// Example_roaring demonstrates how to use the roaring library.
func Example_roaring() {
// example inspired by https://github.com/fzandona/goroar
fmt.Println("==roaring==")
rb1 := roaring.BitmapOf(1, 2, 3, 4, 5, 100, 1000)
fmt.Println(rb1.String())
rb2 := roaring.BitmapOf(3, 4, 1000)
fmt.Println(rb2.String())
rb3 := roaring.NewBitmap()
fmt.Println(rb3.String())
fmt.Println("Cardinality: ", rb1.GetCardinality())
fmt.Println("Contains 3? ", rb1.Contains(3))
rb1.And(rb2)
rb3.Add(1)
rb3.Add(5)
rb3.Or(rb1)
// prints 1, 3, 4, 5, 1000
i := rb3.Iterator()
for i.HasNext() {
fmt.Println(i.Next())
}
fmt.Println()
// next we include an example of serialization
buf := new(bytes.Buffer)
size, err := rb1.WriteTo(buf)
if err != nil {
fmt.Println("Failed writing")
return
} else {
fmt.Println("Wrote ", size, " bytes")
}
newrb := roaring.NewBitmap()
size, err = newrb.ReadFrom(buf)
if err != nil {
fmt.Println("Failed reading")
return
}
if !rb1.Equals(newrb) {
fmt.Println("I did not get back to original bitmap?")
return
} else {
fmt.Println("I wrote the content to a byte stream and read it back.")
}
}
// removeTriple removes a triple from the indices. If the triple
// contains any terms unique to that triple, they will also be removed.
func (db *DB) removeTriple(tx *bolt.Tx, s, p, o uint32) error {
// TODO think about what to do if present in one index but
// not in another: maybe panic? Cause It's a bug that should be fixed.
indices := []struct {
k1 uint32
k2 uint32
v uint32
bk []byte
}{
{s, p, o, bucketSPO},
{o, s, p, bucketOSP},
{p, o, s, bucketPOS},
}
key := make([]byte, 8)
for _, i := range indices {
bkt := tx.Bucket(i.bk)
copy(key, u32tob(i.k1))
copy(key[4:], u32tob(i.k2))
bo := bkt.Get(key)
if bo == nil {
// TODO should never happen, return bug error?
return ErrNotFound
}
bitmap := roaring.NewBitmap()
_, err := bitmap.ReadFrom(bytes.NewReader(bo))
if err != nil {
return err
}
hasTriple := bitmap.CheckedRemove(i.v)
if !hasTriple {
// TODO should never happen, return bug error?
return ErrNotFound
}
// Remove from index if bitmap is empty
if bitmap.GetCardinality() == 0 {
err = bkt.Delete(key)
if err != nil {
return err
}
} else {
var b bytes.Buffer
_, err = bitmap.WriteTo(&b)
if err != nil {
return err
}
err = bkt.Put(key, b.Bytes())
if err != nil {
return err
}
}
}
//atomic.AddInt64(&db.numTr, -1)
return db.removeOrphanedTerms(tx, s, p, o)
}
func (b *baseBlockset) GetLiveINodes() *roaring.Bitmap {
out := roaring.NewBitmap()
for _, blk := range b.blocks {
if blk.IsZero() {
continue
}
out.Add(uint32(blk.INode))
}
return out
}
func (db *DB) forEach(fn func(rdf.Triple) error) error {
return db.kv.View(func(tx *bolt.Tx) error {
