9915780197

Committed 13 Jul 2024 12:30AM UTC coverage: 49.268% (-9.1%) from 58.413%

Build # 9915780197

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github

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web-flow

Commit Message

Merge pull request #8653 from ProofOfKeags/fn-prim

DynComms [0/n]: `fn` package additions

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65.58

/channeldb/db.go

package channeldb

import (
        "bytes"
        "encoding/binary"
        "fmt"
        "net"
        "os"
        "testing"

        "github.com/btcsuite/btcd/btcec/v2"
        "github.com/btcsuite/btcd/wire"
        "github.com/btcsuite/btcwallet/walletdb"
        "github.com/go-errors/errors"
        mig "github.com/lightningnetwork/lnd/channeldb/migration"
        "github.com/lightningnetwork/lnd/channeldb/migration12"
        "github.com/lightningnetwork/lnd/channeldb/migration13"
        "github.com/lightningnetwork/lnd/channeldb/migration16"
        "github.com/lightningnetwork/lnd/channeldb/migration20"
        "github.com/lightningnetwork/lnd/channeldb/migration21"
        "github.com/lightningnetwork/lnd/channeldb/migration23"
        "github.com/lightningnetwork/lnd/channeldb/migration24"
        "github.com/lightningnetwork/lnd/channeldb/migration25"
        "github.com/lightningnetwork/lnd/channeldb/migration26"
        "github.com/lightningnetwork/lnd/channeldb/migration27"
        "github.com/lightningnetwork/lnd/channeldb/migration29"
        "github.com/lightningnetwork/lnd/channeldb/migration30"
        "github.com/lightningnetwork/lnd/channeldb/migration31"
        "github.com/lightningnetwork/lnd/channeldb/migration_01_to_11"
        "github.com/lightningnetwork/lnd/clock"
        "github.com/lightningnetwork/lnd/invoices"
        "github.com/lightningnetwork/lnd/kvdb"
        "github.com/lightningnetwork/lnd/lnwire"
        "github.com/lightningnetwork/lnd/routing/route"
)

const (
        dbName = "channel.db"
)

var (
        // ErrDryRunMigrationOK signals that a migration executed successful,
        // but we intentionally did not commit the result.
        ErrDryRunMigrationOK = errors.New("dry run migration successful")

        // ErrFinalHtlcsBucketNotFound signals that the top-level final htlcs
        // bucket does not exist.
        ErrFinalHtlcsBucketNotFound = errors.New("final htlcs bucket not " +
                "found")

        // ErrFinalChannelBucketNotFound signals that the channel bucket for
        // final htlc outcomes does not exist.
        ErrFinalChannelBucketNotFound = errors.New("final htlcs channel " +
                "bucket not found")
)

// migration is a function which takes a prior outdated version of the database
// instances and mutates the key/bucket structure to arrive at a more
// up-to-date version of the database.
type migration func(tx kvdb.RwTx) error

// mandatoryVersion defines a db version that must be applied before the lnd
// starts.
type mandatoryVersion struct {
        number    uint32
        migration migration
}

// MigrationConfig is an interface combines the config interfaces of all
// optional migrations.
type MigrationConfig interface {
        migration30.MigrateRevLogConfig
}

// MigrationConfigImpl is a super set of all the various migration configs and
// an implementation of MigrationConfig.
type MigrationConfigImpl struct {
        migration30.MigrateRevLogConfigImpl
}

// optionalMigration defines an optional migration function. When a migration
// is optional, it usually involves a large scale of changes that might touch
// millions of keys. Due to OOM concern, the update cannot be safely done
// within one db transaction. Thus, for optional migrations, they must take the
// db backend and construct transactions as needed.
type optionalMigration func(db kvdb.Backend, cfg MigrationConfig) error

// optionalVersion defines a db version that can be optionally applied. When
// applying migrations, we must apply all the mandatory migrations first before
// attempting optional ones.
type optionalVersion struct {
        name      string
        migration optionalMigration
}

var (
        // dbVersions is storing all mandatory versions of database. If current
        // version of database don't match with latest version this list will
        // be used for retrieving all migration function that are need to apply
        // to the current db.
        dbVersions = []mandatoryVersion{
                {
                        // The base DB version requires no migration.
                        number:    0,
                        migration: nil,
                },
                {
                        // The version of the database where two new indexes
                        // for the update time of node and channel updates were
                        // added.
                        number:    1,
                        migration: migration_01_to_11.MigrateNodeAndEdgeUpdateIndex,
                },
                {
                        // The DB version that added the invoice event time
                        // series.
                        number:    2,
                        migration: migration_01_to_11.MigrateInvoiceTimeSeries,
                },
                {
                        // The DB version that updated the embedded invoice in
                        // outgoing payments to match the new format.
                        number:    3,
                        migration: migration_01_to_11.MigrateInvoiceTimeSeriesOutgoingPayments,
                },
                {
                        // The version of the database where every channel
                        // always has two entries in the edges bucket. If
                        // a policy is unknown, this will be represented
                        // by a special byte sequence.
                        number:    4,
                        migration: migration_01_to_11.MigrateEdgePolicies,
                },
                {
                        // The DB version where we persist each attempt to send
                        // an HTLC to a payment hash, and track whether the
                        // payment is in-flight, succeeded, or failed.
                        number:    5,
                        migration: migration_01_to_11.PaymentStatusesMigration,
                },
                {
                        // The DB version that properly prunes stale entries
                        // from the edge update index.
                        number:    6,
                        migration: migration_01_to_11.MigratePruneEdgeUpdateIndex,
                },
                {
                        // The DB version that migrates the ChannelCloseSummary
                        // to a format where optional fields are indicated with
                        // boolean flags.
                        number:    7,
                        migration: migration_01_to_11.MigrateOptionalChannelCloseSummaryFields,
                },
                {
                        // The DB version that changes the gossiper's message
                        // store keys to account for the message's type and
                        // ShortChannelID.
                        number:    8,
                        migration: migration_01_to_11.MigrateGossipMessageStoreKeys,
                },
                {
                        // The DB version where the payments and payment
                        // statuses are moved to being stored in a combined
                        // bucket.
                        number:    9,
                        migration: migration_01_to_11.MigrateOutgoingPayments,
                },
                {
                        // The DB version where we started to store legacy
                        // payload information for all routes, as well as the
                        // optional TLV records.
                        number:    10,
                        migration: migration_01_to_11.MigrateRouteSerialization,
                },
                {
                        // Add invoice htlc and cltv delta fields.
                        number:    11,
                        migration: migration_01_to_11.MigrateInvoices,
                },
                {
                        // Migrate to TLV invoice bodies, add payment address
                        // and features, remove receipt.
                        number:    12,
                        migration: migration12.MigrateInvoiceTLV,
                },
                {
                        // Migrate to multi-path payments.
                        number:    13,
                        migration: migration13.MigrateMPP,
                },
                {
                        // Initialize payment address index and begin using it
                        // as the default index, falling back to payment hash
                        // index.
                        number:    14,
                        migration: mig.CreateTLB(payAddrIndexBucket),
                },
                {
                        // Initialize payment index bucket which will be used
                        // to index payments by sequence number. This index will
                        // be used to allow more efficient ListPayments queries.
                        number:    15,
                        migration: mig.CreateTLB(paymentsIndexBucket),
                },
                {
                        // Add our existing payments to the index bucket created
                        // in migration 15.
                        number:    16,
                        migration: migration16.MigrateSequenceIndex,
                },
                {
                        // Create a top level bucket which will store extra
                        // information about channel closes.
                        number:    17,
                        migration: mig.CreateTLB(closeSummaryBucket),
                },
                {
                        // Create a top level bucket which holds information
                        // about our peers.
                        number:    18,
                        migration: mig.CreateTLB(peersBucket),
                },
                {
                        // Create a top level bucket which holds outpoint
                        // information.
                        number:    19,
                        migration: mig.CreateTLB(outpointBucket),
                },
                {
                        // Migrate some data to the outpoint index.
                        number:    20,
                        migration: migration20.MigrateOutpointIndex,
                },
                {
                        // Migrate to length prefixed wire messages everywhere
                        // in the database.
                        number:    21,
                        migration: migration21.MigrateDatabaseWireMessages,
                },
                {
                        // Initialize set id index so that invoices can be
                        // queried by individual htlc sets.
                        number:    22,
                        migration: mig.CreateTLB(setIDIndexBucket),
                },
                {
                        number:    23,
                        migration: migration23.MigrateHtlcAttempts,
                },
                {
                        // Remove old forwarding packages of closed channels.
                        number:    24,
                        migration: migration24.MigrateFwdPkgCleanup,
                },
                {
                        // Save the initial local/remote balances in channel
                        // info.
                        number:    25,
                        migration: migration25.MigrateInitialBalances,
                },
                {
                        // Migrate the initial local/remote balance fields into
                        // tlv records.
                        number:    26,
                        migration: migration26.MigrateBalancesToTlvRecords,
                },
                {
                        // Patch the initial local/remote balance fields with
                        // empty values for historical channels.
                        number:    27,
                        migration: migration27.MigrateHistoricalBalances,
                },
                {
                        number:    28,
                        migration: mig.CreateTLB(chanIDBucket),
                },
                {
                        number:    29,
                        migration: migration29.MigrateChanID,
                },
                {
                        // Removes the "sweeper-last-tx" bucket. Although we
                        // do not have a mandatory version 30 we skip this
                        // version because its naming is already used for the
                        // first optional migration.
                        number:    31,
                        migration: migration31.DeleteLastPublishedTxTLB,
                },
        }

