channeldb: store the invoice counter within the invoice index bucket

This commit moves the location of the invoice counter key which is an
auto-incrementing primary key for all invoices. Rather than storing the counter
in the same top-level invoice bucket, the counter is now stored within the
invoiceIndex bucket. With this change, the top-level bucket can now cleanly be
scanned in a sequential manner to retrieve all invoices.

channeldb/error.go

@@ -9,6 +9,7 @@ var (
 	ErrChannelNoExist   = fmt.Errorf("this channel does not exist")
 	ErrNoPastDeltas     = fmt.Errorf("channel has no recorded deltas")
 
-	ErrInvoiceNotFound  = fmt.Errorf("unable to locate invoice")
-	ErrDuplicateInvoice = fmt.Errorf("invoice with payment hash already exists")
+	ErrInvoiceNotFound   = fmt.Errorf("unable to locate invoice")
+	ErrNoInvoicesCreated = fmt.Errorf("there are no existing invoices")
+	ErrDuplicateInvoice  = fmt.Errorf("invoice with payment hash already exists")
 )

channeldb/invoices.go

@@ -18,19 +18,20 @@ var (
 	// which is a monotonically increasing uint32.
 	invoiceBucket = []byte("invoices")
 
-	// numInvoicesKey is the name of key which houses the auto-incrementing
-	// invoice ID which is essentially used as a primary key. With each
-	// invoice inserted, the primary key is incremented by one. Within the
-	// above bucket invoices are uniquely identified by the invoice ID.
-	numInvoicesKey = []byte("nik")
-
 	// paymentHashIndexBucket is the name of the sub-bucket within the
 	// invoiceBucket which indexes all invoices by their payment hash. The
 	// payment hash is the sha256 of the invoice's payment preimage. This
 	// index is used to detect duplicates, and also to provide a fast path
 	// for looking up incoming HTLC's to determine if we're able to settle
 	// them fully.
-	paymentHashIndexBucket = []byte("paymenthashes")
+	invoiceIndexBucket = []byte("paymenthashes")
+
+	// numInvoicesKey is the name of key which houses the auto-incrementing
+	// invoice ID which is essentially used as a primary key. With each
+	// invoice inserted, the primary key is incremented by one. This key is
+	// stored within the invoiceIndexBucket. Within the invoiceBucket
+	// invoices are uniquely identified by the invoice ID.
+	numInvoicesKey = []byte("nik")
 )
 
 const (
@@ -43,6 +44,24 @@ const (
 	MaxReceiptSize = 1024
 )
 
+// ContractTerm is a companion struct to the Invoice struct. This struct houses
+// the necessary conditions required before the invoice can be considered fully
+// settled by the payee.
+type ContractTerm struct {
+	// PaymentPreimage is the preimage which is to be revealed in the
+	// occasion that an HTLC paying to the hash of this preimage is
+	// extended.
+	PaymentPreimage [32]byte
+
+	// Value is the expected amount to be payed to an HTLC which can be
+	// satisfied by the above preimage.
+	Value btcutil.Amount
+
+	// Settled indicates if this particular contract term has been fully
+	// settled by the payer.
+	Settled bool
+}
+
 // Invoice is a payment invoice generated by a payee in order to request
 // payment for some good or service. The inclusion of invoices within Lightning
 // creates a payment work flow for merchants very similar to that of the
@@ -78,24 +97,6 @@ type Invoice struct {
 	Terms ContractTerm
 }
 
-// ContractTerm is a companion struct to the Invoice struct. This struct houses
-// the necessary conditions required before the invoice can be considered fully
-// settled by the payee.
-type ContractTerm struct {
-	// PaymentPreimage is the preimage which is to be revealed in the
-	// occasion that an HTLC paying to the hash of this preimage is
-	// extended.
-	PaymentPreimage [32]byte
-
-	// Value is the expected amount to be payed to an HTLC which can be
-	// satisfied by the above preimage.
-	Value btcutil.Amount
-
-	// Settled indicates if this particular contract term has been fully
-	// settled by the payer.
-	Settled bool
-}
-
 // AddInvoice inserts the targeted invoice into the database. If the invoice
 // has *any* payment hashes which already exists within the database, then the
 // insertion will be aborted and rejected due to the strict policy banning any
@@ -107,7 +108,7 @@ func (d *DB) AddInvoice(i *Invoice) error {
 			return err
 		}
 
-		invoiceIndex, err := invoices.CreateBucketIfNotExists(paymentHashIndexBucket)
+		invoiceIndex, err := invoices.CreateBucketIfNotExists(invoiceIndexBucket)
 		if err != nil {
 			return err
 		}
@@ -122,18 +123,17 @@ func (d *DB) AddInvoice(i *Invoice) error {
 		// If the current running payment ID counter hasn't yet been
 		// created, then create it now.
 		var invoiceNum uint32
-		invoiceCounter := invoices.Get(numInvoicesKey)
+		invoiceCounter := invoiceIndex.Get(numInvoicesKey)
 		if invoiceCounter == nil {
 			var scratch [4]byte
 			byteOrder.PutUint32(scratch[:], invoiceNum)
-			if err := invoices.Put(numInvoicesKey, scratch[:]); err != nil {
+			if err := invoiceIndex.Put(numInvoicesKey, scratch[:]); err != nil {
 				return nil
 			}
 		} else {
 			invoiceNum = byteOrder.Uint32(invoiceCounter)
 		}
 
-		// index from payment hash to ID?
 		return putInvoice(invoices, invoiceIndex, i, invoiceNum)
 	})
 }
@@ -151,7 +151,7 @@ func (d *DB) LookupInvoice(paymentHash [32]byte) (*Invoice, error) {
 		if invoices == nil {
 			return ErrInvoiceNotFound
 		}
-		invoiceIndex := invoices.Bucket(paymentHashIndexBucket)
+		invoiceIndex := invoices.Bucket(invoiceIndexBucket)
 		if invoiceIndex == nil {
 			return ErrInvoiceNotFound
 		}
@@ -190,7 +190,7 @@ func (d *DB) SettleInvoice(paymentHash [32]byte) error {
 		if err != nil {
 			return err
 		}
-		invoiceIndex, err := invoices.CreateBucketIfNotExists(paymentHashIndexBucket)
+		invoiceIndex, err := invoices.CreateBucketIfNotExists(invoiceIndexBucket)
 		if err != nil {
 			return err
 		}
@@ -219,7 +219,7 @@ func putInvoice(invoices *bolt.Bucket, invoiceIndex *bolt.Bucket,
 	var scratch [4]byte
 	invoiceCounter := invoiceNum + 1
 	byteOrder.PutUint32(scratch[:], invoiceCounter)
-	if err := invoices.Put(numInvoicesKey, scratch[:]); err != nil {
+	if err := invoiceIndex.Put(numInvoicesKey, scratch[:]); err != nil {
 		return err
 	}