13440912774

Committed 20 Feb 2025 05:14PM UTC coverage: 57.697% (-1.1%) from 58.802%

Build # 13440912774

Build Type

Pull #9535

github

Committed by

guggero

Commit Message

GitHub: remove duplicate caching

Turns out that actions/setup-go starting with @v4 also adds caching.
With that, our cache size on disk has almost doubled, leading to the
GitHub runner running out of space in certain situation.
We fix that by disabling the automated caching since we already have our
own, custom-tailored version.

Pull Request Pull Request #9535: GitHub: remove duplicate caching

Run Details

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69.68

/graph/builder.go

package graph

import (
        "fmt"
        "sync"
        "sync/atomic"
        "time"

        "github.com/btcsuite/btcd/btcec/v2"
        "github.com/btcsuite/btcd/wire"
        "github.com/go-errors/errors"
        "github.com/lightningnetwork/lnd/batch"
        "github.com/lightningnetwork/lnd/chainntnfs"
        graphdb "github.com/lightningnetwork/lnd/graph/db"
        "github.com/lightningnetwork/lnd/graph/db/models"
        "github.com/lightningnetwork/lnd/kvdb"
        "github.com/lightningnetwork/lnd/lnutils"
        "github.com/lightningnetwork/lnd/lnwallet"
        "github.com/lightningnetwork/lnd/lnwire"
        "github.com/lightningnetwork/lnd/multimutex"
        "github.com/lightningnetwork/lnd/netann"
        "github.com/lightningnetwork/lnd/routing/chainview"
        "github.com/lightningnetwork/lnd/routing/route"
        "github.com/lightningnetwork/lnd/ticker"
)

const (
        // DefaultChannelPruneExpiry is the default duration used to determine
        // if a channel should be pruned or not.
        DefaultChannelPruneExpiry = time.Hour * 24 * 14

        // DefaultFirstTimePruneDelay is the time we'll wait after startup
        // before attempting to prune the graph for zombie channels. We don't
        // do it immediately after startup to allow lnd to start up without
        // getting blocked by this job.
        DefaultFirstTimePruneDelay = 30 * time.Second

        // defaultStatInterval governs how often the router will log non-empty
        // stats related to processing new channels, updates, or node
        // announcements.
        defaultStatInterval = time.Minute
)

var (
        // ErrGraphBuilderShuttingDown is returned if the graph builder is in
        // the process of shutting down.
        ErrGraphBuilderShuttingDown = fmt.Errorf("graph builder shutting down")
)

// Config holds the configuration required by the Builder.
type Config struct {
        // SelfNode is the public key of the node that this channel router
        // belongs to.
        SelfNode route.Vertex

        // Graph is the channel graph that the ChannelRouter will use to gather
        // metrics from and also to carry out path finding queries.
        Graph DB

        // Chain is the router's source to the most up-to-date blockchain data.
        // All incoming advertised channels will be checked against the chain
        // to ensure that the channels advertised are still open.
        Chain lnwallet.BlockChainIO

        // ChainView is an instance of a FilteredChainView which is used to
        // watch the sub-set of the UTXO set (the set of active channels) that
        // we need in order to properly maintain the channel graph.
        ChainView chainview.FilteredChainView

        // Notifier is a reference to the ChainNotifier, used to grab
        // the latest blocks if the router is missing any.
        Notifier chainntnfs.ChainNotifier

        // ChannelPruneExpiry is the duration used to determine if a channel
        // should be pruned or not. If the delta between now and when the
        // channel was last updated is greater than ChannelPruneExpiry, then
        // the channel is marked as a zombie channel eligible for pruning.
        ChannelPruneExpiry time.Duration

        // GraphPruneInterval is used as an interval to determine how often we
        // should examine the channel graph to garbage collect zombie channels.
        GraphPruneInterval time.Duration

        // FirstTimePruneDelay is the time we'll wait after startup before
        // attempting to prune the graph for zombie channels. We don't do it
        // immediately after startup to allow lnd to start up without getting
        // blocked by this job.
        FirstTimePruneDelay time.Duration

        // AssumeChannelValid toggles whether the builder will prune channels
        // based on their spentness vs using the fact that they are considered
        // zombies.
        AssumeChannelValid bool

        // StrictZombiePruning determines if we attempt to prune zombie
        // channels according to a stricter criteria. If true, then we'll prune
        // a channel if only *one* of the edges is considered a zombie.
        // Otherwise, we'll only prune the channel when both edges have a very
        // dated last update.
        StrictZombiePruning bool

        // IsAlias returns whether a passed ShortChannelID is an alias. This is
        // only used for our local channels.
        IsAlias func(scid lnwire.ShortChannelID) bool
}

// Builder builds and maintains a view of the Lightning Network graph.
type Builder struct {
        started atomic.Bool
        stopped atomic.Bool

        ntfnClientCounter atomic.Uint64
        bestHeight        atomic.Uint32

        cfg *Config

        // newBlocks is a channel in which new blocks connected to the end of
        // the main chain are sent over, and blocks updated after a call to
        // UpdateFilter.
        newBlocks <-chan *chainview.FilteredBlock

        // staleBlocks is a channel in which blocks disconnected from the end
        // of our currently known best chain are sent over.
        staleBlocks <-chan *chainview.FilteredBlock

        // networkUpdates is a channel that carries new topology updates
        // messages from outside the Builder to be processed by the
        // networkHandler.
        networkUpdates chan *routingMsg

        // topologyClients maps a client's unique notification ID to a
        // topologyClient client that contains its notification dispatch
        // channel.
        topologyClients *lnutils.SyncMap[uint64, *topologyClient]

        // ntfnClientUpdates is a channel that's used to send new updates to
        // topology notification clients to the Builder. Updates either
        // add a new notification client, or cancel notifications for an
        // existing client.
        ntfnClientUpdates chan *topologyClientUpdate

        // channelEdgeMtx is a mutex we use to make sure we process only one
        // ChannelEdgePolicy at a time for a given channelID, to ensure
        // consistency between the various database accesses.
        channelEdgeMtx *multimutex.Mutex[uint64]

        // statTicker is a resumable ticker that logs the router's progress as
        // it discovers channels or receives updates.
        statTicker ticker.Ticker

        // stats tracks newly processed channels, updates, and node
        // announcements over a window of defaultStatInterval.
        stats *builderStats

        quit chan struct{}
        wg   sync.WaitGroup
}

// A compile time check to ensure Builder implements the
// ChannelGraphSource interface.
var _ ChannelGraphSource = (*Builder)(nil)

