102 lines
2.5 KiB
Go
102 lines
2.5 KiB
Go
package truncindex
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import (
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"fmt"
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"index/suffixarray"
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"strings"
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"sync"
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)
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// TruncIndex allows the retrieval of string identifiers by any of their unique prefixes.
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// This is used to retrieve image and container IDs by more convenient shorthand prefixes.
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type TruncIndex struct {
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sync.RWMutex
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index *suffixarray.Index
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ids map[string]bool
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bytes []byte
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}
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func NewTruncIndex(ids []string) (idx *TruncIndex) {
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idx = &TruncIndex{
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ids: make(map[string]bool),
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bytes: []byte{' '},
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}
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for _, id := range ids {
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idx.ids[id] = true
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idx.bytes = append(idx.bytes, []byte(id+" ")...)
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}
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idx.index = suffixarray.New(idx.bytes)
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return
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}
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func (idx *TruncIndex) addId(id string) error {
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if strings.Contains(id, " ") {
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return fmt.Errorf("Illegal character: ' '")
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}
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if _, exists := idx.ids[id]; exists {
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return fmt.Errorf("Id already exists: %s", id)
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}
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idx.ids[id] = true
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idx.bytes = append(idx.bytes, []byte(id+" ")...)
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return nil
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}
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func (idx *TruncIndex) Add(id string) error {
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idx.Lock()
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defer idx.Unlock()
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if err := idx.addId(id); err != nil {
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return err
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}
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idx.index = suffixarray.New(idx.bytes)
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return nil
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}
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func (idx *TruncIndex) AddWithoutSuffixarrayUpdate(id string) error {
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idx.Lock()
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defer idx.Unlock()
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return idx.addId(id)
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}
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func (idx *TruncIndex) UpdateSuffixarray() {
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idx.Lock()
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defer idx.Unlock()
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idx.index = suffixarray.New(idx.bytes)
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}
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func (idx *TruncIndex) Delete(id string) error {
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idx.Lock()
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defer idx.Unlock()
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if _, exists := idx.ids[id]; !exists {
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return fmt.Errorf("No such id: %s", id)
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}
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before, after, err := idx.lookup(id)
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if err != nil {
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return err
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}
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delete(idx.ids, id)
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idx.bytes = append(idx.bytes[:before], idx.bytes[after:]...)
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idx.index = suffixarray.New(idx.bytes)
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return nil
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}
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func (idx *TruncIndex) lookup(s string) (int, int, error) {
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offsets := idx.index.Lookup([]byte(" "+s), -1)
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//log.Printf("lookup(%s): %v (index bytes: '%s')\n", s, offsets, idx.index.Bytes())
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if offsets == nil || len(offsets) == 0 || len(offsets) > 1 {
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return -1, -1, fmt.Errorf("No such id: %s", s)
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}
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offsetBefore := offsets[0] + 1
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offsetAfter := offsetBefore + strings.Index(string(idx.bytes[offsetBefore:]), " ")
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return offsetBefore, offsetAfter, nil
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}
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func (idx *TruncIndex) Get(s string) (string, error) {
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idx.RLock()
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defer idx.RUnlock()
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before, after, err := idx.lookup(s)
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//log.Printf("Get(%s) bytes=|%s| before=|%d| after=|%d|\n", s, idx.bytes, before, after)
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if err != nil {
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return "", err
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}
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return string(idx.bytes[before:after]), err
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}
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