Cache platform settings in Redis

backend/cmd/map/main.go

@@ -234,6 +234,8 @@ func mapCTFService() {
 	if err != nil {
 		log.Fatal().Msgf("Failed to initialize settings: %v", err)
 	}
+	// Cache platform settings in Redis (read-heavy, write-invalidate).
+	settingsMgr.SetCache(redis.Client)
 	if err := settingsMgr.Initialization(flagParams.ConfigValues.Map.UUID); err != nil {
 		log.Fatal().Msgf("Failed to initialize default settings: %v", err)
 	}

backend/go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/stretchr/testify v1.11.1
 	go.yaml.in/yaml/v3 v3.0.4
 	golang.org/x/crypto v0.53.0
+	golang.org/x/sync v0.21.0
 	golang.org/x/text v0.38.0
 	gorm.io/gorm v1.31.1
 )
@@ -36,7 +37,6 @@ require (
 	github.com/subosito/gotenv v1.6.0 // indirect
 	github.com/yuin/gopher-lua v1.1.1 // indirect
 	go.uber.org/atomic v1.11.0 // indirect
-	golang.org/x/sync v0.21.0 // indirect
 	golang.org/x/sys v0.46.0 // indirect
 )
 

backend/pkg/settings/cache.go

@@ -0,0 +1,165 @@
+package settings
+
+import (
+	"context"
+	"encoding/json"
+	"sync"
+	"time"
+
+	redis "github.com/redis/go-redis/v9"
+	"golang.org/x/sync/singleflight"
+)
+
+const (
+	// settingsCacheL1TTL bounds how long an in-process copy is reused, coalescing
+	// repeated reads within a single request burst (e.g. the gameboard handler
+	// reads many settings at once).
+	settingsCacheL1TTL = 2 * time.Second
+	// settingsCacheL2TTL is the Redis TTL; a safety net since writes invalidate.
+	settingsCacheL2TTL     = 60 * time.Second
+	settingsCacheKeyPrefix = "mapctf:settings:"
+)
+
+// settingsCacheEntry holds both views of a UUID's settings: the ordered slice
+// (for GetAll) and a name lookup map (for Get), built once when loaded.
+type settingsCacheEntry struct {
+	slice     []PlatformSetting
+	byName    map[string]PlatformSetting
+	fetchedAt time.Time
+}
+
+func newEntry(slice []PlatformSetting) *settingsCacheEntry {
+	byName := make(map[string]PlatformSetting, len(slice))
+	for _, s := range slice {
+		byName[s.Name] = s
+	}
+	return &settingsCacheEntry{slice: slice, byName: byName, fetchedAt: time.Now()}
+}
+
+func (e *settingsCacheEntry) fresh() bool {
+	return time.Since(e.fetchedAt) < settingsCacheL1TTL
+}
+
+// settingsCache is a per-UUID, two-layer (in-process L1 + Redis L2) cache-aside
+// for platform settings. Settings are read on most requests but change only via
+// admin writes, so reads hit the cache and writes invalidate it.
+type settingsCache struct {
+	rdb *redis.Client
+	l1  sync.Map // uuid -> *settingsCacheEntry
+	sf  singleflight.Group
+}
+
+func settingsCacheKey(uuid string) string { return settingsCacheKeyPrefix + uuid }
+
+// SetCache enables Redis-backed caching for this manager. Passing nil disables
+// it; reads then use only the in-process L1 over the DB.
+func (m *SettingsManager) SetCache(rdb *redis.Client) {
+	if rdb == nil {
+		m.cache = &settingsCache{}
+		return
+	}
+	m.cache = &settingsCache{rdb: rdb}
+}
+
+func (m *settingsCache) l1Get(uuid string) (*settingsCacheEntry, bool) {
+	if m == nil {
+		return nil, false
+	}
+	v, ok := m.l1.Load(uuid)
+	if !ok {
+		return nil, false
+	}
+	e := v.(*settingsCacheEntry)
+	if !e.fresh() {
+		return nil, false
+	}
+	return e, true
+}
+
+func (m *settingsCache) l1Put(uuid string, e *settingsCacheEntry) {
+	if m == nil {
+		return
+	}
+	m.l1.Store(uuid, e)
+}
+
+func (m *settingsCache) l1Delete(uuid string) {
+	if m == nil {
+		return
+	}
+	m.l1.Delete(uuid)
+}
+
+// loadCached returns the cached entry for a UUID, filling L1/Redis from the DB
+// on miss. Cache errors never fail the read: any cache problem falls back to DB.
+func (m *SettingsManager) loadCached(uuid string) (*settingsCacheEntry, error) {
+	if e, ok := m.cacheL1Get(uuid); ok {
+		return e, nil
+	}
+	if m.cache == nil {
+		// Caching disabled: uncached DB read.
+		return m.loadFromDB(uuid)
+	}
+	v, err, _ := m.cache.sf.Do(settingsCacheKey(uuid), func() (any, error) {
+		if e, ok := m.cacheL1Get(uuid); ok {
+			return e, nil
+		}
+		var slice []PlatformSetting
+		// L2: Redis (best-effort; a miss or error falls through to the DB).
+		if m.cache.rdb != nil {
+			ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
+			raw, rerr := m.cache.rdb.Get(ctx, settingsCacheKey(uuid)).Bytes()
+			cancel()
+			if rerr == nil {
+				if json.Unmarshal(raw, &slice) == nil {
+					e := newEntry(slice)
+					m.cacheL1Put(uuid, e)
+					return e, nil
+				}
+			}
+		}
+		// DB load, then populate L2 (if enabled) and L1.
+		var derr error
+		slice, derr = m.getAllFromDB(uuid)
+		if derr != nil {
+			return nil, derr
+		}
+		if m.cache.rdb != nil {
+			if data, merr := json.Marshal(slice); merr == nil {
+				m.cache.rdb.Set(context.Background(), settingsCacheKey(uuid), data, settingsCacheL2TTL)
+			}
+		}
+		e := newEntry(slice)
+		m.cacheL1Put(uuid, e)
+		return e, nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	return v.(*settingsCacheEntry), nil
+}
+
+func (m *SettingsManager) cacheL1Get(uuid string) (*settingsCacheEntry, bool) {
+	if m.cache == nil {
+		return nil, false
+	}
+	return m.cache.l1Get(uuid)
+}
+
+func (m *SettingsManager) cacheL1Put(uuid string, e *settingsCacheEntry) {
+	if m.cache == nil {
+		return
+	}
+	m.cache.l1Put(uuid, e)
+}
+
+// invalidate drops the cached settings for a UUID after a write.
+func (m *SettingsManager) invalidate(uuid string) {
+	if m.cache == nil {
+		return
+	}
+	m.cache.l1Delete(uuid)
+	if m.cache.rdb != nil {
+		m.cache.rdb.Del(context.Background(), settingsCacheKey(uuid))
+	}
+}

