sync: Recreate syncer every try.

.github/workflows/build.yml

@@ -12,13 +12,13 @@ jobs:
         go: ["1.22", "1.23"]
     steps:
       - name: Check out source
-        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 #v4.2.2
       - name: Set up Go
-        uses: actions/setup-go@0a12ed9d6a96ab950c8f026ed9f722fe0da7ef32 # v5.0.2
+        uses: actions/setup-go@f111f3307d8850f501ac008e886eec1fd1932a34 #v5.3.0
         with:
           go-version: ${{ matrix.go }}
       - name: Use lint cache
-        uses: actions/cache@0c45773b623bea8c8e75f6c82b208c3cf94ea4f9 # v4.0.2
+        uses: actions/cache@1bd1e32a3bdc45362d1e726936510720a7c30a57 #v4.2.0
         with:
           path: |
             ~/.cache/golangci-lint

asset/dcr/sync.go

@@ -27,24 +27,36 @@ func (w *Wallet) StartSync(ctx context.Context, ntfns *spv.Notifications, connec
 	addr := &net.TCPAddr{IP: net.ParseIP("::1"), Port: 0}
 	amgr := addrmgr.New(w.dir, net.LookupIP)
 	lp := p2p.NewLocalPeer(w.ChainParams(), addr, amgr)
-	syncer := spv.NewSyncer(w.mainWallet, lp)
-	if len(connectPeers) > 0 {
-		syncer.SetPersistentPeers(connectPeers)
-	}
-	syncer.SetNotifications(ntfns)
 
-	// TODO: Set a birthday to sync from. I don't think dcrwallet allows
-	// this currently.
+	// We must create a new syncer for every attempt or we will get a
+	// closing closed channel panic when close(s.initialSyncDone) happens
+	// for the second time inside dcrwallet.
+	newSyncer := func() *spv.Syncer {
+		w.syncerMtx.Lock()
+		defer w.syncerMtx.Unlock()
+		syncer := spv.NewSyncer(w.mainWallet, lp)
+		if len(connectPeers) > 0 {
+			syncer.SetPersistentPeers(connectPeers)
+		}
+		syncer.SetNotifications(ntfns)
+
+		// TODO: Set a birthday to sync from. I don't think dcrwallet allows
+		// this currently.
 
-	w.syncer = syncer
-	w.SetNetworkBackend(syncer)
+		w.syncer = syncer
+		w.SetNetworkBackend(syncer)
+		return syncer
+	}
 
 	// Start the syncer in a goroutine, monitor when the sync ctx is canceled
 	// and then disconnect the sync.
 	go func() {
 		for {
+			syncer := newSyncer()
 			err := syncer.Run(ctx)
 			if ctx.Err() != nil {
+				w.syncerMtx.Lock()
+				defer w.syncerMtx.Unlock()
 				// sync ctx canceled, quit syncing
 				w.syncer = nil
 				w.SetNetworkBackend(nil)
@@ -77,6 +89,8 @@ func (w *Wallet) IsSyncing(ctx context.Context) bool {
 // IsSynced returns true if the wallet has synced up to the best block on the
 // mainchain.
 func (w *Wallet) IsSynced(ctx context.Context) (bool, int32) {
+	w.syncerMtx.RLock()
+	defer w.syncerMtx.RUnlock()
 	if w.syncer != nil {
 		return w.syncer.Synced(ctx)
 	}
@@ -89,5 +103,7 @@ func (w *Wallet) IsSynced(ctx context.Context) (bool, int32) {
 // completes or ends in an error. p is closed before returning.
 func (w *Wallet) RescanProgressFromHeight(ctx context.Context,
 	startHeight int32, p chan<- dcrwallet.RescanProgress) {
+	w.syncerMtx.RLock()
+	defer w.syncerMtx.RUnlock()
 	w.mainWallet.RescanProgressFromHeight(ctx, w.syncer, startHeight, p)
 }

asset/dcr/transactions.go

@@ -262,5 +262,7 @@ func (w *Wallet) SendRawTransaction(ctx context.Context, txHex string) (*chainha
 	if err := msgTx.FromBytes(msgBytes); err != nil {
 		return nil, fmt.Errorf("unable to create msgtx from bytes: %v", err)
 	}
+	w.syncerMtx.RLock()
+	defer w.syncerMtx.RUnlock()
 	return w.mainWallet.PublishTransaction(ctx, msgTx, w.syncer)
 }

asset/dcr/wallet.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"path/filepath"
+	"sync"
 
 	"decred.org/dcrwallet/v4/spv"
 	"decred.org/dcrwallet/v4/wallet"
@@ -24,7 +25,8 @@ type Wallet struct {
 	db wallet.DB
 	*mainWallet
 
-	syncer *spv.Syncer
+	syncerMtx sync.RWMutex
+	syncer    *spv.Syncer
 }
 
 // MainWallet returns the main dcr wallet with the core wallet functionalities.