gnu-social/docs/developer/src/cache.md

Cache

In the Database chapter you've learned how GNU social allows you to store data in the database. Depending on your server's specification, the database can be a bottleneck. To mitigate that, you can make use of an in-memory data structure storage to cache previous database requests. Using it is a great way of making GNU social run quicker. GNU social supports many adapters to different storages.

Although different cache adapters provide different functionalities that could be nice to take advantage of, we had to limit our cache interface to the basic avaiable in all of them. I.e., store and delete operations.

Store

/**
 * Get the cached avatar file info associated with the given Actor id
 *
 * Returns the avatar file's hash, mimetype, title and path.
 * Ensures exactly one cached value exists
 */
public static function getAvatarFileInfo(int $gsactor_id): array
{
    try {
        $res = GSFile::error(NoAvatarException::class,
            $gsactor_id,
            Cache::get("avatar-file-info-{$gsactor_id}",
                function () use ($gsactor_id) {
                    return DB::dql('select f.file_hash, f.mimetype, f.title ' .
                        'from App\Entity\Attachment f ' .
                        'join App\Entity\Avatar a with f.id = a.attachment_id ' .
                        'where a.gsactor_id = :gsactor_id',
                        ['gsactor_id' => $gsactor_id]);
                }));
        $res['file_path'] = \App\Entity\Avatar::getFilePathStatic($res['file_hash']);
        return $res;
    } catch (Exception $e) {
        $filepath = INSTALLDIR . '/public/assets/default-avatar.svg';
        return ['file_path' => $filepath, 'mimetype' => 'image/svg+xml', 'title' => null];
    }
}

Delete

Cache::delete('avatar-file-info-' . $gsactor_id);