9915780197

Committed 13 Jul 2024 12:30AM UTC coverage: 49.268% (-9.1%) from 58.413%

Build # 9915780197

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github

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web-flow

Commit Message

Merge pull request #8653 from ProofOfKeags/fn-prim

DynComms [0/n]: `fn` package additions

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88.65

/chanbackup/pubsub.go

package chanbackup

import (
        "bytes"
        "fmt"
        "net"
        "os"
        "sync"

        "github.com/btcsuite/btcd/wire"
        "github.com/lightningnetwork/lnd/channeldb"
        "github.com/lightningnetwork/lnd/keychain"
)

// Swapper is an interface that allows the chanbackup.SubSwapper to update the
// main multi backup location once it learns of new channels or that prior
// channels have been closed.
type Swapper interface {
        // UpdateAndSwap attempts to atomically update the main multi back up
        // file location with the new fully packed multi-channel backup.
        UpdateAndSwap(newBackup PackedMulti) error

        // ExtractMulti attempts to obtain and decode the current SCB instance
        // stored by the Swapper instance.
        ExtractMulti(keychain keychain.KeyRing) (*Multi, error)
}

// ChannelWithAddrs bundles an open channel along with all the addresses for
// the channel peer.
type ChannelWithAddrs struct {
        *channeldb.OpenChannel

        // Addrs is the set of addresses that we can use to reach the target
        // peer.
        Addrs []net.Addr
}

// ChannelEvent packages a new update of new channels since subscription, and
// channels that have been opened since prior channel event.
type ChannelEvent struct {
        // ClosedChans are the set of channels that have been closed since the
        // last event.
        ClosedChans []wire.OutPoint

        // NewChans is the set of channels that have been opened since the last
        // event.
        NewChans []ChannelWithAddrs
}

// ChannelSubscription represents an intent to be notified of any updates to
// the primary channel state.
type ChannelSubscription struct {
        // ChanUpdates is a channel that will be sent upon once the primary
        // channel state is updated.
        ChanUpdates chan ChannelEvent

        // Cancel is a closure that allows the caller to cancel their
        // subscription and free up any resources allocated.
        Cancel func()
}

// ChannelNotifier represents a system that allows the chanbackup.SubSwapper to
// be notified of any changes to the primary channel state.
type ChannelNotifier interface {
        // SubscribeChans requests a new channel subscription relative to the
        // initial set of known channels. We use the knownChans as a
        // synchronization point to ensure that the chanbackup.SubSwapper does
        // not miss any channel open or close events in the period between when
        // it's created, and when it requests the channel subscription.
        SubscribeChans(map[wire.OutPoint]struct{}) (*ChannelSubscription, error)
}

// SubSwapper subscribes to new updates to the open channel state, and then
// swaps out the on-disk channel backup state in response.  This sub-system
// that will ensure that the multi chan backup file on disk will always be
// updated with the latest channel back up state. We'll receive new
// opened/closed channels from the ChannelNotifier, then use the Swapper to
// update the file state on disk with the new set of open channels.  This can
// be used to implement a system that always keeps the multi-chan backup file
// on disk in a consistent state for safety purposes.
type SubSwapper struct {
        started sync.Once
        stopped sync.Once

        // backupState are the set of SCBs for all open channels we know of.
        backupState map[wire.OutPoint]Single

        // chanEvents is an active subscription to receive new channel state
        // over.
        chanEvents *ChannelSubscription

        // keyRing is the main key ring that will allow us to pack the new
        // multi backup.
        keyRing keychain.KeyRing

        Swapper

        quit chan struct{}
        wg   sync.WaitGroup
}

// NewSubSwapper creates a new instance of the SubSwapper given the starting
// set of channels, and the required interfaces to be notified of new channel
// updates, pack a multi backup, and swap the current best backup from its
// storage location.
func NewSubSwapper(startingChans []Single, chanNotifier ChannelNotifier,
        keyRing keychain.KeyRing, backupSwapper Swapper) (*SubSwapper, error) {