        // optionalVersions stores all optional migrations that are applied
        // after dbVersions.
        //
        // NOTE: optional migrations must be fault-tolerant and re-run already
        // migrated data must be noop, which means the migration must be able
        // to determine its state.
        optionalVersions = []optionalVersion{
                {
                        name: "prune revocation log",
                        migration: func(db kvdb.Backend,
                                cfg MigrationConfig) error {

                                return migration30.MigrateRevocationLog(db, cfg)
                        },
                },
        }

        // Big endian is the preferred byte order, due to cursor scans over
        // integer keys iterating in order.
        byteOrder = binary.BigEndian

        // channelOpeningStateBucket is the database bucket used to store the
        // channelOpeningState for each channel that is currently in the process
        // of being opened.
        channelOpeningStateBucket = []byte("channelOpeningState")
)

// DB is the primary datastore for the lnd daemon. The database stores
// information related to nodes, routing data, open/closed channels, fee
// schedules, and reputation data.
type DB struct {
        kvdb.Backend

        // channelStateDB separates all DB operations on channel state.
        channelStateDB *ChannelStateDB

        dbPath                    string
        graph                     *ChannelGraph
        clock                     clock.Clock
        dryRun                    bool
        keepFailedPaymentAttempts bool
        storeFinalHtlcResolutions bool

        // noRevLogAmtData if true, means that commitment transaction amount
        // data should not be stored in the revocation log.
        noRevLogAmtData bool
}

// Open opens or creates channeldb. Any necessary schemas migrations due
// to updates will take place as necessary.
// TODO(bhandras): deprecate this function.
func Open(dbPath string, modifiers ...OptionModifier) (*DB, error) {
        opts := DefaultOptions()
        for _, modifier := range modifiers {
                modifier(&opts)
        }

        backend, err := kvdb.GetBoltBackend(&kvdb.BoltBackendConfig{
                DBPath:            dbPath,
                DBFileName:        dbName,
                NoFreelistSync:    opts.NoFreelistSync,
                AutoCompact:       opts.AutoCompact,
                AutoCompactMinAge: opts.AutoCompactMinAge,
                DBTimeout:         opts.DBTimeout,
        })
        if err != nil {
                return nil, err
        }

        db, err := CreateWithBackend(backend, modifiers...)
        if err == nil {
                db.dbPath = dbPath
        }
        return db, err
}

// CreateWithBackend creates channeldb instance using the passed kvdb.Backend.
// Any necessary schemas migrations due to updates will take place as necessary.
func CreateWithBackend(backend kvdb.Backend,
        modifiers ...OptionModifier) (*DB, error) {

        opts := DefaultOptions()
        for _, modifier := range modifiers {
                modifier(&opts)
        }

        if !opts.NoMigration {
                if err := initChannelDB(backend); err != nil {
                        return nil, err
                }
        }

        chanDB := &DB{
                Backend: backend,
                channelStateDB: &ChannelStateDB{
                        linkNodeDB: &LinkNodeDB{
                                backend: backend,
                        },
                        backend: backend,
                },
                clock:                     opts.clock,
                dryRun:                    opts.dryRun,
                keepFailedPaymentAttempts: opts.keepFailedPaymentAttempts,
                storeFinalHtlcResolutions: opts.storeFinalHtlcResolutions,
                noRevLogAmtData:           opts.NoRevLogAmtData,
        }

        // Set the parent pointer (only used in tests).
        chanDB.channelStateDB.parent = chanDB

        var err error
        chanDB.graph, err = NewChannelGraph(
                backend, opts.RejectCacheSize, opts.ChannelCacheSize,
                opts.BatchCommitInterval, opts.PreAllocCacheNumNodes,
                opts.UseGraphCache, opts.NoMigration,
        )
        if err != nil {
                return nil, err
        }

        // Synchronize the version of database and apply migrations if needed.
        if !opts.NoMigration {
                if err := chanDB.syncVersions(dbVersions); err != nil {
                        backend.Close()
                        return nil, err
                }

                // Grab the optional migration config.
                omc := opts.OptionalMiragtionConfig
                if err := chanDB.applyOptionalVersions(omc); err != nil {
                        backend.Close()
                        return nil, err
                }
        }

        return chanDB, nil
}

// Path returns the file path to the channel database.
func (d *DB) Path() string {
        return d.dbPath
}

var dbTopLevelBuckets = [][]byte{
        openChannelBucket,
        closedChannelBucket,
        forwardingLogBucket,
        fwdPackagesKey,
        invoiceBucket,
        payAddrIndexBucket,
        setIDIndexBucket,
        paymentsIndexBucket,
        peersBucket,
        nodeInfoBucket,
        metaBucket,
        closeSummaryBucket,
        outpointBucket,
        chanIDBucket,
        historicalChannelBucket,
}

