routing: add new paymentSession companion struct to missionControl
In this commit, we modify the pruning semantics of the missionControl struct. Before this commit, on each payment attempt, we would fetch a new graph pruned view each time. This served to instantly propagate any detected failures to all outstanding payment attempts. However, this meant that we could at times get stuck in a retry loop if sends take a few second, then we may prune an edge, try another, then the original edge is now unpruned. To remedy this, we now introduce the concept of a paymentSession. The session will start out as a snapshot of the latest graph prune view. Any payment failures are now reported directly to the paymentSession rather than missionControl. The rationale for this is that edges/vertexes pruned as result of failures will never decay for a local payment session, only for the global prune view. With this in place, we ensure that our set of prune view only grows for a session. Fixes #536.
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Olaoluwa Osuntokun
parent
912366ada5
commit
98f63cdce1
@ -77,69 +77,15 @@ func newMissionControl(g *channeldb.ChannelGraph,
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}
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}
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// ReportVertexFailure adds a vertex to the graph prune view after a client
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// reports a routing failure localized to the vertex. The time the vertex was
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// added is noted, as it'll be pruned from the view after a period of
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// vertexDecay.
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func (m *missionControl) ReportVertexFailure(v Vertex) {
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log.Debugf("Reporting vertex %v failure to Mission Control", v)
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// graphPruneView is a filter of sorts that path finding routines should
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// consult during the execution. Any edges or vertexes within the view should
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// be ignored during path finding. The contents of the view reflect the current
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// state of the wider network from the PoV of mission control compiled via HTLC
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// routing attempts in the past.
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type graphPruneView struct {
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edges map[uint64]struct{}
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m.Lock()
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m.failedVertexes[v] = time.Now()
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m.Unlock()
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}
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// ReportChannelFailure adds a channel to the graph prune view. The time the
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// channel was added is noted, as it'll be pruned from the view after a period
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// of edgeDecay.
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//
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// TODO(roasbeef): also add value attempted to send and capacity of channel
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func (m *missionControl) ReportChannelFailure(e uint64) {
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log.Debugf("Reporting edge %v failure to Mission Control", e)
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m.Lock()
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m.failedEdges[e] = time.Now()
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m.Unlock()
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}
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// RequestRoute returns a route which is likely to be capable for successfully
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// routing the specified HTLC payment to the target node. Initially the first
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// set of paths returned from this method may encounter routing failure along
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// the way, however as more payments are sent, mission control will start to
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// build an up to date view of the network itself. With each payment a new area
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// will be explored, which feeds into the recommendations made for routing.
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//
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// NOTE: This function is safe for concurrent access.
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func (m *missionControl) RequestRoute(payment *LightningPayment,
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height uint32, finalCltvDelta uint16) (*Route, error) {
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// First, we'll query mission control for it's current recommendation
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// on the edges/vertexes to ignore during path finding.
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pruneView := m.GraphPruneView()
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// TODO(roasbeef): sync logic amongst dist sys
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// Taking into account this prune view, we'll attempt to locate a path
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// to our destination, respecting the recommendations from
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// missionControl.
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path, err := findPath(nil, m.graph, m.selfNode, payment.Target,
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pruneView.vertexes, pruneView.edges, payment.Amount)
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if err != nil {
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return nil, err
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}
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// With the next candidate path found, we'll attempt to turn this into
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// a route by applying the time-lock and fee requirements.
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sourceVertex := NewVertex(m.selfNode.PubKey)
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route, err := newRoute(payment.Amount, sourceVertex, path, height,
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finalCltvDelta)
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if err != nil {
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// TODO(roasbeef): return which edge/vertex didn't work
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// out
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return nil, err
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}
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return route, err
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vertexes map[Vertex]struct{}
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}
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// GraphPruneView returns a new graphPruneView instance which is to be
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@ -147,7 +93,7 @@ func (m *missionControl) RequestRoute(payment *LightningPayment,
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// prune view, it is to be ignored as a goroutine has had issues routing
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// through it successfully. Within this method the main view of the
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// missionControl is garbage collected as entires are detected to be "stale".
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func (m *missionControl) GraphPruneView() *graphPruneView {
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func (m *missionControl) GraphPruneView() graphPruneView {
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// First, we'll grab the current time, this value will be used to
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// determine if an entry is stale or not.
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now := time.Now()
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@ -190,21 +136,115 @@ func (m *missionControl) GraphPruneView() *graphPruneView {
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log.Debugf("Mission Control returning prune view of %v edges, %v "+
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"vertexes", len(edges), len(vertexes))
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return &graphPruneView{
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return graphPruneView{
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edges: edges,
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vertexes: vertexes,
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}
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}
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// graphPruneView is a filter of sorts that path finding routines should
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// consult during the execution. Any edges or vertexes within the view should
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// be ignored during path finding. The contents of the view reflect the current
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// state of the wider network from the PoV of mission control compiled via HTLC
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// routing attempts in the past.
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type graphPruneView struct {
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edges map[uint64]struct{}
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// paymentSession is used during an HTLC routings session to prune the local
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// chain view in response to failures, and also report those failures back to
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// missionControl. The snapshot copied for this session will only ever grow,
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// and will now be pruned after a decay like the main view within mission
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// control. We do this as we want to avoid the case where we continually try a
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// bad edge or route multiple times in a session. This can lead to an infinite
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// loop if payment attempts take long enough.
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type paymentSession struct {
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pruneViewSnapshot graphPruneView
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vertexes map[Vertex]struct{}
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mc *missionControl
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}
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// NewPaymentSession creates a new payment session backed by the latest prune
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// view from Mission Control.
