12199391122

Committed 06 Dec 2024 01:10PM UTC coverage: 49.807% (-9.1%) from 58.933%

Build # 12199391122

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web-flow

Commit Message

Merge pull request #9337 from Guayaba221/patch-1

chore: fix typo in ruby.md

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90.72

/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"
        "github.com/lightningnetwork/lnd/lnutils"
)

// 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
}

// manualUpdate holds a group of channel state updates and an error channel
// to send back an error happened upon update processing or file updating.
type manualUpdate struct {
        // singles hold channels backups. They can be either new or known
        // channels in the Swapper.
        singles []Single

        // errChan is the channel to send an error back. If the update handling
        // and the subsequent file updating succeeds, nil is sent.
        // The channel must have capacity of 1 to prevent Swapper blocking.
        errChan chan error
}

// 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

        manualUpdates chan manualUpdate

        // 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{}),
                manualUpdates: make(chan manualUpdate),
        }, 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
}

// ManualUpdate inserts/updates channel states into the swapper. The updates
// are processed in another goroutine. The method waits for the updates to be
// fully processed and the file to be updated on-disk before returning.
func (s *SubSwapper) ManualUpdate(singles []Single) error {
        // Create the channel to send an error back. If the update handling
        // and the subsequent file updating succeeds, nil is sent.
        // The channel must have capacity of 1 to prevent Swapper blocking.
        errChan := make(chan error, 1)

        // Create the update object to insert into the processing loop.
        update := manualUpdate{
                singles: singles,
                errChan: errChan,
        }

        select {
        case s.manualUpdates <- update:
        case <-s.quit:
                return fmt.Errorf("swapper stopped when sending manual update")
        }

        // Wait for processing, block on errChan.
        select {
        case err := <-errChan:
                if err != nil {
                        return fmt.Errorf("processing of manual update "+
                                "failed: %w", err)
                }

        case <-s.quit:
                return fmt.Errorf("swapper stopped when waiting for outcome")
        }

        // Success.
        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)

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

                        // 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", lnutils.NewLogClosure(
                                        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)

                        // Without 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)
                        }

                // We received a manual update. Handle it and update the file.
                case manualUpdate := <-s.manualUpdates:
                        oldStateSize := len(s.backupState)

                        // For all open channels, we'll create a new SCB given
                        // the required information.
                        for _, single := range manualUpdate.singles {
                                log.Debugf("Manual update of channel %v",
                                        single.FundingOutpoint)

                                s.backupState[single.FundingOutpoint] = single
                        }

                        newStateSize := len(s.backupState)

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

                        // Without new state constructed, we'll, atomically
                        // update the on-disk backup state.
                        err := s.updateBackupFile()
                        if err != nil {
                                log.Errorf("unable to update backup file: %v",
                                        err)
                        }

