Files
seaweedfs/weed/mount/meta_cache/meta_cache_build_test.go
T
Chris LuandGitHub dd73fee077 mount: read oversized directories through instead of caching them (#10631)
* mount: read oversized directories through instead of caching them

Visiting a directory pulls every child from the filer into the local
LevelDB before the first listing returns. For a directory of a few
million entries that is minutes of streaming, gigabytes of local store,
and gigabytes of decoded entries in flight -- paid by a mount that may
only walk the directory once.

A build that crosses -cacheDirMaxEntries (default ten thousand) now
stops, cleans up, and marks the directory read-through: listings stream
from the filer with pagination, the way update-hot directories already
do, and lookups in it consult the filer per entry as any uncached
directory does. The refusal is remembered, so the next visit fails fast
instead of streaming to the limit again, and an oversized ancestor is
stepped over when caching its subdirectories rather than wedging every
listing beneath it.

The direct path keeps the same pagination state on the handle, so a walk
that crosses the limit mid-flight carries on from where the cached walk
reached.

* mount: an ancestor found oversized must not fail its descendants

Visiting a directory builds its whole uncached ancestor chain in one
group, so the first discovery that an ancestor is oversized cancelled the
group and surfaced as the listed directory's own refusal: the descendant
build was aborted and the caller marked the descendant read-through,
leaving a perfectly cacheable directory streaming from the filer until
its inode was forgotten. The earlier test missed this by pre-marking the
ancestor, which exercises only the fast path.

The refusal of any directory other than the one being listed is now kept
out of the group's result; it is already remembered for the next visit.
2026-08-07 17:48:40 -07:00

636 lines
21 KiB
Go

package meta_cache
import (
"context"
"fmt"
"io"
"sync"
"testing"
"time"
"github.com/seaweedfs/seaweedfs/weed/filer"
"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
"github.com/seaweedfs/seaweedfs/weed/util"
"google.golang.org/grpc"
"google.golang.org/grpc/metadata"
)
type buildListStream struct {
responses []*filer_pb.ListEntriesResponse
onFirstRecv func()
once sync.Once
index int
}
func (s *buildListStream) Recv() (*filer_pb.ListEntriesResponse, error) {
s.once.Do(func() {
if s.onFirstRecv != nil {
s.onFirstRecv()
}
})
if s.index >= len(s.responses) {
return nil, io.EOF
}
resp := s.responses[s.index]
s.index++
return resp, nil
}
func (s *buildListStream) Header() (metadata.MD, error) { return metadata.MD{}, nil }
func (s *buildListStream) Trailer() metadata.MD { return metadata.MD{} }
func (s *buildListStream) CloseSend() error { return nil }
func (s *buildListStream) Context() context.Context { return context.Background() }
func (s *buildListStream) SendMsg(any) error { return nil }
func (s *buildListStream) RecvMsg(any) error { return nil }
type buildListClient struct {
filer_pb.SeaweedFilerClient
responses []*filer_pb.ListEntriesResponse
onFirstRecv func()
}
func (c *buildListClient) ListEntries(ctx context.Context, in *filer_pb.ListEntriesRequest, opts ...grpc.CallOption) (grpc.ServerStreamingClient[filer_pb.ListEntriesResponse], error) {
return &buildListStream{
responses: c.responses,
onFirstRecv: c.onFirstRecv,
}, nil
}
type buildFilerAccessor struct {
client filer_pb.SeaweedFilerClient
}
func (a *buildFilerAccessor) WithFilerClient(_ bool, fn func(filer_pb.SeaweedFilerClient) error) error {
return fn(a.client)
}