// NewBuilder constructs a new Builder.
func NewBuilder(cfg *Config) (*Builder, error) {
        return &Builder{
                cfg:               cfg,
                networkUpdates:    make(chan *routingMsg),
                topologyClients:   &lnutils.SyncMap[uint64, *topologyClient]{},
                ntfnClientUpdates: make(chan *topologyClientUpdate),
                channelEdgeMtx:    multimutex.NewMutex[uint64](),
                statTicker:        ticker.New(defaultStatInterval),
                stats:             new(builderStats),
                quit:              make(chan struct{}),
        }, nil
}

// Start launches all the goroutines the Builder requires to carry out its
// duties. If the builder has already been started, then this method is a noop.
func (b *Builder) Start() error {
        if !b.started.CompareAndSwap(false, true) {
                return nil
        }

        log.Info("Builder starting")

        bestHash, bestHeight, err := b.cfg.Chain.GetBestBlock()
        if err != nil {
                return err
        }

        // If the graph has never been pruned, or hasn't fully been created yet,
        // then we don't treat this as an explicit error.
        if _, _, err := b.cfg.Graph.PruneTip(); err != nil {
                switch {
                case errors.Is(err, graphdb.ErrGraphNeverPruned):
                        fallthrough

                case errors.Is(err, graphdb.ErrGraphNotFound):
                        // If the graph has never been pruned, then we'll set
                        // the prune height to the current best height of the
                        // chain backend.
                        _, err = b.cfg.Graph.PruneGraph(
                                nil, bestHash, uint32(bestHeight),
                        )
                        if err != nil {
                                return err
                        }

                default:
                        return err
                }
        }

        // If AssumeChannelValid is present, then we won't rely on pruning
        // channels from the graph based on their spentness, but whether they
        // are considered zombies or not. We will start zombie pruning after a
        // small delay, to avoid slowing down startup of lnd.
        if b.cfg.AssumeChannelValid { //nolint:nestif
                time.AfterFunc(b.cfg.FirstTimePruneDelay, func() {
                        select {
                        case <-b.quit:
                                return
                        default:
                        }

                        log.Info("Initial zombie prune starting")
                        if err := b.pruneZombieChans(); err != nil {
                                log.Errorf("Unable to prune zombies: %v", err)
                        }
                })
        } else {
                // Otherwise, we'll use our filtered chain view to prune
                // channels as soon as they are detected as spent on-chain.
                if err := b.cfg.ChainView.Start(); err != nil {
                        return err
                }

                // Once the instance is active, we'll fetch the channel we'll
                // receive notifications over.
                b.newBlocks = b.cfg.ChainView.FilteredBlocks()
                b.staleBlocks = b.cfg.ChainView.DisconnectedBlocks()

                // Before we perform our manual block pruning, we'll construct
                // and apply a fresh chain filter to the active
                // FilteredChainView instance.  We do this before, as otherwise
                // we may miss on-chain events as the filter hasn't properly
                // been applied.
                channelView, err := b.cfg.Graph.ChannelView()
                if err != nil && !errors.Is(
                        err, graphdb.ErrGraphNoEdgesFound,
                ) {

                        return err
                }

                log.Infof("Filtering chain using %v channels active",
                        len(channelView))

                if len(channelView) != 0 {
                        err = b.cfg.ChainView.UpdateFilter(
                                channelView, uint32(bestHeight),
                        )
                        if err != nil {
                                return err
                        }
                }

                // The graph pruning might have taken a while and there could be
                // new blocks available.
                _, bestHeight, err = b.cfg.Chain.GetBestBlock()
                if err != nil {
                        return err
                }
                b.bestHeight.Store(uint32(bestHeight))

                // Before we begin normal operation of the router, we first need
                // to synchronize the channel graph to the latest state of the
                // UTXO set.
                if err := b.syncGraphWithChain(); err != nil {
                        return err
                }

                // Finally, before we proceed, we'll prune any unconnected nodes
                // from the graph in order to ensure we maintain a tight graph
                // of "useful" nodes.
                err = b.cfg.Graph.PruneGraphNodes()
                if err != nil &&
                        !errors.Is(err, graphdb.ErrGraphNodesNotFound) {

                        return err
                }
        }

        b.wg.Add(1)
        go b.networkHandler()

        log.Debug("Builder started")

        return nil
}

// Stop signals to the Builder that it should halt all routines. This method
// will *block* until all goroutines have excited. If the builder has already
// stopped then this method will return immediately.
func (b *Builder) Stop() error {
        if !b.stopped.CompareAndSwap(false, true) {
                return nil
        }

        log.Info("Builder shutting down...")

        // Our filtered chain view could've only been started if
        // AssumeChannelValid isn't present.
        if !b.cfg.AssumeChannelValid {
                if err := b.cfg.ChainView.Stop(); err != nil {
                        return err
                }
        }

        close(b.quit)
        b.wg.Wait()

        log.Debug("Builder shutdown complete")

        return nil
}

// syncGraphWithChain attempts to synchronize the current channel graph with
// the latest UTXO set state. This process involves pruning from the channel
// graph any channels which have been closed by spending their funding output
// since we've been down.
func (b *Builder) syncGraphWithChain() error {
        // First, we'll need to check to see if we're already in sync with the
        // latest state of the UTXO set.
        bestHash, bestHeight, err := b.cfg.Chain.GetBestBlock()
        if err != nil {
                return err
        }
        b.bestHeight.Store(uint32(bestHeight))

        pruneHash, pruneHeight, err := b.cfg.Graph.PruneTip()
        if err != nil {
                switch {
                // If the graph has never been pruned, or hasn't fully been
                // created yet, then we don't treat this as an explicit error.
                case errors.Is(err, graphdb.ErrGraphNeverPruned):
                case errors.Is(err, graphdb.ErrGraphNotFound):
                default:
                        return err
                }
        }

        log.Infof("Prune tip for Channel Graph: height=%v, hash=%v",
                pruneHeight, pruneHash)

        switch {
        // If the graph has never been pruned, then we can exit early as this
        // entails it's being created for the first time and hasn't seen any
        // block or created channels.
        case pruneHeight == 0 || pruneHash == nil:
                return nil

        // If the block hashes and heights match exactly, then we don't need to
        // prune the channel graph as we're already fully in sync.
        case bestHash.IsEqual(pruneHash) && uint32(bestHeight) == pruneHeight:
                return nil
        }

