refactor: dataset.Add returns *Dataset, no View; main uses Group for all cases

Remove View[T] — Add now returns *Dataset[T] directly. Callers use Load()
on the returned Dataset; Init/Run belong to the owning Group.

main.go simplified: declare syncer + file paths per case, then one
g.Init() and one g.Run(). No manual loops over individual datasets.
Add gitshallow.Repo.FilePath helper.

cmd/check-ip/main.go

@@ -45,23 +45,24 @@ func main() {
 
 	// -- Blacklist ----------------------------------------------------------
 
-	var inboundDS, outboundDS *dataset.Dataset[ipcohort.Cohort]
+	var (
+		syncer       dataset.Syncer
+		inboundPaths []string
+		outboundPaths []string
+	)
 
 	switch {
 	case *inbound != "" || *outbound != "":
-		inboundDS  = cohortDataset(dataset.NopSyncer{}, splitPaths(*inbound)...)
-		outboundDS = cohortDataset(dataset.NopSyncer{}, splitPaths(*outbound)...)
+		syncer         = dataset.NopSyncer{}
+		inboundPaths   = splitPaths(*inbound)
+		outboundPaths  = splitPaths(*outbound)
 
 	case *gitURL != "":
 		dir := cacheDir(*dataDir, "bitwire-it")
 		gr  := gitshallow.New(*gitURL, dir, 1, "")
-		inSingle  := gr.File("tables/inbound/single_ips.txt")
-		inNetwork := gr.File("tables/inbound/networks.txt")
-		outSingle := gr.File("tables/outbound/single_ips.txt")
-		outNetwork:= gr.File("tables/outbound/networks.txt")
-		// Each File.Fetch deduplicates the git pull via the shared Repo.
-		inboundDS  = cohortDataset(dataset.MultiSyncer{inSingle, inNetwork},  inSingle.Path(), inNetwork.Path())
-		outboundDS = cohortDataset(dataset.MultiSyncer{outSingle, outNetwork}, outSingle.Path(), outNetwork.Path())
+		syncer         = gr
+		inboundPaths   = []string{gr.FilePath("tables/inbound/single_ips.txt"), gr.FilePath("tables/inbound/networks.txt")}
+		outboundPaths  = []string{gr.FilePath("tables/outbound/single_ips.txt"), gr.FilePath("tables/outbound/networks.txt")}
 
 	default:
 		dir        := cacheDir(*dataDir, "bitwire-it")
@@ -69,27 +70,31 @@ func main() {
 		inNetwork  := httpcache.New(inboundNetworkURL,  filepath.Join(dir, "inbound_networks.txt"))
 		outSingle  := httpcache.New(outboundSingleURL,  filepath.Join(dir, "outbound_single_ips.txt"))
 		outNetwork := httpcache.New(outboundNetworkURL, filepath.Join(dir, "outbound_networks.txt"))
-		inboundDS  = cohortDataset(dataset.MultiSyncer{inSingle, inNetwork},   inSingle.Path, inNetwork.Path)
-		outboundDS = cohortDataset(dataset.MultiSyncer{outSingle, outNetwork}, outSingle.Path, outNetwork.Path)
+		syncer        = dataset.MultiSyncer{inSingle, inNetwork, outSingle, outNetwork}
+		inboundPaths  = []string{inSingle.Path, inNetwork.Path}
+		outboundPaths = []string{outSingle.Path, outNetwork.Path}
 	}
 
-	var whitelistDS *dataset.Dataset[ipcohort.Cohort]
-	if *whitelist != "" {
-		whitelistDS = cohortDataset(dataset.NopSyncer{}, splitPaths(*whitelist)...)
-	}
+	g          := dataset.NewGroup(syncer)
+	inboundDS  := dataset.Add(g, loadCohort(inboundPaths...))
+	outboundDS := dataset.Add(g, loadCohort(outboundPaths...))
 
-	for _, ds := range []*dataset.Dataset[ipcohort.Cohort]{whitelistDS, inboundDS, outboundDS} {
-		if ds == nil {
-			continue
-		}
-		if err := ds.Init(); err != nil {
+	if err := g.Init(); err != nil {
 		fmt.Fprintf(os.Stderr, "error: blacklist: %v\n", err)
 		os.Exit(1)
 	}
-	}
 	fmt.Fprintf(os.Stderr, "Loaded inbound=%d outbound=%d\n",
 		inboundDS.Load().Size(), outboundDS.Load().Size())
 
+	var whitelistDS *dataset.Dataset[ipcohort.Cohort]
+	if *whitelist != "" {
+		whitelistDS = dataset.New(dataset.NopSyncer{}, loadCohort(splitPaths(*whitelist)...))
+		if err := whitelistDS.Init(); err != nil {
+			fmt.Fprintf(os.Stderr, "error: whitelist: %v\n", err)
+			os.Exit(1)
+		}
+	}
+
 	// -- GeoIP (optional) --------------------------------------------------
 
 	geo, err := setupGeo(*geoipConf, *cityDB, *asnDB)
@@ -106,11 +111,7 @@ func main() {
 