// Wipe completely deletes all saved state within all used buckets within the
// database. The deletion is done in a single transaction, therefore this
// operation is fully atomic.
func (d *DB) Wipe() error {
        err := kvdb.Update(d, func(tx kvdb.RwTx) error {
                for _, tlb := range dbTopLevelBuckets {
                        err := tx.DeleteTopLevelBucket(tlb)
                        if err != nil && err != kvdb.ErrBucketNotFound {
                                return err
                        }
                }
                return nil
        }, func() {})
        if err != nil {
                return err
        }

        return initChannelDB(d.Backend)
}

// initChannelDB creates and initializes a fresh version of channeldb. In the
// case that the target path has not yet been created or doesn't yet exist, then
// the path is created. Additionally, all required top-level buckets used within
// the database are created.
func initChannelDB(db kvdb.Backend) error {
        err := kvdb.Update(db, func(tx kvdb.RwTx) error {
                // Check if DB was marked as inactive with a tomb stone.
                if err := EnsureNoTombstone(tx); err != nil {
                        return err
                }

                meta := &Meta{}
                // Check if DB is already initialized.
                err := FetchMeta(meta, tx)
                if err == nil {
                        return nil
                }

                for _, tlb := range dbTopLevelBuckets {
                        if _, err := tx.CreateTopLevelBucket(tlb); err != nil {
                                return err
                        }
                }

                meta.DbVersionNumber = getLatestDBVersion(dbVersions)
                return putMeta(meta, tx)
        }, func() {})
        if err != nil {
                return fmt.Errorf("unable to create new channeldb: %w", err)
        }

        return nil
}

// fileExists returns true if the file exists, and false otherwise.
func fileExists(path string) bool {
        if _, err := os.Stat(path); err != nil {
                if os.IsNotExist(err) {
                        return false
                }
        }

        return true
}

// ChannelStateDB is a database that keeps track of all channel state.
type ChannelStateDB struct {
        // linkNodeDB separates all DB operations on LinkNodes.
        linkNodeDB *LinkNodeDB

        // parent holds a pointer to the "main" channeldb.DB object. This is
        // only used for testing and should never be used in production code.
        // For testing use the ChannelStateDB.GetParentDB() function to retrieve
        // this pointer.
        parent *DB

        // backend points to the actual backend holding the channel state
        // database. This may be a real backend or a cache middleware.
        backend kvdb.Backend
}

// GetParentDB returns the "main" channeldb.DB object that is the owner of this
// ChannelStateDB instance. Use this function only in tests where passing around
// pointers makes testing less readable. Never to be used in production code!
func (c *ChannelStateDB) GetParentDB() *DB {
        return c.parent
}

// LinkNodeDB returns the current instance of the link node database.
func (c *ChannelStateDB) LinkNodeDB() *LinkNodeDB {
        return c.linkNodeDB
}

// FetchOpenChannels starts a new database transaction and returns all stored
// currently active/open channels associated with the target nodeID. In the case
// that no active channels are known to have been created with this node, then a
// zero-length slice is returned.
func (c *ChannelStateDB) FetchOpenChannels(nodeID *btcec.PublicKey) (
        []*OpenChannel, error) {

        var channels []*OpenChannel
        err := kvdb.View(c.backend, func(tx kvdb.RTx) error {
                var err error
                channels, err = c.fetchOpenChannels(tx, nodeID)
                return err
        }, func() {
                channels = nil
        })

        return channels, err
}

// fetchOpenChannels uses and existing database transaction and returns all
// stored currently active/open channels associated with the target nodeID. In
// the case that no active channels are known to have been created with this
// node, then a zero-length slice is returned.
func (c *ChannelStateDB) fetchOpenChannels(tx kvdb.RTx,
        nodeID *btcec.PublicKey) ([]*OpenChannel, error) {

        // Get the bucket dedicated to storing the metadata for open channels.
        openChanBucket := tx.ReadBucket(openChannelBucket)
        if openChanBucket == nil {
                return nil, nil
        }

        // Within this top level bucket, fetch the bucket dedicated to storing
        // open channel data specific to the remote node.
        pub := nodeID.SerializeCompressed()
        nodeChanBucket := openChanBucket.NestedReadBucket(pub)
        if nodeChanBucket == nil {
                return nil, nil
        }

        // Next, we'll need to go down an additional layer in order to retrieve
        // the channels for each chain the node knows of.
        var channels []*OpenChannel
        err := nodeChanBucket.ForEach(func(chainHash, v []byte) error {
                // If there's a value, it's not a bucket so ignore it.
                if v != nil {
                        return nil
                }

                // If we've found a valid chainhash bucket, then we'll retrieve
                // that so we can extract all the channels.
                chainBucket := nodeChanBucket.NestedReadBucket(chainHash)
                if chainBucket == nil {
                        return fmt.Errorf("unable to read bucket for chain=%x",
                                chainHash[:])
                }

                // Finally, we both of the necessary buckets retrieved, fetch
                // all the active channels related to this node.
                nodeChannels, err := c.fetchNodeChannels(chainBucket)
                if err != nil {
                        return fmt.Errorf("unable to read channel for "+
                                "chain_hash=%x, node_key=%x: %v",
                                chainHash[:], pub, err)
                }

                channels = append(channels, nodeChannels...)
                return nil
        })

        return channels, err
}

// fetchNodeChannels retrieves all active channels from the target chainBucket
// which is under a node's dedicated channel bucket. This function is typically
// used to fetch all the active channels related to a particular node.
func (c *ChannelStateDB) fetchNodeChannels(chainBucket kvdb.RBucket) (
        []*OpenChannel, error) {

        var channels []*OpenChannel

        // A node may have channels on several chains, so for each known chain,
        // we'll extract all the channels.
        err := chainBucket.ForEach(func(chanPoint, v []byte) error {
                // If there's a value, it's not a bucket so ignore it.
                if v != nil {
                        return nil
                }

                // Once we've found a valid channel bucket, we'll extract it
                // from the node's chain bucket.
                chanBucket := chainBucket.NestedReadBucket(chanPoint)

                var outPoint wire.OutPoint
                err := readOutpoint(bytes.NewReader(chanPoint), &outPoint)
                if err != nil {
                        return err
                }
                oChannel, err := fetchOpenChannel(chanBucket, &outPoint)
                if err != nil {
                        return fmt.Errorf("unable to read channel data for "+
                                "chan_point=%v: %w", outPoint, err)
                }
                oChannel.Db = c

                channels = append(channels, oChannel)

                return nil
        })
        if err != nil {
                return nil, err
        }

        return channels, nil
}

// FetchChannel attempts to locate a channel specified by the passed channel
// point. If the channel cannot be found, then an error will be returned.
// Optionally an existing db tx can be supplied.
func (c *ChannelStateDB) FetchChannel(tx kvdb.RTx, chanPoint wire.OutPoint) (
        *OpenChannel, error) {

        var targetChanPoint bytes.Buffer
        if err := writeOutpoint(&targetChanPoint, &chanPoint); err != nil {
                return nil, err
        }

        targetChanPointBytes := targetChanPoint.Bytes()
        selector := func(chainBkt walletdb.ReadBucket) ([]byte, *wire.OutPoint,
                error) {

                return targetChanPointBytes, &chanPoint, nil
        }

        return c.channelScanner(tx, selector)
}

// FetchChannelByID attempts to locate a channel specified by the passed channel
// ID. If the channel cannot be found, then an error will be returned.
// Optionally an existing db tx can be supplied.
func (c *ChannelStateDB) FetchChannelByID(tx kvdb.RTx, id lnwire.ChannelID) (
        *OpenChannel, error) {

        selector := func(chainBkt walletdb.ReadBucket) ([]byte, *wire.OutPoint,
                error) {

                var (
                        targetChanPointBytes []byte
                        targetChanPoint      *wire.OutPoint

