channeldb: add freelist sync option modifier

channeldb/db.go

@@ -85,7 +85,7 @@ func Open(dbPath string, modifiers ...OptionModifier) (*DB, error) {
 	// Specify bbolt freelist options to reduce heap pressure in case the
 	// freelist grows to be very large.
 	options := &bbolt.Options{
-		NoFreelistSync: true,
+		NoFreelistSync: opts.NoFreelistSync,
 		FreelistType:   bbolt.FreelistMapType,
 	}
 

channeldb/options.go

@@ -21,6 +21,11 @@ type Options struct {
 	// ChannelCacheSize is the maximum number of ChannelEdges to hold in the
 	// channel cache.
 	ChannelCacheSize int
+
+	// NoFreelistSync, if true, prevents the database from syncing its
+	// freelist to disk, resulting in improved performance at the expense of
+	// increased startup time.
+	NoFreelistSync bool
 }
 
 // DefaultOptions returns an Options populated with default values.
@@ -28,6 +33,7 @@ func DefaultOptions() Options {
 	return Options{
 		RejectCacheSize:  DefaultRejectCacheSize,
 		ChannelCacheSize: DefaultChannelCacheSize,
+		NoFreelistSync:   true,
 	}
 }
 
@@ -47,3 +53,10 @@ func OptionSetChannelCacheSize(n int) OptionModifier {
 		o.ChannelCacheSize = n
 	}
 }
+
+// OptionSetSyncFreelist allows the database to sync its freelist.
+func OptionSetSyncFreelist(b bool) OptionModifier {
+	return func(o *Options) {
+		o.NoFreelistSync = !b
+	}
+}