func (qs *QuadStore) indexOf(t quad.Quad) (int64, bool) {
min := maxInt
var tree *b.Tree
for d := quad.Subject; d <= quad.Label; d++ {
sid := t.Get(d)
if d == quad.Label && sid == "" {
continue
}
id, ok := qs.idMap[sid]
// If we've never heard about a node, it must not exist
if !ok {
return 0, false
}
index, ok := qs.index.Get(d, id)
if !ok {
// If it's never been indexed in this direction, it can't exist.
return 0, false
}
if l := index.Len(); l < min {
min, tree = l, index
}
}
it := NewIterator(tree, "", qs)
for it.Next() {
val := it.Result()
if t == qs.log[val.(int64)].Quad {
return val.(int64), true
}
}
return 0, false
}
func (qs *QuadStore) createKeyFor(d [4]quad.Direction, q quad.Quad) []byte {
key := make([]byte, 0, 2+(hashSize*4))
// TODO(kortschak) Remove dependence on String() method.
key = append(key, []byte{d[0].Prefix(), d[1].Prefix()}...)
key = append(key, hashOf(q.Get(d[0]))...)
key = append(key, hashOf(q.Get(d[1]))...)
key = append(key, hashOf(q.Get(d[2]))...)
key = append(key, hashOf(q.Get(d[3]))...)
return key
}
func (qs *QuadStore) buildQuadWrite(batch *leveldb.Batch, q quad.Quad, id int64, isAdd bool) error {
var entry IndexEntry
data, err := qs.db.Get(qs.createKeyFor(spo, q), qs.readopts)
if err != nil && err != leveldb.ErrNotFound {
glog.Error("could not access DB to prepare index: ", err)
return err
}
if err == nil {
// We got something.
err = json.Unmarshal(data, &entry)
if err != nil {
return err
}
} else {
entry.Quad = q
}
if isAdd && len(entry.History)%2 == 1 {
glog.Errorf("attempt to add existing quad %v: %#v", entry, q)
return graph.ErrQuadExists
}
if !isAdd && len(entry.History)%2 == 0 {
glog.Error("attempt to delete non-existent quad %v: %#c", entry, q)
return graph.ErrQuadNotExist
}
entry.History = append(entry.History, id)
bytes, err := json.Marshal(entry)
if err != nil {
glog.Errorf("could not write to buffer for entry %#v: %s", entry, err)
return err
}
batch.Put(qs.createKeyFor(spo, q), bytes)
batch.Put(qs.createKeyFor(osp, q), bytes)
batch.Put(qs.createKeyFor(pos, q), bytes)
if q.Get(quad.Label) != "" {
batch.Put(qs.createKeyFor(cps, q), bytes)
}
return nil
}