        // First, we'll subscribe to the latest set of channel updates given
        // the set of channels we already know of.
        knownChans := make(map[wire.OutPoint]struct{})
        for _, chanBackup := range startingChans {
                knownChans[chanBackup.FundingOutpoint] = struct{}{}
        }
        chanEvents, err := chanNotifier.SubscribeChans(knownChans)
        if err != nil {
                return nil, err
        }

        // Next, we'll construct our own backup state so we can add/remove
        // channels that have been opened and closed.
        backupState := make(map[wire.OutPoint]Single)
        for _, chanBackup := range startingChans {
                backupState[chanBackup.FundingOutpoint] = chanBackup
        }

        return &SubSwapper{
                backupState: backupState,
                chanEvents:  chanEvents,
                keyRing:     keyRing,
                Swapper:     backupSwapper,
                quit:        make(chan struct{}),
        }, nil
}

// Start starts the chanbackup.SubSwapper.
func (s *SubSwapper) Start() error {
        var startErr error
        s.started.Do(func() {
                log.Infof("chanbackup.SubSwapper starting")

                // Before we enter our main loop, we'll update the on-disk
                // state with the latest Single state, as nodes may have new
                // advertised addresses.
                if err := s.updateBackupFile(); err != nil {
                        startErr = fmt.Errorf("unable to refresh backup "+
                                "file: %v", err)
                        return
                }

                s.wg.Add(1)
                go s.backupUpdater()
        })

        return startErr
}

// Stop signals the SubSwapper to being a graceful shutdown.
func (s *SubSwapper) Stop() error {
        s.stopped.Do(func() {
                log.Infof("chanbackup.SubSwapper shutting down...")
                defer log.Debug("chanbackup.SubSwapper shutdown complete")

                close(s.quit)
                s.wg.Wait()
        })
        return nil
}

// updateBackupFile updates the backup file in place given the current state of
// the SubSwapper. We accept the set of channels that were closed between this
// update and the last to make sure we leave them out of our backup set union.
func (s *SubSwapper) updateBackupFile(closedChans ...wire.OutPoint) error {
        // Before we pack the new set of SCBs, we'll first decode what we
        // already have on-disk, to make sure we can decode it (proper seed)
        // and that we're able to combine it with our new data.
        diskMulti, err := s.Swapper.ExtractMulti(s.keyRing)

        // If the file doesn't exist on disk, then that's OK as it was never
        // created. In this case we'll continue onwards as it isn't a critical
        // error.
        if err != nil && !os.IsNotExist(err) {
                return fmt.Errorf("unable to extract on disk encrypted "+
                        "SCB: %v", err)
        }

        // Now that we have channels stored on-disk, we'll create a new set of
        // the combined old and new channels to make sure we retain what's
        // already on-disk.
        //
        // NOTE: The ordering of this operations means that our in-memory
        // structure will replace what we read from disk.
        combinedBackup := make(map[wire.OutPoint]Single)
        if diskMulti != nil {
                for _, diskChannel := range diskMulti.StaticBackups {
                        chanPoint := diskChannel.FundingOutpoint
                        combinedBackup[chanPoint] = diskChannel
                }
        }
        for _, memChannel := range s.backupState {
                chanPoint := memChannel.FundingOutpoint
                if _, ok := combinedBackup[chanPoint]; ok {
                        log.Warnf("Replacing disk backup for ChannelPoint(%v) "+
                                "w/ newer version", chanPoint)
                }

                combinedBackup[chanPoint] = memChannel
        }

        // Remove the set of closed channels from the final set of backups.
        for _, closedChan := range closedChans {
                delete(combinedBackup, closedChan)
        }

        // With our updated channel state obtained, we'll create a new multi
        // from our series of singles.
        var newMulti Multi
        for _, backup := range combinedBackup {
                newMulti.StaticBackups = append(
                        newMulti.StaticBackups, backup,
                )
        }

