cache: add SQLite route persistence; initial TTL and LRU eviction implementation

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I0370d6c114d5490634905c1a831a31526a6a6964

internal/cache/db_test.go

@@ -0,0 +1,157 @@
+package cache_test
+
+import (
+	"os"
+	"testing"
+	"time"
+
+	"notashelf.dev/ncro/internal/cache"
+)
+
+func newTestDB(t *testing.T) *cache.DB {
+	t.Helper()
+	f, err := os.CreateTemp("", "ncro-test-*.db")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+	t.Cleanup(func() { os.Remove(f.Name()) })
+
+	db, err := cache.Open(f.Name(), 1000)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { db.Close() })
+	return db
+}
+
+func TestGetSetRoute(t *testing.T) {
+	db := newTestDB(t)
+
+	entry := &cache.RouteEntry{
+		StorePath:    "abc123xyz-hello-2.12",
+		UpstreamURL:  "https://cache.nixos.org",
+		LatencyMs:    12.5,
+		LatencyEMA:   12.5,
+		LastVerified: time.Now().UTC().Truncate(time.Second),
+		QueryCount:   1,
+		TTL:          time.Now().Add(time.Hour).UTC().Truncate(time.Second),
+	}
+
+	if err := db.SetRoute(entry); err != nil {
+		t.Fatalf("SetRoute: %v", err)
+	}
+
+	got, err := db.GetRoute("abc123xyz-hello-2.12")
+	if err != nil {
+		t.Fatalf("GetRoute: %v", err)
+	}
+	if got == nil {
+		t.Fatal("GetRoute returned nil")
+	}
+	if got.UpstreamURL != entry.UpstreamURL {
+		t.Errorf("upstream = %q, want %q", got.UpstreamURL, entry.UpstreamURL)
+	}
+	if got.QueryCount != 1 {
+		t.Errorf("query_count = %d, want 1", got.QueryCount)
+	}
+}
+
+func TestGetRouteNotFound(t *testing.T) {
+	db := newTestDB(t)
+	got, err := db.GetRoute("nonexistent")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if got != nil {
+		t.Errorf("expected nil, got %+v", got)
+	}
+}
+
+func TestSetRouteUpsert(t *testing.T) {
+	db := newTestDB(t)
+
+	entry := &cache.RouteEntry{
+		StorePath:   "abc123-pkg",
+		UpstreamURL: "https://cache.nixos.org",
+		LatencyMs:   20.0,
+		LatencyEMA:  20.0,
+		QueryCount:  1,
+		TTL:         time.Now().Add(time.Hour),
+	}
+	db.SetRoute(entry)
+
+	entry.LatencyEMA = 18.0
+	entry.QueryCount = 2
+	if err := db.SetRoute(entry); err != nil {
+		t.Fatalf("upsert: %v", err)
+	}
+
+	got, _ := db.GetRoute("abc123-pkg")
+	if got.LatencyEMA != 18.0 {
+		t.Errorf("ema = %f, want 18.0", got.LatencyEMA)
+	}
+	if got.QueryCount != 2 {
+		t.Errorf("query_count = %d, want 2", got.QueryCount)
+	}
+}
+
+func TestExpireOldRoutes(t *testing.T) {
+	db := newTestDB(t)
+
+	// Insert expired route
+	expired := &cache.RouteEntry{
+		StorePath:   "expired-pkg",
+		UpstreamURL: "https://cache.nixos.org",
+		TTL:         time.Now().Add(-time.Minute), // already expired
+	}
+	db.SetRoute(expired)
+
+	// Insert valid route
+	valid := &cache.RouteEntry{
+		StorePath:   "valid-pkg",
+		UpstreamURL: "https://cache.nixos.org",
+		TTL:         time.Now().Add(time.Hour),
+	}
+	db.SetRoute(valid)
+
+	if err := db.ExpireOldRoutes(); err != nil {
+		t.Fatalf("ExpireOldRoutes: %v", err)
+	}
+
+	got, _ := db.GetRoute("expired-pkg")
+	if got != nil {
+		t.Error("expired route should have been deleted")
+	}
+	got2, _ := db.GetRoute("valid-pkg")
+	if got2 == nil {
+		t.Error("valid route should still exist")
+	}
+}
+
+func TestLRUEviction(t *testing.T) {
+	// Use maxEntries=3 to trigger eviction easily
+	f, _ := os.CreateTemp("", "ncro-lru-*.db")
+	f.Close()
+	defer os.Remove(f.Name())
+
+	db, _ := cache.Open(f.Name(), 3)
+	defer db.Close()
+
+	for i := range 4 {
+		db.SetRoute(&cache.RouteEntry{
+			StorePath:    "pkg-" + string(rune('a'+i)),
+			UpstreamURL:  "https://cache.nixos.org",
+			LastVerified: time.Now().Add(time.Duration(i) * time.Second),
+			TTL:          time.Now().Add(time.Hour),
+		})
+	}
+
+	count, err := db.RouteCount()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if count > 3 {
+		t.Errorf("expected count <= 3 after LRU eviction, got %d", count)
+	}
+}