transactions: Accept `Voter` structures on transaction registration

Currently, the transactions manager only accepts a set of node names
when registering a new transaction. With the introduction of weighted
voting, the user registering a transaction may choose to set up
additional information for each node, e.g. its weight. Let's thus expose
the `Voter` structure such that callers may set up this information.

2 files changed, 11 insertions, 9 deletions

diff --git a/internal/praefect/transactions/manager.go b/internal/praefect/transactions/manager.go
index ec4047185..721e47522 100644
--- a/internal/praefect/transactions/manager.go
+++ b/internal/praefect/transactions/manager.go
@@ -107,7 +107,7 @@ type CancelFunc func()
 
 // RegisterTransaction registers a new reference transaction for a set of nodes
 // taking part in the transaction.
-func (mgr *Manager) RegisterTransaction(ctx context.Context, nodes []string) (uint64, CancelFunc, error) {
+func (mgr *Manager) RegisterTransaction(ctx context.Context, voters []Voter) (uint64, CancelFunc, error) {
 	mgr.lock.Lock()
 	defer mgr.lock.Unlock()
 
@@ -117,7 +117,7 @@ func (mgr *Manager) RegisterTransaction(ctx context.Context, nodes []string) (ui
 	// nodes still have in-flight transactions.
 	transactionID := mgr.txIDGenerator.ID()
 
-	transaction, err := newTransaction(nodes)
+	transaction, err := newTransaction(voters)
 	if err != nil {
 		return 0, nil, err
 	}
@@ -129,7 +129,7 @@ func (mgr *Manager) RegisterTransaction(ctx context.Context, nodes []string) (ui
 
 	mgr.log(ctx).WithFields(logrus.Fields{
 		"transaction_id": transactionID,
-		"nodes":          nodes,
+		"voters":         voters,
 	}).Debug("RegisterTransaction")
 
 	mgr.counterMetric.WithLabelValues("registered").Inc()
diff --git a/internal/praefect/transactions/transaction.go b/internal/praefect/transactions/transaction.go
index 7c7fb96bb..a9744e049 100644
--- a/internal/praefect/transactions/transaction.go
+++ b/internal/praefect/transactions/transaction.go
@@ -32,17 +32,19 @@ type transaction struct {
 	votersByNode map[string]*Voter
 }
 
-func newTransaction(nodes []string) (*transaction, error) {
-	if len(nodes) == 0 {
+func newTransaction(voters []Voter) (*transaction, error) {
+	if len(voters) == 0 {
 		return nil, ErrMissingNodes
 	}
 
-	votersByNode := make(map[string]*Voter, len(nodes))
-	for _, node := range nodes {
-		if _, ok := votersByNode[node]; ok {
+	votersByNode := make(map[string]*Voter, len(voters))
+	for _, voter := range voters {
+		if _, ok := votersByNode[voter.Name]; ok {
 			return nil, ErrDuplicateNodes
 		}
-		votersByNode[node] = &Voter{Name: node}
+
+		voter := voter // rescope loop variable
+		votersByNode[voter.Name] = &voter
 	}
 
 	return &transaction{