        // Now that our multi has been assembled, we'll attempt to pack
        // (encrypt+encode) the new channel state to our target reader.
        var b bytes.Buffer
        err = newMulti.PackToWriter(&b, s.keyRing)
        if err != nil {
                return fmt.Errorf("unable to pack multi backup: %w", err)
        }

        // Finally, we'll swap out the old backup for this new one in a single
        // atomic step, combining the file already on-disk with this set of new
        // channels.
        err = s.Swapper.UpdateAndSwap(PackedMulti(b.Bytes()))
        if err != nil {
                return fmt.Errorf("unable to update multi backup: %w", err)
        }

        return nil
}

// backupFileUpdater is the primary goroutine of the SubSwapper which is
// responsible for listening for changes to the channel, and updating the
// persistent multi backup state with a new packed multi of the latest channel
// state.
func (s *SubSwapper) backupUpdater() {
        // Ensure that once we exit, we'll cancel our active channel
        // subscription.
        defer s.chanEvents.Cancel()
        defer s.wg.Done()

        log.Debugf("SubSwapper's backupUpdater is active!")

        for {
                select {
                // The channel state has been modified! We'll evaluate all
                // changes, and swap out the old packed multi with a new one
                // with the latest channel state.
                case chanUpdate := <-s.chanEvents.ChanUpdates:
                        oldStateSize := len(s.backupState)

                        // For all new open channels, we'll create a new SCB
                        // given the required information.
                        for _, newChan := range chanUpdate.NewChans {
                                log.Debugf("Adding channel %v to backup state",
                                        newChan.FundingOutpoint)

                                s.backupState[newChan.FundingOutpoint] = NewSingle(
                                        newChan.OpenChannel, newChan.Addrs,
                                )
                        }

                        // For all closed channels, we'll remove the prior
                        // backup state.
                        closedChans := make(
                                []wire.OutPoint, 0, len(chanUpdate.ClosedChans),
                        )
                        for i, closedChan := range chanUpdate.ClosedChans {
                                log.Debugf("Removing channel %v from backup "+
                                        "state", newLogClosure(func() string {
                                        return chanUpdate.ClosedChans[i].String()
                                }))

                                delete(s.backupState, closedChan)

                                closedChans = append(closedChans, closedChan)
                        }

                        newStateSize := len(s.backupState)

                        log.Infof("Updating on-disk multi SCB backup: "+
                                "num_old_chans=%v, num_new_chans=%v",
                                oldStateSize, newStateSize)

                        // With out new state constructed, we'll, atomically
                        // update the on-disk backup state.
                        if err := s.updateBackupFile(closedChans...); err != nil {
                                log.Errorf("unable to update backup file: %v",
                                        err)
                        }

                // TODO(roasbeef): refresh periodically on a time basis due to
                // possible addr changes from node

                // Exit at once if a quit signal is detected.
                case <-s.quit:
                        return
                }
        }
}