                        // Send the error (or nil) to the caller of
                        // ManualUpdate. The error channel must have capacity of
                        // 1 not to block here.
                        manualUpdate.errChan <- 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	"github.com/lightningnetwork/lnd/lnutils"
14	)
15
16	// Swapper is an interface that allows the chanbackup.SubSwapper to update the
17	// main multi backup location once it learns of new channels or that prior
18	// channels have been closed.
19	type Swapper interface {
20	// UpdateAndSwap attempts to atomically update the main multi back up
21	// file location with the new fully packed multi-channel backup.
22	UpdateAndSwap(newBackup PackedMulti) error
23
24	// ExtractMulti attempts to obtain and decode the current SCB instance
25	// stored by the Swapper instance.
26	ExtractMulti(keychain keychain.KeyRing) (*Multi, error)
27	}
28
29	// ChannelWithAddrs bundles an open channel along with all the addresses for
30	// the channel peer.
31	type ChannelWithAddrs struct {
32	*channeldb.OpenChannel
33
34	// Addrs is the set of addresses that we can use to reach the target
35	// peer.
36	Addrs []net.Addr
37	}
38
39	// ChannelEvent packages a new update of new channels since subscription, and
40	// channels that have been opened since prior channel event.
41	type ChannelEvent struct {
42	// ClosedChans are the set of channels that have been closed since the
43	// last event.
44	ClosedChans []wire.OutPoint
45
46	// NewChans is the set of channels that have been opened since the last
47	// event.
48	NewChans []ChannelWithAddrs
49	}
50
51	// manualUpdate holds a group of channel state updates and an error channel
52	// to send back an error happened upon update processing or file updating.
53	type manualUpdate struct {
54	// singles hold channels backups. They can be either new or known
55	// channels in the Swapper.
56	singles []Single
57
58	// errChan is the channel to send an error back. If the update handling
59	// and the subsequent file updating succeeds, nil is sent.
60	// The channel must have capacity of 1 to prevent Swapper blocking.
61	errChan chan error
62	}
63
64	// ChannelSubscription represents an intent to be notified of any updates to
65	// the primary channel state.
66	type ChannelSubscription struct {
67	// ChanUpdates is a channel that will be sent upon once the primary
68	// channel state is updated.
69	ChanUpdates chan ChannelEvent
70
71	// Cancel is a closure that allows the caller to cancel their
72	// subscription and free up any resources allocated.
73	Cancel func()
74	}
75
76	// ChannelNotifier represents a system that allows the chanbackup.SubSwapper to
77	// be notified of any changes to the primary channel state.
78	type ChannelNotifier interface {
79	// SubscribeChans requests a new channel subscription relative to the
80	// initial set of known channels. We use the knownChans as a
81	// synchronization point to ensure that the chanbackup.SubSwapper does
82	// not miss any channel open or close events in the period between when
83	// it's created, and when it requests the channel subscription.
84	SubscribeChans(map[wire.OutPoint]struct{}) (*ChannelSubscription, error)
85	}
86
87	// SubSwapper subscribes to new updates to the open channel state, and then
88	// swaps out the on-disk channel backup state in response. This sub-system
89	// that will ensure that the multi chan backup file on disk will always be
90	// updated with the latest channel back up state. We'll receive new
91	// opened/closed channels from the ChannelNotifier, then use the Swapper to
92	// update the file state on disk with the new set of open channels. This can
93	// be used to implement a system that always keeps the multi-chan backup file
94	// on disk in a consistent state for safety purposes.
95	type SubSwapper struct {
96	started sync.Once
97	stopped sync.Once
98
99	// backupState are the set of SCBs for all open channels we know of.
100	backupState map[wire.OutPoint]Single
101
102	// chanEvents is an active subscription to receive new channel state
103	// over.
104	chanEvents *ChannelSubscription
105
106	manualUpdates chan manualUpdate
107
108	// keyRing is the main key ring that will allow us to pack the new
109	// multi backup.
110	keyRing keychain.KeyRing
111
112	Swapper
113
114	quit chan struct{}
115	wg sync.WaitGroup
116	}
117
118	// NewSubSwapper creates a new instance of the SubSwapper given the starting
119	// set of channels, and the required interfaces to be notified of new channel
120	// updates, pack a multi backup, and swap the current best backup from its
121	// storage location.
122	func NewSubSwapper(startingChans []Single, chanNotifier ChannelNotifier,
123	keyRing keychain.KeyRing, backupSwapper Swapper) (*SubSwapper, error) {	4✔