func (a *buildFilerAccessor) AdjustedUrl(*filer_pb.Location) string { return "" }
func (a *buildFilerAccessor) GetDataCenter() string { return "" }
func TestEnsureVisitedReplaysBufferedEventsAfterSnapshot(t *testing.T) {
mc, _, _, _ := newTestMetaCache(t, map[util.FullPath]bool{
"/": true,
})
defer mc.Shutdown()
var applyErr error
accessor := &buildFilerAccessor{
client: &buildListClient{
responses: []*filer_pb.ListEntriesResponse{
{
Entry: &filer_pb.Entry{
Name: "base.txt",
Attributes: &filer_pb.FuseAttributes{
Crtime: 1,
Mtime: 1,
FileMode: 0100644,
FileSize: 3,
},
},
SnapshotTsNs: 100,
},
},
onFirstRecv: func() {
applyErr = mc.ApplyMetadataResponse(context.Background(), &filer_pb.SubscribeMetadataResponse{
Directory: "/dir",
EventNotification: &filer_pb.EventNotification{
NewEntry: &filer_pb.Entry{
Name: "after.txt",
Attributes: &filer_pb.FuseAttributes{
Crtime: 2,
Mtime: 2,
FileMode: 0100644,
FileSize: 9,
},
},
},
TsNs: 101,
}, SubscriberMetadataResponseApplyOptions)
},
},
}
if err := EnsureVisited(mc, accessor, util.FullPath("/dir"), 0); err != nil {
t.Fatalf("ensure visited: %v", err)
}
if applyErr != nil {
t.Fatalf("apply buffered event: %v", applyErr)
}
if !mc.IsDirectoryCached(util.FullPath("/dir")) {
t.Fatal("directory /dir should be cached after build completes")
}
baseEntry, _, err := mc.FindEntry(context.Background(), util.FullPath("/dir/base.txt"))
if err != nil {
t.Fatalf("find base entry: %v", err)
}
if baseEntry.FileSize != 3 {
t.Fatalf("base entry size = %d, want 3", baseEntry.FileSize)
}
afterEntry, _, err := mc.FindEntry(context.Background(), util.FullPath("/dir/after.txt"))
if err != nil {
t.Fatalf("find replayed entry: %v", err)
}
if afterEntry.FileSize != 9 {
t.Fatalf("replayed entry size = %d, want 9", afterEntry.FileSize)
}
}
// TestDirectoryNotificationsSuppressedDuringBuild verifies that metadata events
// targeting a directory under active build do NOT fire onDirectoryUpdate for
// that directory. In production, onDirectoryUpdate can trigger
// markDirectoryReadThrough → DeleteFolderChildren, which would wipe entries
// that EnsureVisited already inserted mid-build.
func TestDirectoryNotificationsSuppressedDuringBuild(t *testing.T) {
mc, _, notifications, _ := newTestMetaCache(t, map[util.FullPath]bool{
"/": true,
})
defer mc.Shutdown()
// Start building /dir (simulates the beginning of EnsureVisited)
if err := mc.BeginDirectoryBuild(context.Background(), util.FullPath("/dir")); err != nil {
t.Fatalf("begin build: %v", err)
}
// Insert an entry as EnsureVisited would during the filer listing
if err := mc.InsertEntry(context.Background(), &filer.Entry{
FullPath: "/dir/existing.txt",
Attr: filer.Attr{
Crtime: time.Unix(1, 0),
Mtime: time.Unix(1, 0),
Mode: 0100644,
FileSize: 100,
},
}, 0); err != nil {
t.Fatalf("insert entry during build: %v", err)
}
// Simulate multiple metadata events arriving for /dir while the build
// is in progress. Each event would normally call noteDirectoryUpdate,
// which in production can trigger markDirectoryReadThrough and wipe entries.
for i := 0; i < 5; i++ {
resp := &filer_pb.SubscribeMetadataResponse{
Directory: "/dir",
EventNotification: &filer_pb.EventNotification{
NewEntry: &filer_pb.Entry{
Name: fmt.Sprintf("new-%d.txt", i),
Attributes: &filer_pb.FuseAttributes{
Crtime: int64(10 + i),
Mtime: int64(10 + i),
FileMode: 0100644,
FileSize: uint64(i + 1),
},
},
},
TsNs: int64(200 + i),
}
if err := mc.ApplyMetadataResponse(context.Background(), resp, SubscriberMetadataResponseApplyOptions); err != nil {
t.Fatalf("apply event %d: %v", i, err)
}
}
// The building directory /dir must NOT have received any notifications.