backend/pkg/settings/settings.go

@@ -140,6 +140,7 @@ type SettingLog struct {
 type SettingsManager struct {
 	DB      *gorm.DB
 	Service string
+	cache   *settingsCache
 }
 
 // CreateSettingsManager to initialize the settings struct and tables
@@ -242,6 +243,7 @@ func (m *SettingsManager) Create(setting PlatformSetting) error {
 	if err := m.LogEvent(setting.ID, EventCreate, m.Service, setting.UUID); err != nil {
 		return fmt.Errorf("logEvent PlatformSetting %w", err)
 	}
+	m.invalidate(setting.UUID)
 	return nil
 }
 
@@ -253,23 +255,46 @@ func (m *SettingsManager) Exists(name string, uuid string) bool {
 }
 
 // Get setting by name including service settings
+// Get returns a setting by name, served from the settings cache when enabled.
+// It preserves gorm.ErrRecordNotFound semantics so existing callers are unaffected.
 func (m *SettingsManager) Get(name string, uuid string) (PlatformSetting, error) {
-	var setting PlatformSetting
-	if err := m.DB.Where("name = ? AND uuid = ?", name, uuid).First(&setting).Error; err != nil {
-		return setting, err
+	entry, err := m.loadCached(uuid)
+	if err != nil {
+		return PlatformSetting{}, err
+	}
+	if setting, ok := entry.byName[name]; ok {
+		return setting, nil
 	}
-	return setting, nil
+	return PlatformSetting{}, gorm.ErrRecordNotFound
 }
 
