, f.IgnorePerms)
// We do this at most once per minute which is the
// default rescan time without watcher.
f.scanOnWatchErr()
f.setWatchError(err)
if err != nil {
if prevErr == errWatchNotStarted {
l.Infof("Error while trying to start filesystem watcher for folder %s, trying again in 1min: %v", f.Description(), err)
} else {
l.Debugf("Repeat error while trying to start filesystem watcher for folder %s, trying again in 1min: %v", f.Description(), err)
}
timer.Reset(time.Minute)
failTimer.Reset(time.Minute)
continue
}
f.watchMut.Lock()
defer f.watchMut.Unlock()
watchaggregator.Aggregate(eventChan, f.watchChan, f.FolderConfiguration, f.model.cfg, ctx)
watchaggregator.Aggregate(eventChan, f.watchChan, f.FolderConfiguration, f.model.cfg, aggrCtx)
l.Debugln("Started filesystem watcher for folder", f.Description())
return
case err = <-errChan:
f.setWatchError(err)
// This error was previously a panic and should never occur, so generate
// a warning, but don't do it repetitively.
if !warnedOutside {
if _, ok := err.(*fs.ErrWatchEventOutsideRoot); ok {
l.Warnln(err)
warnedOutside = true
return
}
}
aggrCancel()
errChan = nil
aggrCtx, aggrCancel = context.WithCancel(ctx)
failTimer.Reset(time.Minute)
case <-ctx.Done():
return
}
}
}
// setWatchError sets the current error state of the watch and should be called
// regardless of whether err is nil or not.
func (f *folder) setWatchError(err error) {
f.watchMut.Lock()
prevErr := f.watchErr
f.watchErr = err
f.watchMut.Unlock()
if err != prevErr {
data := map[string]interface{}{
"folder": f.ID,
}
if prevErr != nil {
data["from"] = prevErr.Error()
}
if err != nil {
data["to"] = err.Error()
}
events.Default.Log(events.FolderWatchStateChanged, data)
}
if err == nil {
return
}
if prevErr == errWatchNotStarted {
l.Infof("Error while trying to start filesystem watcher for folder %s, trying again in 1min: %v", f.Description(), err)
return
}
l.Debugf("Repeat error while trying to start filesystem watcher for folder %s, trying again in 1min: %v", f.Description(), err)
}
// scanOnWatchErr schedules a full scan immediately if an error occurred while watching.
func (f *folder) scanOnWatchErr() {
f.watchMut.Lock()
if f.watchErr != nil && f.watchErr != errWatchNotStarted {
f.Delay(0)
}
f.watchMut.Unlock()
}
func (f *folder) setError(err error) {
select {
case <-f.ctx.Done():