124		4✔
125	// First, we'll subscribe to the latest set of channel updates given	4✔
126	// the set of channels we already know of.	4✔
127	knownChans := make(map[wire.OutPoint]struct{})	4✔
128	for _, chanBackup := range startingChans {	8✔
129	knownChans[chanBackup.FundingOutpoint] = struct{}{}	4✔
130	}	4✔
131	chanEvents, err := chanNotifier.SubscribeChans(knownChans)	4✔
132	if err != nil {	4✔
133	return nil, err	×
134	}	×
135
136	// Next, we'll construct our own backup state so we can add/remove
137	// channels that have been opened and closed.
138	backupState := make(map[wire.OutPoint]Single)	4✔
139	for _, chanBackup := range startingChans {	8✔
140	backupState[chanBackup.FundingOutpoint] = chanBackup	4✔
141	}	4✔
142
143	return &SubSwapper{	4✔
144	backupState: backupState,	4✔
145	chanEvents: chanEvents,	4✔
146	keyRing: keyRing,	4✔
147	Swapper: backupSwapper,	4✔
148	quit: make(chan struct{}),	4✔
149	manualUpdates: make(chan manualUpdate),	4✔
150	}, nil	4✔
151	}
152
153	// Start starts the chanbackup.SubSwapper.
154	func (s *SubSwapper) Start() error {	4✔
155	var startErr error	4✔
156	s.started.Do(func() {	8✔
157	log.Infof("chanbackup.SubSwapper starting")	4✔
158		4✔
159	// Before we enter our main loop, we'll update the on-disk	4✔
160	// state with the latest Single state, as nodes may have new	4✔
161	// advertised addresses.	4✔
162	if err := s.updateBackupFile(); err != nil {	4✔
163	startErr = fmt.Errorf("unable to refresh backup "+	×
164	"file: %v", err)	×
165	return	×
166	}	×
167
168	s.wg.Add(1)	4✔
169	go s.backupUpdater()	4✔
170	})
171
172	return startErr	4✔
173	}
174
175	// Stop signals the SubSwapper to being a graceful shutdown.
176	func (s *SubSwapper) Stop() error {	4✔
177	s.stopped.Do(func() {	8✔
178	log.Infof("chanbackup.SubSwapper shutting down...")	4✔
179	defer log.Debug("chanbackup.SubSwapper shutdown complete")	4✔
180		4✔
181	close(s.quit)	4✔
182	s.wg.Wait()	4✔
183	})	4✔
184	return nil	4✔
185	}
186
187	// ManualUpdate inserts/updates channel states into the swapper. The updates
188	// are processed in another goroutine. The method waits for the updates to be
189	// fully processed and the file to be updated on-disk before returning.
190	func (s *SubSwapper) ManualUpdate(singles []Single) error {	4✔
191	// Create the channel to send an error back. If the update handling	4✔
192	// and the subsequent file updating succeeds, nil is sent.	4✔
193	// The channel must have capacity of 1 to prevent Swapper blocking.	4✔
194	errChan := make(chan error, 1)	4✔
195		4✔
196	// Create the update object to insert into the processing loop.	4✔
197	update := manualUpdate{	4✔
198	singles: singles,	4✔
199	errChan: errChan,	4✔
200	}	4✔
201		4✔
202	select {	4✔
203	case s.manualUpdates <- update:	4✔
204	case <-s.quit:	×
205	return fmt.Errorf("swapper stopped when sending manual update")	×
206	}
207
208	// Wait for processing, block on errChan.
209	select {	4✔
210	case err := <-errChan:	4✔
211	if err != nil {	8✔
212	return fmt.Errorf("processing of manual update "+	4✔
213	"failed: %w", err)	4✔
214	}	4✔
215
216	case <-s.quit:	×
217	return fmt.Errorf("swapper stopped when waiting for outcome")	×
218	}
219
220	// Success.
221	return nil	4✔
222	}
223
224	// updateBackupFile updates the backup file in place given the current state of
225	// the SubSwapper. We accept the set of channels that were closed between this
226	// update and the last to make sure we leave them out of our backup set union.
227	func (s *SubSwapper) updateBackupFile(closedChans ...wire.OutPoint) error {	4✔
228	// Before we pack the new set of SCBs, we'll first decode what we	4✔
229	// already have on-disk, to make sure we can decode it (proper seed)	4✔
230	// and that we're able to combine it with our new data.	4✔
231	diskMulti, err := s.Swapper.ExtractMulti(s.keyRing)	4✔
232		4✔
233	// If the file doesn't exist on disk, then that's OK as it was never	4✔
234	// created. In this case we'll continue onwards as it isn't a critical	4✔
235	// error.	4✔
236	if err != nil && !os.IsNotExist(err) {	4✔
237	return fmt.Errorf("unable to extract on disk encrypted "+	×
238	"SCB: %v", err)	×
239	}	×
240
241	// Now that we have channels stored on-disk, we'll create a new set of
242	// the combined old and new channels to make sure we retain what's
243	// already on-disk.
244	//
245	// NOTE: The ordering of this operations means that our in-memory
246	// structure will replace what we read from disk.
247	combinedBackup := make(map[wire.OutPoint]Single)	4✔
248	if diskMulti != nil {	8✔
249	for _, diskChannel := range diskMulti.StaticBackups {	8✔
250	chanPoint := diskChannel.FundingOutpoint	4✔
251	combinedBackup[chanPoint] = diskChannel	4✔
252	}	4✔
253	}
254	for _, memChannel := range s.backupState {	8✔
255	chanPoint := memChannel.FundingOutpoint	4✔
256	if _, ok := combinedBackup[chanPoint]; ok {	8✔
