installed plugin W3 Total Cache version 2.3.2

wp-content/plugins/w3-total-cache/DbCache_Wpdb.php

@@ -0,0 +1,60 @@
+<?php
+namespace W3TC;
+
+/**
+ * class Db
+ * Database access mediator
+ */
+class DbCache_Wpdb extends DbCache_WpdbBase {
+	/**
+	 * Returns object instance. Called by WP engine
+	 *
+	 * @return DbCache_Wpdb
+	 */
+	static function instance() {
+		static $instance = null;
+
+		if ( is_null( $instance ) ) {
+			$processors = array();
+			$call_default_constructor = true;
+
+			// no caching during activation
+			$is_installing = ( defined( 'WP_INSTALLING' ) && WP_INSTALLING );
+
+			$config = Dispatcher::config();
+			if ( !$is_installing && $config->get_boolean( 'dbcache.enabled' ) ) {
+				$processors[] = new DbCache_WpdbInjection_QueryCaching();
+			}
+			if ( Util_Environment::is_dbcluster() ) {
+				// dbcluster use mysqli only since other is obsolete now
+				if ( !defined( 'WP_USE_EXT_MYSQL' ) ) {
+					define( 'WP_USE_EXT_MYSQL', false );
+				}
+
+				$processors[] = new Enterprise_Dbcache_WpdbInjection_Cluster();
+			}
+
+			$processors[] = new DbCache_WpdbInjection();
+
+			global $wp_version;
+			if (version_compare( $wp_version, '5.3') >= 0) {
+				$o = new DbCache_WpdbNew( $processors );
+			} else {
+				$o = new DbCache_WpdbLegacy( $processors );
+			}
+
+			$next_injection = new _CallUnderlying( $o );
+
+			foreach ( $processors as $processor ) {
+				$processor->initialize_injection( $o, $next_injection );
+			}
+
+			// initialize after processors configured
+			$o->initialize();
+
+			$instance = $o;
+		}
+
+		return $instance;
+	}
+}