lnd.xprv/autopilot/manager.go
Johan T. Halseth 6310ed0f1c
autopilot: add autopilot.Manager
This commit adds a new type Manager responsible for managing an
autopilot agent, making it possible to start and stop it at runtime.
2018-12-13 12:26:29 +01:00

268 lines
6.5 KiB
Go

package autopilot
import (
"sync"
"sync/atomic"
"github.com/btcsuite/btcd/btcec"
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/routing"
)
// ManagerCfg houses a set of values and methods that is passed to the Manager
// for it to properly manage its autopilot agent.
type ManagerCfg struct {
// Self is the public key of the lnd instance. It is used to making
// sure the autopilot is not opening channels to itself.
Self *btcec.PublicKey
// PilotCfg is the config of the autopilot agent managed by the
// Manager.
PilotCfg *Config
// ChannelState is a function closure that returns the current set of
// channels managed by this node.
ChannelState func() ([]Channel, error)
// SubscribeTransactions is used to get a subscription for transactions
// relevant to this node's wallet.
SubscribeTransactions func() (lnwallet.TransactionSubscription, error)
// SubscribeTopology is used to get a subscription for topology changes
// on the network.
SubscribeTopology func() (*routing.TopologyClient, error)
}
// Manager is struct that manages an autopilot agent, making it possible to
// enable and disable it at will, and hand it relevant external information.
// It implements the autopilot grpc service, which is used to get data about
// the running autopilot, and give it relevant information.
type Manager struct {
started uint32 // To be used atomically.
stopped uint32 // To be used atomically.
cfg *ManagerCfg
// pilot is the current autopilot agent. It will be nil if the agent is
// disabled.
pilot *Agent
quit chan struct{}
wg sync.WaitGroup
sync.Mutex
}
// NewManager creates a new instance of the Manager from the passed config.
func NewManager(cfg *ManagerCfg) (*Manager, error) {
return &Manager{
cfg: cfg,
quit: make(chan struct{}),
}, nil
}
// Start starts the Manager.
func (m *Manager) Start() error {
if !atomic.CompareAndSwapUint32(&m.started, 0, 1) {
return nil
}
return nil
}
// Stop stops the Manager. If an autopilot agent is active, it will also be
// stopped.
func (m *Manager) Stop() error {
if !atomic.CompareAndSwapUint32(&m.stopped, 0, 1) {
return nil
}
if err := m.StopAgent(); err != nil {
log.Errorf("Unable to stop pilot: %v", err)
}
close(m.quit)
m.wg.Wait()
return nil
}
// IsActive returns whether the autopilot agent is currently active.
func (m *Manager) IsActive() bool {
m.Lock()
defer m.Unlock()
return m.pilot != nil
}
// StartAgent creates and starts an autopilot agent from the Manager's
// config.
func (m *Manager) StartAgent() error {
m.Lock()
defer m.Unlock()
// Already active.
if m.pilot != nil {
return nil
}
// Next, we'll fetch the current state of open channels from the
// database to use as initial state for the auto-pilot agent.
initialChanState, err := m.cfg.ChannelState()
if err != nil {
return err
}
// Now that we have all the initial dependencies, we can create the
// auto-pilot instance itself.
m.pilot, err = New(*m.cfg.PilotCfg, initialChanState)
if err != nil {
return err
}
if err := m.pilot.Start(); err != nil {
return err
}
// Finally, we'll need to subscribe to two things: incoming
// transactions that modify the wallet's balance, and also any graph
// topology updates.
txnSubscription, err := m.cfg.SubscribeTransactions()
if err != nil {
defer m.pilot.Stop()
return err
}
graphSubscription, err := m.cfg.SubscribeTopology()
if err != nil {
defer m.pilot.Stop()
defer txnSubscription.Cancel()
return err
}
// We'll launch a goroutine to provide the agent with notifications
// whenever the balance of the wallet changes.
// TODO(halseth): can lead to panic if in process of shutting down.
m.wg.Add(1)
go func() {
defer txnSubscription.Cancel()
defer m.wg.Done()
for {
select {
case <-txnSubscription.ConfirmedTransactions():
m.pilot.OnBalanceChange()
// We won't act upon new unconfirmed transaction, as
// we'll only use confirmed outputs when funding.
// However, we will still drain this request in order
// to avoid goroutine leaks, and ensure we promptly
// read from the channel if available.
case <-txnSubscription.UnconfirmedTransactions():
case <-m.pilot.quit:
return
case <-m.quit:
return
}
}
}()
// We'll also launch a goroutine to provide the agent with
// notifications for when the graph topology controlled by the node
// changes.
m.wg.Add(1)
go func() {
defer graphSubscription.Cancel()
defer m.wg.Done()
for {
select {
case topChange, ok := <-graphSubscription.TopologyChanges:
// If the router is shutting down, then we will
// as well.
if !ok {
return
}
for _, edgeUpdate := range topChange.ChannelEdgeUpdates {
// If this isn't an advertisement by
// the backing lnd node, then we'll
// continue as we only want to add
// channels that we've created
// ourselves.
if !edgeUpdate.AdvertisingNode.IsEqual(m.cfg.Self) {
continue
}
// If this is indeed a channel we
// opened, then we'll convert it to the
// autopilot.Channel format, and notify
// the pilot of the new channel.
chanNode := NewNodeID(
edgeUpdate.ConnectingNode,
)
chanID := lnwire.NewShortChanIDFromInt(
edgeUpdate.ChanID,
)
edge := Channel{
ChanID: chanID,
Capacity: edgeUpdate.Capacity,
Node: chanNode,
}
m.pilot.OnChannelOpen(edge)
}
// For each closed channel, we'll obtain
// the chanID of the closed channel and send it
// to the pilot.
for _, chanClose := range topChange.ClosedChannels {
chanID := lnwire.NewShortChanIDFromInt(
chanClose.ChanID,
)
m.pilot.OnChannelClose(chanID)
}
// If new nodes were added to the graph, or nod
// information has changed, we'll poke autopilot
// to see if it can make use of them.
if len(topChange.NodeUpdates) > 0 {
m.pilot.OnNodeUpdates()
}
case <-m.pilot.quit:
return
case <-m.quit:
return
}
}
}()
log.Debugf("Manager started autopilot agent")
return nil
}
// StopAgent stops any active autopilot agent.
func (m *Manager) StopAgent() error {
m.Lock()
defer m.Unlock()
// Not active, so we can return early.
if m.pilot == nil {
return nil
}
if err := m.pilot.Stop(); err != nil {
return err
}
// Make sure to nil the current agent, indicating it is no longer
// active.
m.pilot = nil
log.Debugf("Manager stopped autopilot agent")
return nil
}