83 lines
2.5 KiB
Go
83 lines
2.5 KiB
Go
package orm
|
|
|
|
import (
|
|
"encoding/binary"
|
|
|
|
"github.com/cosmos/cosmos-sdk/store/prefix"
|
|
sdk "github.com/cosmos/cosmos-sdk/types"
|
|
sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
|
|
"github.com/cosmos/cosmos-sdk/x/group/errors"
|
|
)
|
|
|
|
// sequenceStorageKey is a fix key to read/ write data on the storage layer
|
|
var sequenceStorageKey = []byte{0x1}
|
|
|
|
// sequence is a persistent unique key generator based on a counter.
|
|
type Sequence struct {
|
|
prefix byte
|
|
}
|
|
|
|
func NewSequence(prefix byte) Sequence {
|
|
return Sequence{
|
|
prefix: prefix,
|
|
}
|
|
}
|
|
|
|
// NextVal increments and persists the counter by one and returns the value.
|
|
func (s Sequence) NextVal(store sdk.KVStore) uint64 {
|
|
pStore := prefix.NewStore(store, []byte{s.prefix})
|
|
v := pStore.Get(sequenceStorageKey)
|
|
seq := DecodeSequence(v)
|
|
seq++
|
|
pStore.Set(sequenceStorageKey, EncodeSequence(seq))
|
|
return seq
|
|
}
|
|
|
|
// CurVal returns the last value used. 0 if none.
|
|
func (s Sequence) CurVal(store sdk.KVStore) uint64 {
|
|
pStore := prefix.NewStore(store, []byte{s.prefix})
|
|
v := pStore.Get(sequenceStorageKey)
|
|
return DecodeSequence(v)
|
|
}
|
|
|
|
// PeekNextVal returns the CurVal + increment step. Not persistent.
|
|
func (s Sequence) PeekNextVal(store sdk.KVStore) uint64 {
|
|
pStore := prefix.NewStore(store, []byte{s.prefix})
|
|
v := pStore.Get(sequenceStorageKey)
|
|
return DecodeSequence(v) + 1
|
|
}
|
|
|
|
// InitVal sets the start value for the sequence. It must be called only once on an empty DB.
|
|
// Otherwise an error is returned when the key exists. The given start value is stored as current
|
|
// value.
|
|
//
|
|
// It is recommended to call this method only for a sequence start value other than `1` as the
|
|
// method consumes unnecessary gas otherwise. A scenario would be an import from genesis.
|
|
func (s Sequence) InitVal(store sdk.KVStore, seq uint64) error {
|
|
pStore := prefix.NewStore(store, []byte{s.prefix})
|
|
if pStore.Has(sequenceStorageKey) {
|
|
return sdkerrors.Wrap(errors.ErrORMUniqueConstraint, "already initialized")
|
|
}
|
|
pStore.Set(sequenceStorageKey, EncodeSequence(seq))
|
|
return nil
|
|
}
|
|
|
|
// DecodeSequence converts the binary representation into an Uint64 value.
|
|
func DecodeSequence(bz []byte) uint64 {
|
|
if bz == nil {
|
|
return 0
|
|
}
|
|
val := binary.BigEndian.Uint64(bz)
|
|
return val
|
|
}
|
|
|
|
// EncodedSeqLength number of bytes used for the binary representation of a sequence value.
|
|
const EncodedSeqLength = 8
|
|
|
|
// EncodeSequence converts the sequence value into the binary representation.
|
|
func EncodeSequence(val uint64) []byte {
|
|
bz := make([]byte, EncodedSeqLength)
|
|
binary.BigEndian.PutUint64(bz, val)
|
|
return bz
|
|
}
|