17027244024

Committed 17 Aug 2025 11:32PM UTC coverage: 57.287% (-9.5%) from 66.765%

Build # 17027244024

Build Type

Pull #10167

github

Committed by

web-flow

Commit Message

Merge fcb4f4303 into fb1adfc21

Pull Request Pull Request #10167: multi: bump Go to 1.24.6

Run Details

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89.11

/chanbackup/pubsub.go

package chanbackup

import (
        "bytes"
        "context"
        "fmt"
        "net"
        "os"
        "sync"
        "sync/atomic"

        "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(context.Context,
                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 tracks whether the SubSwapper has been started and ensures
        // it can only be started once.
        started sync.Once

        // stopped tracks whether the SubSwapper has been stopped and ensures
        // it can only be stopped 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

        // isActive tracks whether the SubSwapper is active and ready to receive
        // messages. It is used to prevent manual updates from being sent to the
        // SubSwapper after it has been stopped or not yet started.
        isActive atomic.Bool
}

// 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(ctx context.Context, 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(ctx, 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")

                // Mark the SubSwapper as not running.
                s.isActive.Store(false)

                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 {
        if !s.isActive.Load() {
                return fmt.Errorf("swapper is not active, cannot perform " +
                        "manual update")
        }

        // 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. Once active, it will process subscription updates and manual updates
// until the SubSwapper is stopped.
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!")

        // Mark the SubSwapper as active.
        s.isActive.Store(true)

