15370: Fix flaky test.

[arvados.git] / sdk / go / arvados / fs_lookup.go

diff --git a/sdk/go/arvados/fs_lookup.go b/sdk/go/arvados/fs_lookup.go
index cb4ccfcf92b7d2f90c14d7b7856b717b55c19f92..471dc69c82f75318d290eaccfa7b8d4a542540f1 100644 (file)
--- a/sdk/go/arvados/fs_lookup.go
+++ b/sdk/go/arvados/fs_lookup.go
@@ -50,9 +50,11 @@ func (ln *lookupnode) Readdir() ([]os.FileInfo, error) {
                        return nil, err
                }
                for _, child := range all {
+                       ln.treenode.Lock()
                        _, err = ln.treenode.Child(child.FileInfo().Name(), func(inode) (inode, error) {
                                return child, nil
                        })
+                       ln.treenode.Unlock()
                        if err != nil {
                                return nil, err
                        }
@@ -66,22 +68,44 @@ func (ln *lookupnode) Readdir() ([]os.FileInfo, error) {
        return ln.treenode.Readdir()
 }
 
+// Child rejects (with ErrInvalidOperation) calls to add/replace
+// children, instead calling loadOne when a non-existing child is
+// looked up.
 func (ln *lookupnode) Child(name string, replace func(inode) (inode, error)) (inode, error) {
        ln.staleLock.Lock()
        defer ln.staleLock.Unlock()
        checkTime := time.Now()
+       var existing inode
+       var err error
        if ln.stale(ln.staleAll) && ln.stale(ln.staleOne[name]) {
-               _, err := ln.treenode.Child(name, func(inode) (inode, error) {
+               existing, err = ln.treenode.Child(name, func(inode) (inode, error) {
                        return ln.loadOne(ln, name)
                })
-               if err != nil {
-                       return nil, err
+               if err == nil && existing != nil {
+                       if ln.staleOne == nil {
+                               ln.staleOne = map[string]time.Time{name: checkTime}
+                       } else {
+                               ln.staleOne[name] = checkTime
+                       }
                }
-               if ln.staleOne == nil {
-                       ln.staleOne = map[string]time.Time{name: checkTime}
-               } else {
-                       ln.staleOne[name] = checkTime
+       } else {
+               existing, err = ln.treenode.Child(name, nil)
+               if err != nil && !os.IsNotExist(err) {
+                       return existing, err
+               }
+       }
+       if replace != nil {
+               // Let the callback try to delete or replace the
+               // existing node; if it does, return
+               // ErrInvalidOperation.
+               if tryRepl, err := replace(existing); err != nil {
+                       // Propagate error from callback
+                       return existing, err
+               } else if tryRepl != existing {
+                       return existing, ErrInvalidOperation
                }
        }
-       return ln.treenode.Child(name, replace)
+       // Return original error from ln.treenode.Child() (it might be
+       // ErrNotExist).
+       return existing, err
 }