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archiver: Fix race condition triggered by TestArchiverAbortEarlyOnError

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The Save methods of the BlobSaver, FileSaver and TreeSaver return early
on when the archiver is stopped due to an error. For that they select on
both the tomb.Dying() and context.Done() channels, which can lead to a
race condition when the tomb is killed due to an error: The tomb first
closes its Dying channel before canceling all child contexts.
Archiver.SaveDir only aborts its execution once the context was
canceled. When the tomb killing is paused between closing its Dying
channel and canceling the child contexts, this lets the
FileSaver/TreeSaver.Save methods return immediately, however, ScanDir
still reads further files causing the test case to fail.

As a killed tomb always cancels all child contexts and as the Savers
always use a context bound to the tomb, it is sufficient to just use
context.Done() as escape hatch in the Save functions. This fixes the
mismatch between SaveDir and Save.

Adjust the tests to use contexts bound to the tomb for all interactions
with the Savers.
This commit is contained in:
Michael Eischer 2020-04-13 16:20:59 +02:00
parent 3ee6b8ec63
commit bdf7ba20cb
6 changed files with 16 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
internal/archiver/blob_saver.go
View File

@ -22,8 +22,7 @@ type BlobSaver struct {
m sync.Mutex
knownBlobs restic.BlobSet
ch chan<- saveBlobJob
done <-chan struct{}
ch chan<- saveBlobJob
}
// NewBlobSaver returns a new blob. A worker pool is started, it is stopped
@ -34,7 +33,6 @@ func NewBlobSaver(ctx context.Context, t *tomb.Tomb, repo Saver, workers uint) *
repo: repo,
knownBlobs: restic.NewBlobSet(),
ch: ch,
done: t.Dying(),
}
for i := uint(0); i < workers; i++ {
@ -53,10 +51,6 @@ func (s *BlobSaver) Save(ctx context.Context, t restic.BlobType, buf *Buffer) Fu
ch := make(chan saveBlobResponse, 1)
select {
case s.ch <- saveBlobJob{BlobType: t, buf: buf, ch: ch}:
case <-s.done:
debug.Log("not sending job, BlobSaver is done")
close(ch)
return FutureBlob{ch: ch}
case <-ctx.Done():
debug.Log("not sending job, context is cancelled")
close(ch)

8
internal/archiver/blob_saver_test.go
View File

@ -38,12 +38,12 @@ func TestBlobSaver(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
var tmb tomb.Tomb
tmb, ctx := tomb.WithContext(ctx)
saver := &saveFail{
idx: repository.NewIndex(),
}
b := NewBlobSaver(ctx, &tmb, saver, uint(runtime.NumCPU()))
b := NewBlobSaver(ctx, tmb, saver, uint(runtime.NumCPU()))
var results []FutureBlob
@ -84,13 +84,13 @@ func TestBlobSaverError(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
var tmb tomb.Tomb
tmb, ctx := tomb.WithContext(ctx)
saver := &saveFail{
idx: repository.NewIndex(),
failAt: int32(test.failAt),
}
b := NewBlobSaver(ctx, &tmb, saver, uint(runtime.NumCPU()))
b := NewBlobSaver(ctx, tmb, saver, uint(runtime.NumCPU()))
var results []FutureBlob

9
internal/archiver/file_saver.go
View File

@ -58,8 +58,7 @@ type FileSaver struct {
pol chunker.Pol
ch chan<- saveFileJob
done <-chan struct{}
ch chan<- saveFileJob
CompleteBlob func(filename string, bytes uint64)
@ -80,7 +79,6 @@ func NewFileSaver(ctx context.Context, t *tomb.Tomb, save SaveBlobFn, pol chunke
saveFilePool: NewBufferPool(ctx, int(poolSize), chunker.MaxSize),
pol: pol,
ch: ch,
done: t.Dying(),
CompleteBlob: func(string, uint64) {},
}
@ -113,11 +111,6 @@ func (s *FileSaver) Save(ctx context.Context, snPath string, file fs.File, fi os
select {
case s.ch <- job:
case <-s.done:
debug.Log("not sending job, FileSaver is done")
_ = file.Close()
close(ch)
return FutureFile{ch: ch}
case <-ctx.Done():
debug.Log("not sending job, context is cancelled: %v", ctx.Err())
_ = file.Close()

