lnd.xprv/invoices/invoiceregistry.go

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package invoices
import (
"errors"
"fmt"
"sync"
"sync/atomic"
"github.com/davecgh/go-spew/spew"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/lntypes"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/queue"
)
var (
// ErrInvoiceExpiryTooSoon is returned when an invoice is attempted to be
// accepted or settled with not enough blocks remaining.
ErrInvoiceExpiryTooSoon = errors.New("invoice expiry too soon")
// ErrInvoiceAmountTooLow is returned when an invoice is attempted to be
// accepted or settled with an amount that is too low.
ErrInvoiceAmountTooLow = errors.New("paid amount less than invoice amount")
// ErrShuttingDown is returned when an operation failed because the
// invoice registry is shutting down.
ErrShuttingDown = errors.New("invoice registry shutting down")
)
// HodlEvent describes how an htlc should be resolved. If HodlEvent.Preimage is
// set, the event indicates a settle event. If Preimage is nil, it is a cancel
// event.
type HodlEvent struct {
// Preimage is the htlc preimage. Its value is nil in case of a cancel.
Preimage *lntypes.Preimage
// Hash is the htlc hash.
Hash lntypes.Hash
}
// InvoiceRegistry is a central registry of all the outstanding invoices
// created by the daemon. The registry is a thin wrapper around a map in order
// to ensure that all updates/reads are thread safe.
type InvoiceRegistry struct {
sync.RWMutex
cdb *channeldb.DB
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clientMtx sync.Mutex
nextClientID uint32
notificationClients map[uint32]*InvoiceSubscription
singleNotificationClients map[uint32]*SingleInvoiceSubscription
newSubscriptions chan *InvoiceSubscription
subscriptionCancels chan uint32
// invoiceEvents is a single channel over which both invoice updates and
// new single invoice subscriptions are carried.
invoiceEvents chan interface{}
// decodeFinalCltvExpiry is a function used to decode the final expiry
// value from the payment request.
decodeFinalCltvExpiry func(invoice string) (uint32, error)
// subscriptions is a map from a payment hash to a list of subscribers.
// It is used for efficient notification of links.
hodlSubscriptions map[lntypes.Hash]map[chan<- interface{}]struct{}
// reverseSubscriptions tracks hashes subscribed to per subscriber. This
// is used to unsubscribe from all hashes efficiently.
hodlReverseSubscriptions map[chan<- interface{}]map[lntypes.Hash]struct{}
// finalCltvRejectDelta defines the number of blocks before the expiry
// of the htlc where we no longer settle it as an exit hop and instead
// cancel it back. Normally this value should be lower than the cltv
// expiry of any invoice we create and the code effectuating this should
// not be hit.
finalCltvRejectDelta int32
wg sync.WaitGroup
quit chan struct{}
}
// NewRegistry creates a new invoice registry. The invoice registry
// wraps the persistent on-disk invoice storage with an additional in-memory
// layer. The in-memory layer is in place such that debug invoices can be added
// which are volatile yet available system wide within the daemon.
func NewRegistry(cdb *channeldb.DB, decodeFinalCltvExpiry func(invoice string) (
uint32, error), finalCltvRejectDelta int32) *InvoiceRegistry {
return &InvoiceRegistry{
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cdb: cdb,
notificationClients: make(map[uint32]*InvoiceSubscription),
singleNotificationClients: make(map[uint32]*SingleInvoiceSubscription),
newSubscriptions: make(chan *InvoiceSubscription),
subscriptionCancels: make(chan uint32),
invoiceEvents: make(chan interface{}, 100),
hodlSubscriptions: make(map[lntypes.Hash]map[chan<- interface{}]struct{}),
hodlReverseSubscriptions: make(map[chan<- interface{}]map[lntypes.Hash]struct{}),
decodeFinalCltvExpiry: decodeFinalCltvExpiry,
finalCltvRejectDelta: finalCltvRejectDelta,
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quit: make(chan struct{}),
}
}
// Start starts the registry and all goroutines it needs to carry out its task.
func (i *InvoiceRegistry) Start() error {
i.wg.Add(1)
go i.invoiceEventNotifier()
return nil
}
// Stop signals the registry for a graceful shutdown.
func (i *InvoiceRegistry) Stop() {
close(i.quit)
i.wg.Wait()
}
// invoiceEvent represents a new event that has modified on invoice on disk.