                        // errChanFound is used to signal that the channel has
                        // been found so that iteration through the DB buckets
                        // can stop.
                        errChanFound = errors.New("channel found")
                )
                err := chainBkt.ForEach(func(k, _ []byte) error {
                        var outPoint wire.OutPoint
                        err := readOutpoint(bytes.NewReader(k), &outPoint)
                        if err != nil {
                                return err
                        }

                        chanID := lnwire.NewChanIDFromOutPoint(outPoint)
                        if chanID != id {
                                return nil
                        }

                        targetChanPoint = &outPoint
                        targetChanPointBytes = k

                        return errChanFound
                })
                if err != nil && !errors.Is(err, errChanFound) {
                        return nil, nil, err
                }
                if targetChanPoint == nil {
                        return nil, nil, ErrChannelNotFound
                }

                return targetChanPointBytes, targetChanPoint, nil
        }

        return c.channelScanner(tx, selector)
}

// channelSelector describes a function that takes a chain-hash bucket from
// within the open-channel DB and returns the wanted channel point bytes, and
// channel point. It must return the ErrChannelNotFound error if the wanted
// channel is not in the given bucket.
type channelSelector func(chainBkt walletdb.ReadBucket) ([]byte, *wire.OutPoint,
        error)

// channelScanner will traverse the DB to each chain-hash bucket of each node
// pub-key bucket in the open-channel-bucket. The chanSelector will then be used
// to fetch the wanted channel outpoint from the chain bucket.
func (c *ChannelStateDB) channelScanner(tx kvdb.RTx,
        chanSelect channelSelector) (*OpenChannel, error) {

        var (
                targetChan *OpenChannel

                // errChanFound is used to signal that the channel has been
                // found so that iteration through the DB buckets can stop.
                errChanFound = errors.New("channel found")
        )

        // chanScan will traverse the following bucket structure:
        //  * nodePub => chainHash => chanPoint
        //
        // At each level we go one further, ensuring that we're traversing the
        // proper key (that's actually a bucket). By only reading the bucket
        // structure and skipping fully decoding each channel, we save a good
        // bit of CPU as we don't need to do things like decompress public
        // keys.
        chanScan := func(tx kvdb.RTx) error {
                // Get the bucket dedicated to storing the metadata for open
                // channels.
                openChanBucket := tx.ReadBucket(openChannelBucket)
                if openChanBucket == nil {
                        return ErrNoActiveChannels
                }

                // Within the node channel bucket, are the set of node pubkeys
                // we have channels with, we don't know the entire set, so we'll
                // check them all.
                return openChanBucket.ForEach(func(nodePub, v []byte) error {
                        // Ensure that this is a key the same size as a pubkey,
                        // and also that it leads directly to a bucket.
                        if len(nodePub) != 33 || v != nil {
                                return nil
                        }

                        nodeChanBucket := openChanBucket.NestedReadBucket(
                                nodePub,
                        )
                        if nodeChanBucket == nil {
                                return nil
                        }

                        // The next layer down is all the chains that this node
                        // has channels on with us.
                        return nodeChanBucket.ForEach(func(chainHash,
                                v []byte) error {

                                // If there's a value, it's not a bucket so
                                // ignore it.
                                if v != nil {
                                        return nil
                                }

                                chainBucket := nodeChanBucket.NestedReadBucket(
                                        chainHash,
                                )
                                if chainBucket == nil {
                                        return fmt.Errorf("unable to read "+
                                                "bucket for chain=%x",
                                                chainHash)
                                }

                                // Finally, we reach the leaf bucket that stores
                                // all the chanPoints for this node.
                                targetChanBytes, chanPoint, err := chanSelect(
                                        chainBucket,
                                )
                                if errors.Is(err, ErrChannelNotFound) {
                                        return nil
                                } else if err != nil {
                                        return err
                                }

                                chanBucket := chainBucket.NestedReadBucket(
                                        targetChanBytes,
                                )
                                if chanBucket == nil {
                                        return nil
                                }

                                channel, err := fetchOpenChannel(
                                        chanBucket, chanPoint,
                                )
                                if err != nil {
                                        return err
                                }

                                targetChan = channel
                                targetChan.Db = c

                                return errChanFound
                        })
                })
        }

        var err error
        if tx == nil {
                err = kvdb.View(c.backend, chanScan, func() {})
        } else {
                err = chanScan(tx)
        }
        if err != nil && !errors.Is(err, errChanFound) {
                return nil, err
        }

        if targetChan != nil {
                return targetChan, nil
        }

        // If we can't find the channel, then we return with an error, as we
        // have nothing to back up.
        return nil, ErrChannelNotFound
}

// FetchAllChannels attempts to retrieve all open channels currently stored
// within the database, including pending open, fully open and channels waiting
// for a closing transaction to confirm.
func (c *ChannelStateDB) FetchAllChannels() ([]*OpenChannel, error) {
        return fetchChannels(c)
}

// FetchAllOpenChannels will return all channels that have the funding
// transaction confirmed, and is not waiting for a closing transaction to be
// confirmed.
func (c *ChannelStateDB) FetchAllOpenChannels() ([]*OpenChannel, error) {
        return fetchChannels(
                c,
                pendingChannelFilter(false),
                waitingCloseFilter(false),
        )
}

// FetchPendingChannels will return channels that have completed the process of
// generating and broadcasting funding transactions, but whose funding
// transactions have yet to be confirmed on the blockchain.
func (c *ChannelStateDB) FetchPendingChannels() ([]*OpenChannel, error) {
        return fetchChannels(c,
                pendingChannelFilter(true),
                waitingCloseFilter(false),
        )
}

// FetchWaitingCloseChannels will return all channels that have been opened,
// but are now waiting for a closing transaction to be confirmed.
//
// NOTE: This includes channels that are also pending to be opened.
func (c *ChannelStateDB) FetchWaitingCloseChannels() ([]*OpenChannel, error) {
        return fetchChannels(
                c, waitingCloseFilter(true),
        )
}

// fetchChannelsFilter applies a filter to channels retrieved in fetchchannels.
// A set of filters can be combined to filter across multiple dimensions.
type fetchChannelsFilter func(channel *OpenChannel) bool

// pendingChannelFilter returns a filter based on whether channels are pending
// (ie, their funding transaction still needs to confirm). If pending is false,
// channels with confirmed funding transactions are returned.
func pendingChannelFilter(pending bool) fetchChannelsFilter {
        return func(channel *OpenChannel) bool {
                return channel.IsPending == pending
        }
}

// waitingCloseFilter returns a filter which filters channels based on whether
// they are awaiting the confirmation of their closing transaction. If waiting
// close is true, channels that have had their closing tx broadcast are
// included. If it is false, channels that are not awaiting confirmation of
// their close transaction are returned.
func waitingCloseFilter(waitingClose bool) fetchChannelsFilter {
        return func(channel *OpenChannel) bool {
                // If the channel is in any other state than Default,
                // then it means it is waiting to be closed.
                channelWaitingClose :=
                        channel.ChanStatus() != ChanStatusDefault