bkt := tx.Bucket(bucketSPO)
// iterate over each each triple in SPO index
if err := bkt.ForEach(func(k, v []byte) error {
if len(k) != 8 {
panic("len(SPO key) != 8")
}
sID := btou32(k[:4])
pID := btou32(k[4:])
var tr rdf.Triple
var err error
var term rdf.Term
if term, err = db.getTerm(tx, sID); err != nil {
return err
}
tr.Subj = term.(rdf.URI)
if term, err = db.getTerm(tx, pID); err != nil {
return err
}
tr.Pred = term.(rdf.URI)
bitmap := roaring.NewBitmap()
if _, err := bitmap.ReadFrom(bytes.NewReader(v)); err != nil {
return err
}
// Iterate over each term in object bitmap
i := bitmap.Iterator()
for i.HasNext() {
if tr.Obj, err = db.getTerm(tx, i.Next()); err != nil {
return err
}
if err := fn(tr); err != nil {
return err
}
}
return nil
}); err != nil {
return err
}
return nil
})
}
func (db *DB) storeTriple(tx *bolt.Tx, s, p, o uint32) error {
indices := []struct {
k1 uint32
k2 uint32
v uint32
bk []byte
}{
{s, p, o, bucketSPO},
{o, s, p, bucketOSP},
{p, o, s, bucketPOS},
}
key := make([]byte, 8)
for _, i := range indices {
bkt := tx.Bucket(i.bk)
copy(key, u32tob(i.k1))
copy(key[4:], u32tob(i.k2))
bitmap := roaring.NewBitmap()
bo := bkt.Get(key)
if bo != nil {
_, err := bitmap.ReadFrom(bytes.NewReader(bo))
if err != nil {
return err
}
}
newTriple := bitmap.CheckedAdd(i.v)
if !newTriple {
// Triple is allready stored
return nil
}
var b bytes.Buffer
_, err := bitmap.WriteTo(&b)
if err != nil {
return err
}
err = bkt.Put(key, b.Bytes())
if err != nil {
return err
}
}
//atomic.AddInt64(&db.numTr, 1)
return nil
}
// Has checks if the given Triple is stored.
func (db *DB) Has(tr rdf.Triple) (exists bool, err error) {
err = db.kv.View(func(tx *bolt.Tx) error {
sID, err := db.getID(tx, tr.Subj)
if err == ErrNotFound {
return nil
} else if err != nil {
return err
}
// TODO get pID from cache, and move to top before sID
pID, err := db.getID(tx, tr.Pred)
if err == ErrNotFound {
return nil
} else if err != nil {
return err
}
oID, err := db.getID(tx, tr.Obj)
if err == ErrNotFound {
return nil
} else if err != nil {
return err
}
bkt := tx.Bucket(bucketSPO)
sp := make([]byte, 8)
copy(sp, u32tob(sID))
copy(sp[4:], u32tob(pID))
bitmap := roaring.NewBitmap()
bo := bkt.Get(sp)
if bo == nil {
return nil
}
_, err = bitmap.ReadFrom(bytes.NewReader(bo))
if err != nil {
return err
}
exists = bitmap.Contains(oID)
return nil
})
return exists, err
}
func (me *Bitmap) lazyRB() *roaring.Bitmap {
if me.rb == nil {
me.rb = roaring.NewBitmap()
}
return me.rb
}
// Dump writes the entire database as a Turtle serialization to the given writer.
func (db *DB) Dump(to io.Writer) error {
// TODO getTerm without expanding base URI?