// Only two event types are currently supported: newly created invoices, and
// instance where invoices are settled.
type invoiceEvent struct {
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hash lntypes.Hash
invoice *channeldb.Invoice
}
// invoiceEventNotifier is the dedicated goroutine responsible for accepting
// new notification subscriptions, cancelling old subscriptions, and
// dispatching new invoice events.
func (i *InvoiceRegistry) invoiceEventNotifier() {
defer i.wg.Done()
for {
select {
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// A new invoice subscription for all invoices has just arrived!
// We'll query for any backlog notifications, then add it to the
// set of clients.
case newClient := <-i.newSubscriptions:
// Before we add the client to our set of active
// clients, we'll first attempt to deliver any backlog
// invoice events.
err := i.deliverBacklogEvents(newClient)
if err != nil {
log.Errorf("unable to deliver backlog invoice "+
"notifications: %v", err)
}
log.Infof("New invoice subscription "+
"client: id=%v", newClient.id)
// With the backlog notifications delivered (if any),
// we'll add this to our active subscriptions and
// continue.
i.notificationClients[newClient.id] = newClient
// A client no longer wishes to receive invoice notifications.
// So we'll remove them from the set of active clients.
case clientID := <-i.subscriptionCancels:
log.Infof("Cancelling invoice subscription for "+
"client=%v", clientID)
delete(i.notificationClients, clientID)
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delete(i.singleNotificationClients, clientID)
// An invoice event has come in. This can either be an update to
// an invoice or a new single invoice subscriber. Both type of
// events are passed in via the same channel, to make sure that
// subscribers get a consistent view of the event sequence.
case event := <-i.invoiceEvents:
switch e := event.(type) {
// A sub-systems has just modified the invoice state, so
// we'll dispatch notifications to all registered
// clients.
case *invoiceEvent:
// For backwards compatibility, do not notify
// all invoice subscribers of cancel and accept
// events.
state := e.invoice.Terms.State
if state != channeldb.ContractCanceled &&
state != channeldb.ContractAccepted {
i.dispatchToClients(e)
}
i.dispatchToSingleClients(e)
// A new single invoice subscription has arrived. Add it
// to the set of clients. It is important to do this in
// sequence with any other invoice events, because an
// initial invoice update has already been sent out to
// the subscriber.
case *SingleInvoiceSubscription:
log.Infof("New single invoice subscription "+
"client: id=%v, hash=%v", e.id, e.hash)
i.singleNotificationClients[e.id] = e
}
case <-i.quit:
return
}
}
}
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// dispatchToSingleClients passes the supplied event to all notification clients
// that subscribed to all the invoice this event applies to.
func (i *InvoiceRegistry) dispatchToSingleClients(event *invoiceEvent) {
// Dispatch to single invoice subscribers.
for _, client := range i.singleNotificationClients {
if client.hash != event.hash {
continue
}
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client.notify(event)
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}
}
// dispatchToClients passes the supplied event to all notification clients that
// subscribed to all invoices. Add and settle indices are used to make sure that
// clients don't receive duplicate or unwanted events.
func (i *InvoiceRegistry) dispatchToClients(event *invoiceEvent) {
invoice := event.invoice
for clientID, client := range i.notificationClients {
// Before we dispatch this event, we'll check
// to ensure that this client hasn't already
// received this notification in order to
// ensure we don't duplicate any events.
// TODO(joostjager): Refactor switches.
state := event.invoice.Terms.State
switch {
// If we've already sent this settle event to
// the client, then we can skip this.
case state == channeldb.ContractSettled &&
client.settleIndex >= invoice.SettleIndex:
continue
// Similarly, if we've already sent this add to
// the client then we can skip this one.
case state == channeldb.ContractOpen &&
client.addIndex >= invoice.AddIndex:
continue
// These two states should never happen, but we
// log them just in case so we can detect this
// instance.