                // Include the channel if it matches the value for
                // waiting close that we are filtering on.
                return channelWaitingClose == waitingClose
        }
}

// fetchChannels attempts to retrieve channels currently stored in the
// database. It takes a set of filters which are applied to each channel to
// obtain a set of channels with the desired set of properties. Only channels
// which have a true value returned for *all* of the filters will be returned.
// If no filters are provided, every channel in the open channels bucket will
// be returned.
func fetchChannels(c *ChannelStateDB, filters ...fetchChannelsFilter) (
        []*OpenChannel, error) {

        var channels []*OpenChannel

        err := kvdb.View(c.backend, func(tx kvdb.RTx) error {
                // Get the bucket dedicated to storing the metadata for open
                // channels.
                openChanBucket := tx.ReadBucket(openChannelBucket)
                if openChanBucket == nil {
                        return ErrNoActiveChannels
                }

                // Next, fetch the bucket dedicated to storing metadata related
                // to all nodes. All keys within this bucket are the serialized
                // public keys of all our direct counterparties.
                nodeMetaBucket := tx.ReadBucket(nodeInfoBucket)
                if nodeMetaBucket == nil {
                        return fmt.Errorf("node bucket not created")
                }

                // Finally for each node public key in the bucket, fetch all
                // the channels related to this particular node.
                return nodeMetaBucket.ForEach(func(k, v []byte) error {
                        nodeChanBucket := openChanBucket.NestedReadBucket(k)
                        if nodeChanBucket == nil {
                                return nil
                        }

                        return nodeChanBucket.ForEach(func(chainHash, v []byte) error {
                                // If there's a value, it's not a bucket so
                                // ignore it.
                                if v != nil {
                                        return nil
                                }

                                // If we've found a valid chainhash bucket,
                                // then we'll retrieve that so we can extract
                                // all the channels.
                                chainBucket := nodeChanBucket.NestedReadBucket(
                                        chainHash,
                                )
                                if chainBucket == nil {
                                        return fmt.Errorf("unable to read "+
                                                "bucket for chain=%x", chainHash[:])
                                }

                                nodeChans, err := c.fetchNodeChannels(chainBucket)
                                if err != nil {
                                        return fmt.Errorf("unable to read "+
                                                "channel for chain_hash=%x, "+
                                                "node_key=%x: %v", chainHash[:], k, err)
                                }
                                for _, channel := range nodeChans {
                                        // includeChannel indicates whether the channel
                                        // meets the criteria specified by our filters.
                                        includeChannel := true

                                        // Run through each filter and check whether the
                                        // channel should be included.
                                        for _, f := range filters {
                                                // If the channel fails the filter, set
                                                // includeChannel to false and don't bother
                                                // checking the remaining filters.
                                                if !f(channel) {
                                                        includeChannel = false
                                                        break
                                                }
                                        }

                                        // If the channel passed every filter, include it in
                                        // our set of channels.
                                        if includeChannel {
                                                channels = append(channels, channel)
                                        }
                                }
                                return nil
                        })

                })
        }, func() {
                channels = nil
        })
        if err != nil {
                return nil, err
        }

        return channels, nil
}

// FetchClosedChannels attempts to fetch all closed channels from the database.
// The pendingOnly bool toggles if channels that aren't yet fully closed should
// be returned in the response or not. When a channel was cooperatively closed,
// it becomes fully closed after a single confirmation.  When a channel was
// forcibly closed, it will become fully closed after _all_ the pending funds
// (if any) have been swept.
func (c *ChannelStateDB) FetchClosedChannels(pendingOnly bool) (
        []*ChannelCloseSummary, error) {

        var chanSummaries []*ChannelCloseSummary

        if err := kvdb.View(c.backend, func(tx kvdb.RTx) error {
                closeBucket := tx.ReadBucket(closedChannelBucket)
                if closeBucket == nil {
                        return ErrNoClosedChannels
                }

                return closeBucket.ForEach(func(chanID []byte, summaryBytes []byte) error {
                        summaryReader := bytes.NewReader(summaryBytes)
                        chanSummary, err := deserializeCloseChannelSummary(summaryReader)
                        if err != nil {
                                return err
                        }

                        // If the query specified to only include pending
                        // channels, then we'll skip any channels which aren't
                        // currently pending.
                        if !chanSummary.IsPending && pendingOnly {
                                return nil
                        }

                        chanSummaries = append(chanSummaries, chanSummary)
                        return nil
                })
        }, func() {
                chanSummaries = nil
        }); err != nil {
                return nil, err
        }

        return chanSummaries, nil
}

// ErrClosedChannelNotFound signals that a closed channel could not be found in
// the channeldb.
var ErrClosedChannelNotFound = errors.New("unable to find closed channel summary")

// FetchClosedChannel queries for a channel close summary using the channel
// point of the channel in question.
func (c *ChannelStateDB) FetchClosedChannel(chanID *wire.OutPoint) (
        *ChannelCloseSummary, error) {

        var chanSummary *ChannelCloseSummary
        if err := kvdb.View(c.backend, func(tx kvdb.RTx) error {
                closeBucket := tx.ReadBucket(closedChannelBucket)
                if closeBucket == nil {
                        return ErrClosedChannelNotFound
                }

                var b bytes.Buffer
                var err error
                if err = writeOutpoint(&b, chanID); err != nil {
                        return err
                }

                summaryBytes := closeBucket.Get(b.Bytes())
                if summaryBytes == nil {
                        return ErrClosedChannelNotFound
                }

                summaryReader := bytes.NewReader(summaryBytes)
                chanSummary, err = deserializeCloseChannelSummary(summaryReader)

                return err
        }, func() {
                chanSummary = nil
        }); err != nil {
                return nil, err
        }

        return chanSummary, nil
}

// FetchClosedChannelForID queries for a channel close summary using the
// channel ID of the channel in question.
func (c *ChannelStateDB) FetchClosedChannelForID(cid lnwire.ChannelID) (
        *ChannelCloseSummary, error) {

        var chanSummary *ChannelCloseSummary
        if err := kvdb.View(c.backend, func(tx kvdb.RTx) error {
                closeBucket := tx.ReadBucket(closedChannelBucket)
                if closeBucket == nil {
                        return ErrClosedChannelNotFound
                }

                // The first 30 bytes of the channel ID and outpoint will be
                // equal.
                cursor := closeBucket.ReadCursor()
                op, c := cursor.Seek(cid[:30])

                // We scan over all possible candidates for this channel ID.
                for ; op != nil && bytes.Compare(cid[:30], op[:30]) <= 0; op, c = cursor.Next() {
                        var outPoint wire.OutPoint
                        err := readOutpoint(bytes.NewReader(op), &outPoint)
                        if err != nil {
                                return err
                        }

                        // If the found outpoint does not correspond to this
                        // channel ID, we continue.
                        if !cid.IsChanPoint(&outPoint) {
                                continue
                        }

                        // Deserialize the close summary and return.
                        r := bytes.NewReader(c)
                        chanSummary, err = deserializeCloseChannelSummary(r)
                        if err != nil {
                                return err
                        }