        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	"context"
6	"fmt"
7	"net"
8	"os"
9	"sync"
10	"sync/atomic"
11
12	"github.com/btcsuite/btcd/wire"
13	"github.com/lightningnetwork/lnd/channeldb"
14	"github.com/lightningnetwork/lnd/keychain"
15	"github.com/lightningnetwork/lnd/lnutils"
16	)
17
18	// Swapper is an interface that allows the chanbackup.SubSwapper to update the
19	// main multi backup location once it learns of new channels or that prior
20	// channels have been closed.
21	type Swapper interface {
22	// UpdateAndSwap attempts to atomically update the main multi back up
23	// file location with the new fully packed multi-channel backup.
24	UpdateAndSwap(newBackup PackedMulti) error
25
26	// ExtractMulti attempts to obtain and decode the current SCB instance
27	// stored by the Swapper instance.
28	ExtractMulti(keychain keychain.KeyRing) (*Multi, error)
29	}
30
31	// ChannelWithAddrs bundles an open channel along with all the addresses for
32	// the channel peer.
33	type ChannelWithAddrs struct {
34	*channeldb.OpenChannel
35
36	// Addrs is the set of addresses that we can use to reach the target
37	// peer.
38	Addrs []net.Addr
39	}
40
41	// ChannelEvent packages a new update of new channels since subscription, and
42	// channels that have been opened since prior channel event.
43	type ChannelEvent struct {
44	// ClosedChans are the set of channels that have been closed since the
45	// last event.
46	ClosedChans []wire.OutPoint
47
48	// NewChans is the set of channels that have been opened since the last
49	// event.
50	NewChans []ChannelWithAddrs
51	}
52
53	// manualUpdate holds a group of channel state updates and an error channel
54	// to send back an error happened upon update processing or file updating.
55	type manualUpdate struct {
56	// singles hold channels backups. They can be either new or known
57	// channels in the Swapper.
58	singles []Single
59
60	// errChan is the channel to send an error back. If the update handling
61	// and the subsequent file updating succeeds, nil is sent.
62	// The channel must have capacity of 1 to prevent Swapper blocking.
63	errChan chan error
64	}
65
66	// ChannelSubscription represents an intent to be notified of any updates to
67	// the primary channel state.
68	type ChannelSubscription struct {
69	// ChanUpdates is a channel that will be sent upon once the primary
70	// channel state is updated.
71	ChanUpdates chan ChannelEvent
72
73	// Cancel is a closure that allows the caller to cancel their
74	// subscription and free up any resources allocated.
75	Cancel func()
76	}
77
78	// ChannelNotifier represents a system that allows the chanbackup.SubSwapper to
79	// be notified of any changes to the primary channel state.
80	type ChannelNotifier interface {
81	// SubscribeChans requests a new channel subscription relative to the
82	// initial set of known channels. We use the knownChans as a
83	// synchronization point to ensure that the chanbackup.SubSwapper does
84	// not miss any channel open or close events in the period between when
85	// it's created, and when it requests the channel subscription.
86	SubscribeChans(context.Context,
87	map[wire.OutPoint]struct{}) (*ChannelSubscription, error)
88	}
89
90	// SubSwapper subscribes to new updates to the open channel state, and then
91	// swaps out the on-disk channel backup state in response. This sub-system
92	// that will ensure that the multi chan backup file on disk will always be
93	// updated with the latest channel back up state. We'll receive new
94	// opened/closed channels from the ChannelNotifier, then use the Swapper to
95	// update the file state on disk with the new set of open channels. This can
96	// be used to implement a system that always keeps the multi-chan backup file
97	// on disk in a consistent state for safety purposes.
98	type SubSwapper struct {
99	// started tracks whether the SubSwapper has been started and ensures
100	// it can only be started once.
101	started sync.Once
102
103	// stopped tracks whether the SubSwapper has been stopped and ensures
104	// it can only be stopped once.
105	stopped sync.Once
106
107	// backupState are the set of SCBs for all open channels we know of.
108	backupState map[wire.OutPoint]Single
109
110	// chanEvents is an active subscription to receive new channel state
111	// over.
112	chanEvents *ChannelSubscription
113
114	manualUpdates chan manualUpdate
115
116	// keyRing is the main key ring that will allow us to pack the new
117	// multi backup.
118	keyRing keychain.KeyRing
119
120	Swapper
121
122	quit chan struct{}
123	wg sync.WaitGroup
124
125	// isActive tracks whether the SubSwapper is active and ready to receive
126	// messages. It is used to prevent manual updates from being sent to the
127	// SubSwapper after it has been stopped or not yet started.
128	isActive atomic.Bool
129	}
130
131	// NewSubSwapper creates a new instance of the SubSwapper given the starting
132	// set of channels, and the required interfaces to be notified of new channel
133	// updates, pack a multi backup, and swap the current best backup from its
134	// storage location.