        // If the main chain blockhash at prune height is different from the
        // prune hash, this might indicate the database is on a stale branch.
        mainBlockHash, err := b.cfg.Chain.GetBlockHash(int64(pruneHeight))
        if err != nil {
                return err
        }

        // While we are on a stale branch of the chain, walk backwards to find
        // first common block.
        for !pruneHash.IsEqual(mainBlockHash) {
                log.Infof("channel graph is stale. Disconnecting block %v "+
                        "(hash=%v)", pruneHeight, pruneHash)
                // Prune the graph for every channel that was opened at height
                // >= pruneHeight.
                _, err := b.cfg.Graph.DisconnectBlockAtHeight(pruneHeight)
                if err != nil {
                        return err
                }

                pruneHash, pruneHeight, err = b.cfg.Graph.PruneTip()
                switch {
                // If at this point the graph has never been pruned, we can exit
                // as this entails we are back to the point where it hasn't seen
                // any block or created channels, alas there's nothing left to
                // prune.
                case errors.Is(err, graphdb.ErrGraphNeverPruned):
                        return nil

                case errors.Is(err, graphdb.ErrGraphNotFound):
                        return nil

                case err != nil:
                        return err

                default:
                }

                mainBlockHash, err = b.cfg.Chain.GetBlockHash(
                        int64(pruneHeight),
                )
                if err != nil {
                        return err
                }
        }

        log.Infof("Syncing channel graph from height=%v (hash=%v) to "+
                "height=%v (hash=%v)", pruneHeight, pruneHash, bestHeight,
                bestHash)

        // If we're not yet caught up, then we'll walk forward in the chain
        // pruning the channel graph with each new block that hasn't yet been
        // consumed by the channel graph.
        var spentOutputs []*wire.OutPoint
        for nextHeight := pruneHeight + 1; nextHeight <= uint32(bestHeight); nextHeight++ { //nolint:ll
                // Break out of the rescan early if a shutdown has been
                // requested, otherwise long rescans will block the daemon from
                // shutting down promptly.
                select {
                case <-b.quit:
                        return ErrGraphBuilderShuttingDown
                default:
                }

                // Using the next height, request a manual block pruning from
                // the chainview for the particular block hash.
                log.Infof("Filtering block for closed channels, at height: %v",
                        int64(nextHeight))
                nextHash, err := b.cfg.Chain.GetBlockHash(int64(nextHeight))
                if err != nil {
                        return err
                }
                log.Tracef("Running block filter on block with hash: %v",
                        nextHash)
                filterBlock, err := b.cfg.ChainView.FilterBlock(nextHash)
                if err != nil {
                        return err
                }

                // We're only interested in all prior outputs that have been
                // spent in the block, so collate all the referenced previous
                // outpoints within each tx and input.
                for _, tx := range filterBlock.Transactions {
                        for _, txIn := range tx.TxIn {
                                spentOutputs = append(spentOutputs,
                                        &txIn.PreviousOutPoint)
                        }
                }
        }

        // With the spent outputs gathered, attempt to prune the channel graph,
        // also passing in the best hash+height so the prune tip can be updated.
        closedChans, err := b.cfg.Graph.PruneGraph(
                spentOutputs, bestHash, uint32(bestHeight),
        )
        if err != nil {
                return err
        }

        log.Infof("Graph pruning complete: %v channels were closed since "+
                "height %v", len(closedChans), pruneHeight)

        return nil
}

// isZombieChannel takes two edge policy updates and determines if the
// corresponding channel should be considered a zombie. The first boolean is
// true if the policy update from node 1 is considered a zombie, the second
// boolean is that of node 2, and the final boolean is true if the channel
// is considered a zombie.
func (b *Builder) isZombieChannel(e1,
        e2 *models.ChannelEdgePolicy) (bool, bool, bool) {

        chanExpiry := b.cfg.ChannelPruneExpiry

        e1Zombie := e1 == nil || time.Since(e1.LastUpdate) >= chanExpiry
        e2Zombie := e2 == nil || time.Since(e2.LastUpdate) >= chanExpiry

        var e1Time, e2Time time.Time
        if e1 != nil {
                e1Time = e1.LastUpdate
        }
        if e2 != nil {
                e2Time = e2.LastUpdate
        }

        return e1Zombie, e2Zombie, b.IsZombieChannel(e1Time, e2Time)
}

// IsZombieChannel takes the timestamps of the latest channel updates for a
// channel and returns true if the channel should be considered a zombie based
// on these timestamps.
func (b *Builder) IsZombieChannel(updateTime1,
        updateTime2 time.Time) bool {

        chanExpiry := b.cfg.ChannelPruneExpiry

        e1Zombie := updateTime1.IsZero() ||
                time.Since(updateTime1) >= chanExpiry

        e2Zombie := updateTime2.IsZero() ||
                time.Since(updateTime2) >= chanExpiry

        // If we're using strict zombie pruning, then a channel is only
        // considered live if both edges have a recent update we know of.
        if b.cfg.StrictZombiePruning {
                return e1Zombie || e2Zombie
        }

        // Otherwise, if we're using the less strict variant, then a channel is
        // considered live if either of the edges have a recent update.
        return e1Zombie && e2Zombie
}

// pruneZombieChans is a method that will be called periodically to prune out
// any "zombie" channels. We consider channels zombies if *both* edges haven't
// been updated since our zombie horizon. If AssumeChannelValid is present,
// we'll also consider channels zombies if *both* edges are disabled. This
// usually signals that a channel has been closed on-chain. We do this
// periodically to keep a healthy, lively routing table.
func (b *Builder) pruneZombieChans() error {
        chansToPrune := make(map[uint64]struct{})
        chanExpiry := b.cfg.ChannelPruneExpiry

        log.Infof("Examining channel graph for zombie channels")

        // A helper method to detect if the channel belongs to this node
        isSelfChannelEdge := func(info *models.ChannelEdgeInfo) bool {
                return info.NodeKey1Bytes == b.cfg.SelfNode ||
                        info.NodeKey2Bytes == b.cfg.SelfNode
        }

        // First, we'll collect all the channels which are eligible for garbage
        // collection due to being zombies.
        filterPruneChans := func(info *models.ChannelEdgeInfo,
                e1, e2 *models.ChannelEdgePolicy) error {

                // Exit early in case this channel is already marked to be
                // pruned
                _, markedToPrune := chansToPrune[info.ChannelID]
                if markedToPrune {
                        return nil
                }