                        return nil
                }
                return ErrClosedChannelNotFound
        }, func() {
                chanSummary = nil
        }); err != nil {
                return nil, err
        }

        return chanSummary, nil
}

// MarkChanFullyClosed marks a channel as fully closed within the database. A
// channel should be marked as fully closed if the channel was initially
// cooperatively closed and it's reached a single confirmation, or after all
// the pending funds in a channel that has been forcibly closed have been
// swept.
func (c *ChannelStateDB) MarkChanFullyClosed(chanPoint *wire.OutPoint) error {
        var (
                openChannels  []*OpenChannel
                pruneLinkNode *btcec.PublicKey
        )
        err := kvdb.Update(c.backend, func(tx kvdb.RwTx) error {
                var b bytes.Buffer
                if err := writeOutpoint(&b, chanPoint); err != nil {
                        return err
                }

                chanID := b.Bytes()

                closedChanBucket, err := tx.CreateTopLevelBucket(
                        closedChannelBucket,
                )
                if err != nil {
                        return err
                }

                chanSummaryBytes := closedChanBucket.Get(chanID)
                if chanSummaryBytes == nil {
                        return fmt.Errorf("no closed channel for "+
                                "chan_point=%v found", chanPoint)
                }

                chanSummaryReader := bytes.NewReader(chanSummaryBytes)
                chanSummary, err := deserializeCloseChannelSummary(
                        chanSummaryReader,
                )
                if err != nil {
                        return err
                }

                chanSummary.IsPending = false

                var newSummary bytes.Buffer
                err = serializeChannelCloseSummary(&newSummary, chanSummary)
                if err != nil {
                        return err
                }

                err = closedChanBucket.Put(chanID, newSummary.Bytes())
                if err != nil {
                        return err
                }

                // Now that the channel is closed, we'll check if we have any
                // other open channels with this peer. If we don't we'll
                // garbage collect it to ensure we don't establish persistent
                // connections to peers without open channels.
                pruneLinkNode = chanSummary.RemotePub
                openChannels, err = c.fetchOpenChannels(
                        tx, pruneLinkNode,
                )
                if err != nil {
                        return fmt.Errorf("unable to fetch open channels for "+
                                "peer %x: %v",
                                pruneLinkNode.SerializeCompressed(), err)
                }

                return nil
        }, func() {
                openChannels = nil
                pruneLinkNode = nil
        })
        if err != nil {
                return err
        }

        // Decide whether we want to remove the link node, based upon the number
        // of still open channels.
        return c.pruneLinkNode(openChannels, pruneLinkNode)
}

// pruneLinkNode determines whether we should garbage collect a link node from
// the database due to no longer having any open channels with it. If there are
// any left, then this acts as a no-op.
func (c *ChannelStateDB) pruneLinkNode(openChannels []*OpenChannel,
        remotePub *btcec.PublicKey) error {

        if len(openChannels) > 0 {
                return nil
        }

        log.Infof("Pruning link node %x with zero open channels from database",
                remotePub.SerializeCompressed())

        return c.linkNodeDB.DeleteLinkNode(remotePub)
}

// PruneLinkNodes attempts to prune all link nodes found within the database
// with whom we no longer have any open channels with.
func (c *ChannelStateDB) PruneLinkNodes() error {
        allLinkNodes, err := c.linkNodeDB.FetchAllLinkNodes()
        if err != nil {
                return err
        }

        for _, linkNode := range allLinkNodes {
                var (
                        openChannels []*OpenChannel
                        linkNode     = linkNode
                )
                err := kvdb.View(c.backend, func(tx kvdb.RTx) error {
                        var err error
                        openChannels, err = c.fetchOpenChannels(
                                tx, linkNode.IdentityPub,
                        )
                        return err
                }, func() {
                        openChannels = nil
                })
                if err != nil {
                        return err
                }

                err = c.pruneLinkNode(openChannels, linkNode.IdentityPub)
                if err != nil {
                        return err
                }
        }

        return nil
}

// ChannelShell is a shell of a channel that is meant to be used for channel
// recovery purposes. It contains a minimal OpenChannel instance along with
// addresses for that target node.
type ChannelShell struct {
        // NodeAddrs the set of addresses that this node has known to be
        // reachable at in the past.
        NodeAddrs []net.Addr

        // Chan is a shell of an OpenChannel, it contains only the items
        // required to restore the channel on disk.
        Chan *OpenChannel
}

// RestoreChannelShells is a method that allows the caller to reconstruct the
// state of an OpenChannel from the ChannelShell. We'll attempt to write the
// new channel to disk, create a LinkNode instance with the passed node
// addresses, and finally create an edge within the graph for the channel as
// well. This method is idempotent, so repeated calls with the same set of
// channel shells won't modify the database after the initial call.
func (c *ChannelStateDB) RestoreChannelShells(channelShells ...*ChannelShell) error {
        err := kvdb.Update(c.backend, func(tx kvdb.RwTx) error {
                for _, channelShell := range channelShells {
                        channel := channelShell.Chan

                        // When we make a channel, we mark that the channel has
                        // been restored, this will signal to other sub-systems
                        // to not attempt to use the channel as if it was a
                        // regular one.
                        channel.chanStatus |= ChanStatusRestored

                        // First, we'll attempt to create a new open channel
                        // and link node for this channel. If the channel
                        // already exists, then in order to ensure this method
                        // is idempotent, we'll continue to the next step.
                        channel.Db = c
                        err := syncNewChannel(
                                tx, channel, channelShell.NodeAddrs,
                        )
                        if err != nil {
                                return err
                        }
                }

                return nil
        }, func() {})
        if err != nil {
                return err
        }

        return nil
}

// AddrsForNode consults the graph and channel database for all addresses known
// to the passed node public key.
func (d *DB) AddrsForNode(nodePub *btcec.PublicKey) ([]net.Addr,
        error) {

        linkNode, err := d.channelStateDB.linkNodeDB.FetchLinkNode(nodePub)
        if err != nil {
                return nil, err
        }

        // We'll also query the graph for this peer to see if they have any
        // addresses that we don't currently have stored within the link node
        // database.
        pubKey, err := route.NewVertexFromBytes(nodePub.SerializeCompressed())
        if err != nil {
                return nil, err
        }
        graphNode, err := d.graph.FetchLightningNode(nil, pubKey)
        if err != nil && err != ErrGraphNodeNotFound {
                return nil, err
        } else if err == ErrGraphNodeNotFound {
                // If the node isn't found, then that's OK, as we still have the
                // link node data. But any other error needs to be returned.
                graphNode = &LightningNode{}
        }

        // Now that we have both sources of addrs for this node, we'll use a
        // map to de-duplicate any addresses between the two sources, and
        // produce a final list of the combined addrs.
        addrs := make(map[string]net.Addr)
        for _, addr := range linkNode.Addresses {
                addrs[addr.String()] = addr
        }
        for _, addr := range graphNode.Addresses {
                addrs[addr.String()] = addr
        }
        dedupedAddrs := make([]net.Addr, 0, len(addrs))
        for _, addr := range addrs {
                dedupedAddrs = append(dedupedAddrs, addr)
        }

        return dedupedAddrs, nil
}

// AbandonChannel attempts to remove the target channel from the open channel
// database. If the channel was already removed (has a closed channel entry),
// then we'll return a nil error. Otherwise, we'll insert a new close summary
// into the database.
func (c *ChannelStateDB) AbandonChannel(chanPoint *wire.OutPoint,
        bestHeight uint32) error {