1	package chanbackup
2
3	import (
4	"bytes"
5	"fmt"
6	"net"
7	"os"
8	"sync"
9
10	"github.com/btcsuite/btcd/wire"
11	"github.com/lightningnetwork/lnd/channeldb"
12	"github.com/lightningnetwork/lnd/keychain"
13	)
14
15	// Swapper is an interface that allows the chanbackup.SubSwapper to update the
16	// main multi backup location once it learns of new channels or that prior
17	// channels have been closed.
18	type Swapper interface {
19	// UpdateAndSwap attempts to atomically update the main multi back up
20	// file location with the new fully packed multi-channel backup.
21	UpdateAndSwap(newBackup PackedMulti) error
22
23	// ExtractMulti attempts to obtain and decode the current SCB instance
24	// stored by the Swapper instance.
25	ExtractMulti(keychain keychain.KeyRing) (*Multi, error)
26	}
27
28	// ChannelWithAddrs bundles an open channel along with all the addresses for
29	// the channel peer.
30	type ChannelWithAddrs struct {
31	*channeldb.OpenChannel
32
33	// Addrs is the set of addresses that we can use to reach the target
34	// peer.
35	Addrs []net.Addr
36	}
37
38	// ChannelEvent packages a new update of new channels since subscription, and
39	// channels that have been opened since prior channel event.
40	type ChannelEvent struct {
41	// ClosedChans are the set of channels that have been closed since the
42	// last event.
43	ClosedChans []wire.OutPoint
44
45	// NewChans is the set of channels that have been opened since the last
46	// event.
47	NewChans []ChannelWithAddrs
48	}
49
50	// ChannelSubscription represents an intent to be notified of any updates to
51	// the primary channel state.
52	type ChannelSubscription struct {
53	// ChanUpdates is a channel that will be sent upon once the primary
54	// channel state is updated.
55	ChanUpdates chan ChannelEvent
56
57	// Cancel is a closure that allows the caller to cancel their
58	// subscription and free up any resources allocated.
59	Cancel func()
60	}
61
62	// ChannelNotifier represents a system that allows the chanbackup.SubSwapper to
63	// be notified of any changes to the primary channel state.
64	type ChannelNotifier interface {
65	// SubscribeChans requests a new channel subscription relative to the
66	// initial set of known channels. We use the knownChans as a
67	// synchronization point to ensure that the chanbackup.SubSwapper does
68	// not miss any channel open or close events in the period between when
69	// it's created, and when it requests the channel subscription.
70	SubscribeChans(map[wire.OutPoint]struct{}) (*ChannelSubscription, error)
71	}
72
73	// SubSwapper subscribes to new updates to the open channel state, and then
74	// swaps out the on-disk channel backup state in response. This sub-system
75	// that will ensure that the multi chan backup file on disk will always be
76	// updated with the latest channel back up state. We'll receive new
77	// opened/closed channels from the ChannelNotifier, then use the Swapper to
78	// update the file state on disk with the new set of open channels. This can
79	// be used to implement a system that always keeps the multi-chan backup file
80	// on disk in a consistent state for safety purposes.
81	type SubSwapper struct {
82	started sync.Once
83	stopped sync.Once
84
85	// backupState are the set of SCBs for all open channels we know of.
86	backupState map[wire.OutPoint]Single
87
88	// chanEvents is an active subscription to receive new channel state
89	// over.
90	chanEvents *ChannelSubscription
91
92	// keyRing is the main key ring that will allow us to pack the new
93	// multi backup.
94	keyRing keychain.KeyRing
95
96	Swapper
97
98	quit chan struct{}
99	wg sync.WaitGroup
100	}
101
102	// NewSubSwapper creates a new instance of the SubSwapper given the starting
