[performance] cache more database calls, reduce required database calls overall (#3290)

* improvements to caching for lists and relationship to accounts / follows

* fix nil panic in AddToList()

* ensure list related caches are correctly invalidated

* ensure returned ID lists are ordered correctly

* bump go-structr to v0.8.9 (returns early if zero uncached keys to be loaded)

* remove zero checks in uncached key load functions (go-structr now handles this)

* fix issues after rebase on upstream/main

* update the expected return order of CSV exports (since list entries are now down by entry creation date)

* rename some funcs, allow deleting list entries for multiple follow IDs at a time, fix up more tests

* use returning statements on delete to get cache invalidation info

* fixes to recent database delete changes

* fix broken list entries delete sql

* remove unused db function

* update remainder of delete functions to behave in similar way, some other small tweaks

* fix delete user sql, allow returning on err no entries

* uncomment + fix list database tests

* update remaining list tests

* update envparsing test

* add comments to each specific key being invalidated

* add more cache invalidation explanatory comments

* whoops; actually delete poll votes from database in the DeletePollByID() func

* remove added but-commented-out field

* improved comment regarding paging being disabled

* make cache invalidation comments match what's actually happening

* fix up delete query comments to match what is happening

* rename function to read a bit better

* don't use ErrNoEntries on delete when not needed (it's only needed for a RETURNING call)

* update function name in test

* move list exclusivity check to AFTER eligibility check. use log.Panic() instead of panic()

* use the poll_id column in poll_votes for selecting votes in poll ID

* fix function name

1 files changed, 17 insertions, 19 deletions

diff --git a/internal/db/bundb/user.go b/internal/db/bundb/user.go
index 1ca65f016..fc8effa91 100644
--- a/internal/db/bundb/user.go
+++ b/internal/db/bundb/user.go
@@ -19,10 +19,8 @@ package bundb
 
 import (
 	"context"
-	"errors"
 	"time"
 
-	"github.com/superseriousbusiness/gotosocial/internal/db"
 	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
@@ -209,26 +207,26 @@ func (u *userDB) UpdateUser(ctx context.Context, user *gtsmodel.User, columns ..
 }
 
 func (u *userDB) DeleteUserByID(ctx context.Context, userID string) error {
-	defer u.state.Caches.DB.User.Invalidate("ID", userID)
-
-	// Load user into cache before attempting a delete,
-	// as we need it cached in order to trigger the invalidate
-	// callback. This in turn invalidates others.
-	_, err := u.GetUserByID(gtscontext.SetBarebones(ctx), userID)
-	if err != nil {
-		if errors.Is(err, db.ErrNoEntries) {
-			// not an issue.
-			err = nil
-		}
+	// Gather necessary fields from
+	// deleted for cache invaliation.
+	var deleted gtsmodel.User
+	deleted.ID = userID
+
+	// Delete user from DB.
+	if _, err := u.db.NewDelete().
+		Model(&deleted).
+		Where("? = ?", bun.Ident("id"), userID).
+		Returning("?", bun.Ident("account_id")).
+		Exec(ctx); err != nil {
 		return err
 	}
 
-	// Finally delete user from DB.
-	_, err = u.db.NewDelete().
-		TableExpr("? AS ?", bun.Ident("users"), bun.Ident("user")).
-		Where("? = ?", bun.Ident("user.id"), userID).
-		Exec(ctx)
-	return err
+	// Invalidate cached user by ID, manually
+	// call invalidate hook in case not cached.
+	u.state.Caches.DB.User.Invalidate("ID", userID)
+	u.state.Caches.OnInvalidateUser(&deleted)
+
+	return nil
 }
 
 func (u *userDB) PutDeniedUser(ctx context.Context, deniedUser *gtsmodel.DeniedUser) error {