case state == channeldb.ContractOpen &&
client.addIndex+1 != invoice.AddIndex:
log.Warnf("client=%v for invoice "+
"notifications missed an update, "+
"add_index=%v, new add event index=%v",
clientID, client.addIndex,
invoice.AddIndex)
case state == channeldb.ContractSettled &&
client.settleIndex+1 != invoice.SettleIndex:
log.Warnf("client=%v for invoice "+
"notifications missed an update, "+
"settle_index=%v, new settle event index=%v",
clientID, client.settleIndex,
invoice.SettleIndex)
}
select {
case client.ntfnQueue.ChanIn() <- &invoiceEvent{
invoice: invoice,
}:
case <-i.quit:
return
}
// Each time we send a notification to a client, we'll record
// the latest add/settle index it has. We'll use this to ensure
// we don't send a notification twice, which can happen if a new
// event is added while we're catching up a new client.
switch event.invoice.Terms.State {
case channeldb.ContractSettled:
client.settleIndex = invoice.SettleIndex
case channeldb.ContractOpen:
client.addIndex = invoice.AddIndex
default:
log.Errorf("unexpected invoice state: %v",
event.invoice.Terms.State)
}
}
}
// deliverBacklogEvents will attempts to query the invoice database for any
// notifications that the client has missed since it reconnected last.
func (i *InvoiceRegistry) deliverBacklogEvents(client *InvoiceSubscription) error {
// First, we'll query the database to see if based on the provided
// addIndex and settledIndex we need to deliver any backlog
// notifications.
addEvents, err := i.cdb.InvoicesAddedSince(client.addIndex)
if err != nil {
return err
}
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settleEvents, err := i.cdb.InvoicesSettledSince(client.settleIndex)
if err != nil {
return err
}
// If we have any to deliver, then we'll append them to the end of the
// notification queue in order to catch up the client before delivering
// any new notifications.
for _, addEvent := range addEvents {
// We re-bind the loop variable to ensure we don't hold onto
// the loop reference causing is to point to the same item.
addEvent := addEvent
select {
case client.ntfnQueue.ChanIn() <- &invoiceEvent{
invoice: &addEvent,
}:
case <-i.quit:
return ErrShuttingDown
}
}
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for _, settleEvent := range settleEvents {
// We re-bind the loop variable to ensure we don't hold onto
// the loop reference causing is to point to the same item.
settleEvent := settleEvent
select {
case client.ntfnQueue.ChanIn() <- &invoiceEvent{
invoice: &settleEvent,
}:
case <-i.quit:
return ErrShuttingDown
}
}
return nil
}
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// deliverSingleBacklogEvents will attempt to query the invoice database to
// retrieve the current invoice state and deliver this to the subscriber. Single
// invoice subscribers will always receive the current state right after
// subscribing. Only in case the invoice does not yet exist, nothing is sent
// yet.
func (i *InvoiceRegistry) deliverSingleBacklogEvents(
client *SingleInvoiceSubscription) error {
invoice, err := i.cdb.LookupInvoice(client.hash)
// It is possible that the invoice does not exist yet, but the client is
// already watching it in anticipation.
if err == channeldb.ErrInvoiceNotFound ||
err == channeldb.ErrNoInvoicesCreated {
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return nil
}
if err != nil {
return err
}
err = client.notify(&invoiceEvent{
hash: client.hash,
invoice: &invoice,
})
if err != nil {
return err
}
return nil
}
// AddInvoice adds a regular invoice for the specified amount, identified by
// the passed preimage. Additionally, any memo or receipt data provided will
// also be stored on-disk. Once this invoice is added, subsystems within the
// daemon add/forward HTLCs are able to obtain the proper preimage required for
// redemption in the case that we're the final destination. We also return the
// addIndex of the newly created invoice which monotonically increases for each
// new invoice added. A side effect of this function is that it also sets
// AddIndex on the invoice argument.
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func (i *InvoiceRegistry) AddInvoice(invoice *channeldb.Invoice,
paymentHash lntypes.Hash) (uint64, error) {
i.Lock()
defer i.Unlock()
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log.Debugf("Invoice(%v): added %v", paymentHash,
newLogClosure(func() string {
return spew.Sdump(invoice)
}),
)
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addIndex, err := i.cdb.AddInvoice(invoice, paymentHash)
if err != nil {
return 0, err
}
// Now that we've added the invoice, we'll send dispatch a message to
// notify the clients of this new invoice.
