X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/bdddd6c310ce73958b251e977faab7bbadd75452..afbea0d985d273232291f03f343baed727393108:/sdk/go/arvados/fs_lookup.go

diff --git a/sdk/go/arvados/fs_lookup.go b/sdk/go/arvados/fs_lookup.go
index cb4ccfcf92..2bb09995e1 100644
--- a/sdk/go/arvados/fs_lookup.go
+++ b/sdk/go/arvados/fs_lookup.go
@@ -6,7 +6,6 @@ package arvados
 
 import (
 	"os"
-	"sync"
 	"time"
 )
 
@@ -21,9 +20,8 @@ type lookupnode struct {
 	stale   func(time.Time) bool
 
 	// internal fields
-	staleLock sync.Mutex
-	staleAll  time.Time
-	staleOne  map[string]time.Time
+	staleAll time.Time
+	staleOne map[string]time.Time
 }
 
 // Sync flushes pending writes for loaded children and, if successful,
@@ -33,20 +31,20 @@ func (ln *lookupnode) Sync() error {
 	if err != nil {
 		return err
 	}
-	ln.staleLock.Lock()
+	ln.Lock()
 	ln.staleAll = time.Time{}
 	ln.staleOne = nil
-	ln.staleLock.Unlock()
+	ln.Unlock()
 	return nil
 }
 
 func (ln *lookupnode) Readdir() ([]os.FileInfo, error) {
-	ln.staleLock.Lock()
-	defer ln.staleLock.Unlock()
+	ln.Lock()
 	checkTime := time.Now()
 	if ln.stale(ln.staleAll) {
 		all, err := ln.loadAll(ln)
 		if err != nil {
+			ln.Unlock()
 			return nil, err
 		}
 		for _, child := range all {
@@ -54,6 +52,7 @@ func (ln *lookupnode) Readdir() ([]os.FileInfo, error) {
 				return child, nil
 			})
 			if err != nil {
+				ln.Unlock()
 				return nil, err
 			}
 		}
@@ -63,25 +62,46 @@ func (ln *lookupnode) Readdir() ([]os.FileInfo, error) {
 		// newer than ln.staleAll. Reclaim memory.
 		ln.staleOne = nil
 	}
+	ln.Unlock()
 	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
 }