[performance] temporarily cache account status counts to reduce no. account counts (#2620)

* temporarily cache account status counts to reduce no. account counts

* whoops, forgot to initAccountCounts()

* use already fetched cache capacity value

* make cache a ptr type

* whoops, use count instead of just select

* fix to correctly use the transaction

* properly wrap that tx 😇

* correctly wrap both tx types

* outline retryOnBusy() to allow the fast path to be inlined

* return err on context cancelled

* remove unnecessary storage of context in stmt, fix Exec and Query interface implementations

* shutup linter

internal/db/bundb/account.go

@@ -532,20 +532,56 @@ func (a *accountDB) GetAccountFaves(ctx context.Context, accountID string) ([]*g
 }
 
 func (a *accountDB) CountAccountStatuses(ctx context.Context, accountID string) (int, error) {
-	return a.db.
-		NewSelect().
-		TableExpr("? AS ?", bun.Ident("statuses"), bun.Ident("status")).
-		Where("? = ?", bun.Ident("status.account_id"), accountID).
-		Count(ctx)
+	counts, err := a.getAccountStatusCounts(ctx, accountID)
+	return counts.Statuses, err
 }
 
 func (a *accountDB) CountAccountPinned(ctx context.Context, accountID string) (int, error) {
-	return a.db.
-		NewSelect().
-		TableExpr("? AS ?", bun.Ident("statuses"), bun.Ident("status")).
-		Where("? = ?", bun.Ident("status.account_id"), accountID).
-		Where("? IS NOT NULL", bun.Ident("status.pinned_at")).
-		Count(ctx)
+	counts, err := a.getAccountStatusCounts(ctx, accountID)
+	return counts.Pinned, err
+}
+
+func (a *accountDB) getAccountStatusCounts(ctx context.Context, accountID string) (struct {
+	Statuses int
+	Pinned   int
+}, error) {
+	// Check for an already cached copy of account status counts.
+	counts, ok := a.state.Caches.GTS.AccountCounts.Get(accountID)
+	if ok {
+		return counts, nil
+	}
+
+	if err := a.db.RunInTx(ctx, nil, func(ctx context.Context, tx bun.Tx) error {
+		var err error
+
+		// Scan database for account statuses.
+		counts.Statuses, err = tx.NewSelect().
+			Table("statuses").
+			Where("? = ?", bun.Ident("account_id"), accountID).
+			Count(ctx)
+		if err != nil {
+			return err
+		}
+
+		// Scan database for pinned statuses.
+		counts.Pinned, err = tx.NewSelect().
+			Table("statuses").
+			Where("? = ?", bun.Ident("account_id"), accountID).
+			Where("? IS NOT NULL", bun.Ident("pinned_at")).
+			Count(ctx)
+		if err != nil {
+			return err
+		}
+
+		return nil
+	}); err != nil {
+		return counts, err
+	}
+
+	// Store this account counts result in the cache.
+	a.state.Caches.GTS.AccountCounts.Set(accountID, counts)
+
+	return counts, nil
 }
 
 func (a *accountDB) GetAccountStatuses(ctx context.Context, accountID string, limit int, excludeReplies bool, excludeReblogs bool, maxID string, minID string, mediaOnly bool, publicOnly bool) ([]*gtsmodel.Status, error) {