forked from asdine/storm
/
list.go
283 lines (227 loc) · 5.39 KB
/
list.go
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package index
import (
"bytes"
"github.com/asdine/storm/internal"
"github.com/coreos/bbolt"
)
// NewListIndex loads a ListIndex
func NewListIndex(parent *bolt.Bucket, indexName []byte) (*ListIndex, error) {
var err error
b := parent.Bucket(indexName)
if b == nil {
if !parent.Writable() {
return nil, ErrNotFound
}
b, err = parent.CreateBucket(indexName)
if err != nil {
return nil, err
}
}
ids, err := NewUniqueIndex(b, []byte("storm__ids"))
if err != nil {
return nil, err
}
return &ListIndex{
IndexBucket: b,
Parent: parent,
IDs: ids,
}, nil
}
// ListIndex is an index that references values and the corresponding IDs.
type ListIndex struct {
Parent *bolt.Bucket
IndexBucket *bolt.Bucket
IDs *UniqueIndex
}
// Add a value to the list index
func (idx *ListIndex) Add(newValue []byte, targetID []byte) error {
if newValue == nil || len(newValue) == 0 {
return ErrNilParam
}
if targetID == nil || len(targetID) == 0 {
return ErrNilParam
}
key := idx.IDs.Get(targetID)
if key != nil {
err := idx.IndexBucket.Delete(key)
if err != nil {
return err
}
err = idx.IDs.Remove(targetID)
if err != nil {
return err
}
key = key[:0]
}
key = append(key, newValue...)
key = append(key, '_')
key = append(key, '_')
key = append(key, targetID...)
err := idx.IDs.Add(targetID, key)
if err != nil {
return err
}
return idx.IndexBucket.Put(key, targetID)
}
// Remove a value from the unique index
func (idx *ListIndex) Remove(value []byte) error {
var err error
var keys [][]byte
c := idx.IndexBucket.Cursor()
prefix := generatePrefix(value)
for k, _ := c.Seek(prefix); bytes.HasPrefix(k, prefix); k, _ = c.Next() {
keys = append(keys, k)
}
for _, k := range keys {
err = idx.IndexBucket.Delete(k)
if err != nil {
return err
}
}
return idx.IDs.RemoveID(value)
}
// RemoveID removes an ID from the list index
func (idx *ListIndex) RemoveID(targetID []byte) error {
value := idx.IDs.Get(targetID)
if value == nil {
return nil
}
err := idx.IndexBucket.Delete(value)
if err != nil {
return err
}
return idx.IDs.Remove(targetID)
}
// Get the first ID corresponding to the given value
func (idx *ListIndex) Get(value []byte) []byte {
c := idx.IndexBucket.Cursor()
prefix := generatePrefix(value)
for k, id := c.Seek(prefix); bytes.HasPrefix(k, prefix); k, id = c.Next() {
return id
}
return nil
}
// All the IDs corresponding to the given value
func (idx *ListIndex) All(value []byte, opts *Options) ([][]byte, error) {
var list [][]byte
c := idx.IndexBucket.Cursor()
cur := internal.Cursor{C: c, Reverse: opts != nil && opts.Reverse}
prefix := generatePrefix(value)
k, id := c.Seek(prefix)
if cur.Reverse {
var count int
kc := k
idc := id
for ; kc != nil && bytes.HasPrefix(kc, prefix); kc, idc = c.Next() {
count++
k, id = kc, idc
}
if kc != nil {
k, id = c.Prev()
}
list = make([][]byte, 0, count)
}
for ; bytes.HasPrefix(k, prefix); k, id = cur.Next() {
if opts != nil && opts.Skip > 0 {
opts.Skip--
continue
}
if opts != nil && opts.Limit == 0 {
break
}
if opts != nil && opts.Limit > 0 {
opts.Limit--
}
list = append(list, id)
}
return list, nil
}
// AllRecords returns all the IDs of this index
func (idx *ListIndex) AllRecords(opts *Options) ([][]byte, error) {
var list [][]byte
c := internal.Cursor{C: idx.IndexBucket.Cursor(), Reverse: opts != nil && opts.Reverse}
for k, id := c.First(); k != nil; k, id = c.Next() {
if id == nil || bytes.Equal(k, []byte("storm__ids")) {
continue
}
if opts != nil && opts.Skip > 0 {
opts.Skip--
continue
}
if opts != nil && opts.Limit == 0 {
break
}
if opts != nil && opts.Limit > 0 {
opts.Limit--
}
list = append(list, id)
}
return list, nil
}
// Range returns the ids corresponding to the given range of values
func (idx *ListIndex) Range(min []byte, max []byte, opts *Options) ([][]byte, error) {
var list [][]byte
c := internal.RangeCursor{
C: idx.IndexBucket.Cursor(),
Reverse: opts != nil && opts.Reverse,
Min: min,
Max: max,
CompareFn: func(val, limit []byte) int {
pos := bytes.LastIndex(val, []byte("__"))
return bytes.Compare(val[:pos], limit)
},
}
for k, id := c.First(); c.Continue(k); k, id = c.Next() {
if id == nil || bytes.Equal(k, []byte("storm__ids")) {
continue
}
if opts != nil && opts.Skip > 0 {
opts.Skip--
continue
}
if opts != nil && opts.Limit == 0 {
break
}
if opts != nil && opts.Limit > 0 {
opts.Limit--
}
list = append(list, id)
}
return list, nil
}
// Prefix returns the ids whose values have the given prefix.
func (idx *ListIndex) Prefix(prefix []byte, opts *Options) ([][]byte, error) {
var list [][]byte
c := internal.PrefixCursor{
C: idx.IndexBucket.Cursor(),
Reverse: opts != nil && opts.Reverse,
Prefix: prefix,
}
for k, id := c.First(); k != nil && c.Continue(k); k, id = c.Next() {
if id == nil || bytes.Equal(k, []byte("storm__ids")) {
continue
}
if opts != nil && opts.Skip > 0 {
opts.Skip--
continue
}
if opts != nil && opts.Limit == 0 {
break
}
if opts != nil && opts.Limit > 0 {
opts.Limit--
}
list = append(list, id)
}
return list, nil
}
func generatePrefix(value []byte) []byte {
prefix := make([]byte, len(value)+2)
var i int
for i = range value {
prefix[i] = value[i]
}
prefix[i+1] = '_'
prefix[i+2] = '_'
return prefix
}