WP Super cache: make sure the debug log viewer isn't deleted by garbage collection (#38276)

* We always want a debug log viewer. Don't GC it.

* changelog

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/9872485011

Upstream-Ref: Automattic/jetpack@bf25dce

Author: dilirity

CHANGELOG.md

@@ -12,6 +12,9 @@ This is an alpha version! The changes listed here are not final.
 ### Changed
 - Updated package dependencies.
 
+### Fixed
+- WPSC: Don't delete the log viewer when doing garbage collection
+
 ## [1.12.2] - 2024-06-27
 ### Added
 - add an admin notice to encourage migration to Jetpack Boost [#37933]

wp-cache-phase2.php

@@ -2775,7 +2775,7 @@ function wp_cache_rebuild_or_delete( $file ) {
 }
 
 function wp_cache_phase2_clean_expired( $file_prefix, $force = false ) {
-	global $cache_path, $cache_max_time, $blog_cache_dir, $wp_cache_preload_on;
+	global $cache_path, $cache_max_time, $blog_cache_dir, $wp_cache_preload_on, $wp_cache_debug_log;
 
 	if ( $cache_max_time == 0 ) {
 		wp_cache_debug( 'wp_cache_phase2_clean_expired: disabled because GC disabled.', 2 );
@@ -2786,6 +2786,14 @@ function wp_cache_phase2_clean_expired( $file_prefix, $force = false ) {
 	if ( ! wp_cache_writers_entry() ) {
 		return false;
 	}
+
+	// make sure we have a debug log viewer
+	if ( empty( $wp_cache_debug_log ) ) {
+		wpsc_create_debug_log();
+	} else {
+		touch( $cache_path . 'view_' . $wp_cache_debug_log ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_touch
+	}
+
 	$now = time();
 	wp_cache_debug( "Cleaning expired cache files in $blog_cache_dir", 2 );
 	$deleted = 0;