135 lines
3.5 KiB
Go
135 lines
3.5 KiB
Go
package flags
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import (
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"context"
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"fmt"
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"sync"
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"time"
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)
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// FeatureFlag represents a boolean on/off flag scoped to a tenant or global (tenant_id = "").
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type FeatureFlag struct {
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ID string
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TenantID string // empty string = global flag
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Name string
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IsEnabled bool
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CreatedAt time.Time
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UpdatedAt time.Time
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}
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// FlagStore is the persistence interface for feature flags.
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type FlagStore interface {
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// IsEnabled returns true if the flag is enabled for the given tenant.
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// Lookup order: tenant-specific flag → global flag (tenant_id="") → false.
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IsEnabled(ctx context.Context, tenantID, name string) (bool, error)
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// Get returns a single flag by tenantID + name.
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Get(ctx context.Context, tenantID, name string) (FeatureFlag, error)
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// Set creates or updates a flag for the given tenant (or global if tenantID="").
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Set(ctx context.Context, tenantID, name string, enabled bool) (FeatureFlag, error)
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// List returns all flags for a tenant plus global flags.
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List(ctx context.Context, tenantID string) ([]FeatureFlag, error)
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// Delete removes a flag. Returns ErrNotFound if absent.
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Delete(ctx context.Context, tenantID, name string) error
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}
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// ErrNotFound is returned when a flag does not exist.
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var ErrNotFound = fmt.Errorf("feature flag not found")
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// ─── MemFlagStore ─────────────────────────────────────────────────────────────
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// MemFlagStore is a thread-safe, in-memory FlagStore for tests and local dev.
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type MemFlagStore struct {
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mu sync.RWMutex
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flags map[string]FeatureFlag // key = tenantID + ":" + name (empty tenant = ":" + name)
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seq int
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}
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func NewMemFlagStore() *MemFlagStore {
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return &MemFlagStore{flags: make(map[string]FeatureFlag)}
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}
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func flagKey(tenantID, name string) string { return tenantID + ":" + name }
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func (m *MemFlagStore) IsEnabled(ctx context.Context, tenantID, name string) (bool, error) {
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m.mu.RLock()
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defer m.mu.RUnlock()
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// Tenant-specific flag takes precedence
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if f, ok := m.flags[flagKey(tenantID, name)]; ok {
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return f.IsEnabled, nil
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}
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// Global fallback
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if f, ok := m.flags[flagKey("", name)]; ok {
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return f.IsEnabled, nil
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}
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return false, nil
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}
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func (m *MemFlagStore) Get(ctx context.Context, tenantID, name string) (FeatureFlag, error) {
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m.mu.RLock()
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defer m.mu.RUnlock()
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f, ok := m.flags[flagKey(tenantID, name)]
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if !ok {
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return FeatureFlag{}, ErrNotFound
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}
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return f, nil
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}
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func (m *MemFlagStore) Set(ctx context.Context, tenantID, name string, enabled bool) (FeatureFlag, error) {
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m.mu.Lock()
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defer m.mu.Unlock()
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now := time.Now()
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key := flagKey(tenantID, name)
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existing, ok := m.flags[key]
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if ok {
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existing.IsEnabled = enabled
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existing.UpdatedAt = now
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m.flags[key] = existing
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return existing, nil
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}
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m.seq++
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f := FeatureFlag{
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ID: fmt.Sprintf("mem-%d", m.seq),
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TenantID: tenantID,
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Name: name,
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IsEnabled: enabled,
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CreatedAt: now,
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UpdatedAt: now,
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}
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m.flags[key] = f
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return f, nil
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}
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func (m *MemFlagStore) List(ctx context.Context, tenantID string) ([]FeatureFlag, error) {
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m.mu.RLock()
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defer m.mu.RUnlock()
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var out []FeatureFlag
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for _, f := range m.flags {
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if f.TenantID == tenantID || f.TenantID == "" {
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out = append(out, f)
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}
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}
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return out, nil
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}
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func (m *MemFlagStore) Delete(ctx context.Context, tenantID, name string) error {
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m.mu.Lock()
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defer m.mu.Unlock()
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key := flagKey(tenantID, name)
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if _, ok := m.flags[key]; !ok {
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return ErrNotFound
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}
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delete(m.flags, key)
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return nil
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}
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