-// GetAll settings for a given uuid
+// GetAll settings for a given uuid, served from the settings cache when enabled.
 func (m *SettingsManager) GetAll(uuid string) ([]PlatformSetting, error) {
+	entry, err := m.loadCached(uuid)
+	if err != nil {
+		return nil, err
+	}
+	return entry.slice, nil
+}
+
+// getAllFromDB is the uncached DB read used to populate the cache.
+func (m *SettingsManager) getAllFromDB(uuid string) ([]PlatformSetting, error) {
 	var settings []PlatformSetting
 	if err := m.DB.Where("uuid = ?", uuid).Find(&settings).Error; err != nil {
 		return nil, err
 	}
 	return settings, nil
 }
 
+// loadFromDB builds a cache entry straight from the database.
+func (m *SettingsManager) loadFromDB(uuid string) (*settingsCacheEntry, error) {
+	slice, err := m.getAllFromDB(uuid)
+	if err != nil {
+		return nil, err
+	}
+	return newEntry(slice), nil
+}
+
 // ExistsGet checks if setting exists and returns the setting
 func (m *SettingsManager) ExistsGet(name string, uuid string) (bool, PlatformSetting) {
 	setting, err := m.Get(name, uuid)
@@ -330,6 +355,7 @@ func (m *SettingsManager) Save(setting PlatformSetting, username string) error {
 	if err := m.LogEvent(setting.ID, EventUpdate, username, setting.UUID); err != nil {
 		return fmt.Errorf("logEvent PlatformSetting %w", err)
 	}
+	m.invalidate(setting.UUID)
 	return nil
 }
 
@@ -339,6 +365,7 @@ func (m *SettingsManager) Change(name, valueType string, uuid string, value any,
 	if err != nil {
 		return fmt.Errorf("failed to get setting: %w", err)
 	}
+	defer m.invalidate(uuid)
 	column, err := valueColumnByType(valueType)
 	if err != nil {
 		return fmt.Errorf("failed to resolve setting value column: %w", err)

backend/pkg/settings/settings_test.go

@@ -576,3 +576,43 @@ func TestSaveFailsWhenLogInsertFails(t *testing.T) {
 	require.Error(t, err)
 	require.Contains(t, err.Error(), "logEvent PlatformSetting")
 }
+
+func TestSettingsCacheServesReadsAndInvalidatesOnWrite(t *testing.T) {
+	// L1-only cache (no Redis) keeps the test network-free; the Redis L2 path
+	// uses the same load/invalidate logic and is exercised in environments with
+	// a reachable Redis.
+	db, sqlDB := newTestDB(t)
+	defer sqlDB.Close()
+	m, err := CreateSettingsManager(db, "test-service")
+	require.NoError(t, err)
+	m.SetCache(nil)
+	require.NoError(t, m.Initialization("tenant-a"))
+
+	// Seed a value through the manager (write path invalidates the cache).
+	require.NoError(t, m.SetLanguage("es", "alice", "tenant-a"))
+	got, err := m.GetLanguage("tenant-a")
+	require.NoError(t, err)
+	require.Equal(t, "es", got) // miss -> DB -> populate cache
+
+	// Mutate the DB directly, bypassing the manager so no invalidation happens.
+	require.NoError(t, db.Model(&PlatformSetting{}).
+		Where("name = ? AND uuid = ?", Language, "tenant-a").
+		Update("value_string", "fr").Error)
+
+	// Cached read still returns the stale value, proving the cache served it.
+	got, err = m.GetLanguage("tenant-a")
+	require.NoError(t, err)
+	require.Equal(t, "es", got, "cached read should not reflect a bypassing DB write")
+
+	// After invalidation the next read picks up the DB value.
+	m.invalidate("tenant-a")
+	got, err = m.GetLanguage("tenant-a")
+	require.NoError(t, err)
+	require.Equal(t, "fr", got)
+
+	// A manager write invalidates, so the new value is visible immediately.
+	require.NoError(t, m.SetLanguage("de", "alice", "tenant-a"))
+	got, err = m.GetLanguage("tenant-a")
+	require.NoError(t, err)
+	require.Equal(t, "de", got)
+}