// If it did, markDirectoryReadThrough would wipe the cache mid-build.
for _, p := range notifications.paths() {
if p == util.FullPath("/dir") {
t.Fatal("onDirectoryUpdate was called for /dir during build; this would cause markDirectoryReadThrough to wipe entries mid-build")
}
}
// The entry inserted during the build must still be present
entry, _, err := mc.FindEntry(context.Background(), util.FullPath("/dir/existing.txt"))
if err != nil {
t.Fatalf("entry wiped during build: %v", err)
}
if entry.FileSize != 100 {
t.Fatalf("entry size = %d, want 100", entry.FileSize)
}
// Complete the build — buffered events should be replayed
if err := mc.CompleteDirectoryBuild(context.Background(), util.FullPath("/dir"), 150); err != nil {
t.Fatalf("complete build: %v", err)
}
// After build completes, the entry from the listing should still exist
entry, _, err = mc.FindEntry(context.Background(), util.FullPath("/dir/existing.txt"))
if err != nil {
t.Fatalf("entry lost after build completion: %v", err)
}
if entry.FileSize != 100 {
t.Fatalf("entry size after build = %d, want 100", entry.FileSize)
}
// Buffered events with TsNs > snapshotTsNs (150) should have been replayed
for i := 0; i < 5; i++ {
name := fmt.Sprintf("new-%d.txt", i)
e, _, err := mc.FindEntry(context.Background(), util.FullPath("/dir/"+name))
if err != nil {
t.Fatalf("replayed entry %s not found: %v", name, err)
}
if e.FileSize != uint64(i+1) {
t.Fatalf("replayed entry %s size = %d, want %d", name, e.FileSize, i+1)
}
}
}
// TestEmptyDirectoryBuildReplaysAllBufferedEvents verifies that when a
// directory build completes with snapshotTsNs=0 (empty directory — server
// returned no entries and no snapshot), ALL buffered events are replayed
// without any TsNs filtering. This prevents clock-skew between client and
// filer from dropping legitimate mutations.
func TestEmptyDirectoryBuildReplaysAllBufferedEvents(t *testing.T) {
mc, _, _, _ := newTestMetaCache(t, map[util.FullPath]bool{
"/": true,
})
defer mc.Shutdown()
if err := mc.BeginDirectoryBuild(context.Background(), util.FullPath("/empty")); err != nil {
t.Fatalf("begin build: %v", err)
}
// Buffer events with a range of TsNs values — some very old, some recent.
// With a client-synthesized snapshot, old events could be incorrectly filtered.
tsValues := []int64{1, 50, 500, 5000, 50000}
for i, ts := range tsValues {
resp := &filer_pb.SubscribeMetadataResponse{
Directory: "/empty",
EventNotification: &filer_pb.EventNotification{
NewEntry: &filer_pb.Entry{
Name: fmt.Sprintf("file-%d.txt", i),
Attributes: &filer_pb.FuseAttributes{
Crtime: ts,
Mtime: ts,
FileMode: 0100644,
FileSize: uint64(i + 10),
},
},
},
TsNs: ts,
}
if err := mc.ApplyMetadataResponse(context.Background(), resp, SubscriberMetadataResponseApplyOptions); err != nil {
t.Fatalf("apply event %d: %v", i, err)
}
}
// Complete with snapshotTsNs=0 — simulates empty directory listing
if err := mc.CompleteDirectoryBuild(context.Background(), util.FullPath("/empty"), 0); err != nil {
t.Fatalf("complete build: %v", err)
}
// Every buffered event must have been replayed, regardless of TsNs
for i := range tsValues {
name := fmt.Sprintf("file-%d.txt", i)
e, _, err := mc.FindEntry(context.Background(), util.FullPath("/empty/"+name))
if err != nil {
t.Fatalf("replayed entry %s not found: %v", name, err)
}
if e.FileSize != uint64(i+10) {
t.Fatalf("replayed entry %s size = %d, want %d", name, e.FileSize, i+10)
}
}
if !mc.IsDirectoryCached(util.FullPath("/empty")) {
t.Fatal("/empty should be marked cached after build completes")
}
}
// TestBuildCompletionSurvivesCallerCancellation verifies that once
// CompleteDirectoryBuild is enqueued, a cancelled caller context does not
// prevent the build from completing. The apply loop uses context.Background()
// internally, so the operation finishes even if the caller gives up waiting.