135	func NewSubSwapper(ctx context.Context, startingChans []Single,
136	chanNotifier ChannelNotifier, keyRing keychain.KeyRing,
137	backupSwapper Swapper) (*SubSwapper, error) {	3✔
138		3✔
139	// First, we'll subscribe to the latest set of channel updates given	3✔
140	// the set of channels we already know of.	3✔
141	knownChans := make(map[wire.OutPoint]struct{})	3✔
142	for _, chanBackup := range startingChans {	6✔
143	knownChans[chanBackup.FundingOutpoint] = struct{}{}	3✔
144	}	3✔
145	chanEvents, err := chanNotifier.SubscribeChans(ctx, knownChans)	3✔
146	if err != nil {	3✔
UNCOV 147	return nil, err	×
UNCOV 148	}	×
149
150	// Next, we'll construct our own backup state so we can add/remove
151	// channels that have been opened and closed.
152	backupState := make(map[wire.OutPoint]Single)	3✔
153	for _, chanBackup := range startingChans {	6✔
154	backupState[chanBackup.FundingOutpoint] = chanBackup	3✔
155	}	3✔
156
157	return &SubSwapper{	3✔
158	backupState: backupState,	3✔
159	chanEvents: chanEvents,	3✔
160	keyRing: keyRing,	3✔
161	Swapper: backupSwapper,	3✔
162	quit: make(chan struct{}),	3✔
163	manualUpdates: make(chan manualUpdate),	3✔
164	}, nil	3✔
165	}
166
167	// Start starts the chanbackup.SubSwapper.
168	func (s *SubSwapper) Start() error {	3✔
169	var startErr error	3✔
170	s.started.Do(func() {	6✔
171	log.Infof("chanbackup.SubSwapper starting")	3✔
172		3✔
173	// Before we enter our main loop, we'll update the on-disk	3✔
174	// state with the latest Single state, as nodes may have new	3✔
175	// advertised addresses.	3✔
176	if err := s.updateBackupFile(); err != nil {	3✔
177	startErr = fmt.Errorf("unable to refresh backup "+	×
178	"file: %v", err)	×
179		×
180	return	×
181	}	×
182
183	s.wg.Add(1)	3✔
184	go s.backupUpdater()	3✔
185	})
186
187	return startErr	3✔
188	}
189
190	// Stop signals the SubSwapper to being a graceful shutdown.
191	func (s *SubSwapper) Stop() error {	3✔
192	s.stopped.Do(func() {	6✔
193	log.Infof("chanbackup.SubSwapper shutting down...")	3✔
194	defer log.Debug("chanbackup.SubSwapper shutdown complete")	3✔
195		3✔
196	// Mark the SubSwapper as not running.	3✔
197	s.isActive.Store(false)	3✔
198		3✔
199	close(s.quit)	3✔
200	s.wg.Wait()	3✔
201	})	3✔
202
203	return nil	3✔
204	}
205
206	// ManualUpdate inserts/updates channel states into the swapper. The updates
207	// are processed in another goroutine. The method waits for the updates to be
208	// fully processed and the file to be updated on-disk before returning.
209	func (s *SubSwapper) ManualUpdate(singles []Single) error {	3✔
210	if !s.isActive.Load() {	3✔
211	return fmt.Errorf("swapper is not active, cannot perform " +	×
212	"manual update")	×
213	}	×
214
215	// Create the channel to send an error back. If the update handling
216	// and the subsequent file updating succeeds, nil is sent.
217	// The channel must have capacity of 1 to prevent Swapper blocking.
218	errChan := make(chan error, 1)	3✔
219		3✔
220	// Create the update object to insert into the processing loop.	3✔
221	update := manualUpdate{	3✔
222	singles: singles,	3✔
223	errChan: errChan,	3✔
224	}	3✔
225		3✔
226	select {	3✔
227	case s.manualUpdates <- update:	3✔
228	case <-s.quit:	×
229	return fmt.Errorf("swapper stopped when sending manual update")	×
230	}
231
232	// Wait for processing, block on errChan.
233	select {	3✔
234	case err := <-errChan:	3✔
235	if err != nil {	6✔
236	return fmt.Errorf("processing of manual update "+	3✔
237	"failed: %w", err)	3✔
238	}	3✔
239
240	case <-s.quit:	×
241	return fmt.Errorf("swapper stopped when waiting for outcome")	×
242	}
243
244	// Success.
245	return nil	3✔
246	}
247
248	// updateBackupFile updates the backup file in place given the current state of
249	// the SubSwapper. We accept the set of channels that were closed between this
250	// update and the last to make sure we leave them out of our backup set union.
251	func (s *SubSwapper) updateBackupFile(closedChans ...wire.OutPoint) error {	3✔
252	// Before we pack the new set of SCBs, we'll first decode what we	3✔
253	// already have on-disk, to make sure we can decode it (proper seed)	3✔
254	// and that we're able to combine it with our new data.	3✔
255	diskMulti, err := s.Swapper.ExtractMulti(s.keyRing)	3✔
256		3✔
257	// If the file doesn't exist on disk, then that's OK as it was never	3✔
258	// created. In this case we'll continue onwards as it isn't a critical	3✔
259	// error.	3✔
260	if err != nil && !os.IsNotExist(err) {	3✔
261	return fmt.Errorf("unable to extract on disk encrypted "+	×
262	"SCB: %v", err)	×
263	}	×
264
265	// Now that we have channels stored on-disk, we'll create a new set of
266	// the combined old and new channels to make sure we retain what's
267	// already on-disk.
268	//
269	// NOTE: The ordering of this operations means that our in-memory
270	// structure will replace what we read from disk.
271	combinedBackup := make(map[wire.OutPoint]Single)	3✔
272	if diskMulti != nil {	6✔
273	for _, diskChannel := range diskMulti.StaticBackups {	6✔
274	chanPoint := diskChannel.FundingOutpoint	3✔
275	combinedBackup[chanPoint] = diskChannel	3✔
276	}	3✔
277	}
278	for _, memChannel := range s.backupState {	6✔
