multi: add a re-usable TxOptions type

Add a re-usable implementation of the sqldb.TxOptions interface and make
use of this in the various spots (invoices, batch and graph/db) where we
had previously defined individual implementations that were all doing
the same thing.

batch/batch.go

@@ -14,19 +14,6 @@ var errSolo = errors.New(
 	"batch function returned an error and should be re-run solo",
 )
 
-// txOpts implements the sqldb.TxOptions interface. It is used to indicate that
-// the transaction can be read-only or not transaction.
-type txOpts struct {
-	readOnly bool
-}
-
-// ReadOnly returns true if the transaction should be read only.
-//
-// NOTE: This is part of the sqldb.TxOptions interface.
-func (t *txOpts) ReadOnly() bool {
-	return t.readOnly
-}
-
 type request[Q any] struct {
 	*Request[Q]
 	errChan chan error
@@ -38,7 +25,7 @@ type batch[Q any] struct {
 	reqs   []*request[Q]
 	clear  func(b *batch[Q])
 	locker sync.Locker
-	txOpts txOpts
+	txOpts sqldb.TxOptions
 }
 
 // trigger is the entry point for the batch and ensures that run is started at
@@ -68,7 +55,7 @@ func (b *batch[Q]) run(ctx context.Context) {
 	// that fail will be retried individually.
 	for len(b.reqs) > 0 {
 		var failIdx = -1
-		err := b.db.ExecTx(ctx, &b.txOpts, func(tx Q) error {
+		err := b.db.ExecTx(ctx, b.txOpts, func(tx Q) error {
 			for i, req := range b.reqs {
 				err := req.Do(tx)
 				if err != nil {

batch/batch_test.go

@@ -550,7 +550,7 @@ func benchmarkSQLBatching(b *testing.B, sqlite bool) {
 	}
 
 	ctx := context.Background()
-	var opts txOpts
+	opts := sqldb.WriteTxOpt()
 
 	// writeRecord is a helper that adds a single new invoice to the
 	// database. It uses the 'i' argument to create a unique hash for the
@@ -578,13 +578,12 @@ func benchmarkSQLBatching(b *testing.B, sqlite bool) {
 		var hash [8]byte
 		binary.BigEndian.PutUint64(hash[:], uint64(N-1))
 
-		err := tx.ExecTx(
-			ctx, &txOpts{}, func(queries *sqlc.Queries) error {
-				_, err := queries.GetInvoiceByHash(ctx, hash[:])
-				require.NoError(b, err)
+		err := tx.ExecTx(ctx, opts, func(queries *sqlc.Queries) error {
+			_, err := queries.GetInvoiceByHash(ctx, hash[:])
+			require.NoError(b, err)
 
-				return nil
-			}, func() {},
+			return nil
+		}, func() {},
 		)
 		require.NoError(b, err)
 	}
@@ -602,7 +601,7 @@ func benchmarkSQLBatching(b *testing.B, sqlite bool) {
 				defer wg.Done()
 
 				err := db.ExecTx(
-					ctx, &opts,
+					ctx, opts,
 					func(tx *sqlc.Queries) error {
 						writeRecord(b, tx, int64(j))
 						return nil
@@ -624,7 +623,7 @@ func benchmarkSQLBatching(b *testing.B, sqlite bool) {
 		b.ResetTimer()
 
 		err := db.ExecTx(
-			ctx, &opts,
+			ctx, opts,
 			func(tx *sqlc.Queries) error {
 				for i := 0; i < b.N; i++ {
 					writeRecord(b, tx, int64(i))

batch/scheduler.go

@@ -65,9 +65,7 @@ func (s *TimeScheduler[Q]) Execute(ctx context.Context, r *Request[Q]) error {
 			// By default, we assume that the batch is read-only,
 			// and we only upgrade it to read-write if a request
 			// is added that is not read-only.
-			txOpts: txOpts{
-				readOnly: true,
-			},
+			txOpts: sqldb.ReadTxOpt(),
 		}
 		trigger := s.b.trigger
 		time.AfterFunc(s.duration, func() {
@@ -78,8 +76,8 @@ func (s *TimeScheduler[Q]) Execute(ctx context.Context, r *Request[Q]) error {
 
 	// We only upgrade the batch to read-write if the new request is not
 	// read-only. If it is already read-write, we don't need to do anything.
-	if s.b.txOpts.readOnly && !r.Opts.ReadOnly {
-		s.b.txOpts.readOnly = false
+	if s.b.txOpts.ReadOnly() && !r.Opts.ReadOnly {
+		s.b.txOpts = sqldb.WriteTxOpt()
 	}
 
 	// If this is a non-lazy request, we'll execute the batch immediately.
@@ -109,7 +107,7 @@ func (s *TimeScheduler[Q]) Execute(ctx context.Context, r *Request[Q]) error {
 	}
 
 	// Otherwise, run the request on its own.
-	commitErr := s.db.ExecTx(ctx, &txOpts, func(tx Q) error {
+	commitErr := s.db.ExecTx(ctx, txOpts, func(tx Q) error {
 		return req.Do(tx)
 	}, func() {
 		if req.Reset != nil {