// base is prefixed added, but then stripped again here
w := bufio.NewWriter(to)
w.WriteString("@base <")
w.WriteString(db.base)
w.WriteString(">")
return db.kv.View(func(tx *bolt.Tx) error {
defer w.Flush()
var curSubj uint32
var subj, pred, obj rdf.Term
bkt := tx.Bucket(bucketSPO)
if err := bkt.ForEach(func(k, v []byte) error {
if len(k) != 8 {
panic("len(SPO key) != 8")
}
var err error
sID := btou32(k[:4])
if sID != curSubj {
// end previous statement
w.WriteString(" .\n")
curSubj = sID
if subj, err = db.getTerm(tx, sID); err != nil {
return err
}
w.WriteRune('<')
w.WriteString(strings.TrimPrefix(subj.String(), db.base))
w.WriteString("> ")
} else {
// continue with same subject
w.WriteString(" ;\n\t")
}
pID := btou32(k[4:])
if pred, err = db.getTerm(tx, pID); err != nil {
return err
}
if pred == rdf.RDFtype {
w.WriteString("a ")
} else {
w.WriteRune('<')
w.WriteString(strings.TrimPrefix(pred.String(), db.base))
w.WriteString("> ")
}
bitmap := roaring.NewBitmap()
if _, err := bitmap.ReadFrom(bytes.NewReader(v)); err != nil {
return err
}
i := bitmap.Iterator()
c := 0
for i.HasNext() {
if obj, err = db.getTerm(tx, i.Next()); err != nil {
return err
}
if c > 0 {
w.WriteString(", ")
}
switch t := obj.(type) {
case rdf.URI:
w.WriteRune('<')
w.WriteString(strings.TrimPrefix(obj.String(), db.base))
w.WriteRune('>')
case rdf.Literal:
// TODO bench & optimize
switch t.DataType() {
case rdf.RDFlangString:
fmt.Fprintf(w, "%q@%s", t.String(), t.Lang())
case rdf.XSDstring:
fmt.Fprintf(w, "%q", t.String())
default:
fmt.Fprintf(w, "%q^^<%s>", t.String(), strings.TrimPrefix(t.DataType().String(), db.base))
}
}
c++
}
return nil
}); err != nil {
return err
}
w.WriteString(" .\n")
return nil
})
}
// Describe returns a graph with all the triples where the given node
// is subject. If asObject is true, it also includes the triples where
// the node is object.
func (db *DB) Describe(node rdf.URI, asObject bool) (*rdf.Graph, error) {
g := rdf.NewGraph()
err := db.kv.View(func(tx *bolt.Tx) error {
bkt := tx.Bucket(bucketIdxTerms)
bt := db.encode(node)
bs := bkt.Get(bt)
if bs == nil {
return nil
}
// seek in SPO index:
// WHERE { <node> ?p ?o }
sid := btou32(bs)
cur := tx.Bucket(bucketSPO).Cursor()
outerSPO:
for k, v := cur.Seek(u32tob(sid - 1)); k != nil; k, v = cur.Next() {
switch bytes.Compare(k[:4], bs) {
case 0:
bkt = tx.Bucket(bucketTerms)
b := bkt.Get(k[4:])
if b == nil {
return errors.New("bug: term ID in index, but not stored")
}
// TODO get pred from cache
pred, err := db.decode(b)
if err != nil {
return err
}
bitmap := roaring.NewBitmap()
_, err = bitmap.ReadFrom(bytes.NewReader(v))
if err != nil {
return err
}
it := bitmap.Iterator()
for it.HasNext() {
o := it.Next()
b = bkt.Get(u32tob(o))
if b == nil {
return errors.New("bug: term ID in index, but not stored")
}
obj, err := db.decode(b)
if err != nil {
return err
}
g.Insert(rdf.Triple{Subj: node, Pred: pred.(rdf.URI), Obj: obj})
}
case 1:
break outerSPO
}
}
if !asObject {
return nil
}
// seek in OSP index:
// WHERE { ?s ?p <node> }
cur = tx.Bucket(bucketOSP).Cursor()
outerOSP:
for k, v := cur.Seek(u32tob(sid - 1)); k != nil; k, v = cur.Next() {
switch bytes.Compare(k[:4], bs) {
case 0:
bkt = tx.Bucket(bucketTerms)
b := bkt.Get(k[4:])
if b == nil {
return errors.New("bug: term ID in index, but not stored")
}
subj, err := db.decode(b)
if err != nil {
return err
}
bitmap := roaring.NewBitmap()
_, err = bitmap.ReadFrom(bytes.NewReader(v))
if err != nil {
return err
}
it := bitmap.Iterator()
for it.HasNext() {
o := it.Next()
b = bkt.Get(u32tob(o))
if b == nil {
return errors.New("bug: term ID in index, but not stored")
}
// TODO get pred from cache
pred, err := db.decode(b)
if err != nil {
return err
}
g.Insert(rdf.Triple{Subj: subj.(rdf.URI), Pred: pred.(rdf.URI), Obj: node})
}
case 1:
break outerOSP
}
}
return nil
})
return g, err
}
