// ChildrenChange blocks until the children of the watched Zookeeper node change
// relative to the returned values of the last invokation of Children or ChildrenChange.
// It returns the new children and stat values.
func (w *Watch) ChildrenChange(sinceStat *zookeeper.Stat, expire time.Duration) (children []string, stat *zookeeper.Stat, err error) {
// Still alive?
w.lk.Lock()
z, cwatch := w.zookeeper, w.cwatch
w.lk.Unlock()
if z == nil {
return nil, nil, ErrClosed
}
// Wait if watch present, otherwise read from Zookeeper
if cwatch != nil {
// If we already have a newer revision, return it
w.lk.Lock()
if sinceStat == nil || w.cstat.CVersion() > sinceStat.CVersion() {
defer w.lk.Unlock()
return w.children, w.cstat, nil
}
w.lk.Unlock()
if expire == 0 {
<-cwatch
} else {
select {
case <-cwatch:
case <-time.After(expire):
return nil, nil, ErrExpire
}
}
}
return w.fetchChildren()
}
func (dir *Dir) update(children []string, stat *zookeeper.Stat) {
// If no change since last time, just return
dir.Lock()
defer dir.Unlock()
if dir.stat != nil && dir.stat.CVersion() >= stat.CVersion() {
return
}
dir.stat = stat
dir.children = make(map[string]durablefs.Info)
for _, c := range children {
nodepath := path.Join(dir.zroot, dir.dpath, c)
// Get node data
data, dstat, err := dir.conn.Get(nodepath)
if zutil.IsNoNode(err) {
continue
} else if err != nil {
println("problem fetching durable node data", nodepath, err.Error())
continue
}
// Get node children
chld, cstat, err := dir.conn.Children(nodepath)
if zutil.IsNoNode(err) {
continue
} else if err != nil {
println("problem fetching durable node children", nodepath, err.Error())
continue
}
// TODO: To implement efficient recursive garbage collection, we'd need to keep a global in-memory
// directories structure, as in for the anchor file system
info := durablefs.Info{
Name: c,
HasBody: len(data) > 0,
HasChildren: len(chld) > 0,
}
if cstat.Version() != dstat.Version() {
println("durable file", nodepath, "changed during pruning; leaving alone")
} else if !info.HasBody && !info.HasChildren {
if err = dir.conn.Delete(nodepath, dstat.Version()); err != nil && !zutil.IsNoNode(err) {
// panic(err)
}
continue
}
dir.children[c] = info
}
}