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func (m *missionControl) NewPaymentSession() *paymentSession {
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viewSnapshot := m.GraphPruneView()
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return &paymentSession{
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pruneViewSnapshot: viewSnapshot,
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mc: m,
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}
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}
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// ReportVertexFailure adds a vertex to the graph prune view after a client
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// reports a routing failure localized to the vertex. The time the vertex was
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// added is noted, as it'll be pruned from the shared view after a period of
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// vertexDecay. However, the vertex will remain pruned for the *local* session.
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// This ensures we don't retry this vertex during the payment attempt.
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func (p *paymentSession) ReportVertexFailure(v Vertex) {
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log.Debugf("Reporting vertex %v failure to Mission Control", v)
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// First, we'll add the failed vertex to our local prune view snapshot.
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p.pruneViewSnapshot.vertexes[v] = struct{}{}
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// With the vertex added, we'll now report back to the global prune
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// view, with this new piece of information so it can be utilized for
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// new payment sessions.
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p.mc.Lock()
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p.mc.failedVertexes[v] = time.Now()
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p.mc.Unlock()
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}
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// ReportChannelFailure adds a channel to the graph prune view. The time the
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// channel was added is noted, as it'll be pruned from the global view after a
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// period of edgeDecay. However, the edge will remain pruned for the duration
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// of the *local* session. This ensures that we don't flap by continually
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// retrying an edge after its pruning has expired.
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//
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// TODO(roasbeef): also add value attempted to send and capacity of channel
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func (p *paymentSession) ReportChannelFailure(e uint64) {
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log.Debugf("Reporting edge %v failure to Mission Control", e)
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// First, we'll add the failed edge to our local prune view snapshot.
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p.pruneViewSnapshot.edges[e] = struct{}{}
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// With the edge added, we'll now report back to the global prune view,
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// with this new piece of information so it can be utilized for new
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// payment sessions.
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p.mc.Lock()
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p.mc.failedEdges[e] = time.Now()
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p.mc.Unlock()
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}
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// RequestRoute returns a route which is likely to be capable for successfully
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// routing the specified HTLC payment to the target node. Initially the first
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// set of paths returned from this method may encounter routing failure along
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// the way, however as more payments are sent, mission control will start to
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// build an up to date view of the network itself. With each payment a new area
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// will be explored, which feeds into the recommendations made for routing.
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//
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// NOTE: This function is safe for concurrent access.
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func (p *paymentSession) RequestRoute(payment *LightningPayment,
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height uint32, finalCltvDelta uint16) (*Route, error) {
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// First, we'll obtain our current prune view snapshot. This view will
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// only ever grow during the duration of this payment session, never
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// shrinking.
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pruneView := p.pruneViewSnapshot
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// TODO(roasbeef): sync logic amongst dist sys
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// Taking into account this prune view, we'll attempt to locate a path
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// to our destination, respecting the recommendations from
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// missionControl.
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path, err := findPath(nil, p.mc.graph, p.mc.selfNode, payment.Target,
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pruneView.vertexes, pruneView.edges, payment.Amount)
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if err != nil {
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return nil, err
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}
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// With the next candidate path found, we'll attempt to turn this into
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// a route by applying the time-lock and fee requirements.
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sourceVertex := NewVertex(p.mc.selfNode.PubKey)
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route, err := newRoute(payment.Amount, sourceVertex, path, height,
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finalCltvDelta)
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if err != nil {
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// TODO(roasbeef): return which edge/vertex didn't work
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// out
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return nil, err
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}
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return route, err
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}
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// ResetHistory resets the history of missionControl returning it to a state as
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@ -1372,15 +1372,21 @@ func (r *ChannelRouter) SendPayment(payment *LightningPayment) ([32]byte, *Route
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finalCLTVDelta = *payment.FinalCLTVDelta
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}
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// Before starting the HTLC routing attempt, we'll create a fresh
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// payment session which will report our errors back to mission
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// control.
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paySession := r.missionControl.NewPaymentSession()
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// We'll continue until either our payment succeeds, or we encounter a
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// critical error during path finding.
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for {
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// We'll kick things off by requesting a new route from mission
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// control, which will incoroporate the current best known
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// state of the channel graph and our past HTLC routing
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// control, which will incorporate the current best known state
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// of the channel graph and our past HTLC routing
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// successes/failures.
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route, err := r.missionControl.RequestRoute(payment,
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uint32(currentHeight), finalCLTVDelta)
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route, err := paySession.RequestRoute(
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payment, uint32(currentHeight), finalCLTVDelta,
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)
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if err != nil {
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// If we're unable to successfully make a payment using
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// any of the routes we've found, then return an error.
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@ -1546,7 +1552,7 @@ func (r *ChannelRouter) SendPayment(payment *LightningPayment) ([32]byte, *Route
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// If the channel was found, then we'll inform
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// mission control of this failure so future
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// attempts avoid this link temporarily.
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r.missionControl.ReportChannelFailure(badChan)
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paySession.ReportChannelFailure(badChan)
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continue
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// If the send fail due to a node not having the
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@ -1581,7 +1587,7 @@ func (r *ChannelRouter) SendPayment(payment *LightningPayment) ([32]byte, *Route
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// Once we've located the vertex, we'll report
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// this failure to missionControl and restart
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// path finding.
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r.missionControl.ReportVertexFailure(missingNode)
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paySession.ReportVertexFailure(missingNode)
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continue
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// If the node wasn't able to forward for which ever
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@ -1593,7 +1599,7 @@ func (r *ChannelRouter) SendPayment(payment *LightningPayment) ([32]byte, *Route
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continue
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}
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r.missionControl.ReportVertexFailure(missingNode)
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paySession.ReportVertexFailure(missingNode)
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continue
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// If we get a permanent channel or node failure, then
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