279	chanPoint := memChannel.FundingOutpoint	3✔
280	if _, ok := combinedBackup[chanPoint]; ok {	6✔
281	log.Warnf("Replacing disk backup for ChannelPoint(%v) "+	3✔
282	"w/ newer version", chanPoint)	3✔
283	}	3✔
284
285	combinedBackup[chanPoint] = memChannel	3✔
286	}
287
288	// Remove the set of closed channels from the final set of backups.
289	for _, closedChan := range closedChans {	6✔
290	delete(combinedBackup, closedChan)	3✔
291	}	3✔
292
293	// With our updated channel state obtained, we'll create a new multi
294	// from our series of singles.
295	var newMulti Multi	3✔
296	for _, backup := range combinedBackup {	6✔
297	newMulti.StaticBackups = append(	3✔
298	newMulti.StaticBackups, backup,	3✔
299	)	3✔
300	}	3✔
301
302	// Now that our multi has been assembled, we'll attempt to pack
303	// (encrypt+encode) the new channel state to our target reader.
304	var b bytes.Buffer	3✔
305	err = newMulti.PackToWriter(&b, s.keyRing)	3✔
306	if err != nil {	3✔
307	return fmt.Errorf("unable to pack multi backup: %w", err)	×
308	}	×
309
310	// Finally, we'll swap out the old backup for this new one in a single
311	// atomic step, combining the file already on-disk with this set of new
312	// channels.
313	err = s.Swapper.UpdateAndSwap(PackedMulti(b.Bytes()))	3✔
314	if err != nil {	6✔
315	return fmt.Errorf("unable to update multi backup: %w", err)	3✔
316	}	3✔
317
318	return nil	3✔
319	}
320
321	// backupFileUpdater is the primary goroutine of the SubSwapper which is
322	// responsible for listening for changes to the channel, and updating the
323	// persistent multi backup state with a new packed multi of the latest channel
324	// state. Once active, it will process subscription updates and manual updates
325	// until the SubSwapper is stopped.
326	func (s *SubSwapper) backupUpdater() {	3✔
327	// Ensure that once we exit, we'll cancel our active channel	3✔
328	// subscription.	3✔
329	defer s.chanEvents.Cancel()	3✔
330	defer s.wg.Done()	3✔
331		3✔
332	log.Debugf("SubSwapper's backupUpdater is active!")	3✔
333		3✔
334	// Mark the SubSwapper as active.	3✔
335	s.isActive.Store(true)	3✔
336		3✔
337	for {	6✔
338	select {	3✔
339	// The channel state has been modified! We'll evaluate all
340	// changes, and swap out the old packed multi with a new one
341	// with the latest channel state.
342	case chanUpdate := <-s.chanEvents.ChanUpdates:	3✔
343	oldStateSize := len(s.backupState)	3✔
344		3✔
345	// For all new open channels, we'll create a new SCB	3✔
346	// given the required information.	3✔
347	for _, newChan := range chanUpdate.NewChans {	6✔
348	log.Debugf("Adding channel %v to backup state",	3✔
349	newChan.FundingOutpoint)	3✔
350		3✔
351	single := NewSingle(	3✔
352	newChan.OpenChannel, newChan.Addrs,	3✔
353	)	3✔
354	s.backupState[newChan.FundingOutpoint] = single	3✔
355	}	3✔
356
357	// For all closed channels, we'll remove the prior
358	// backup state.
359	closedChans := make(	3✔
360	[]wire.OutPoint, 0, len(chanUpdate.ClosedChans),	3✔
361	)	3✔
362	for i, closedChan := range chanUpdate.ClosedChans {	6✔
363	log.Debugf("Removing channel %v from backup "+	3✔
364	"state", lnutils.NewLogClosure(	3✔
365	chanUpdate.ClosedChans[i].String))	3✔
366		3✔
367	delete(s.backupState, closedChan)	3✔
368		3✔
369	closedChans = append(closedChans, closedChan)	3✔
370	}	3✔
371
372	newStateSize := len(s.backupState)	3✔
373		3✔
374	log.Infof("Updating on-disk multi SCB backup: "+	3✔
375	"num_old_chans=%v, num_new_chans=%v",	3✔
376	oldStateSize, newStateSize)	3✔
377		3✔
378	// Without new state constructed, we'll, atomically	3✔
379	// update the on-disk backup state.	3✔
380	if err := s.updateBackupFile(closedChans...); err != nil {	3✔
381	log.Errorf("unable to update backup file: %v",	×
382	err)	×
383	}	×
384
385	// We received a manual update. Handle it and update the file.
386	case manualUpdate := <-s.manualUpdates:	3✔
387	oldStateSize := len(s.backupState)	3✔
388		3✔
389	// For all open channels, we'll create a new SCB given	3✔
390	// the required information.	3✔
391	for _, single := range manualUpdate.singles {	6✔
392	log.Debugf("Manual update of channel %v",	3✔
393	single.FundingOutpoint)	3✔
394		3✔
395	s.backupState[single.FundingOutpoint] = single	3✔
396	}	3✔
397
398	newStateSize := len(s.backupState)	3✔
399		3✔
400	log.Infof("Updating on-disk multi SCB backup: "+	3✔
401	"num_old_chans=%v, num_new_chans=%v",	3✔
402	oldStateSize, newStateSize)	3✔
403		3✔
404	// Without new state constructed, we'll, atomically	3✔
405	// update the on-disk backup state.	3✔
406	err := s.updateBackupFile()	3✔
407	if err != nil {	6✔
408	log.Errorf("unable to update backup file: %v",	3✔
409	err)	3✔
410	}	3✔
411
412	// Send the error (or nil) to the caller of
413	// ManualUpdate. The error channel must have capacity of
414	// 1 not to block here.
415	manualUpdate.errChan <- err	3✔
416
417	// TODO(roasbeef): refresh periodically on a time basis due to
418	// possible addr changes from node
419
420	// Exit at once if a quit signal is detected.
421	case <-s.quit:	3✔
422	return	3✔
423	}
424	}
425	}

lightningnetwork / lnd / 17027244024

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