neoneo-go/pkg/core/interop/storage/find.go

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package storage
import (
"context"
"fmt"
"github.com/nspcc-dev/neo-go/pkg/core/interop"
"github.com/nspcc-dev/neo-go/pkg/core/storage"
"github.com/nspcc-dev/neo-go/pkg/util/slice"
"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
)
// Storage iterator options.
const (
FindDefault = 0
FindKeysOnly = 1 << 0
FindRemovePrefix = 1 << 1
FindValuesOnly = 1 << 2
FindDeserialize = 1 << 3
FindPick0 = 1 << 4
FindPick1 = 1 << 5
FindAll = FindDefault | FindKeysOnly | FindRemovePrefix | FindValuesOnly |
FindDeserialize | FindPick0 | FindPick1
)
// Iterator is an iterator state representation.
type Iterator struct {
seekCh chan storage.KeyValue
curr storage.KeyValue
next bool
opts int64
prefix []byte
}
// NewIterator creates a new Iterator with the given options for the given channel of store.Seek results.
func NewIterator(seekCh chan storage.KeyValue, prefix []byte, opts int64) *Iterator {
return &Iterator{
seekCh: seekCh,
opts: opts,
prefix: slice.Copy(prefix),
}
}
// Next advances the iterator and returns true if Value can be called at the
// current position.
func (s *Iterator) Next() bool {
s.curr, s.next = <-s.seekCh
return s.next
}
// Value returns current iterators value (exact type depends on options this
// iterator was created with).
func (s *Iterator) Value() stackitem.Item {
if !s.next {
panic("iterator index out of range")
}
key := s.curr.Key
if s.opts&FindRemovePrefix == 0 {
key = append(s.prefix, key...)
}
if s.opts&FindKeysOnly != 0 {
return stackitem.NewByteArray(key)
}
value := stackitem.Item(stackitem.NewByteArray(s.curr.Value))
if s.opts&FindDeserialize != 0 {
bs := s.curr.Value
var err error
value, err = stackitem.Deserialize(bs)
if err != nil {
panic(err)
}
}
if s.opts&FindPick0 != 0 {
value = value.Value().([]stackitem.Item)[0]
} else if s.opts&FindPick1 != 0 {
value = value.Value().([]stackitem.Item)[1]
}
if s.opts&FindValuesOnly != 0 {
return value
}
return stackitem.NewStruct([]stackitem.Item{
stackitem.NewByteArray(key),
value,
})
}
// Find finds stored key-value pair.
func Find(ic *interop.Context) error {
stcInterface := ic.VM.Estack().Pop().Value()
stc, ok := stcInterface.(*Context)
if !ok {
return fmt.Errorf("%T is not a storage,Context", stcInterface)
}
prefix := ic.VM.Estack().Pop().Bytes()
opts := ic.VM.Estack().Pop().BigInt().Int64()
if opts&^FindAll != 0 {
return fmt.Errorf("%w: unknown flag", errFindInvalidOptions)
}
if opts&FindKeysOnly != 0 &&
opts&(FindDeserialize|FindPick0|FindPick1) != 0 {
return fmt.Errorf("%w KeysOnly conflicts with other options", errFindInvalidOptions)
}
if opts&FindValuesOnly != 0 &&
opts&(FindKeysOnly|FindRemovePrefix) != 0 {
return fmt.Errorf("%w: KeysOnly conflicts with ValuesOnly", errFindInvalidOptions)
}
if opts&FindPick0 != 0 && opts&FindPick1 != 0 {
return fmt.Errorf("%w: Pick0 conflicts with Pick1", errFindInvalidOptions)
}
if opts&FindDeserialize == 0 && (opts&FindPick0 != 0 || opts&FindPick1 != 0) {
return fmt.Errorf("%w: PickN is specified without Deserialize", errFindInvalidOptions)
}
ctx, cancel := context.WithCancel(context.Background())
seekres := ic.DAO.SeekAsync(ctx, stc.ID, storage.SeekRange{Prefix: prefix})
item := NewIterator(seekres, prefix, opts)
ic.VM.Estack().PushItem(stackitem.NewInterop(item))
ic.RegisterCancelFunc(func() {
cancel()
// Underlying persistent store is likely to be a private MemCachedStore. Thus,
// to avoid concurrent map iteration and map write we need to wait until internal
// seek goroutine is finished, because it can access underlying persistent store.
for range seekres {
}
})
return nil
}