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-	for _, ds := range []*dataset.Dataset[ipcohort.Cohort]{whitelistDS, inboundDS, outboundDS} {
-		if ds != nil {
-			go ds.Run(ctx, 47*time.Minute)
-		}
-	}
+	go g.Run(ctx, 47*time.Minute)
 	geo.Run(ctx, 47*time.Minute)
 
 	// -- Check and report --------------------------------------------------
@@ -135,11 +136,10 @@ func main() {
 	}
 }
 
-// cohortDataset creates a Dataset that fetches via syncer and loads paths as a Cohort.
-func cohortDataset(syncer dataset.Syncer, paths ...string) *dataset.Dataset[ipcohort.Cohort] {
-	return dataset.New(syncer, func() (*ipcohort.Cohort, error) {
+func loadCohort(paths ...string) func() (*ipcohort.Cohort, error) {
+	return func() (*ipcohort.Cohort, error) {
 		return ipcohort.LoadFiles(paths...)
-	})
+	}
 }
 
 func isBlocked(ip string, whitelist, cohort *dataset.Dataset[ipcohort.Cohort]) bool {

net/dataset/dataset.go

@@ -11,13 +11,14 @@
 //	go ds.Run(ctx, 47*time.Minute)
 //	val := ds.Load() // *MyType, lock-free
 //
-// Group (one syncer, multiple values):
+// Group (one syncer, multiple datasets):
 //
 //	g := dataset.NewGroup(repo)
 //	inbound  := dataset.Add(g, func() (*ipcohort.Cohort, error) { ... })
 //	outbound := dataset.Add(g, func() (*ipcohort.Cohort, error) { ... })
 //	if err := g.Init(); err != nil { ... }
 //	go g.Run(ctx, 47*time.Minute)
+//	val := inbound.Load() // lock-free; Init/Run belong to the Group
 package dataset
 
 import (
@@ -56,6 +57,9 @@ func (NopSyncer) Fetch() (bool, error) { return false, nil }
 
 // Dataset couples a Syncer, a load function, and an atomic.Pointer[T].
 // Load is safe for concurrent use without locks.
+//
+// When a Dataset is added to a Group via Add, Init and Run belong to the
+// Group; call Load on the Dataset to read the current value.
 type Dataset[T any] struct {
 	// Name is used in error messages.
 	Name string
@@ -140,6 +144,9 @@ type member interface {
 
 // Group ties one Syncer to multiple datasets so a single Fetch drives all
 // swaps — no redundant network calls when datasets share a source.
+//
+// Datasets added via Add are owned by the Group; call Init and Run on the
+// Group, not on individual datasets.
 type Group struct {
 	syncer  Syncer
 	members []member
@@ -197,20 +204,10 @@ func (g *Group) Run(ctx context.Context, interval time.Duration) {
 	}
 }
 
-// View is the read-only handle returned by Add. Sync is driven by the owning
-// Group.
-type View[T any] struct {
-	d *Dataset[T]
-}
-
-// Load returns the current value. Returns nil before the Group is initialised.
-func (v *View[T]) Load() *T { return v.d.ptr.Load() }
-
-func (v *View[T]) swap() error { return v.d.swap() }
-
-// Add registers a new dataset in g and returns a View for reading.
-func Add[T any](g *Group, load func() (*T, error)) *View[T] {
-	v := &View[T]{d: &Dataset[T]{load: load}}
-	g.members = append(g.members, v)
-	return v
+// Add registers a new dataset in g and returns it for reading via Load.
+// Init and Run are driven by the Group; do not call them on the returned Dataset.
+func Add[T any](g *Group, load func() (*T, error)) *Dataset[T] {
+	d := &Dataset[T]{load: load}
+	g.members = append(g.members, d)
+	return d
 }

net/formmailer/formmailer.go

@@ -102,7 +102,7 @@ type FormMailer struct {
 	ContentType string // inferred from SuccessBody if empty
 
 	// Blacklist — if set, matching IPs are rejected before any other processing.
-	Blacklist *dataset.View[ipcohort.Cohort]
+	Blacklist *dataset.Dataset[ipcohort.Cohort]
 
 	// AllowedCountries — if non-nil, only requests from listed ISO codes are
 	// accepted. Unknown country ("") is always allowed.

net/gitshallow/gitshallow.go

@@ -173,6 +173,11 @@ func (r *Repo) Fetch() (bool, error) {
 	return r.syncGit()
 }
 
+// FilePath returns the absolute path to relPath within this repo.
+func (r *Repo) FilePath(rel string) string {
+	return filepath.Join(r.Path, rel)
+}
+
 // File returns a handle to relPath within this repo.
 // The handle's Path and Open methods give access to the file; its Fetch method
 // syncs the repo and reports whether this specific file changed (by mtime).