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i.notifyClients(paymentHash, invoice, channeldb.ContractOpen)
return addIndex, nil
}
// LookupInvoice looks up an invoice by its payment hash (R-Hash), if found
// then we're able to pull the funds pending within an HTLC. We'll also return
// what the expected min final CLTV delta is, pre-parsed from the payment
// request. This may be used by callers to determine if an HTLC is well formed
// according to the cltv delta.
//
// TODO(roasbeef): ignore if settled?
func (i *InvoiceRegistry) LookupInvoice(rHash lntypes.Hash) (channeldb.Invoice, uint32, error) {
// We'll check the database to see if there's an existing matching
// invoice.
invoice, err := i.cdb.LookupInvoice(rHash)
if err != nil {
return channeldb.Invoice{}, 0, err
}
expiry, err := i.decodeFinalCltvExpiry(string(invoice.PaymentRequest))
if err != nil {
return channeldb.Invoice{}, 0, err
}
return invoice, expiry, nil
}
// checkHtlcParameters is a callback used inside invoice db transactions to
// atomically check-and-update an invoice.
func (i *InvoiceRegistry) checkHtlcParameters(invoice *channeldb.Invoice,
amtPaid lnwire.MilliSatoshi, htlcExpiry uint32, currentHeight int32) error {
// If the invoice is already canceled, there is no further checking to
// do.
if invoice.Terms.State == channeldb.ContractCanceled {
return channeldb.ErrInvoiceAlreadyCanceled
}
// If a payment has already been made, we only accept more payments if
// the amount is the exact same. This prevents probing with small
// amounts on settled invoices to find out the receiver node.
if invoice.AmtPaid != 0 && amtPaid != invoice.AmtPaid {
return ErrInvoiceAmountTooLow
}
// Return early in case the invoice was already accepted or settled. We
// don't want to check the expiry again, because it may be that we are
// just restarting.
switch invoice.Terms.State {
case channeldb.ContractAccepted:
return channeldb.ErrInvoiceAlreadyAccepted
case channeldb.ContractSettled:
return channeldb.ErrInvoiceAlreadySettled
}
// The invoice is still open. Check the expiry.
expiry, err := i.decodeFinalCltvExpiry(string(invoice.PaymentRequest))
if err != nil {
return err
}
if htlcExpiry < uint32(currentHeight+i.finalCltvRejectDelta) {
return ErrInvoiceExpiryTooSoon
}
if htlcExpiry < uint32(currentHeight)+expiry {
return ErrInvoiceExpiryTooSoon
}
// If an invoice amount is specified, check that enough is paid.
if invoice.Terms.Value > 0 && amtPaid < invoice.Terms.Value {
return ErrInvoiceAmountTooLow
}
return nil
}
// NotifyExitHopHtlc attempts to mark an invoice as settled. If the invoice is a
// debug invoice, then this method is a noop as debug invoices are never fully
// settled. The return value describes how the htlc should be resolved.
//
// When the preimage of the invoice is not yet known (hodl invoice), this
// function moves the invoice to the accepted state. When SettleHoldInvoice is
// called later, a resolution message will be send back to the caller via the
// provided hodlChan. Invoice registry sends on this channel what action needs
// to be taken on the htlc (settle or cancel). The caller needs to ensure that
// the channel is either buffered or received on from another goroutine to
// prevent deadlock.
func (i *InvoiceRegistry) NotifyExitHopHtlc(rHash lntypes.Hash,
amtPaid lnwire.MilliSatoshi, expiry uint32, currentHeight int32,
hodlChan chan<- interface{}, eob []byte) (*HodlEvent, error) {
i.Lock()
defer i.Unlock()
debugLog := func(s string) {
log.Debugf("Invoice(%x): %v, amt=%v, expiry=%v",
rHash[:], s, amtPaid, expiry)
}
// If this isn't a debug invoice, then we'll attempt to settle an
// invoice matching this rHash on disk (if one exists).
invoice, err := i.cdb.AcceptOrSettleInvoice(
rHash, amtPaid,
func(inv *channeldb.Invoice) error {
return i.checkHtlcParameters(
inv, amtPaid, expiry, currentHeight,
)
},
)
switch err {
// If invoice is already settled, settle htlc. This means we accept more
// payments to the same invoice hash.
