loopdb: make new loopdb package to house persistent storage

loopdb/interface.go

@@ -0,0 +1,27 @@
+package loopdb
+
+import (
+	"time"
+
+	"github.com/lightningnetwork/lnd/lntypes"
+)
+
+// SwapStore is the priamry database interface used by the loopd system. It
+// houses informatino for all pending completed/failed swaps.
+type SwapStore interface {
+	// FetchUnchargeSwaps returns all swaps currently in the store.
+	FetchUnchargeSwaps() ([]*PersistentUncharge, error)
+
+	// CreateUncharge adds an initiated swap to the store.
+	CreateUncharge(hash lntypes.Hash, swap *UnchargeContract) error
+
+	// UpdateUncharge stores a swap updateUncharge. This appends to the
+	// event log for a particular swap as it goes through the various
+	// stages in its lifetime.
+	UpdateUncharge(hash lntypes.Hash, time time.Time, state SwapState) error
+
+	// Close closes the underlying database.
+	Close() error
+}
+
+// TODO(roasbeef): back up method in interface?