257	log.Warnf("Replacing disk backup for ChannelPoint(%v) "+	4✔
258	"w/ newer version", chanPoint)	4✔
259	}	4✔
260
261	combinedBackup[chanPoint] = memChannel	4✔
262	}
263
264	// Remove the set of closed channels from the final set of backups.
265	for _, closedChan := range closedChans {	8✔
266	delete(combinedBackup, closedChan)	4✔
267	}	4✔
268
269	// With our updated channel state obtained, we'll create a new multi
270	// from our series of singles.
271	var newMulti Multi	4✔
272	for _, backup := range combinedBackup {	8✔
273	newMulti.StaticBackups = append(	4✔
274	newMulti.StaticBackups, backup,	4✔
275	)	4✔
276	}	4✔
277
278	// Now that our multi has been assembled, we'll attempt to pack
279	// (encrypt+encode) the new channel state to our target reader.
280	var b bytes.Buffer	4✔
281	err = newMulti.PackToWriter(&b, s.keyRing)	4✔
282	if err != nil {	4✔
283	return fmt.Errorf("unable to pack multi backup: %w", err)	×
284	}	×
285
286	// Finally, we'll swap out the old backup for this new one in a single
287	// atomic step, combining the file already on-disk with this set of new
288	// channels.
289	err = s.Swapper.UpdateAndSwap(PackedMulti(b.Bytes()))	4✔
290	if err != nil {	8✔
291	return fmt.Errorf("unable to update multi backup: %w", err)	4✔
292	}	4✔
293
294	return nil	4✔
295	}
296
297	// backupFileUpdater is the primary goroutine of the SubSwapper which is
298	// responsible for listening for changes to the channel, and updating the
299	// persistent multi backup state with a new packed multi of the latest channel
300	// state.
301	func (s *SubSwapper) backupUpdater() {	4✔
302	// Ensure that once we exit, we'll cancel our active channel	4✔
303	// subscription.	4✔
304	defer s.chanEvents.Cancel()	4✔
305	defer s.wg.Done()	4✔
306		4✔
307	log.Debugf("SubSwapper's backupUpdater is active!")	4✔
308		4✔
309	for {	8✔
310	select {	4✔
311	// The channel state has been modified! We'll evaluate all
312	// changes, and swap out the old packed multi with a new one
313	// with the latest channel state.
314	case chanUpdate := <-s.chanEvents.ChanUpdates:	4✔
315	oldStateSize := len(s.backupState)	4✔
316		4✔
317	// For all new open channels, we'll create a new SCB	4✔
318	// given the required information.	4✔
319	for _, newChan := range chanUpdate.NewChans {	8✔
320	log.Debugf("Adding channel %v to backup state",	4✔
321	newChan.FundingOutpoint)	4✔
322		4✔
323	single := NewSingle(	4✔
324	newChan.OpenChannel, newChan.Addrs,	4✔
325	)	4✔
326	s.backupState[newChan.FundingOutpoint] = single	4✔
327	}	4✔
328
329	// For all closed channels, we'll remove the prior
330	// backup state.
331	closedChans := make(	4✔
332	[]wire.OutPoint, 0, len(chanUpdate.ClosedChans),	4✔
333	)	4✔
334	for i, closedChan := range chanUpdate.ClosedChans {	8✔
335	log.Debugf("Removing channel %v from backup "+	4✔
336	"state", lnutils.NewLogClosure(	4✔
337	chanUpdate.ClosedChans[i].String))	4✔
338		4✔
339	delete(s.backupState, closedChan)	4✔
340		4✔
341	closedChans = append(closedChans, closedChan)	4✔
342	}	4✔
343
344	newStateSize := len(s.backupState)	4✔
345		4✔
346	log.Infof("Updating on-disk multi SCB backup: "+	4✔
347	"num_old_chans=%v, num_new_chans=%v",	4✔
348	oldStateSize, newStateSize)	4✔
349		4✔
350	// Without new state constructed, we'll, atomically	4✔
351	// update the on-disk backup state.	4✔
352	if err := s.updateBackupFile(closedChans...); err != nil {	4✔
353	log.Errorf("unable to update backup file: %v",	×
354	err)	×
355	}	×
356
357	// We received a manual update. Handle it and update the file.
358	case manualUpdate := <-s.manualUpdates:	4✔
359	oldStateSize := len(s.backupState)	4✔
360		4✔
361	// For all open channels, we'll create a new SCB given	4✔
362	// the required information.	4✔
363	for _, single := range manualUpdate.singles {	8✔
364	log.Debugf("Manual update of channel %v",	4✔
365	single.FundingOutpoint)	4✔
366		4✔
367	s.backupState[single.FundingOutpoint] = single	4✔
368	}	4✔
369
370	newStateSize := len(s.backupState)	4✔
371		4✔
372	log.Infof("Updating on-disk multi SCB backup: "+	4✔
373	"num_old_chans=%v, num_new_chans=%v",	4✔
374	oldStateSize, newStateSize)	4✔
375		4✔
376	// Without new state constructed, we'll, atomically	4✔
377	// update the on-disk backup state.	4✔
378	err := s.updateBackupFile()	4✔
379	if err != nil {	8✔
380	log.Errorf("unable to update backup file: %v",	4✔
381	err)	4✔
382	}	4✔
383
384	// Send the error (or nil) to the caller of
385	// ManualUpdate. The error channel must have capacity of
386	// 1 not to block here.
387	manualUpdate.errChan <- err	4✔
388
389	// TODO(roasbeef): refresh periodically on a time basis due to
390	// possible addr changes from node
391
392	// Exit at once if a quit signal is detected.
393	case <-s.quit:	4✔
394	return	4✔
395	}
396	}
397	}

lightningnetwork / lnd / 12199391122

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