loopdb/loopout: add field SwapPublicationDeadline to LoopOutContract

We also add a migration for the new LoopOut DB format.

loopdb/loopout.go

@@ -45,6 +45,12 @@ type LoopOutContract struct {
 	// MaxPrepayRoutingFee is the maximum off-chain fee in msat that may be
 	// paid for the prepayment to the server.
 	MaxPrepayRoutingFee btcutil.Amount
+
+	// SwapPublicationDeadline is a timestamp that the server commits to
+	// have the on-chain swap published by. It is set by the client to
+	// allow the server to delay the publication in exchange for possibly
+	// lower fees.
+	SwapPublicationDeadline time.Time
 }
 
 // LoopOut is a combination of the contract and the updates.
@@ -158,6 +164,13 @@ func deserializeLoopOutContract(value []byte, chainParams *chaincfg.Params) (
 		contract.UnchargeChannel = &unchargeChannel
 	}
 
+	var deadlineNano int64
+	err = binary.Read(r, byteOrder, &deadlineNano)
+	if err != nil {
+		return nil, err
+	}
+	contract.SwapPublicationDeadline = time.Unix(0, deadlineNano)
+
 	return &contract, nil
 }
 
@@ -243,5 +256,10 @@ func serializeLoopOutContract(swap *LoopOutContract) (
 		return nil, err
 	}
 
+	err = binary.Write(&b, byteOrder, swap.SwapPublicationDeadline.UnixNano())
+	if err != nil {
+		return nil, err
+	}
+
 	return b.Bytes(), nil
 }

loopdb/meta.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 
+	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/coreos/bbolt"
 )
 
@@ -24,14 +25,17 @@ var (
 // migration is a function which takes a prior outdated version of the database
 // instances and mutates the key/bucket structure to arrive at a more
 // up-to-date version of the database.
-type migration func(tx *bbolt.Tx) error
+type migration func(tx *bbolt.Tx, chainParams *chaincfg.Params) error
 
 var (
 	// dbVersions is storing all versions of database. If current version
 	// of database don't match with latest version this list will be used
 	// for retrieving all migration function that are need to apply to the
 	// current db.
-	migrations = []migration{migrateCosts}
+	migrations = []migration{
+		migrateCosts,
+		migrateSwapPublicationDeadline,
+	}
 
 	latestDBVersion = uint32(len(migrations))
 )
@@ -76,7 +80,7 @@ func setDBVersion(tx *bbolt.Tx, version uint32) error {
 // syncVersions function is used for safe db version synchronization. It
 // applies migration functions to the current database and recovers the
 // previous state of db if at least one error/panic appeared during migration.
-func syncVersions(db *bbolt.DB) error {
+func syncVersions(db *bbolt.DB, chainParams *chaincfg.Params) error {
 	currentVersion, err := getDBVersion(db)
 	if err != nil {
 		return err
@@ -112,7 +116,7 @@ func syncVersions(db *bbolt.DB) error {
 			log.Infof("Applying migration #%v", v+1)
 
 			migration := migrations[v]
-			if err := migration(tx); err != nil {
+			if err := migration(tx, chainParams); err != nil {
 				log.Infof("Unable to apply migration #%v",
 					v+1)
 				return err

loopdb/migration_01_costs.go

@@ -4,12 +4,13 @@ import (
 	"errors"
 	"fmt"
 
+	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/coreos/bbolt"
 )
 
 // noMigrationAvailable is the fall back migration in case there is no migration
 // implemented.
-func migrateCosts(tx *bbolt.Tx) error {
+func migrateCosts(tx *bbolt.Tx, _ *chaincfg.Params) error {
 	if err := migrateCostsForBucket(tx, loopInBucketKey); err != nil {
 		return err
 	}

loopdb/migration_02_swap_publication_deadline.go

@@ -0,0 +1,58 @@
+package loopdb
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+
+	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/coreos/bbolt"
+)
+
+// migrateSwapPublicationDeadline migrates the database to v02, by adding the
+// SwapPublicationDeadline field to loop out contracts.
+func migrateSwapPublicationDeadline(tx *bbolt.Tx, chainParams *chaincfg.Params) error {
+	rootBucket := tx.Bucket(loopOutBucketKey)
+	if rootBucket == nil {
+		return errors.New("bucket does not exist")
+	}
+
+	return rootBucket.ForEach(func(swapHash, v []byte) error {
+		// Only go into things that we know are sub-bucket
+		// keys.
+		if v != nil {
+			return nil
+		}
+
+		// From the root bucket, we'll grab the next swap
+		// bucket for this swap from its swaphash.
+		swapBucket := rootBucket.Bucket(swapHash)
+		if swapBucket == nil {
+			return fmt.Errorf("swap bucket %x not found",
+				swapHash)
+		}
+
+		// With the main swap bucket obtained, we'll grab the
+		// raw swap contract bytes.
+		contractBytes := swapBucket.Get(contractKey)
+		if contractBytes == nil {
+			return errors.New("contract not found")
+		}
+
+		// Write the current contract serialization into a buffer.
+		b := &bytes.Buffer{}
+		if _, err := b.Write(contractBytes); err != nil {
+			return err
+		}
+
+		// We migrate to the new format by copying the first 8 bytes
+		// (the creation time) to the end (the swap deadline)
+		var swapDeadline [8]byte
+		copy(swapDeadline[:], contractBytes[:8])
+		if _, err := b.Write(swapDeadline[:]); err != nil {
+			return err
+		}
+
+		return swapBucket.Put(contractKey, b.Bytes())
+	})
+}

loopdb/store.go

@@ -135,7 +135,7 @@ func NewBoltSwapStore(dbPath string, chainParams *chaincfg.Params) (
 
 	// Finally, before we start, we'll sync the DB versions to pick up any
 	// possible DB migrations.
-	err = syncVersions(bdb)
+	err = syncVersions(bdb, chainParams)
 	if err != nil {
 		return nil, err
 	}

loopdb/store_test.go

@@ -82,12 +82,13 @@ func TestLoopOutStore(t *testing.T) {
 			// doesn't interfere with DeepEqual.
 			InitiationTime: time.Unix(0, initiationTime.UnixNano()),
 		},
-		MaxPrepayRoutingFee: 40,
-		PrepayInvoice:       "prepayinvoice",
-		DestAddr:            destAddr,
-		SwapInvoice:         "swapinvoice",
-		MaxSwapRoutingFee:   30,
-		SweepConfTarget:     2,
+		MaxPrepayRoutingFee:     40,
+		PrepayInvoice:           "prepayinvoice",
+		DestAddr:                destAddr,
+		SwapInvoice:             "swapinvoice",
+		MaxSwapRoutingFee:       30,
+		SweepConfTarget:         2,
+		SwapPublicationDeadline: time.Unix(0, initiationTime.UnixNano()),
 	}
 
 	// checkSwap is a test helper function that'll assert the state of a