lnd.xprv/channeldb/migration16/migration.go

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package migration16
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"github.com/btcsuite/btcd/wire"
"github.com/lightningnetwork/lnd/channeldb/kvdb"
)
var (
paymentsRootBucket = []byte("payments-root-bucket")
paymentSequenceKey = []byte("payment-sequence-key")
duplicatePaymentsBucket = []byte("payment-duplicate-bucket")
paymentsIndexBucket = []byte("payments-index-bucket")
byteOrder = binary.BigEndian
)
// paymentIndexType indicates the type of index we have recorded in the payment
// indexes bucket.
type paymentIndexType uint8
// paymentIndexTypeHash is a payment index type which indicates that we have
// created an index of payment sequence number to payment hash.
const paymentIndexTypeHash paymentIndexType = 0
// paymentIndex stores all the information we require to create an index by
// sequence number for a payment.
type paymentIndex struct {
// paymentHash is the hash of the payment, which is its key in the
// payment root bucket.
paymentHash []byte
// sequenceNumbers is the set of sequence numbers associated with this
// payment hash. There will be more than one sequence number in the
// case where duplicate payments are present.
sequenceNumbers [][]byte
}
// MigrateSequenceIndex migrates the payments db to contain a new bucket which
// provides an index from sequence number to payment hash. This is required
// for more efficient sequential lookup of payments, which are keyed by payment
// hash before this migration.
func MigrateSequenceIndex(tx kvdb.RwTx) error {
log.Infof("Migrating payments to add sequence number index")
// Get a list of indices we need to write.
indexList, err := getPaymentIndexList(tx)
if err != nil {
return err
}
// Create the top level bucket that we will use to index payments in.
bucket, err := tx.CreateTopLevelBucket(paymentsIndexBucket)
if err != nil {
return err
}
// Write an index for each of our payments.
for _, index := range indexList {
// Write indexes for each of our sequence numbers.
for _, seqNr := range index.sequenceNumbers {
err := putIndex(bucket, seqNr, index.paymentHash)
if err != nil {
return err
}
}
}
return nil
}
// putIndex performs a sanity check that ensures we are not writing duplicate
// indexes to disk then creates the index provided.
func putIndex(bucket kvdb.RwBucket, sequenceNr, paymentHash []byte) error {
// Add a sanity check that we do not already have an entry with
// this sequence number.
existingEntry := bucket.Get(sequenceNr)
if existingEntry != nil {
return fmt.Errorf("sequence number: %x duplicated",
sequenceNr)
}
bytes, err := serializePaymentIndexEntry(paymentHash)
if err != nil {
return err
}
return bucket.Put(sequenceNr, bytes)
}
// serializePaymentIndexEntry serializes a payment hash typed index. The value
// produced contains a payment index type (which can be used in future to
// signal different payment index types) and the payment hash.
func serializePaymentIndexEntry(hash []byte) ([]byte, error) {
var b bytes.Buffer
err := binary.Write(&b, byteOrder, paymentIndexTypeHash)
if err != nil {
return nil, err
}
if err := wire.WriteVarBytes(&b, 0, hash); err != nil {
return nil, err
}
return b.Bytes(), nil
}
// getPaymentIndexList gets a list of indices we need to write for our current
// set of payments.
func getPaymentIndexList(tx kvdb.RTx) ([]paymentIndex, error) {
// Iterate over all payments and store their indexing keys. This is
// needed, because no modifications are allowed inside a Bucket.ForEach
// loop.
paymentsBucket := tx.ReadBucket(paymentsRootBucket)
if paymentsBucket == nil {
return nil, nil
}
var indexList []paymentIndex
err := paymentsBucket.ForEach(func(k, v []byte) error {
// Get the bucket which contains the payment, fail if the key
// does not have a bucket.
bucket := paymentsBucket.NestedReadBucket(k)
if bucket == nil {
return fmt.Errorf("non bucket element in " +
"payments bucket")
}
seqBytes := bucket.Get(paymentSequenceKey)
if seqBytes == nil {
return fmt.Errorf("nil sequence number bytes")
}
seqNrs, err := fetchSequenceNumbers(bucket)
if err != nil {
return err
}
// Create an index object with our payment hash and sequence
// numbers and append it to our set of indexes.
index := paymentIndex{
paymentHash: k,
sequenceNumbers: seqNrs,
}
indexList = append(indexList, index)
return nil
})
if err != nil {
return nil, err
}
return indexList, nil
}
// fetchSequenceNumbers fetches all the sequence numbers associated with a
// payment, including those belonging to any duplicate payments.
func fetchSequenceNumbers(paymentBucket kvdb.RBucket) ([][]byte, error) {
seqNum := paymentBucket.Get(paymentSequenceKey)
if seqNum == nil {
return nil, errors.New("expected sequence number")
}
sequenceNumbers := [][]byte{seqNum}
// Get the duplicate payments bucket, if it has no duplicates, just
// return early with the payment sequence number.
duplicates := paymentBucket.NestedReadBucket(duplicatePaymentsBucket)
if duplicates == nil {
return sequenceNumbers, nil
}
// If we do have duplicated, they are keyed by sequence number, so we
// iterate through the duplicates bucket and add them to our set of
// sequence numbers.
if err := duplicates.ForEach(func(k, v []byte) error {
sequenceNumbers = append(sequenceNumbers, k)
return nil
}); err != nil {
return nil, err
}
return sequenceNumbers, nil
}