[bugfix] Deref stats async, serve stub collections if handshaking (#2990)

* [bugfix] Deref stats async, allow peek if handshaking

* don't return totalItems when handshaking or hiding collections

* use GetLimit()

* use StubAccountStats

internal/db/account.go

@@ -140,10 +140,23 @@ type Account interface {
 	// Update local account settings.
 	UpdateAccountSettings(ctx context.Context, settings *gtsmodel.AccountSettings, columns ...string) error
 
-	// PopulateAccountStats gets (or creates and gets) account stats for
-	// the given account, and attaches them to the account model.
+	// PopulateAccountStats either creates account stats for the given
+	// account by performing COUNT(*) database queries, or retrieves
+	// existing stats from the database, and attaches stats to account.
+	//
+	// If account is local and stats were last regenerated > 48 hours ago,
+	// stats will always be regenerated using COUNT(*) queries, to prevent drift.
 	PopulateAccountStats(ctx context.Context, account *gtsmodel.Account) error
 
+	// StubAccountStats creates zeroed account stats for the given account,
+	// skipping COUNT(*) queries, upserts them in the DB, and attaches them
+	// to the account model.
+	//
+	// Useful following fresh dereference of a remote account, or fresh
+	// creation of a local account, when you know all COUNT(*) queries
+	// would return 0 anyway.
+	StubAccountStats(ctx context.Context, account *gtsmodel.Account) error
+
 	// RegenerateAccountStats creates, upserts, and returns stats
 	// for the given account, and attaches them to the account model.
 	//

internal/db/bundb/account.go

@@ -1217,6 +1217,35 @@ func (a *accountDB) PopulateAccountStats(ctx context.Context, account *gtsmodel.
 	return nil
 }
 
+func (a *accountDB) StubAccountStats(ctx context.Context, account *gtsmodel.Account) error {
+	stats := &gtsmodel.AccountStats{
+		AccountID:           account.ID,
+		RegeneratedAt:       time.Now(),
+		FollowersCount:      util.Ptr(0),
+		FollowingCount:      util.Ptr(0),
+		FollowRequestsCount: util.Ptr(0),
+		StatusesCount:       util.Ptr(0),
+		StatusesPinnedCount: util.Ptr(0),
+	}
+
+	// Upsert this stats in case a race
+	// meant someone else inserted it first.
+	if err := a.state.Caches.GTS.AccountStats.Store(stats, func() error {
+		if _, err := NewUpsert(a.db).
+			Model(stats).
+			Constraint("account_id").
+			Exec(ctx); err != nil {
+			return err
+		}
+		return nil
+	}); err != nil {
+		return err
+	}
+
+	account.Stats = stats
+	return nil
+}
+
 func (a *accountDB) RegenerateAccountStats(ctx context.Context, account *gtsmodel.Account) error {
 	// Initialize a new stats struct.
 	stats := &gtsmodel.AccountStats{

internal/db/bundb/admin.go

@@ -120,16 +120,6 @@ func (a *adminDB) NewSignup(ctx context.Context, newSignup gtsmodel.NewSignup) (
 			return nil, err
 		}
 
-		settings := &gtsmodel.AccountSettings{
-			AccountID: accountID,
-			Privacy:   gtsmodel.VisibilityDefault,
-		}
-
-		// Insert the settings!
-		if err := a.state.DB.PutAccountSettings(ctx, settings); err != nil {
-			return nil, err
-		}
-
 		account = &gtsmodel.Account{
 			ID:                    accountID,
 			Username:              newSignup.Username,
@@ -145,13 +135,26 @@ func (a *adminDB) NewSignup(ctx context.Context, newSignup gtsmodel.NewSignup) (
 			PrivateKey:            privKey,
 			PublicKey:             &privKey.PublicKey,
 			PublicKeyURI:          uris.PublicKeyURI,
-			Settings:              settings,
 		}
 
 		// Insert the new account!
 		if err := a.state.DB.PutAccount(ctx, account); err != nil {
 			return nil, err
 		}
+
+		// Insert basic settings for new account.
+		account.Settings = &gtsmodel.AccountSettings{
+			AccountID: accountID,
+			Privacy:   gtsmodel.VisibilityDefault,
+		}
+		if err := a.state.DB.PutAccountSettings(ctx, account.Settings); err != nil {
+			return nil, err
+		}
+
+		// Stub empty stats for new account.
+		if err := a.state.DB.StubAccountStats(ctx, account); err != nil {
+			return nil, err
+		}
 	}
 
 	// Created or already had an account.