fix(user): serialize level experience awards

src/AKSRT/User/Level.php

@@ -232,6 +232,21 @@ class Level {
 	 * @return int|false Granted amount or false.
 	 */
 	public static function add(int $user_id, string $key, int $points = 0, bool $bypass_day_max = false) {
+		if ($user_id <= 0) {
+			return false;
+		}
+		$lock = self::acquire_lock('user:' . $user_id);
+		if ($lock === '') {
+			return false;
+		}
+		try {
+			return self::add_locked($user_id, $key, $points, $bypass_day_max);
+		} finally {
+			self::release_lock($lock);
+		}
+	}
+
+	private static function add_locked(int $user_id, string $key, int $points, bool $bypass_day_max) {
 		$cfg = self::settings();
 		$key = sanitize_key($key);
 		if ($user_id <= 0 || !$cfg['enabled'] || $key === '' || $key === 'day_max') {
@@ -282,10 +297,34 @@ class Level {
 		return $points;
 	}
 
+	private static function acquire_lock(string $scope): string {
+		global $wpdb;
+		$name = substr($wpdb->prefix . 'aksrt_level_' . md5($scope), 0, 64);
+		$acquired = (int) $wpdb->get_var($wpdb->prepare('SELECT GET_LOCK(%s, %d)', $name, 5));
+		return $acquired === 1 ? $name : '';
+	}
+
+	private static function release_lock(string $name): void {
+		global $wpdb;
+		$wpdb->get_var($wpdb->prepare('SELECT RELEASE_LOCK(%s)', $name));
+	}
+
 	private static function award_once(int $user_id, string $key, string $meta_type, int $entity_id, string $marker, int $limit = 1, int $actor_id = 0): void {
 		if ($user_id <= 0 || $entity_id <= 0) {
 			return;
 		}
+		$lock = self::acquire_lock($meta_type . ':' . $entity_id . ':' . $marker);
+		if ($lock === '') {
+			return;
+		}
+		try {
+			self::award_once_locked($user_id, $key, $meta_type, $entity_id, $marker, $limit, $actor_id);
+		} finally {
+			self::release_lock($lock);
+		}
+	}
+
+	private static function award_once_locked(int $user_id, string $key, string $meta_type, int $entity_id, string $marker, int $limit, int $actor_id): void {
 		$get = $meta_type === 'comment' ? 'get_comment_meta' : 'get_post_meta';
 		$update = $meta_type === 'comment' ? 'update_comment_meta' : 'update_post_meta';
 		$awarded = $get($entity_id, $marker, true);
@@ -310,12 +349,23 @@ class Level {
 	public function on_login($user_login, $user): void {
 		$user_id = $user instanceof \WP_User ? (int) $user->ID : 0;
 		$today = current_time('Ymd');
-		if ($user_id <= 0 || get_user_meta($user_id, self::META_LOGIN_DAY, true) === $today) {
+		if ($user_id <= 0) {
+			return;
+		}
+		$lock = self::acquire_lock('login:' . $user_id . ':' . $today);
+		if ($lock === '') {
+			return;
+		}
+		try {
+			if (get_user_meta($user_id, self::META_LOGIN_DAY, true) === $today) {
 				return;
 			}
 			if (self::add($user_id, 'sign_in')) {
 				update_user_meta($user_id, self::META_LOGIN_DAY, $today);
 			}
+		} finally {
+			self::release_lock($lock);
+		}
 	}
 
 	public function on_checkin(int $user_id): void {
@@ -367,15 +417,26 @@ class Level {
 	public function on_followed($follower_id, $followed_id): void {
 		$follower_id = (int) $follower_id;
 		$followed_id = (int) $followed_id;
+		if ($follower_id <= 0 || $followed_id <= 0) {
+			return;
+		}
+		$lock = self::acquire_lock('follow:' . $followed_id);
+		if ($lock === '') {
+			return;
+		}
+		try {
 			$awarded = get_user_meta($followed_id, self::META_FOLLOWED, true);
 			$awarded = is_array($awarded) ? array_map('intval', $awarded) : [];
-		if ($follower_id <= 0 || $followed_id <= 0 || in_array($follower_id, $awarded, true)) {
+			if (in_array($follower_id, $awarded, true)) {
 				return;
 			}
 			if (self::add($followed_id, 'followed')) {
 				$awarded[] = $follower_id;
 				update_user_meta($followed_id, self::META_FOLLOWED, array_values(array_unique($awarded)));
 			}
+		} finally {
+			self::release_lock($lock);
+		}
 	}
 
 	public function on_post_like($post_id, $user_id, $active = true): void {