        // With the chanPoint constructed, we'll attempt to find the target
        // channel in the database. If we can't find the channel, then we'll
        // return the error back to the caller.
        dbChan, err := c.FetchChannel(nil, *chanPoint)
        switch {
        // If the channel wasn't found, then it's possible that it was already
        // abandoned from the database.
        case err == ErrChannelNotFound:
                _, closedErr := c.FetchClosedChannel(chanPoint)
                if closedErr != nil {
                        return closedErr
                }

                // If the channel was already closed, then we don't return an
                // error as we'd like this step to be repeatable.
                return nil
        case err != nil:
                return err
        }

        // Now that we've found the channel, we'll populate a close summary for
        // the channel, so we can store as much information for this abounded
        // channel as possible. We also ensure that we set Pending to false, to
        // indicate that this channel has been "fully" closed.
        summary := &ChannelCloseSummary{
                CloseType:               Abandoned,
                ChanPoint:               *chanPoint,
                ChainHash:               dbChan.ChainHash,
                CloseHeight:             bestHeight,
                RemotePub:               dbChan.IdentityPub,
                Capacity:                dbChan.Capacity,
                SettledBalance:          dbChan.LocalCommitment.LocalBalance.ToSatoshis(),
                ShortChanID:             dbChan.ShortChanID(),
                RemoteCurrentRevocation: dbChan.RemoteCurrentRevocation,
                RemoteNextRevocation:    dbChan.RemoteNextRevocation,
                LocalChanConfig:         dbChan.LocalChanCfg,
        }

        // Finally, we'll close the channel in the DB, and return back to the
        // caller. We set ourselves as the close initiator because we abandoned
        // the channel.
        return dbChan.CloseChannel(summary, ChanStatusLocalCloseInitiator)
}

// SaveChannelOpeningState saves the serialized channel state for the provided
// chanPoint to the channelOpeningStateBucket.
func (c *ChannelStateDB) SaveChannelOpeningState(outPoint,
        serializedState []byte) error {

        return kvdb.Update(c.backend, func(tx kvdb.RwTx) error {
                bucket, err := tx.CreateTopLevelBucket(channelOpeningStateBucket)
                if err != nil {
                        return err
                }

                return bucket.Put(outPoint, serializedState)
        }, func() {})
}

// GetChannelOpeningState fetches the serialized channel state for the provided
// outPoint from the database, or returns ErrChannelNotFound if the channel
// is not found.
func (c *ChannelStateDB) GetChannelOpeningState(outPoint []byte) ([]byte,
        error) {

        var serializedState []byte
        err := kvdb.View(c.backend, func(tx kvdb.RTx) error {
                bucket := tx.ReadBucket(channelOpeningStateBucket)
                if bucket == nil {
                        // If the bucket does not exist, it means we never added
                        //  a channel to the db, so return ErrChannelNotFound.
                        return ErrChannelNotFound
                }

                stateBytes := bucket.Get(outPoint)
                if stateBytes == nil {
                        return ErrChannelNotFound
                }

                serializedState = append(serializedState, stateBytes...)

                return nil
        }, func() {
                serializedState = nil
        })
        return serializedState, err
}

// DeleteChannelOpeningState removes any state for outPoint from the database.
func (c *ChannelStateDB) DeleteChannelOpeningState(outPoint []byte) error {
        return kvdb.Update(c.backend, func(tx kvdb.RwTx) error {
                bucket := tx.ReadWriteBucket(channelOpeningStateBucket)
                if bucket == nil {
                        return ErrChannelNotFound
                }

                return bucket.Delete(outPoint)
        }, func() {})
}

// syncVersions function is used for safe db version synchronization. It
// applies migration functions to the current database and recovers the
// previous state of db if at least one error/panic appeared during migration.
func (d *DB) syncVersions(versions []mandatoryVersion) error {
        meta, err := d.FetchMeta()
        if err != nil {
                if err == ErrMetaNotFound {
                        meta = &Meta{}
                } else {
                        return err
                }
        }

        latestVersion := getLatestDBVersion(versions)
        log.Infof("Checking for schema update: latest_version=%v, "+
                "db_version=%v", latestVersion, meta.DbVersionNumber)

        switch {

        // If the database reports a higher version that we are aware of, the
        // user is probably trying to revert to a prior version of lnd. We fail
        // here to prevent reversions and unintended corruption.
        case meta.DbVersionNumber > latestVersion:
                log.Errorf("Refusing to revert from db_version=%d to "+
                        "lower version=%d", meta.DbVersionNumber,
                        latestVersion)
                return ErrDBReversion

        // If the current database version matches the latest version number,
        // then we don't need to perform any migrations.
        case meta.DbVersionNumber == latestVersion:
                return nil
        }

        log.Infof("Performing database schema migration")

        // Otherwise, we fetch the migrations which need to applied, and
        // execute them serially within a single database transaction to ensure
        // the migration is atomic.
        migrations, migrationVersions := getMigrationsToApply(
                versions, meta.DbVersionNumber,
        )
        return kvdb.Update(d, func(tx kvdb.RwTx) error {
                for i, migration := range migrations {
                        if migration == nil {
                                continue
                        }

                        log.Infof("Applying migration #%v",
                                migrationVersions[i])

                        if err := migration(tx); err != nil {
                                log.Infof("Unable to apply migration #%v",
                                        migrationVersions[i])
                                return err
                        }
                }

                meta.DbVersionNumber = latestVersion
                err := putMeta(meta, tx)
                if err != nil {
                        return err
                }

                // In dry-run mode, return an error to prevent the transaction
                // from committing.
                if d.dryRun {
                        return ErrDryRunMigrationOK
                }

                return nil
        }, func() {})
}

// applyOptionalVersions takes a config to determine whether the optional
// migrations will be applied.
//
// NOTE: only support the prune_revocation_log optional migration atm.
func (d *DB) applyOptionalVersions(cfg OptionalMiragtionConfig) error {
        // TODO(yy): need to design the db to support dry run for optional
        // migrations.
        if d.dryRun {
                log.Info("Skipped optional migrations as dry run mode is not " +
                        "supported yet")
                return nil
        }

        om, err := d.fetchOptionalMeta()
        if err != nil {
                if err == ErrMetaNotFound {
                        om = &OptionalMeta{
                                Versions: make(map[uint64]string),
                        }
                } else {
                        return err
                }
        }

        log.Infof("Checking for optional update: prune_revocation_log=%v, "+
                "db_version=%s", cfg.PruneRevocationLog, om)

        // Exit early if the optional migration is not specified.
        if !cfg.PruneRevocationLog {
                return nil
        }

        // Exit early if the optional migration has already been applied.
        if _, ok := om.Versions[0]; ok {
                return nil
        }

        // Get the optional version.
        version := optionalVersions[0]
        log.Infof("Performing database optional migration: %s", version.name)

        migrationCfg := &MigrationConfigImpl{
                migration30.MigrateRevLogConfigImpl{
                        NoAmountData: d.noRevLogAmtData,
                },
        }

        // Migrate the data.
        if err := version.migration(d, migrationCfg); err != nil {
                log.Errorf("Unable to apply optional migration: %s, error: %v",
                        version.name, err)
                return err
        }