func TestBuildCompletionSurvivesCallerCancellation(t *testing.T) {
mc, _, _, _ := newTestMetaCache(t, map[util.FullPath]bool{
"/": true,
})
defer mc.Shutdown()
if err := mc.BeginDirectoryBuild(context.Background(), util.FullPath("/dir")); err != nil {
t.Fatalf("begin build: %v", err)
}
// Insert an entry during the build (as EnsureVisited would)
if err := mc.InsertEntry(context.Background(), &filer.Entry{
FullPath: "/dir/kept.txt",
Attr: filer.Attr{
Crtime: time.Unix(1, 0),
Mtime: time.Unix(1, 0),
Mode: 0100644,
FileSize: 42,
},
}, 0); err != nil {
t.Fatalf("insert entry: %v", err)
}
// Buffer an event that should be replayed
if err := mc.ApplyMetadataResponse(context.Background(), &filer_pb.SubscribeMetadataResponse{
Directory: "/dir",
EventNotification: &filer_pb.EventNotification{
NewEntry: &filer_pb.Entry{
Name: "buffered.txt",
Attributes: &filer_pb.FuseAttributes{
Crtime: 5,
Mtime: 5,
FileMode: 0100644,
FileSize: 77,
},
},
},
TsNs: 200,
}, SubscriberMetadataResponseApplyOptions); err != nil {
t.Fatalf("apply event: %v", err)
}
// Complete with an already-cancelled context. The operation should still
// succeed because enqueueAndWait sets req.ctx = context.Background().
cancelledCtx, cancel := context.WithCancel(context.Background())
cancel() // cancel immediately
// CompleteDirectoryBuild may return ctx.Err() if the select picks
// ctx.Done() first, but the operation itself still completes in the
// apply loop. Poll for the observable side effect instead of using
// a fixed sleep.
_ = mc.CompleteDirectoryBuild(cancelledCtx, util.FullPath("/dir"), 100)
// Poll until the build completes or a deadline elapses.
deadline := time.After(2 * time.Second)
for !mc.IsDirectoryCached(util.FullPath("/dir")) {
select {
case <-deadline:
t.Fatal("/dir should be cached — CompleteDirectoryBuild must have executed despite cancelled context")
default:
time.Sleep(5 * time.Millisecond)
}
}
// The pre-existing entry must survive
entry, _, findErr := mc.FindEntry(context.Background(), util.FullPath("/dir/kept.txt"))
if findErr != nil {
t.Fatalf("find kept entry: %v", findErr)
}
if entry.FileSize != 42 {
t.Fatalf("kept entry size = %d, want 42", entry.FileSize)
}
// The buffered event (TsNs 200 > snapshot 100) must have been replayed
buffered, _, findErr := mc.FindEntry(context.Background(), util.FullPath("/dir/buffered.txt"))
if findErr != nil {
t.Fatalf("find buffered entry: %v", findErr)
}
if buffered.FileSize != 77 {
t.Fatalf("buffered entry size = %d, want 77", buffered.FileSize)
}
}
func TestBufferedRenameUpdatesOtherDirectoryBeforeBuildCompletes(t *testing.T) {
mc, _, _, _ := newTestMetaCache(t, map[util.FullPath]bool{
"/": true,
"/src": true,
})
defer mc.Shutdown()
if err := mc.InsertEntry(context.Background(), &filer.Entry{
FullPath: "/src/from.txt",
Attr: filer.Attr{
Crtime: time.Unix(1, 0),
Mtime: time.Unix(1, 0),
Mode: 0100644,
FileSize: 7,
},
}, 0); err != nil {
t.Fatalf("insert source entry: %v", err)
}
if err := mc.BeginDirectoryBuild(context.Background(), util.FullPath("/dst")); err != nil {
t.Fatalf("begin build: %v", err)
}
renameResp := &filer_pb.SubscribeMetadataResponse{
Directory: "/src",
EventNotification: &filer_pb.EventNotification{
OldEntry: &filer_pb.Entry{
Name: "from.txt",
},
NewEntry: &filer_pb.Entry{
Name: "to.txt",
Attributes: &filer_pb.FuseAttributes{
Crtime: 2,
Mtime: 2,
FileMode: 0100644,
FileSize: 12,
},
},
NewParentPath: "/dst",
},
TsNs: 101,
}
if err := mc.ApplyMetadataResponse(context.Background(), renameResp, SubscriberMetadataResponseApplyOptions); err != nil {
t.Fatalf("apply rename: %v", err)
}
oldEntry, _, err := mc.FindEntry(context.Background(), util.FullPath("/src/from.txt"))
if err != filer_pb.ErrNotFound {
t.Fatalf("find old path error = %v, want %v", err, filer_pb.ErrNotFound)
}
if oldEntry != nil {
t.Fatalf("old path should be removed before build completes: %+v", oldEntry)
}
newEntry, _, err := mc.FindEntry(context.Background(), util.FullPath("/dst/to.txt"))
if err != filer_pb.ErrNotFound {
t.Fatalf("find buffered new path error = %v, want %v", err, filer_pb.ErrNotFound)
}
if newEntry != nil {
t.Fatalf("new path should stay hidden until build completes: %+v", newEntry)
}
if err := mc.CompleteDirectoryBuild(context.Background(), util.FullPath("/dst"), 100); err != nil {
t.Fatalf("complete build: %v", err)
}
newEntry, _, err = mc.FindEntry(context.Background(), util.FullPath("/dst/to.txt"))
if err != nil {
t.Fatalf("find replayed new path: %v", err)
}
if newEntry.FileSize != 12 {
t.Fatalf("replayed new path size = %d, want 12", newEntry.FileSize)
}
}
// TestEnsureVisitedPreservesLocalOnlyEntry reproduces the residual coherence
// gap behind the FUSE ConcurrentReadWrite ENOENT flake.