//
// NOTE: Though our recovery and forwarding logic is predominately
// batched, settling invoices happens iteratively. We may reject one of
// two payments for the same rhash at first, but then restart and reject
// both after seeing that the invoice has been settled. Without any
// record of which one settles first, it is ambiguous as to which one
// actually settled the invoice. Thus, by accepting all payments, we
// eliminate the race condition that can lead to this inconsistency.
//
// TODO(conner): track ownership of settlements to properly recover from
// failures? or add batch invoice settlement
case channeldb.ErrInvoiceAlreadySettled:
debugLog("accepting duplicate payment to settled invoice")
return &HodlEvent{
Hash: rHash,
Preimage: &invoice.Terms.PaymentPreimage,
}, nil
// If invoice is already canceled, cancel htlc.
case channeldb.ErrInvoiceAlreadyCanceled:
debugLog("invoice already canceled")
return &HodlEvent{
Hash: rHash,
}, nil
// If invoice is already accepted, add this htlc to the list of
// subscribers.
case channeldb.ErrInvoiceAlreadyAccepted:
debugLog("accepting duplicate payment to accepted invoice")
i.hodlSubscribe(hodlChan, rHash)
return nil, nil
// If there are not enough blocks left, cancel the htlc.
case ErrInvoiceExpiryTooSoon:
debugLog("expiry too soon")
return &HodlEvent{
Hash: rHash,
}, nil
// If there are not enough blocks left, cancel the htlc.
case ErrInvoiceAmountTooLow:
debugLog("amount too low")
return &HodlEvent{
Hash: rHash,
}, nil
// If this call settled the invoice, settle the htlc. Otherwise
// subscribe for a future hodl event.
case nil:
i.notifyClients(rHash, invoice, invoice.Terms.State)
switch invoice.Terms.State {
case channeldb.ContractSettled:
debugLog("settled")
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return &HodlEvent{
Hash: rHash,
Preimage: &invoice.Terms.PaymentPreimage,
}, nil
case channeldb.ContractAccepted:
debugLog("accepted")
// Subscribe to updates to this invoice.
i.hodlSubscribe(hodlChan, rHash)
return nil, nil
default:
return nil, fmt.Errorf("unexpected invoice state %v",
invoice.Terms.State)
}
default:
debugLog(err.Error())
return nil, err
}
}
// SettleHodlInvoice sets the preimage of a hodl invoice.
func (i *InvoiceRegistry) SettleHodlInvoice(preimage lntypes.Preimage) error {
i.Lock()
defer i.Unlock()
invoice, err := i.cdb.SettleHoldInvoice(preimage)
if err != nil {
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log.Errorf("SettleHodlInvoice with preimage %v: %v", preimage, err)
return err
}
hash := preimage.Hash()
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log.Debugf("Invoice(%v): settled with preimage %v", hash,
invoice.Terms.PaymentPreimage)
i.notifyHodlSubscribers(HodlEvent{
Hash: hash,
Preimage: &preimage,
})
i.notifyClients(hash, invoice, invoice.Terms.State)
return nil
}
// CancelInvoice attempts to cancel the invoice corresponding to the passed
// payment hash.
func (i *InvoiceRegistry) CancelInvoice(payHash lntypes.Hash) error {
i.Lock()
defer i.Unlock()
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log.Debugf("Invoice(%v): canceling invoice", payHash)
invoice, err := i.cdb.CancelInvoice(payHash)
// Implement idempotency by returning success if the invoice was already
// canceled.
if err == channeldb.ErrInvoiceAlreadyCanceled {
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log.Debugf("Invoice(%v): already canceled", payHash)
return nil
}
if err != nil {
return err
}
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log.Debugf("Invoice(%v): canceled", payHash)
i.notifyHodlSubscribers(HodlEvent{
Hash: payHash,
})
i.notifyClients(payHash, invoice, channeldb.ContractCanceled)
return nil
}
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// notifyClients notifies all currently registered invoice notification clients
// of a newly added/settled invoice.