        // Update the optional meta. Notice that unlike the mandatory db
        // migrations where we perform the migration and updating meta in a
        // single db transaction, we use different transactions here. Even when
        // the following update is failed, we should be fine here as we would
        // re-run the optional migration again, which is a noop, during next
        // startup.
        om.Versions[0] = version.name
        if err := d.putOptionalMeta(om); err != nil {
                log.Errorf("Unable to update optional meta: %v", err)
                return err
        }

        return nil
}

// ChannelGraph returns the current instance of the directed channel graph.
func (d *DB) ChannelGraph() *ChannelGraph {
        return d.graph
}

// ChannelStateDB returns the sub database that is concerned with the channel
// state.
func (d *DB) ChannelStateDB() *ChannelStateDB {
        return d.channelStateDB
}

// LatestDBVersion returns the number of the latest database version currently
// known to the channel DB.
func LatestDBVersion() uint32 {
        return getLatestDBVersion(dbVersions)
}

func getLatestDBVersion(versions []mandatoryVersion) uint32 {
        return versions[len(versions)-1].number
}

// getMigrationsToApply retrieves the migration function that should be
// applied to the database.
func getMigrationsToApply(versions []mandatoryVersion,
        version uint32) ([]migration, []uint32) {

        migrations := make([]migration, 0, len(versions))
        migrationVersions := make([]uint32, 0, len(versions))

        for _, v := range versions {
                if v.number > version {
                        migrations = append(migrations, v.migration)
                        migrationVersions = append(migrationVersions, v.number)
                }
        }

        return migrations, migrationVersions
}

// fetchHistoricalChanBucket returns a the channel bucket for a given outpoint
// from the historical channel bucket. If the bucket does not exist,
// ErrNoHistoricalBucket is returned.
func fetchHistoricalChanBucket(tx kvdb.RTx,
        outPoint *wire.OutPoint) (kvdb.RBucket, error) {

        // First fetch the top level bucket which stores all data related to
        // historically stored channels.
        historicalChanBucket := tx.ReadBucket(historicalChannelBucket)
        if historicalChanBucket == nil {
                return nil, ErrNoHistoricalBucket
        }

        // With the bucket for the node and chain fetched, we can now go down
        // another level, for the channel itself.
        var chanPointBuf bytes.Buffer
        if err := writeOutpoint(&chanPointBuf, outPoint); err != nil {
                return nil, err
        }
        chanBucket := historicalChanBucket.NestedReadBucket(
                chanPointBuf.Bytes(),
        )
        if chanBucket == nil {
                return nil, ErrChannelNotFound
        }

        return chanBucket, nil
}

// FetchHistoricalChannel fetches open channel data from the historical channel
// bucket.
func (c *ChannelStateDB) FetchHistoricalChannel(outPoint *wire.OutPoint) (
        *OpenChannel, error) {

        var channel *OpenChannel
        err := kvdb.View(c.backend, func(tx kvdb.RTx) error {
                chanBucket, err := fetchHistoricalChanBucket(tx, outPoint)
                if err != nil {
                        return err
                }

                channel, err = fetchOpenChannel(chanBucket, outPoint)
                if err != nil {
                        return err
                }

                channel.Db = c
                return nil
        }, func() {
                channel = nil
        })
        if err != nil {
                return nil, err
        }

        return channel, nil
}

func fetchFinalHtlcsBucket(tx kvdb.RTx,
        chanID lnwire.ShortChannelID) (kvdb.RBucket, error) {

        finalHtlcsBucket := tx.ReadBucket(finalHtlcsBucket)
        if finalHtlcsBucket == nil {
                return nil, ErrFinalHtlcsBucketNotFound
        }

        var chanIDBytes [8]byte
        byteOrder.PutUint64(chanIDBytes[:], chanID.ToUint64())

        chanBucket := finalHtlcsBucket.NestedReadBucket(chanIDBytes[:])
        if chanBucket == nil {
                return nil, ErrFinalChannelBucketNotFound
        }

        return chanBucket, nil
}

var ErrHtlcUnknown = errors.New("htlc unknown")

// LookupFinalHtlc retrieves a final htlc resolution from the database. If the
// htlc has no final resolution yet, ErrHtlcUnknown is returned.
func (c *ChannelStateDB) LookupFinalHtlc(chanID lnwire.ShortChannelID,
        htlcIndex uint64) (*FinalHtlcInfo, error) {

        var idBytes [8]byte
        byteOrder.PutUint64(idBytes[:], htlcIndex)

        var settledByte byte

        err := kvdb.View(c.backend, func(tx kvdb.RTx) error {
                finalHtlcsBucket, err := fetchFinalHtlcsBucket(
                        tx, chanID,
                )
                switch {
                case errors.Is(err, ErrFinalHtlcsBucketNotFound):
                        fallthrough

                case errors.Is(err, ErrFinalChannelBucketNotFound):
                        return ErrHtlcUnknown

                case err != nil:
                        return fmt.Errorf("cannot fetch final htlcs bucket: %w",
                                err)
                }

                value := finalHtlcsBucket.Get(idBytes[:])
                if value == nil {
                        return ErrHtlcUnknown
                }

                if len(value) != 1 {
                        return errors.New("unexpected final htlc value length")
                }

                settledByte = value[0]

                return nil
        }, func() {
                settledByte = 0
        })
        if err != nil {
                return nil, err
        }

        info := FinalHtlcInfo{
                Settled:  settledByte&byte(FinalHtlcSettledBit) != 0,
                Offchain: settledByte&byte(FinalHtlcOffchainBit) != 0,
        }

        return &info, nil
}

// PutOnchainFinalHtlcOutcome stores the final on-chain outcome of an htlc in
// the database.
func (c *ChannelStateDB) PutOnchainFinalHtlcOutcome(
        chanID lnwire.ShortChannelID, htlcID uint64, settled bool) error {

        // Skip if the user did not opt in to storing final resolutions.
        if !c.parent.storeFinalHtlcResolutions {
                return nil
        }

        return kvdb.Update(c.backend, func(tx kvdb.RwTx) error {
                finalHtlcsBucket, err := fetchFinalHtlcsBucketRw(tx, chanID)
                if err != nil {
                        return err
                }

                return putFinalHtlc(
                        finalHtlcsBucket, htlcID,
                        FinalHtlcInfo{
                                Settled:  settled,
                                Offchain: false,
                        },
                )
        }, func() {})
}

// MakeTestInvoiceDB is used to create a test invoice database for testing
// purposes. It simply calls into MakeTestDB so the same modifiers can be used.
func MakeTestInvoiceDB(t *testing.T, modifiers ...OptionModifier) (
        invoices.InvoiceDB, error) {

        return MakeTestDB(t, modifiers...)
}

// MakeTestDB creates a new instance of the ChannelDB for testing purposes.
// A callback which cleans up the created temporary directories is also
// returned and intended to be executed after the test completes.
func MakeTestDB(t *testing.T, modifiers ...OptionModifier) (*DB, error) {
        // First, create a temporary directory to be used for the duration of
        // this test.
        tempDirName := t.TempDir()

        // Next, create channeldb for the first time.
        backend, backendCleanup, err := kvdb.GetTestBackend(tempDirName, "cdb")
        if err != nil {
                backendCleanup()
                return nil, err
        }

        cdb, err := CreateWithBackend(backend, modifiers...)
        if err != nil {
                backendCleanup()
                return nil, err
        }

        t.Cleanup(func() {
                cdb.Close()
                backendCleanup()
        })

        return cdb, nil
}

lightningnetwork / lnd / 9915780197

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