//
// A FUSE create on the writeback/deferFilerCreate path inserts the entry into
// the local store directly (weedfs_file_mkrm.go createFile), off the metaCache
// apply loop, before the filer holds it. A concurrent rebuild of the parent —
// triggered when the directory falls out of cache (idle evict, hot-dir
// read-through) — wipes the store and refills it from a filer listing that does
// not yet include the un-flushed local create, then publishes the directory
// authoritatively cached (markCachedFn). The local entry vanishes although the
// client created it: lookupEntry then returns an authoritative ENOENT for it.
func TestEnsureVisitedPreservesLocalOnlyEntry(t *testing.T) {
mc, _, _, _ := newTestMetaCache(t, map[util.FullPath]bool{"/": true})
defer mc.Shutdown()
// The mount pins the un-flushed create (open dirty handle / pending flush),
// keyed off the inode the entry carries so a kernel Forget that dropped the
// path→inode mapping cannot unpin an in-flight create.
mc.SetPinnedChildFn(func(e *filer.Entry) bool { return e.Attr.Inode == 42 })
// A deferred local create lands before the rebuild; /dir is not yet cached.
// It carries its allocated inode, as createFile's placeholder does.
if err := mc.InsertEntry(context.Background(), &filer.Entry{
FullPath: "/dir/pending.txt",
Attr: filer.Attr{Crtime: time.Unix(1, 0), Mtime: time.Unix(1, 0), Mode: 0100644, FileSize: 1, Inode: 42},
}, 0); err != nil {
t.Fatalf("insert pending entry: %v", err)
}
// A concurrent rebuild lists the filer, whose snapshot pre-dates the
// un-flushed create, so it returns only the already-persisted sibling.
accessor := &buildFilerAccessor{client: &buildListClient{
responses: []*filer_pb.ListEntriesResponse{{
Entry: &filer_pb.Entry{
Name: "base.txt",
Attributes: &filer_pb.FuseAttributes{
Crtime: 1,
Mtime: 1,
FileMode: 0100644,
FileSize: 3,
},
},
SnapshotTsNs: 100,
}},
}}
if err := EnsureVisited(mc, accessor, util.FullPath("/dir"), 0); err != nil {
t.Fatalf("ensure visited: %v", err)
}
if !mc.IsDirectoryCached(util.FullPath("/dir")) {
t.Fatal("/dir should be cached after build completes")
}
// base.txt from the listing is present.
if _, _, err := mc.FindEntry(context.Background(), util.FullPath("/dir/base.txt")); err != nil {
t.Fatalf("listed entry missing after build: %v", err)
}
// The un-flushed local create must survive the rebuild. With /dir now
// authoritatively cached, losing it is the file-vanishes flake.
if _, _, err := mc.FindEntry(context.Background(), util.FullPath("/dir/pending.txt")); err != nil {
t.Fatalf("local-only entry lost across concurrent rebuild: %v", err)
}
}
// TestEnsureVisitedDropsUnpinnedStaleEntry guards the preservation's selectivity:
// a cached child the filer listing no longer returns and that is NOT pinned must
// still be wiped, so the rebuild can't resurrect a deleted/renamed entry.
func TestEnsureVisitedDropsUnpinnedStaleEntry(t *testing.T) {
mc, _, _, _ := newTestMetaCache(t, map[util.FullPath]bool{"/": true})
defer mc.Shutdown()
mc.SetPinnedChildFn(func(*filer.Entry) bool { return false })
// A stale child sits in the cache; the filer no longer has it.