103	// set of channels, and the required interfaces to be notified of new channel
104	// updates, pack a multi backup, and swap the current best backup from its
105	// storage location.
106	func NewSubSwapper(startingChans []Single, chanNotifier ChannelNotifier,
107	keyRing keychain.KeyRing, backupSwapper Swapper) (*SubSwapper, error) {	3✔
108		3✔
109	// First, we'll subscribe to the latest set of channel updates given	3✔
110	// the set of channels we already know of.	3✔
111	knownChans := make(map[wire.OutPoint]struct{})	3✔
112	for _, chanBackup := range startingChans {	6✔
113	knownChans[chanBackup.FundingOutpoint] = struct{}{}	3✔
114	}	3✔
115	chanEvents, err := chanNotifier.SubscribeChans(knownChans)	3✔
116	if err != nil {	3✔
117	return nil, err	×
118	}	×
119
120	// Next, we'll construct our own backup state so we can add/remove
121	// channels that have been opened and closed.
122	backupState := make(map[wire.OutPoint]Single)	3✔
123	for _, chanBackup := range startingChans {	6✔
124	backupState[chanBackup.FundingOutpoint] = chanBackup	3✔
125	}	3✔
126
127	return &SubSwapper{	3✔
128	backupState: backupState,	3✔
129	chanEvents: chanEvents,	3✔
130	keyRing: keyRing,	3✔
131	Swapper: backupSwapper,	3✔
132	quit: make(chan struct{}),	3✔
133	}, nil	3✔
134	}
135
136	// Start starts the chanbackup.SubSwapper.
137	func (s *SubSwapper) Start() error {	3✔
138	var startErr error	3✔
139	s.started.Do(func() {	6✔
140	log.Infof("chanbackup.SubSwapper starting")	3✔
141		3✔
142	// Before we enter our main loop, we'll update the on-disk	3✔
143	// state with the latest Single state, as nodes may have new	3✔
144	// advertised addresses.	3✔
145	if err := s.updateBackupFile(); err != nil {	3✔
146	startErr = fmt.Errorf("unable to refresh backup "+	×
147	"file: %v", err)	×
148	return	×
149	}	×
150
151	s.wg.Add(1)	3✔
152	go s.backupUpdater()	3✔
153	})
154
155	return startErr	3✔
156	}
157
158	// Stop signals the SubSwapper to being a graceful shutdown.
159	func (s *SubSwapper) Stop() error {	3✔
160	s.stopped.Do(func() {	6✔
161	log.Infof("chanbackup.SubSwapper shutting down...")	3✔
162	defer log.Debug("chanbackup.SubSwapper shutdown complete")	3✔
163		3✔
164	close(s.quit)	3✔
165	s.wg.Wait()	3✔
166	})	3✔
167	return nil	3✔
168	}
169
170	// updateBackupFile updates the backup file in place given the current state of
171	// the SubSwapper. We accept the set of channels that were closed between this
172	// update and the last to make sure we leave them out of our backup set union.
173	func (s *SubSwapper) updateBackupFile(closedChans ...wire.OutPoint) error {	3✔
174	// Before we pack the new set of SCBs, we'll first decode what we	3✔
175	// already have on-disk, to make sure we can decode it (proper seed)	3✔
176	// and that we're able to combine it with our new data.	3✔
177	diskMulti, err := s.Swapper.ExtractMulti(s.keyRing)	3✔
178		3✔
179	// If the file doesn't exist on disk, then that's OK as it was never	3✔
180	// created. In this case we'll continue onwards as it isn't a critical	3✔
181	// error.	3✔
182	if err != nil && !os.IsNotExist(err) {	3✔
183	return fmt.Errorf("unable to extract on disk encrypted "+	×
184	"SCB: %v", err)	×
185	}	×
186
187	// Now that we have channels stored on-disk, we'll create a new set of
188	// the combined old and new channels to make sure we retain what's
189	// already on-disk.
190	//
191	// NOTE: The ordering of this operations means that our in-memory
192	// structure will replace what we read from disk.
193	combinedBackup := make(map[wire.OutPoint]Single)	3✔
194	if diskMulti != nil {	6✔
195	for _, diskChannel := range diskMulti.StaticBackups {	6✔
196	chanPoint := diskChannel.FundingOutpoint	3✔
197	combinedBackup[chanPoint] = diskChannel	3✔
198	}	3✔
199	}
200	for _, memChannel := range s.backupState {	6✔
201	chanPoint := memChannel.FundingOutpoint	3✔