                // We'll ensure that we don't attempt to prune our *own*
                // channels from the graph, as in any case this should be
                // re-advertised by the sub-system above us.
                if isSelfChannelEdge(info) {
                        return nil
                }

                e1Zombie, e2Zombie, isZombieChan := b.isZombieChannel(e1, e2)

                if e1Zombie {
                        log.Tracef("Node1 pubkey=%x of chan_id=%v is zombie",
                                info.NodeKey1Bytes, info.ChannelID)
                }

                if e2Zombie {
                        log.Tracef("Node2 pubkey=%x of chan_id=%v is zombie",
                                info.NodeKey2Bytes, info.ChannelID)
                }

                // If either edge hasn't been updated for a period of
                // chanExpiry, then we'll mark the channel itself as eligible
                // for graph pruning.
                if !isZombieChan {
                        return nil
                }

                log.Debugf("ChannelID(%v) is a zombie, collecting to prune",
                        info.ChannelID)

                // TODO(roasbeef): add ability to delete single directional edge
                chansToPrune[info.ChannelID] = struct{}{}

                return nil
        }

        // If AssumeChannelValid is present we'll look at the disabled bit for
        // both edges. If they're both disabled, then we can interpret this as
        // the channel being closed and can prune it from our graph.
        if b.cfg.AssumeChannelValid {
                disabledChanIDs, err := b.cfg.Graph.DisabledChannelIDs()
                if err != nil {
                        return fmt.Errorf("unable to get disabled channels "+
                                "ids chans: %v", err)
                }

                disabledEdges, err := b.cfg.Graph.FetchChanInfos(
                        disabledChanIDs,
                )
                if err != nil {
                        return fmt.Errorf("unable to fetch disabled channels "+
                                "edges chans: %v", err)
                }

                // Ensuring we won't prune our own channel from the graph.
                for _, disabledEdge := range disabledEdges {
                        if !isSelfChannelEdge(disabledEdge.Info) {
                                chansToPrune[disabledEdge.Info.ChannelID] =
                                        struct{}{}
                        }
                }
        }

        startTime := time.Unix(0, 0)
        endTime := time.Now().Add(-1 * chanExpiry)
        oldEdges, err := b.cfg.Graph.ChanUpdatesInHorizon(startTime, endTime)
        if err != nil {
                return fmt.Errorf("unable to fetch expired channel updates "+
                        "chans: %v", err)
        }

        for _, u := range oldEdges {
                err = filterPruneChans(u.Info, u.Policy1, u.Policy2)
                if err != nil {
                        return fmt.Errorf("error filtering channels to "+
                                "prune: %w", err)
                }
        }

        log.Infof("Pruning %v zombie channels", len(chansToPrune))
        if len(chansToPrune) == 0 {
                return nil
        }

        // With the set of zombie-like channels obtained, we'll do another pass
        // to delete them from the channel graph.
        toPrune := make([]uint64, 0, len(chansToPrune))
        for chanID := range chansToPrune {
                toPrune = append(toPrune, chanID)
                log.Tracef("Pruning zombie channel with ChannelID(%v)", chanID)
        }
        err = b.cfg.Graph.DeleteChannelEdges(
                b.cfg.StrictZombiePruning, true, toPrune...,
        )
        if err != nil {
                return fmt.Errorf("unable to delete zombie channels: %w", err)
        }

        // With the channels pruned, we'll also attempt to prune any nodes that
        // were a part of them.
        err = b.cfg.Graph.PruneGraphNodes()
        if err != nil && !errors.Is(err, graphdb.ErrGraphNodesNotFound) {
                return fmt.Errorf("unable to prune graph nodes: %w", err)
        }

        return nil
}

// handleNetworkUpdate is responsible for processing the update message and
// notifies topology changes, if any.
//
// NOTE: must be run inside goroutine.
func (b *Builder) handleNetworkUpdate(update *routingMsg) {
        defer b.wg.Done()

        // Process the routing update to determine if this is either a new
        // update from our PoV or an update to a prior vertex/edge we
        // previously accepted.
        var err error
        switch msg := update.msg.(type) {
        case *models.LightningNode:
                err = b.addNode(msg, update.op...)

        case *models.ChannelEdgeInfo:
                err = b.addEdge(msg, update.op...)

        case *models.ChannelEdgePolicy:
                err = b.updateEdge(msg, update.op...)

        default:
                err = errors.Errorf("wrong routing update message type")
        }
        update.err <- err

        // If the error is not nil here, there's no need to send topology
        // change.
        if err != nil {
                // Log as a debug message if this is not an error we need to be
                // concerned about.
                if IsError(err, ErrIgnored, ErrOutdated) {
                        log.Debugf("process network updates got: %v", err)
                } else {
                        log.Errorf("process network updates got: %v", err)
                }

                return
        }

        // Otherwise, we'll send off a new notification for the newly accepted
        // update, if any.
        topChange := &TopologyChange{}
        err = addToTopologyChange(b.cfg.Graph, topChange, update.msg)
        if err != nil {
                log.Errorf("unable to update topology change notification: %v",
                        err)
                return
        }

        if !topChange.isEmpty() {
                b.notifyTopologyChange(topChange)
        }
}

// networkHandler is the primary goroutine for the Builder. The roles of
// this goroutine include answering queries related to the state of the
// network, pruning the graph on new block notification, applying network
// updates, and registering new topology clients.
//
// NOTE: This MUST be run as a goroutine.
func (b *Builder) networkHandler() {
        defer b.wg.Done()

        graphPruneTicker := time.NewTicker(b.cfg.GraphPruneInterval)
        defer graphPruneTicker.Stop()

        defer b.statTicker.Stop()

        b.stats.Reset()

        for {
                // If there are stats, resume the statTicker.
                if !b.stats.Empty() {
                        b.statTicker.Resume()
                }

                select {
                // A new fully validated network update has just arrived. As a
                // result we'll modify the channel graph accordingly depending
                // on the exact type of the message.
                case update := <-b.networkUpdates:
                        b.wg.Add(1)
                        go b.handleNetworkUpdate(update)

                        // TODO(roasbeef): remove all unconnected vertexes
                        // after N blocks pass with no corresponding
                        // announcements.

                case chainUpdate, ok := <-b.staleBlocks:
                        // If the channel has been closed, then this indicates
                        // the daemon is shutting down, so we exit ourselves.
                        if !ok {
                                return
                        }

                        // Since this block is stale, we update our best height
                        // to the previous block.
                        blockHeight := chainUpdate.Height
                        b.bestHeight.Store(blockHeight - 1)

                        // Update the channel graph to reflect that this block
                        // was disconnected.
                        _, err := b.cfg.Graph.DisconnectBlockAtHeight(
                                blockHeight,
                        )
                        if err != nil {
                                log.Errorf("unable to prune graph with stale "+
                                        "block: %v", err)
                                continue
                        }

                        // TODO(halseth): notify client about the reorg?