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func (i *InvoiceRegistry) notifyClients(hash lntypes.Hash,
invoice *channeldb.Invoice,
state channeldb.ContractState) {
event := &invoiceEvent{
invoice: invoice,
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hash: hash,
}
select {
case i.invoiceEvents <- event:
case <-i.quit:
}
}
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// invoiceSubscriptionKit defines that are common to both all invoice
// subscribers and single invoice subscribers.
type invoiceSubscriptionKit struct {
id uint32
inv *InvoiceRegistry
ntfnQueue *queue.ConcurrentQueue
cancelled uint32 // To be used atomically.
cancelChan chan struct{}
wg sync.WaitGroup
}
// InvoiceSubscription represents an intent to receive updates for newly added
// or settled invoices. For each newly added invoice, a copy of the invoice
// will be sent over the NewInvoices channel. Similarly, for each newly settled
// invoice, a copy of the invoice will be sent over the SettledInvoices
// channel.
type InvoiceSubscription struct {
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invoiceSubscriptionKit
// NewInvoices is a channel that we'll use to send all newly created
// invoices with an invoice index greater than the specified
// StartingInvoiceIndex field.
NewInvoices chan *channeldb.Invoice
// SettledInvoices is a channel that we'll use to send all setted
// invoices with an invoices index greater than the specified
// StartingInvoiceIndex field.
SettledInvoices chan *channeldb.Invoice
// addIndex is the highest add index the caller knows of. We'll use
// this information to send out an event backlog to the notifications
// subscriber. Any new add events with an index greater than this will
// be dispatched before any new notifications are sent out.
addIndex uint64
// settleIndex is the highest settle index the caller knows of. We'll
// use this information to send out an event backlog to the
// notifications subscriber. Any new settle events with an index
// greater than this will be dispatched before any new notifications
// are sent out.
settleIndex uint64
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}
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// SingleInvoiceSubscription represents an intent to receive updates for a
// specific invoice.
type SingleInvoiceSubscription struct {
invoiceSubscriptionKit
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hash lntypes.Hash
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// Updates is a channel that we'll use to send all invoice events for
// the invoice that is subscribed to.
Updates chan *channeldb.Invoice
}
// Cancel unregisters the InvoiceSubscription, freeing any previously allocated
// resources.
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func (i *invoiceSubscriptionKit) Cancel() {
if !atomic.CompareAndSwapUint32(&i.cancelled, 0, 1) {
return
}
select {
case i.inv.subscriptionCancels <- i.id:
case <-i.inv.quit:
}
i.ntfnQueue.Stop()
close(i.cancelChan)
i.wg.Wait()
}
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func (i *invoiceSubscriptionKit) notify(event *invoiceEvent) error {
select {
case i.ntfnQueue.ChanIn() <- event:
case <-i.inv.quit:
return ErrShuttingDown
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}
return nil
}
// SubscribeNotifications returns an InvoiceSubscription which allows the
// caller to receive async notifications when any invoices are settled or
// added. The invoiceIndex parameter is a streaming "checkpoint". We'll start
// by first sending out all new events with an invoice index _greater_ than
// this value. Afterwards, we'll send out real-time notifications.
func (i *InvoiceRegistry) SubscribeNotifications(addIndex, settleIndex uint64) *InvoiceSubscription {
client := &InvoiceSubscription{
NewInvoices: make(chan *channeldb.Invoice),
SettledInvoices: make(chan *channeldb.Invoice),
addIndex: addIndex,
settleIndex: settleIndex,
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invoiceSubscriptionKit: invoiceSubscriptionKit{
inv: i,
ntfnQueue: queue.NewConcurrentQueue(20),
cancelChan: make(chan struct{}),
},
}
client.ntfnQueue.Start()
i.clientMtx.Lock()
client.id = i.nextClientID
i.nextClientID++
i.clientMtx.Unlock()
// Before we register this new invoice subscription, we'll launch a new
// goroutine that will proxy all notifications appended to the end of
// the concurrent queue to the two client-side channels the caller will
// feed off of.
i.wg.Add(1)
go func() {
defer i.wg.Done()
for {
select {
// A new invoice event has been sent by the
// invoiceRegistry! We'll figure out if this is an add
// event or a settle event, then dispatch the event to
// the client.
