lnd.xprv/channelnotifier/channelnotifier.go

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package channelnotifier
import (
"sync"
"github.com/btcsuite/btcd/wire"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/subscribe"
)
// ChannelNotifier is a subsystem which all active, inactive, and closed channel
// events pipe through. It takes subscriptions for its events, and whenever
// it receives a new event it notifies its subscribers over the proper channel.
type ChannelNotifier struct {
started sync.Once
stopped sync.Once
ntfnServer *subscribe.Server
chanDB *channeldb.DB
}
// PendingOpenChannelEvent represents a new event where a new channel has
// entered a pending open state.
type PendingOpenChannelEvent struct {
// ChannelPoint is the channel outpoint for the new channel.
ChannelPoint *wire.OutPoint
// PendingChannel is the channel configuration for the newly created
// channel. This might not have been persisted to the channel DB yet
// because we are still waiting for the final message from the remote
// peer.
PendingChannel *channeldb.OpenChannel
}
// OpenChannelEvent represents a new event where a channel goes from pending
// open to open.
type OpenChannelEvent struct {
// Channel is the channel that has become open.
Channel *channeldb.OpenChannel
}
// ActiveLinkEvent represents a new event where the link becomes active in the
// switch. This happens before the ActiveChannelEvent.
type ActiveLinkEvent struct {
// ChannelPoint is the channel point for the newly active channel.
ChannelPoint *wire.OutPoint
}
// ActiveChannelEvent represents a new event where a channel becomes active.
type ActiveChannelEvent struct {
// ChannelPoint is the channelpoint for the newly active channel.
ChannelPoint *wire.OutPoint
}
// InactiveChannelEvent represents a new event where a channel becomes inactive.
type InactiveChannelEvent struct {
// ChannelPoint is the channelpoint for the newly inactive channel.
ChannelPoint *wire.OutPoint
}
// ClosedChannelEvent represents a new event where a channel becomes closed.
type ClosedChannelEvent struct {
// CloseSummary is the summary of the channel close that has occurred.
CloseSummary *channeldb.ChannelCloseSummary
}
// New creates a new channel notifier. The ChannelNotifier gets channel
// events from peers and from the chain arbitrator, and dispatches them to
// its clients.
func New(chanDB *channeldb.DB) *ChannelNotifier {
return &ChannelNotifier{
ntfnServer: subscribe.NewServer(),
chanDB: chanDB,
}
}
// Start starts the ChannelNotifier and all goroutines it needs to carry out its task.
func (c *ChannelNotifier) Start() error {
var err error
c.started.Do(func() {
log.Trace("ChannelNotifier starting")
err = c.ntfnServer.Start()
})
return err
}
// Stop signals the notifier for a graceful shutdown.
func (c *ChannelNotifier) Stop() error {
var err error
c.stopped.Do(func() {
err = c.ntfnServer.Stop()
})
return err
}
// SubscribeChannelEvents returns a subscribe.Client that will receive updates
// any time the Server is made aware of a new event. The subscription provides
// channel events from the point of subscription onwards.
//
// TODO(carlaKC): update to allow subscriptions to specify a block height from
// which we would like to subscribe to events.
func (c *ChannelNotifier) SubscribeChannelEvents() (*subscribe.Client, error) {
return c.ntfnServer.Subscribe()
}
// NotifyPendingOpenChannelEvent notifies the channelEventNotifier goroutine
// that a new channel is pending. The pending channel is passed as a parameter
// instead of read from the database because it might not yet have been
// persisted to the DB because we still wait for the final message from the
// remote peer.
func (c *ChannelNotifier) NotifyPendingOpenChannelEvent(chanPoint wire.OutPoint,
pendingChan *channeldb.OpenChannel) {
event := PendingOpenChannelEvent{
ChannelPoint: &chanPoint,
PendingChannel: pendingChan,
}
if err := c.ntfnServer.SendUpdate(event); err != nil {
log.Warnf("Unable to send pending open channel update: %v", err)
}
}
// NotifyOpenChannelEvent notifies the channelEventNotifier goroutine that a
// channel has gone from pending open to open.
func (c *ChannelNotifier) NotifyOpenChannelEvent(chanPoint wire.OutPoint) {
// Fetch the relevant channel from the database.
channel, err := c.chanDB.FetchChannel(chanPoint)
if err != nil {
log.Warnf("Unable to fetch open channel from the db: %v", err)
}
// Send the open event to all channel event subscribers.
event := OpenChannelEvent{Channel: channel}
if err := c.ntfnServer.SendUpdate(event); err != nil {
log.Warnf("Unable to send open channel update: %v", err)
}
}
// NotifyClosedChannelEvent notifies the channelEventNotifier goroutine that a
// channel has closed.
func (c *ChannelNotifier) NotifyClosedChannelEvent(chanPoint wire.OutPoint) {
// Fetch the relevant closed channel from the database.
closeSummary, err := c.chanDB.FetchClosedChannel(&chanPoint)
if err != nil {
log.Warnf("Unable to fetch closed channel summary from the db: %v", err)
}
// Send the closed event to all channel event subscribers.
event := ClosedChannelEvent{CloseSummary: closeSummary}
if err := c.ntfnServer.SendUpdate(event); err != nil {
log.Warnf("Unable to send closed channel update: %v", err)
}
}
// NotifyActiveLinkEvent notifies the channelEventNotifier goroutine that a
// link has been added to the switch.
func (c *ChannelNotifier) NotifyActiveLinkEvent(chanPoint wire.OutPoint) {
event := ActiveLinkEvent{ChannelPoint: &chanPoint}
if err := c.ntfnServer.SendUpdate(event); err != nil {
log.Warnf("Unable to send active link update: %v", err)
}
}
// NotifyActiveChannelEvent notifies the channelEventNotifier goroutine that a
// channel is active.
func (c *ChannelNotifier) NotifyActiveChannelEvent(chanPoint wire.OutPoint) {
event := ActiveChannelEvent{ChannelPoint: &chanPoint}
if err := c.ntfnServer.SendUpdate(event); err != nil {
log.Warnf("Unable to send active channel update: %v", err)
}
}
// NotifyInactiveChannelEvent notifies the channelEventNotifier goroutine that a
// channel is inactive.
func (c *ChannelNotifier) NotifyInactiveChannelEvent(chanPoint wire.OutPoint) {
event := InactiveChannelEvent{ChannelPoint: &chanPoint}
if err := c.ntfnServer.SendUpdate(event); err != nil {
log.Warnf("Unable to send inactive channel update: %v", err)
}
}