feat(sync): full code sync from release

backend/internal/service/billing_cache_service_singleflight_test.go

@@ -0,0 +1,115 @@
+//go:build unit
+
+package service
+
+import (
+	"context"
+	"errors"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+	"github.com/stretchr/testify/require"
+)
+
+type billingCacheMissStub struct {
+	setBalanceCalls atomic.Int64
+}
+
+func (s *billingCacheMissStub) GetUserBalance(ctx context.Context, userID int64) (float64, error) {
+	return 0, errors.New("cache miss")
+}
+
+func (s *billingCacheMissStub) SetUserBalance(ctx context.Context, userID int64, balance float64) error {
+	s.setBalanceCalls.Add(1)
+	return nil
+}
+
+func (s *billingCacheMissStub) DeductUserBalance(ctx context.Context, userID int64, amount float64) error {
+	return nil
+}
+
+func (s *billingCacheMissStub) InvalidateUserBalance(ctx context.Context, userID int64) error {
+	return nil
+}
+
+func (s *billingCacheMissStub) GetSubscriptionCache(ctx context.Context, userID, groupID int64) (*SubscriptionCacheData, error) {
+	return nil, errors.New("cache miss")
+}
+
+func (s *billingCacheMissStub) SetSubscriptionCache(ctx context.Context, userID, groupID int64, data *SubscriptionCacheData) error {
+	return nil
+}
+
+func (s *billingCacheMissStub) UpdateSubscriptionUsage(ctx context.Context, userID, groupID int64, cost float64) error {
+	return nil
+}
+
+func (s *billingCacheMissStub) InvalidateSubscriptionCache(ctx context.Context, userID, groupID int64) error {
+	return nil
+}
+
+type balanceLoadUserRepoStub struct {
+	mockUserRepo
+	calls   atomic.Int64
+	delay   time.Duration
+	balance float64
+}
+
+func (s *balanceLoadUserRepoStub) GetByID(ctx context.Context, id int64) (*User, error) {
+	s.calls.Add(1)
+	if s.delay > 0 {
+		select {
+		case <-time.After(s.delay):
+		case <-ctx.Done():
+			return nil, ctx.Err()
+		}
+	}
+	return &User{ID: id, Balance: s.balance}, nil
+}
+
+func TestBillingCacheServiceGetUserBalance_Singleflight(t *testing.T) {
+	cache := &billingCacheMissStub{}
+	userRepo := &balanceLoadUserRepoStub{
+		delay:   80 * time.Millisecond,
+		balance: 12.34,
+	}
+	svc := NewBillingCacheService(cache, userRepo, nil, &config.Config{})
+	t.Cleanup(svc.Stop)
+
+	const goroutines = 16
+	start := make(chan struct{})
+	var wg sync.WaitGroup
+	errCh := make(chan error, goroutines)
+	balCh := make(chan float64, goroutines)
+
+	for i := 0; i < goroutines; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			<-start
+			bal, err := svc.GetUserBalance(context.Background(), 99)
+			errCh <- err
+			balCh <- bal
+		}()
+	}
+
+	close(start)
+	wg.Wait()
+	close(errCh)
+	close(balCh)
+
+	for err := range errCh {
+		require.NoError(t, err)
+	}
+	for bal := range balCh {
+		require.Equal(t, 12.34, bal)
+	}
+
+	require.Equal(t, int64(1), userRepo.calls.Load(), "并发穿透应被 singleflight 合并")
+	require.Eventually(t, func() bool {
+		return cache.setBalanceCalls.Load() >= 1
+	}, time.Second, 10*time.Millisecond)
+}