channeldb/migration: remove old forwarding packages

channeldb/migration24/migration.go

@@ -0,0 +1,119 @@
+package migration24
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+
+	mig "github.com/lightningnetwork/lnd/channeldb/migration_01_to_11"
+	"github.com/lightningnetwork/lnd/kvdb"
+)
+
+var (
+	// closedChannelBucket stores summarization information concerning
+	// previously open, but now closed channels.
+	closedChannelBucket = []byte("closed-chan-bucket")
+
+	// fwdPackagesKey is the root-level bucket that all forwarding packages
+	// are written. This bucket is further subdivided based on the short
+	// channel ID of each channel.
+	fwdPackagesKey = []byte("fwd-packages")
+)
+
+// MigrateFwdPkgCleanup deletes all the forwarding packages of closed channels.
+// It determines the closed channels by iterating closedChannelBucket. The
+// ShortChanID found in the ChannelCloseSummary is then used as a key to query
+// the forwarding packages bucket. If a match is found, it will be deleted.
+func MigrateFwdPkgCleanup(tx kvdb.RwTx) error {
+	log.Infof("Deleting forwarding packages for closed channels")
+
+	// Find all closed channel summaries, which are stored in the
+	// closeBucket.
+	closeBucket := tx.ReadBucket(closedChannelBucket)
+	if closeBucket == nil {
+		return nil
+	}
+
+	var chanSummaries []*mig.ChannelCloseSummary
+
+	// appendSummary is a function closure to help put deserialized close
+	// summeries into chanSummaries.
+	appendSummary := func(_ []byte, summaryBytes []byte) error {
+		summaryReader := bytes.NewReader(summaryBytes)
+		chanSummary, err := deserializeCloseChannelSummary(
+			summaryReader,
+		)
+		if err != nil {
+			return err
+		}
+
+		// Skip pending channels
+		if chanSummary.IsPending {
+			return nil
+		}
+
+		chanSummaries = append(chanSummaries, chanSummary)
+		return nil
+	}
+
+	if err := closeBucket.ForEach(appendSummary); err != nil {
+		return err
+	}
+
+	// Now we will load the forwarding packages bucket, delete all the
+	// nested buckets whose source matches the ShortChanID found in the
+	// closed channel summeraries.
+	fwdPkgBkt := tx.ReadWriteBucket(fwdPackagesKey)
+	if fwdPkgBkt == nil {
+		return nil
+	}
+
+	// Iterate over all close channels and remove their forwarding packages.
+	for _, summery := range chanSummaries {
+		sourceBytes := makeLogKey(summery.ShortChanID.ToUint64())
+
+		// First, we will try to find the corresponding bucket. If there
+		// is not a nested bucket matching the ShortChanID, we will skip
+		// it.
+		if fwdPkgBkt.NestedReadBucket(sourceBytes[:]) == nil {
+			continue
+		}
+
+		// Otherwise, wipe all the forwarding packages.
+		if err := fwdPkgBkt.DeleteNestedBucket(
+			sourceBytes[:]); err != nil {
+
+			return err
+		}
+	}
+
+	log.Infof("Deletion of forwarding packages of closed channels " +
+		"complete! DB compaction is recommended to free up the" +
+		"disk space.")
+	return nil
+}
+
+// deserializeCloseChannelSummary will decode a CloseChannelSummary with no
+// optional fields.
+func deserializeCloseChannelSummary(
+	r io.Reader) (*mig.ChannelCloseSummary, error) {
+
+	c := &mig.ChannelCloseSummary{}
+	err := mig.ReadElements(
+		r,
+		&c.ChanPoint, &c.ShortChanID, &c.ChainHash, &c.ClosingTXID,
+		&c.CloseHeight, &c.RemotePub, &c.Capacity, &c.SettledBalance,
+		&c.TimeLockedBalance, &c.CloseType, &c.IsPending,
+	)
+	if err != nil {
+		return nil, err
+	}
+	return c, nil
+}
+
+// makeLogKey converts a uint64 into an 8 byte array.
+func makeLogKey(updateNum uint64) [8]byte {
+	var key [8]byte
+	binary.BigEndian.PutUint64(key[:], updateNum)
+	return key
+}