drive: fix "panic: send on closed channel" when recycling dir entries
In this commit:
cbf3d43561
drive: fix missing items when listing using --fast-list / ListR
We introduced a bug where under specific circumstances it could cause
a "panic: send on closed channel".
This was caused by:
- rclone engaging the workaround from the commit above
- one of the listing routines returning an error
- this caused the `in` channel to be closed to stop the readers
- however the workaround was recycling stuff into the `in` channel at the time
- hence the panic on closed channel
This fix factors out the sending to the `in` channel into `sendJob`
and calls this both from the master go routine and the list
runners. `sendJob` detects the `in` channel being closed properly and
also deals correctly with contention on the `in` channel.
Fixes #4511
This commit is contained in:
parent
7d62d1fc97
commit
068cfdaa00
1 changed files with 30 additions and 25 deletions
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@ -1643,7 +1643,7 @@ func (s listRSlices) Less(i, j int) bool {
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// In each cycle it will read up to grouping entries from the in channel without blocking.
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// If an error occurs it will be send to the out channel and then return. Once the in channel is closed,
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// nil is send to the out channel and the function returns.
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func (f *Fs) listRRunner(ctx context.Context, wg *sync.WaitGroup, in chan listREntry, out chan<- error, cb func(fs.DirEntry) error) {
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func (f *Fs) listRRunner(ctx context.Context, wg *sync.WaitGroup, in chan listREntry, out chan<- error, cb func(fs.DirEntry) error, sendJob func(listREntry)) {
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var dirs []string
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var paths []string
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var grouping int32
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@ -1724,24 +1724,17 @@ func (f *Fs) listRRunner(ctx context.Context, wg *sync.WaitGroup, in chan listRE
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if atomic.SwapInt32(&f.grouping, 1) != 1 {
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fs.Debugf(f, "Disabling ListR to work around bug in drive as multi listing (%d) returned no entries", len(dirs))
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}
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var recycled = make([]listREntry, len(dirs))
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f.listRmu.Lock()
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for i := range dirs {
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recycled[i] = listREntry{id: dirs[i], path: paths[i]}
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// Requeue the jobs
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job := listREntry{id: dirs[i], path: paths[i]}
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sendJob(job)
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// Make a note of these dirs - if they all turn
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// out to be empty then we can re-enable grouping
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f.listRempties[dirs[i]] = struct{}{}
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}
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f.listRmu.Unlock()
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// recycle these in the background so we don't deadlock
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// the listR runners if they all get here
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wg.Add(len(recycled))
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go func() {
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for _, entry := range recycled {
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in <- entry
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}
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fs.Debugf(f, "Recycled %d entries", len(recycled))
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}()
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fs.Debugf(f, "Recycled %d entries", len(dirs))
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}
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// If using a grouping of 1 and dir was empty then check to see if it
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// is part of the group that caused grouping to be disabled.
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@ -1810,21 +1803,33 @@ func (f *Fs) ListR(ctx context.Context, dir string, callback fs.ListRCallback) (
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overflow := []listREntry{}
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listed := 0
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cb := func(entry fs.DirEntry) error {
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// Send a job to the input channel if not closed. If the job
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// won't fit then queue it in the overflow slice.
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//
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// This will not block if the channel is full.
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sendJob := func(job listREntry) {
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mu.Lock()
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defer mu.Unlock()
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if d, isDir := entry.(*fs.Dir); isDir && in != nil {
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job := listREntry{actualID(d.ID()), d.Remote()}
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select {
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case in <- job:
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// Adding the wg after we've entered the item is
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// safe here because we know when the callback
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// is called we are holding a waitgroup.
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wg.Add(1)
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default:
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overflow = append(overflow, job)
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}
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if in == nil {
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return
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}
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wg.Add(1)
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select {
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case in <- job:
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default:
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overflow = append(overflow, job)
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wg.Add(-1)
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}
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}
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// Send the entry to the caller, queueing any directories as new jobs
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cb := func(entry fs.DirEntry) error {
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if d, isDir := entry.(*fs.Dir); isDir {
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job := listREntry{actualID(d.ID()), d.Remote()}
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sendJob(job)
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}
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mu.Lock()
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defer mu.Unlock()
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listed++
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return list.Add(entry)
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}
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@ -1833,7 +1838,7 @@ func (f *Fs) ListR(ctx context.Context, dir string, callback fs.ListRCallback) (
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in <- listREntry{directoryID, dir}
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for i := 0; i < fs.Config.Checkers; i++ {
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go f.listRRunner(ctx, &wg, in, out, cb)
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go f.listRRunner(ctx, &wg, in, out, cb, sendJob)
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}
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go func() {
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// wait until the all directories are processed
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