                // A new block has arrived, so we can prune the channel graph
                // of any channels which were closed in the block.
                case chainUpdate, ok := <-b.newBlocks:
                        // If the channel has been closed, then this indicates
                        // the daemon is shutting down, so we exit ourselves.
                        if !ok {
                                return
                        }

                        // We'll ensure that any new blocks received attach
                        // directly to the end of our main chain. If not, then
                        // we've somehow missed some blocks. Here we'll catch
                        // up the chain with the latest blocks.
                        currentHeight := b.bestHeight.Load()
                        switch {
                        case chainUpdate.Height == currentHeight+1:
                                err := b.updateGraphWithClosedChannels(
                                        chainUpdate,
                                )
                                if err != nil {
                                        log.Errorf("unable to prune graph "+
                                                "with closed channels: %v", err)
                                }

                        case chainUpdate.Height > currentHeight+1:
                                log.Errorf("out of order block: expecting "+
                                        "height=%v, got height=%v",
                                        currentHeight+1, chainUpdate.Height)

                                err := b.getMissingBlocks(
                                        currentHeight, chainUpdate,
                                )
                                if err != nil {
                                        log.Errorf("unable to retrieve missing"+
                                                "blocks: %v", err)
                                }

                        case chainUpdate.Height < currentHeight+1:
                                log.Errorf("out of order block: expecting "+
                                        "height=%v, got height=%v",
                                        currentHeight+1, chainUpdate.Height)

                                log.Infof("Skipping channel pruning since "+
                                        "received block height %v was already"+
                                        " processed.", chainUpdate.Height)
                        }

                // A new notification client update has arrived. We're either
                // gaining a new client, or cancelling notifications for an
                // existing client.
                case ntfnUpdate := <-b.ntfnClientUpdates:
                        clientID := ntfnUpdate.clientID

                        if ntfnUpdate.cancel {
                                client, ok := b.topologyClients.LoadAndDelete(
                                        clientID,
                                )
                                if ok {
                                        close(client.exit)
                                        client.wg.Wait()

                                        close(client.ntfnChan)
                                }

                                continue
                        }

                        b.topologyClients.Store(clientID, &topologyClient{
                                ntfnChan: ntfnUpdate.ntfnChan,
                                exit:     make(chan struct{}),
                        })

                // The graph prune ticker has ticked, so we'll examine the
                // state of the known graph to filter out any zombie channels
                // for pruning.
                case <-graphPruneTicker.C:
                        if err := b.pruneZombieChans(); err != nil {
                                log.Errorf("Unable to prune zombies: %v", err)
                        }

                // Log any stats if we've processed a non-empty number of
                // channels, updates, or nodes. We'll only pause the ticker if
                // the last window contained no updates to avoid resuming and
                // pausing while consecutive windows contain new info.
                case <-b.statTicker.Ticks():
                        if !b.stats.Empty() {
                                log.Infof(b.stats.String())
                        } else {
                                b.statTicker.Pause()
                        }
                        b.stats.Reset()

                // The router has been signalled to exit, to we exit our main
                // loop so the wait group can be decremented.
                case <-b.quit:
                        return
                }
        }
}

// getMissingBlocks walks through all missing blocks and updates the graph
// closed channels accordingly.
func (b *Builder) getMissingBlocks(currentHeight uint32,
        chainUpdate *chainview.FilteredBlock) error {

        outdatedHash, err := b.cfg.Chain.GetBlockHash(int64(currentHeight))
        if err != nil {
                return err
        }

        outdatedBlock := &chainntnfs.BlockEpoch{
                Height: int32(currentHeight),
                Hash:   outdatedHash,
        }

        epochClient, err := b.cfg.Notifier.RegisterBlockEpochNtfn(
                outdatedBlock,
        )
        if err != nil {
                return err
        }
        defer epochClient.Cancel()

        blockDifference := int(chainUpdate.Height - currentHeight)

        // We'll walk through all the outdated blocks and make sure we're able
        // to update the graph with any closed channels from them.
        for i := 0; i < blockDifference; i++ {
                var (
                        missingBlock *chainntnfs.BlockEpoch
                        ok           bool
                )

                select {
                case missingBlock, ok = <-epochClient.Epochs:
                        if !ok {
                                return nil
                        }

                case <-b.quit:
                        return nil
                }

                filteredBlock, err := b.cfg.ChainView.FilterBlock(
                        missingBlock.Hash,
                )
                if err != nil {
                        return err
                }

                err = b.updateGraphWithClosedChannels(
                        filteredBlock,
                )
                if err != nil {
                        return err
                }
        }

        return nil
}

// updateGraphWithClosedChannels prunes the channel graph of closed channels
// that are no longer needed.
func (b *Builder) updateGraphWithClosedChannels(
        chainUpdate *chainview.FilteredBlock) error {

        // Once a new block arrives, we update our running track of the height
        // of the chain tip.
        blockHeight := chainUpdate.Height

        b.bestHeight.Store(blockHeight)
        log.Infof("Pruning channel graph using block %v (height=%v)",
                chainUpdate.Hash, blockHeight)

        // We're only interested in all prior outputs that have been spent in
        // the block, so collate all the referenced previous outpoints within
        // each tx and input.
        var spentOutputs []*wire.OutPoint
        for _, tx := range chainUpdate.Transactions {
                for _, txIn := range tx.TxIn {
                        spentOutputs = append(spentOutputs,
                                &txIn.PreviousOutPoint)
                }
        }

        // With the spent outputs gathered, attempt to prune the channel graph,
        // also passing in the hash+height of the block being pruned so the
        // prune tip can be updated.
        chansClosed, err := b.cfg.Graph.PruneGraph(spentOutputs,
                &chainUpdate.Hash, chainUpdate.Height)
        if err != nil {
                log.Errorf("unable to prune routing table: %v", err)
                return err
        }

        log.Infof("Block %v (height=%v) closed %v channels", chainUpdate.Hash,
                blockHeight, len(chansClosed))

        if len(chansClosed) == 0 {
                return err
        }

        // Notify all currently registered clients of the newly closed channels.
        closeSummaries := createCloseSummaries(blockHeight, chansClosed...)
        b.notifyTopologyChange(&TopologyChange{
                ClosedChannels: closeSummaries,
        })

        return nil
}

// assertNodeAnnFreshness returns a non-nil error if we have an announcement in
// the database for the passed node with a timestamp newer than the passed
// timestamp. ErrIgnored will be returned if we already have the node, and
// ErrOutdated will be returned if we have a timestamp that's after the new
// timestamp.
func (b *Builder) assertNodeAnnFreshness(node route.Vertex,
        msgTimestamp time.Time) error {

