// Wrap wraps a given datastore with a key-prefix.
func Wrap(child ds.Datastore, prefix ds.Key) ktds.Datastore {
if child == nil {
panic("child (ds.Datastore) is nil")
}
d := ktds.Wrap(child, PrefixTransform(prefix))
return &datastore{Datastore: d, raw: child, prefix: prefix}
}
func (d *Datastore) Query(q query.Query) (query.Results, error) {
if len(q.Filters) > 0 ||
len(q.Orders) > 0 ||
q.Limit > 0 ||
q.Offset > 0 {
// TODO this is overly simplistic, but the only caller is
// `ipfs refs local` for now, and this gets us moving.
return nil, errors.New("mount only supports listing all prefixed keys in random order")
}
key := datastore.NewKey(q.Prefix)
ds, mount, k := d.lookup(key)
if ds == nil {
return nil, errors.New("mount only supports listing a mount point")
}
// TODO support listing cross mount points too
// delegate the query to the mounted datastore, while adjusting
// keys in and out
q2 := q
q2.Prefix = k.String()
wrapDS := keytransform.Wrap(ds, &keytransform.Pair{
Convert: func(datastore.Key) datastore.Key {
panic("this should never be called")
},
Invert: func(k datastore.Key) datastore.Key {
return mount.Child(k)
},
})
r, err := wrapDS.Query(q2)
if err != nil {
return nil, err
}
r = query.ResultsReplaceQuery(r, q)
return r, nil
}
func (ks *DSSuite) TestBasic(c *C) {
pair := &kt.Pair{
Convert: func(k ds.Key) ds.Key {
return ds.NewKey("/abc").Child(k)
},
Invert: func(k ds.Key) ds.Key {
// remove abc prefix
l := k.List()
if l[0] != "abc" {
panic("key does not have prefix. convert failed?")
}
return ds.KeyWithNamespaces(l[1:])
},
}
mpds := ds.NewMapDatastore()
ktds := kt.Wrap(mpds, pair)
keys := strsToKeys([]string{
"foo",
"foo/bar",
"foo/bar/baz",
"foo/barb",
"foo/bar/bazb",
"foo/bar/baz/barb",
})
for _, k := range keys {
err := ktds.Put(k, []byte(k.String()))
c.Check(err, Equals, nil)
}
for _, k := range keys {
v1, err := ktds.Get(k)
c.Check(err, Equals, nil)
c.Check(bytes.Equal(v1.([]byte), []byte(k.String())), Equals, true)
v2, err := mpds.Get(ds.NewKey("abc").Child(k))
c.Check(err, Equals, nil)
c.Check(bytes.Equal(v2.([]byte), []byte(k.String())), Equals, true)
}
run := func(d ds.Datastore, q dsq.Query) []ds.Key {
r, err := d.Query(q)
c.Check(err, Equals, nil)
e, err := r.Rest()
c.Check(err, Equals, nil)
return ds.EntryKeys(e)
}
listA := run(mpds, dsq.Query{})
listB := run(ktds, dsq.Query{})
c.Check(len(listA), Equals, len(listB))
// sort them cause yeah.
sort.Sort(ds.KeySlice(listA))
sort.Sort(ds.KeySlice(listB))
for i, kA := range listA {
kB := listB[i]
c.Check(pair.Invert(kA), Equals, kB)
c.Check(kA, Equals, pair.Convert(kB))
}
c.Log("listA: ", listA)
c.Log("listB: ", listB)
}