10
internal/archiver/file_saver_test.go
View File

@ -30,8 +30,8 @@ func createTestFiles(t testing.TB, num int) (files []string, cleanup func()) {
return files, cleanup
}
func startFileSaver(ctx context.Context, t testing.TB) (*FileSaver, *tomb.Tomb) {
var tmb tomb.Tomb
func startFileSaver(ctx context.Context, t testing.TB) (*FileSaver, context.Context, *tomb.Tomb) {
tmb, ctx := tomb.WithContext(ctx)
saveBlob := func(ctx context.Context, tpe restic.BlobType, buf *Buffer) FutureBlob {
ch := make(chan saveBlobResponse)
@ -45,10 +45,10 @@ func startFileSaver(ctx context.Context, t testing.TB) (*FileSaver, *tomb.Tomb)
t.Fatal(err)
}
s := NewFileSaver(ctx, &tmb, saveBlob, pol, workers, workers)
s := NewFileSaver(ctx, tmb, saveBlob, pol, workers, workers)
s.NodeFromFileInfo = restic.NodeFromFileInfo
return s, &tmb
return s, ctx, tmb
}
func TestFileSaver(t *testing.T) {
@ -62,7 +62,7 @@ func TestFileSaver(t *testing.T) {
completeFn := func(*restic.Node, ItemStats) {}
testFs := fs.Local{}
s, tmb := startFileSaver(ctx, t)
s, ctx, tmb := startFileSaver(ctx, t)
var results []FutureFile

8
internal/archiver/tree_saver.go
View File

@ -42,8 +42,7 @@ type TreeSaver struct {
saveTree func(context.Context, *restic.Tree) (restic.ID, ItemStats, error)
errFn ErrorFunc
ch chan<- saveTreeJob
done <-chan struct{}
ch chan<- saveTreeJob
}
// NewTreeSaver returns a new tree saver. A worker pool with treeWorkers is
@ -53,7 +52,6 @@ func NewTreeSaver(ctx context.Context, t *tomb.Tomb, treeWorkers uint, saveTree
s := &TreeSaver{
ch: ch,
done: t.Dying(),
saveTree: saveTree,
errFn: errFn,
}
@ -78,10 +76,6 @@ func (s *TreeSaver) Save(ctx context.Context, snPath string, node *restic.Node,
}
select {
case s.ch <- job:
case <-s.done:
debug.Log("not saving tree, TreeSaver is done")
close(ch)
return FutureTree{ch: ch}
case <-ctx.Done():
debug.Log("not saving tree, context is cancelled")
close(ch)

8
internal/archiver/tree_saver_test.go
View File

@ -17,7 +17,7 @@ func TestTreeSaver(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
var tmb tomb.Tomb
tmb, ctx := tomb.WithContext(ctx)
saveFn := func(context.Context, *restic.Tree) (restic.ID, ItemStats, error) {
return restic.NewRandomID(), ItemStats{TreeBlobs: 1, TreeSize: 123}, nil
@ -27,7 +27,7 @@ func TestTreeSaver(t *testing.T) {
return nil
}
b := NewTreeSaver(ctx, &tmb, uint(runtime.NumCPU()), saveFn, errFn)
b := NewTreeSaver(ctx, tmb, uint(runtime.NumCPU()), saveFn, errFn)
var results []FutureTree
@ -71,7 +71,7 @@ func TestTreeSaverError(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
var tmb tomb.Tomb
tmb, ctx := tomb.WithContext(ctx)
var num int32
saveFn := func(context.Context, *restic.Tree) (restic.ID, ItemStats, error) {
@ -88,7 +88,7 @@ func TestTreeSaverError(t *testing.T) {
return nil
}
b := NewTreeSaver(ctx, &tmb, uint(runtime.NumCPU()), saveFn, errFn)
b := NewTreeSaver(ctx, tmb, uint(runtime.NumCPU()), saveFn, errFn)
var results []FutureTree