        // If we are not already aware of this node, it means that we don't
        // know about any channel using this node. To avoid a DoS attack by
        // node announcements, we will ignore such nodes. If we do know about
        // this node, check that this update brings info newer than what we
        // already have.
        lastUpdate, exists, err := b.cfg.Graph.HasLightningNode(node)
        if err != nil {
                return errors.Errorf("unable to query for the "+
                        "existence of node: %v", err)
        }
        if !exists {
                return NewErrf(ErrIgnored, "Ignoring node announcement"+
                        " for node not found in channel graph (%x)",
                        node[:])
        }

        // If we've reached this point then we're aware of the vertex being
        // advertised. So we now check if the new message has a new time stamp,
        // if not then we won't accept the new data as it would override newer
        // data.
        if !lastUpdate.Before(msgTimestamp) {
                return NewErrf(ErrOutdated, "Ignoring outdated "+
                        "announcement for %x", node[:])
        }

        return nil
}

// MarkZombieEdge adds a channel that failed complete validation into the zombie
// index so we can avoid having to re-validate it in the future.
func (b *Builder) MarkZombieEdge(chanID uint64) error {
        // If the edge fails validation we'll mark the edge itself as a zombie
        // so we don't continue to request it. We use the "zero key" for both
        // node pubkeys so this edge can't be resurrected.
        var zeroKey [33]byte
        err := b.cfg.Graph.MarkEdgeZombie(chanID, zeroKey, zeroKey)
        if err != nil {
                return fmt.Errorf("unable to mark spent chan(id=%v) as a "+
                        "zombie: %w", chanID, err)
        }

        return nil
}

// routingMsg couples a routing related routing topology update to the
// error channel.
type routingMsg struct {
        msg interface{}
        op  []batch.SchedulerOption
        err chan error
}

// ApplyChannelUpdate validates a channel update and if valid, applies it to the
// database. It returns a bool indicating whether the updates were successful.
func (b *Builder) ApplyChannelUpdate(msg *lnwire.ChannelUpdate1) bool {
        ch, _, _, err := b.GetChannelByID(msg.ShortChannelID)
        if err != nil {
                log.Errorf("Unable to retrieve channel by id: %v", err)
                return false
        }

        var pubKey *btcec.PublicKey

        switch msg.ChannelFlags & lnwire.ChanUpdateDirection {
        case 0:
                pubKey, _ = ch.NodeKey1()

        case 1:
                pubKey, _ = ch.NodeKey2()
        }

        // Exit early if the pubkey cannot be decided.
        if pubKey == nil {
                log.Errorf("Unable to decide pubkey with ChannelFlags=%v",
                        msg.ChannelFlags)
                return false
        }

        err = netann.ValidateChannelUpdateAnn(pubKey, ch.Capacity, msg)
        if err != nil {
                log.Errorf("Unable to validate channel update: %v", err)
                return false
        }

        err = b.UpdateEdge(&models.ChannelEdgePolicy{
                SigBytes:                  msg.Signature.ToSignatureBytes(),
                ChannelID:                 msg.ShortChannelID.ToUint64(),
                LastUpdate:                time.Unix(int64(msg.Timestamp), 0),
                MessageFlags:              msg.MessageFlags,
                ChannelFlags:              msg.ChannelFlags,
                TimeLockDelta:             msg.TimeLockDelta,
                MinHTLC:                   msg.HtlcMinimumMsat,
                MaxHTLC:                   msg.HtlcMaximumMsat,
                FeeBaseMSat:               lnwire.MilliSatoshi(msg.BaseFee),
                FeeProportionalMillionths: lnwire.MilliSatoshi(msg.FeeRate),
                ExtraOpaqueData:           msg.ExtraOpaqueData,
        })
        if err != nil && !IsError(err, ErrIgnored, ErrOutdated) {
                log.Errorf("Unable to apply channel update: %v", err)
                return false
        }

        return true
}

// AddNode is used to add information about a node to the router database. If
// the node with this pubkey is not present in an existing channel, it will
// be ignored.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) AddNode(node *models.LightningNode,
        op ...batch.SchedulerOption) error {

        rMsg := &routingMsg{
                msg: node,
                op:  op,
                err: make(chan error, 1),
        }

        select {
        case b.networkUpdates <- rMsg:
                select {
                case err := <-rMsg.err:
                        return err
                case <-b.quit:
                        return ErrGraphBuilderShuttingDown
                }
        case <-b.quit:
                return ErrGraphBuilderShuttingDown
        }
}

// addNode does some basic checks on the given LightningNode against what we
// currently have persisted in the graph, and then adds it to the graph. If we
// already know about the node, then we only update our DB if the new update
// has a newer timestamp than the last one we received.
func (b *Builder) addNode(node *models.LightningNode,
        op ...batch.SchedulerOption) error {

        // Before we add the node to the database, we'll check to see if the
        // announcement is "fresh" or not. If it isn't, then we'll return an
        // error.
        err := b.assertNodeAnnFreshness(node.PubKeyBytes, node.LastUpdate)
        if err != nil {
                return err
        }

        if err := b.cfg.Graph.AddLightningNode(node, op...); err != nil {
                return errors.Errorf("unable to add node %x to the "+
                        "graph: %v", node.PubKeyBytes, err)
        }

        log.Tracef("Updated vertex data for node=%x", node.PubKeyBytes)
        b.stats.incNumNodeUpdates()

        return nil
}

// AddEdge is used to add edge/channel to the topology of the router, after all
// information about channel will be gathered this edge/channel might be used
// in construction of payment path.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) AddEdge(edge *models.ChannelEdgeInfo,
        op ...batch.SchedulerOption) error {

        rMsg := &routingMsg{
                msg: edge,
                op:  op,
                err: make(chan error, 1),
        }

        select {
        case b.networkUpdates <- rMsg:
                select {
                case err := <-rMsg.err:
                        return err
                case <-b.quit:
                        return ErrGraphBuilderShuttingDown
                }
        case <-b.quit:
                return ErrGraphBuilderShuttingDown
        }
}