case ntfn := <-client.ntfnQueue.ChanOut():
invoiceEvent := ntfn.(*invoiceEvent)
var targetChan chan *channeldb.Invoice
state := invoiceEvent.invoice.Terms.State
switch state {
case channeldb.ContractOpen:
targetChan = client.NewInvoices
case channeldb.ContractSettled:
targetChan = client.SettledInvoices
default:
log.Errorf("unknown invoice "+
"state: %v", state)
continue
}
select {
case targetChan <- invoiceEvent.invoice:
case <-client.cancelChan:
return
case <-i.quit:
return
}
case <-client.cancelChan:
return
case <-i.quit:
return
}
}
}()
select {
case i.newSubscriptions <- client:
case <-i.quit:
}
return client
}
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// SubscribeSingleInvoice returns an SingleInvoiceSubscription which allows the
// caller to receive async notifications for a specific invoice.
func (i *InvoiceRegistry) SubscribeSingleInvoice(
hash lntypes.Hash) (*SingleInvoiceSubscription, error) {
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client := &SingleInvoiceSubscription{
Updates: make(chan *channeldb.Invoice),
invoiceSubscriptionKit: invoiceSubscriptionKit{
inv: i,
ntfnQueue: queue.NewConcurrentQueue(20),
cancelChan: make(chan struct{}),
},
hash: hash,
}
client.ntfnQueue.Start()
i.clientMtx.Lock()
client.id = i.nextClientID
i.nextClientID++
i.clientMtx.Unlock()
// Before we register this new invoice subscription, we'll launch a new
// goroutine that will proxy all notifications appended to the end of
// the concurrent queue to the two client-side channels the caller will
// feed off of.
i.wg.Add(1)
go func() {
defer i.wg.Done()
for {
select {
// A new invoice event has been sent by the
// invoiceRegistry. We will dispatch the event to the
// client.
case ntfn := <-client.ntfnQueue.ChanOut():
invoiceEvent := ntfn.(*invoiceEvent)
select {
case client.Updates <- invoiceEvent.invoice:
case <-client.cancelChan:
return
case <-i.quit:
return
}
case <-client.cancelChan:
return
case <-i.quit:
return
}
}
}()
// Within the lock, we both query the invoice state and pass the client
// subscription to the invoiceEvents channel. This is to make sure that
// the client receives a consistent stream of events.
i.Lock()
defer i.Unlock()
err := i.deliverSingleBacklogEvents(client)
if err != nil {
return nil, err
}
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select {
case i.invoiceEvents <- client:
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case <-i.quit:
return nil, ErrShuttingDown
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}
return client, nil
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}
// notifyHodlSubscribers sends out the hodl event to all current subscribers.
func (i *InvoiceRegistry) notifyHodlSubscribers(hodlEvent HodlEvent) {
subscribers, ok := i.hodlSubscriptions[hodlEvent.Hash]
if !ok {
return
}
// Notify all interested subscribers and remove subscription from both
// maps. The subscription can be removed as there only ever will be a
// single resolution for each hash.
for subscriber := range subscribers {
select {
case subscriber <- hodlEvent:
case <-i.quit:
return
}
delete(i.hodlReverseSubscriptions[subscriber], hodlEvent.Hash)
}
delete(i.hodlSubscriptions, hodlEvent.Hash)
}
// hodlSubscribe adds a new invoice subscription.
func (i *InvoiceRegistry) hodlSubscribe(subscriber chan<- interface{},
hash lntypes.Hash) {
log.Debugf("Hodl subscribe for %v", hash)
subscriptions, ok := i.hodlSubscriptions[hash]
if !ok {
subscriptions = make(map[chan<- interface{}]struct{})
i.hodlSubscriptions[hash] = subscriptions
}
subscriptions[subscriber] = struct{}{}
reverseSubscriptions, ok := i.hodlReverseSubscriptions[subscriber]
if !ok {
reverseSubscriptions = make(map[lntypes.Hash]struct{})
i.hodlReverseSubscriptions[subscriber] = reverseSubscriptions
}
reverseSubscriptions[hash] = struct{}{}
}
// HodlUnsubscribeAll cancels the subscription.
func (i *InvoiceRegistry) HodlUnsubscribeAll(subscriber chan<- interface{}) {
i.Lock()
defer i.Unlock()
hashes := i.hodlReverseSubscriptions[subscriber]
for hash := range hashes {
delete(i.hodlSubscriptions[hash], subscriber)
}
delete(i.hodlReverseSubscriptions, subscriber)
}