202	if _, ok := combinedBackup[chanPoint]; ok {	6✔
203	log.Warnf("Replacing disk backup for ChannelPoint(%v) "+	3✔
204	"w/ newer version", chanPoint)	3✔
205	}	3✔
206
207	combinedBackup[chanPoint] = memChannel	3✔
208	}
209
210	// Remove the set of closed channels from the final set of backups.
211	for _, closedChan := range closedChans {	6✔
212	delete(combinedBackup, closedChan)	3✔
213	}	3✔
214
215	// With our updated channel state obtained, we'll create a new multi
216	// from our series of singles.
217	var newMulti Multi	3✔
218	for _, backup := range combinedBackup {	6✔
219	newMulti.StaticBackups = append(	3✔
220	newMulti.StaticBackups, backup,	3✔
221	)	3✔
222	}	3✔
223
224	// Now that our multi has been assembled, we'll attempt to pack
225	// (encrypt+encode) the new channel state to our target reader.
226	var b bytes.Buffer	3✔
227	err = newMulti.PackToWriter(&b, s.keyRing)	3✔
228	if err != nil {	3✔
229	return fmt.Errorf("unable to pack multi backup: %w", err)	×
230	}	×
231
232	// Finally, we'll swap out the old backup for this new one in a single
233	// atomic step, combining the file already on-disk with this set of new
234	// channels.
235	err = s.Swapper.UpdateAndSwap(PackedMulti(b.Bytes()))	3✔
236	if err != nil {	3✔
237	return fmt.Errorf("unable to update multi backup: %w", err)	×
238	}	×
239
240	return nil	3✔
241	}
242
243	// backupFileUpdater is the primary goroutine of the SubSwapper which is
244	// responsible for listening for changes to the channel, and updating the
245	// persistent multi backup state with a new packed multi of the latest channel
246	// state.
247	func (s *SubSwapper) backupUpdater() {	3✔
248	// Ensure that once we exit, we'll cancel our active channel	3✔
249	// subscription.	3✔
250	defer s.chanEvents.Cancel()	3✔
251	defer s.wg.Done()	3✔
252		3✔
253	log.Debugf("SubSwapper's backupUpdater is active!")	3✔
254		3✔
255	for {	6✔
256	select {	3✔
257	// The channel state has been modified! We'll evaluate all
258	// changes, and swap out the old packed multi with a new one
259	// with the latest channel state.
260	case chanUpdate := <-s.chanEvents.ChanUpdates:	3✔
261	oldStateSize := len(s.backupState)	3✔
262		3✔
263	// For all new open channels, we'll create a new SCB	3✔
264	// given the required information.	3✔
265	for _, newChan := range chanUpdate.NewChans {	6✔
266	log.Debugf("Adding channel %v to backup state",	3✔
267	newChan.FundingOutpoint)	3✔
268		3✔
269	s.backupState[newChan.FundingOutpoint] = NewSingle(	3✔
270	newChan.OpenChannel, newChan.Addrs,	3✔
271	)	3✔
272	}	3✔
273
274	// For all closed channels, we'll remove the prior
275	// backup state.
276	closedChans := make(	3✔
277	[]wire.OutPoint, 0, len(chanUpdate.ClosedChans),	3✔
278	)	3✔
279	for i, closedChan := range chanUpdate.ClosedChans {	6✔
280	log.Debugf("Removing channel %v from backup "+	3✔
281	"state", newLogClosure(func() string {	6✔
282	return chanUpdate.ClosedChans[i].String()	3✔
283	}))	3✔
284
285	delete(s.backupState, closedChan)	3✔
286		3✔
287	closedChans = append(closedChans, closedChan)	3✔
288	}
289
290	newStateSize := len(s.backupState)	3✔
291		3✔
292	log.Infof("Updating on-disk multi SCB backup: "+	3✔
293	"num_old_chans=%v, num_new_chans=%v",	3✔
294	oldStateSize, newStateSize)	3✔
295		3✔
296	// With out new state constructed, we'll, atomically	3✔
297	// update the on-disk backup state.	3✔
298	if err := s.updateBackupFile(closedChans...); err != nil {	3✔
299	log.Errorf("unable to update backup file: %v",	×
300	err)	×
301	}	×
302
303	// TODO(roasbeef): refresh periodically on a time basis due to
304	// possible addr changes from node
305
306	// Exit at once if a quit signal is detected.
307	case <-s.quit:	3✔
308	return	3✔
309	}
310	}
311	}

lightningnetwork / lnd / 9915780197

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