// addEdge does some validation on the new channel edge against what we
// currently have persisted in the graph, and then adds it to the graph. The
// Chain View is updated with the new edge if it is successfully added to the
// graph. We only persist the channel if we currently dont have it at all in
// our graph.
//
// TODO(elle): this currently also does funding-transaction validation. But this
// should be moved to the gossiper instead.
func (b *Builder) addEdge(edge *models.ChannelEdgeInfo,
        op ...batch.SchedulerOption) error {

        log.Debugf("Received ChannelEdgeInfo for channel %v", edge.ChannelID)

        // Prior to processing the announcement we first check if we
        // already know of this channel, if so, then we can exit early.
        _, _, exists, isZombie, err := b.cfg.Graph.HasChannelEdge(
                edge.ChannelID,
        )
        if err != nil && !errors.Is(err, graphdb.ErrGraphNoEdgesFound) {
                return errors.Errorf("unable to check for edge existence: %v",
                        err)
        }
        if isZombie {
                return NewErrf(ErrIgnored, "ignoring msg for zombie chan_id=%v",
                        edge.ChannelID)
        }
        if exists {
                return NewErrf(ErrIgnored, "ignoring msg for known chan_id=%v",
                        edge.ChannelID)
        }

        if err := b.cfg.Graph.AddChannelEdge(edge, op...); err != nil {
                return fmt.Errorf("unable to add edge: %w", err)
        }

        b.stats.incNumEdgesDiscovered()

        // If AssumeChannelValid is present, of if the SCID is an alias, then
        // the gossiper would not have done the expensive work of fetching
        // a funding transaction and validating it. So we won't have the channel
        // capacity nor the funding script. So we just log and return here.
        scid := lnwire.NewShortChanIDFromInt(edge.ChannelID)
        if b.cfg.AssumeChannelValid || b.cfg.IsAlias(scid) {
                log.Tracef("New channel discovered! Link connects %x and %x "+
                        "with ChannelID(%v)", edge.NodeKey1Bytes,
                        edge.NodeKey2Bytes, edge.ChannelID)

                return nil
        }

        log.Debugf("New channel discovered! Link connects %x and %x with "+
                "ChannelPoint(%v): chan_id=%v, capacity=%v", edge.NodeKey1Bytes,
                edge.NodeKey2Bytes, edge.ChannelPoint, edge.ChannelID,
                edge.Capacity)

        // Otherwise, then we expect the funding script to be present on the
        // edge since it would have been fetched when the gossiper validated the
        // announcement.
        fundingPkScript, err := edge.FundingScript.UnwrapOrErr(fmt.Errorf(
                "expected the funding transaction script to be set",
        ))
        if err != nil {
                return err
        }

        // As a new edge has been added to the channel graph, we'll update the
        // current UTXO filter within our active FilteredChainView so we are
        // notified if/when this channel is closed.
        filterUpdate := []graphdb.EdgePoint{
                {
                        FundingPkScript: fundingPkScript,
                        OutPoint:        edge.ChannelPoint,
                },
        }

        err = b.cfg.ChainView.UpdateFilter(filterUpdate, b.bestHeight.Load())
        if err != nil {
                return errors.Errorf("unable to update chain "+
                        "view: %v", err)
        }

        return nil
}

// UpdateEdge is used to update edge information, without this message edge
// considered as not fully constructed.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) UpdateEdge(update *models.ChannelEdgePolicy,
        op ...batch.SchedulerOption) error {

        rMsg := &routingMsg{
                msg: update,
                op:  op,
                err: make(chan error, 1),
        }

        select {
        case b.networkUpdates <- rMsg:
                select {
                case err := <-rMsg.err:
                        return err
                case <-b.quit:
                        return ErrGraphBuilderShuttingDown
                }
        case <-b.quit:
                return ErrGraphBuilderShuttingDown
        }
}

// updateEdge validates the new edge policy against what we currently have
// persisted in the graph, and then applies it to the graph if the update is
// considered fresh enough and if we actually have a channel persisted for the
// given update.
func (b *Builder) updateEdge(policy *models.ChannelEdgePolicy,
        op ...batch.SchedulerOption) error {

        log.Debugf("Received ChannelEdgePolicy for channel %v",
                policy.ChannelID)

        // We make sure to hold the mutex for this channel ID, such that no
        // other goroutine is concurrently doing database accesses for the same
        // channel ID.
        b.channelEdgeMtx.Lock(policy.ChannelID)
        defer b.channelEdgeMtx.Unlock(policy.ChannelID)

        edge1Timestamp, edge2Timestamp, exists, isZombie, err :=
                b.cfg.Graph.HasChannelEdge(policy.ChannelID)
        if err != nil && !errors.Is(err, graphdb.ErrGraphNoEdgesFound) {
                return errors.Errorf("unable to check for edge existence: %v",
                        err)
        }

        // If the channel is marked as a zombie in our database, and
        // we consider this a stale update, then we should not apply the
        // policy.
        isStaleUpdate := time.Since(policy.LastUpdate) >
                b.cfg.ChannelPruneExpiry

        if isZombie && isStaleUpdate {
                return NewErrf(ErrIgnored, "ignoring stale update "+
                        "(flags=%v|%v) for zombie chan_id=%v",
                        policy.MessageFlags, policy.ChannelFlags,
                        policy.ChannelID)
        }

        // If the channel doesn't exist in our database, we cannot apply the
        // updated policy.
        if !exists {
                return NewErrf(ErrIgnored, "ignoring update (flags=%v|%v) for "+
                        "unknown chan_id=%v", policy.MessageFlags,
                        policy.ChannelFlags, policy.ChannelID)
        }

        log.Debugf("Found edge1Timestamp=%v, edge2Timestamp=%v",
                edge1Timestamp, edge2Timestamp)

        // As edges are directional edge node has a unique policy for the
        // direction of the edge they control. Therefore, we first check if we
        // already have the most up-to-date information for that edge. If this
        // message has a timestamp not strictly newer than what we already know
        // of we can exit early.
        switch policy.ChannelFlags & lnwire.ChanUpdateDirection {
        // A flag set of 0 indicates this is an announcement for the "first"
        // node in the channel.
        case 0:
                // Ignore outdated message.
                if !edge1Timestamp.Before(policy.LastUpdate) {
                        return NewErrf(ErrOutdated, "Ignoring "+
                                "outdated update (flags=%v|%v) for "+
                                "known chan_id=%v", policy.MessageFlags,
                                policy.ChannelFlags, policy.ChannelID)
                }