insertCacheEntry(t, mc, "/dir/stale.txt")
accessor := &buildFilerAccessor{client: &buildListClient{
responses: []*filer_pb.ListEntriesResponse{{
Entry: &filer_pb.Entry{
Name: "base.txt",
Attributes: &filer_pb.FuseAttributes{
Crtime: 1,
Mtime: 1,
FileMode: 0100644,
FileSize: 3,
},
},
SnapshotTsNs: 100,
}},
}}
if err := EnsureVisited(mc, accessor, util.FullPath("/dir"), 0); err != nil {
t.Fatalf("ensure visited: %v", err)
}
if entry, _, err := mc.FindEntry(context.Background(), util.FullPath("/dir/stale.txt")); err != filer_pb.ErrNotFound || entry != nil {
t.Fatalf("unpinned stale entry survived rebuild = %+v, %v; want nil, %v", entry, err, filer_pb.ErrNotFound)
}
}
// sequencedListClient returns a different ListEntries result per call (repeating
// the last), modelling a filer that lists empty transiently then the real entries.
type sequencedListClient struct {
filer_pb.SeaweedFilerClient
mu sync.Mutex
perCall [][]*filer_pb.ListEntriesResponse
calls int
}
func (c *sequencedListClient) ListEntries(ctx context.Context, in *filer_pb.ListEntriesRequest, opts ...grpc.CallOption) (grpc.ServerStreamingClient[filer_pb.ListEntriesResponse], error) {
c.mu.Lock()
idx := c.calls
if idx >= len(c.perCall) {
idx = len(c.perCall) - 1
}
c.calls++
resp := c.perCall[idx]
c.mu.Unlock()
return &buildListStream{responses: resp}, nil
}
// TestEnsureVisitedConfirmsTransientEmptyListing: a rebuild whose first filer
// listing comes back empty must re-read and cache the real entries, not strand
// the directory cached over an empty store (the ConcurrentReadWrite ENOENT flake).
func TestEnsureVisitedConfirmsTransientEmptyListing(t *testing.T) {
mc, _, _, _ := newTestMetaCache(t, map[util.FullPath]bool{"/": true})
defer mc.Shutdown()
entry := &filer_pb.Entry{
Name: "keep.txt",
Attributes: &filer_pb.FuseAttributes{Crtime: 1, Mtime: 1, FileMode: 0100644, FileSize: 7},
}
accessor := &buildFilerAccessor{client: &sequencedListClient{
perCall: [][]*filer_pb.ListEntriesResponse{
{}, // first read: transient empty
{{Entry: entry, SnapshotTsNs: 100}}, // confirm read: the real entry
},
}}
if err := EnsureVisited(mc, accessor, util.FullPath("/dir"), 0); err != nil {
t.Fatalf("ensure visited: %v", err)
}
if !mc.IsDirectoryCached(util.FullPath("/dir")) {
t.Fatal("/dir should be cached after build completes")
}
if _, _, err := mc.FindEntry(context.Background(), util.FullPath("/dir/keep.txt")); err != nil {
t.Fatalf("/dir/keep.txt stranded after transient empty listing: %v", err)
}
}
// TestEnsureVisitedCachesGenuinelyEmptyDirectory: a really-empty directory lists
// empty on every confirm and must still end up cached.
func TestEnsureVisitedCachesGenuinelyEmptyDirectory(t *testing.T) {
mc, _, _, _ := newTestMetaCache(t, map[util.FullPath]bool{"/": true})
defer mc.Shutdown()
client := &sequencedListClient{
perCall: [][]*filer_pb.ListEntriesResponse{{}}, // always empty
}
accessor := &buildFilerAccessor{client: client}
if err := EnsureVisited(mc, accessor, util.FullPath("/empty"), 0); err != nil {
t.Fatalf("ensure visited: %v", err)
}
if !mc.IsDirectoryCached(util.FullPath("/empty")) {
t.Fatal("/empty should be cached even though it has no entries")
}
// The empty result must have been confirmed, not trusted on the first read.
client.mu.Lock()
calls := client.calls
client.mu.Unlock()
if calls != emptyRebuildConfirmations+1 {
t.Fatalf("list calls = %d, want %d (initial + confirmations)", calls, emptyRebuildConfirmations+1)
}
}