        // Similarly, a flag set of 1 indicates this is an announcement
        // for the "second" node in the channel.
        case 1:
                // Ignore outdated message.
                if !edge2Timestamp.Before(policy.LastUpdate) {
                        return NewErrf(ErrOutdated, "Ignoring "+
                                "outdated update (flags=%v|%v) for "+
                                "known chan_id=%v", policy.MessageFlags,
                                policy.ChannelFlags, policy.ChannelID)
                }
        }

        // Now that we know this isn't a stale update, we'll apply the new edge
        // policy to the proper directional edge within the channel graph.
        if err = b.cfg.Graph.UpdateEdgePolicy(policy, op...); err != nil {
                err := errors.Errorf("unable to add channel: %v", err)
                log.Error(err)
                return err
        }

        log.Tracef("New channel update applied: %v",
                lnutils.SpewLogClosure(policy))
        b.stats.incNumChannelUpdates()

        return nil
}

// CurrentBlockHeight returns the block height from POV of the router subsystem.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) CurrentBlockHeight() (uint32, error) {
        _, height, err := b.cfg.Chain.GetBestBlock()
        return uint32(height), err
}

// SyncedHeight returns the block height to which the router subsystem currently
// is synced to. This can differ from the above chain height if the goroutine
// responsible for processing the blocks isn't yet up to speed.
func (b *Builder) SyncedHeight() uint32 {
        return b.bestHeight.Load()
}

// GetChannelByID return the channel by the channel id.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) GetChannelByID(chanID lnwire.ShortChannelID) (
        *models.ChannelEdgeInfo,
        *models.ChannelEdgePolicy,
        *models.ChannelEdgePolicy, error) {

        return b.cfg.Graph.FetchChannelEdgesByID(chanID.ToUint64())
}

// FetchLightningNode attempts to look up a target node by its identity public
// key. graphdb.ErrGraphNodeNotFound is returned if the node doesn't exist
// within the graph.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) FetchLightningNode(
        node route.Vertex) (*models.LightningNode, error) {

        return b.cfg.Graph.FetchLightningNode(node)
}

// ForAllOutgoingChannels is used to iterate over all outgoing channels owned by
// the router.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) ForAllOutgoingChannels(cb func(*models.ChannelEdgeInfo,
        *models.ChannelEdgePolicy) error) error {

        return b.cfg.Graph.ForEachNodeChannel(b.cfg.SelfNode,
                func(_ kvdb.RTx, c *models.ChannelEdgeInfo,
                        e *models.ChannelEdgePolicy,
                        _ *models.ChannelEdgePolicy) error {

                        if e == nil {
                                return fmt.Errorf("channel from self node " +
                                        "has no policy")
                        }

                        return cb(c, e)
                },
        )
}

// AddProof updates the channel edge info with proof which is needed to
// properly announce the edge to the rest of the network.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) AddProof(chanID lnwire.ShortChannelID,
        proof *models.ChannelAuthProof) error {

        return b.cfg.Graph.AddEdgeProof(chanID, proof)
}

// IsStaleNode returns true if the graph source has a node announcement for the
// target node with a more recent timestamp.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) IsStaleNode(node route.Vertex,
        timestamp time.Time) bool {

        // If our attempt to assert that the node announcement is fresh fails,
        // then we know that this is actually a stale announcement.
        err := b.assertNodeAnnFreshness(node, timestamp)
        if err != nil {
                log.Debugf("Checking stale node %x got %v", node, err)
                return true
        }

        return false
}

// IsPublicNode determines whether the given vertex is seen as a public node in
// the graph from the graph's source node's point of view.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) IsPublicNode(node route.Vertex) (bool, error) {
        return b.cfg.Graph.IsPublicNode(node)
}

// IsKnownEdge returns true if the graph source already knows of the passed
// channel ID either as a live or zombie edge.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) IsKnownEdge(chanID lnwire.ShortChannelID) bool {
        _, _, exists, isZombie, _ := b.cfg.Graph.HasChannelEdge(
                chanID.ToUint64(),
        )

        return exists || isZombie
}

// IsZombieEdge returns true if the graph source has marked the given channel ID
// as a zombie edge.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) IsZombieEdge(chanID lnwire.ShortChannelID) (bool, error) {
        _, _, _, isZombie, err := b.cfg.Graph.HasChannelEdge(chanID.ToUint64())

        return isZombie, err
}

// IsStaleEdgePolicy returns true if the graph source has a channel edge for
// the passed channel ID (and flags) that have a more recent timestamp.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) IsStaleEdgePolicy(chanID lnwire.ShortChannelID,
        timestamp time.Time, flags lnwire.ChanUpdateChanFlags) bool {

        edge1Timestamp, edge2Timestamp, exists, isZombie, err :=
                b.cfg.Graph.HasChannelEdge(chanID.ToUint64())
        if err != nil {
                log.Debugf("Check stale edge policy got error: %v", err)
                return false
        }

        // If we know of the edge as a zombie, then we'll make some additional
        // checks to determine if the new policy is fresh.
        if isZombie {
                // When running with AssumeChannelValid, we also prune channels
                // if both of their edges are disabled. We'll mark the new
                // policy as stale if it remains disabled.
                if b.cfg.AssumeChannelValid {
                        isDisabled := flags&lnwire.ChanUpdateDisabled ==
                                lnwire.ChanUpdateDisabled
                        if isDisabled {
                                return true
                        }
                }

                // Otherwise, we'll fall back to our usual ChannelPruneExpiry.
                return time.Since(timestamp) > b.cfg.ChannelPruneExpiry
        }

        // If we don't know of the edge, then it means it's fresh (thus not
        // stale).
        if !exists {
                return false
        }

        // As edges are directional edge node has a unique policy for the
        // direction of the edge they control. Therefore, we first check if we
        // already have the most up-to-date information for that edge. If so,
        // then we can exit early.
        switch {
        // A flag set of 0 indicates this is an announcement for the "first"
        // node in the channel.
        case flags&lnwire.ChanUpdateDirection == 0:
                return !edge1Timestamp.Before(timestamp)

        // Similarly, a flag set of 1 indicates this is an announcement for the
        // "second" node in the channel.
        case flags&lnwire.ChanUpdateDirection == 1:
                return !edge2Timestamp.Before(timestamp)
        }

        return false
}

// MarkEdgeLive clears an edge from our zombie index, deeming it as live.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (b *Builder) MarkEdgeLive(chanID lnwire.ShortChannelID) error {
        return b.cfg.Graph.MarkEdgeLive(chanID.ToUint64())
}

lightningnetwork / lnd / 13440912774

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