tion add_nonpersistent_groups( $groups ) {
		if ( !is_array( $groups ) ) {
			$groups = (array) $groups;
		}

		$this->nonpersistent_groups = array_merge( $this->nonpersistent_groups, $groups );
		$this->nonpersistent_groups = array_unique( $this->nonpersistent_groups );
	}

	/**
	 * Increment numeric cache item's value
	 *
	 * @param int|string $key    The cache key to increment
	 * @param int     $offset The amount by which to increment the item's value. Default is 1.
	 * @param string  $group  The group the key is in.
	 * @return bool|int False on failure, the item's new value on success.
	 */
	function incr( $key, $offset = 1, $group = 'default' ) {
		$value = $this->get( $key, $group );
		if ( $value === false )
			return false;

		if ( !is_numeric( $value ) )
			$value = 0;

		$offset = (int) $offset;
		$value += $offset;

		if ( $value < 0 )
			$value = 0;
		$this->replace( $key, $value, $group );
		return $value;
	}

	/**
	 * Decrement numeric cache item's value
	 *
	 * @param int|string $key    The cache key to increment
	 * @param int     $offset The amount by which to decrement the item's value. Default is 1.
	 * @param string  $group  The group the key is in.
	 * @return bool|int False on failure, the item's new value on success.
	 */
	function decr( $key, $offset = 1, $group = 'default' ) {
		$value = $this->get( $key, $group );
		if ( $value === false )
			return false;

		if ( !is_numeric( $value ) )
			$value = 0;

		$offset = (int) $offset;
		$value -= $offset;

		if ( $value < 0 )
			$value = 0;
		$this->replace( $key, $value, $group );
		return $value;
	}

	private function _transient_fallback_get( $transient, $group ) {
		if ( $group == 'transient' ) {
			$transient_option = '_transient_' . $transient;
			if ( function_exists( 'wp_installing') && ! wp_installing() ) {
				// If option is not in alloptions, it is not autoloaded and thus has a timeout
				$alloptions = wp_load_alloptions();
				if ( !isset( $alloptions[$transient_option] ) ) {
					$transient_timeout = '_transient_timeout_' . $transient;
					$timeout = get_option( $transient_timeout );
					if ( false !== $timeout && $timeout < time() ) {
						delete_option( $transient_option  );
						delete_option( $transient_timeout );
						$value = false;
					}
				}
			}

			if ( ! isset( $value ) )
				$value = get_option( $transient_option );
		} elseif ( $group == 'site-transient' ) {
			// Core transients that do not have a timeout. Listed here so querying timeouts can be avoided.
			$no_timeout = array('update_core', 'update_plugins', 'update_themes');
			$transient_option = '_site_transient_' . $transient;
			if ( ! in_array( $transient, $no_timeout ) ) {
				$transient_timeout = '_site_transient_timeout_' . $transient;
				$timeout = get_site_option( $transient_timeout );
				if ( false !== $timeout && $timeout < time() ) {
					delete_site_option( $transient_option  );
					delete_site_option( $transient_timeout );
					$value = false;
				}
			}

			if ( ! isset( $value ) )
				$value = get_site_option( $transient_option );
		} else {
			$value = false;
		}

		return $value;
	}

	private function _transient_fallback_delete( $transient, $group ) {
		if ( $group == 'transient' ) {
			$option_timeout = '_transient_timeout_' . $transient;
			$option = '_transient_' . $transient;
			$result = delete_option( $option );
			if ( $result )
				delete_option( $option_timeout );
		} elseif ( $group == 'site-transient' ) {
			$option_timeout = '_site_transient_timeout_' . $transient;
			$option = '_site_transient_' . $transient;
			$result = delete_site_option( $option );
			if ( $result )
				delete_site_option( $option_timeout );
		}
	}

	private function _transient_fallback_set( $transient, $value, $group, $expiration ) {
		if ( $group == 'transient' ) {
			$transient_timeout = '_transient_timeout_' . $transient;
			$transient_option = '_transient_' . $transient;
			if ( false === get_option( $transient_option ) ) {
				$autoload = 'yes';
				if ( $expiration ) {
					$autoload = 'no';
					add_option( $transient_timeout, time() + $expiration, '', 'no' );
				}
				$result = add_option( $transient_option, $value, '', $autoload );
			} else {
				// If expiration is requested, but the transient has no timeout option,
				// delete, then re-create transient rather than update.
				$update = true;
				if ( $expiration ) {
					if ( false === get_option( $transient_timeout ) ) {
						delete_option( $transient_option );
						add_option( $transient_timeout, time() + $expiration, '', 'no' );
						$result = add_option( $transient_option, $value, '', 'no' );
						$update = false;
					} else {
						update_option( $transient_timeout, time() + $expiration );
					}
				}
				if ( $update ) {
					$result = update_option( $transient_option, $value );
				}
			}
		} elseif ( $group == 'site-transient' ) {
			$transient_timeout = '_site_transient_timeout_' . $transient;
			$option = '_site_transient_' . $transient;
			if ( false === get_site_option( $option ) ) {
				if ( $expiration )
					add_site_option( $transient_timeout, time() + $expiration );
				$result = add_site_option( $option, $value );
			} else {
				if ( $expiration )
					update_site_option( $transient_timeout, time() + $expiration );
				$result = update_site_option( $option, $value );
			}
		}
	}

	/**
	 * Switches context to another blog
	 *
	 * @param integer $blog_id
	 */
	function switch_blog( $blog_id ) {
		$this->reset();
		$this->_blog_id = $blog_id;
	}

	/**
	 * Returns cache key
	 *
	 * @param string  $id
	 * @param string  $group
	 * @return string
	 */
	function _get_cache_key( $id, $group = 'default' ) {
		if ( !$group ) {
			$group = 'default';
		}

		$blog_id = $this->_blog_id;
		if ( in_array( $group, $this->global_groups ) )
			$blog_id = 0;

		return $blog_id . $group . $id;
	}

	public function get_usage_statistics_cache_config() {
		$engine = $this->_config->get_string( 'objectcache.engine' );

		switch ( $engine ) {
		case 'memcached':
			$engineConfig = array(
				'servers' => $this->_config->get_array( 'objectcache.memcached.servers' ),
				'persistent' => $this->_config->get_boolean( 'objectcache.memcached.persistent' ),
				'aws_autodiscovery' => $this->_config->get_boolean( 'objectcache.memcached.aws_autodiscovery' ),
				'username' => $this->_config->get_string( 'objectcache.memcached.username' ),
				'password' => $this->_config->get_string( 'objectcache.memcached.password' ),
				'binary_protocol' => $this->_config->get_boolean( 'objectcache.memcached.binary_protocol' )
			);
			break;

		case 'redis':
			$engineConfig = array(
				'servers' => $this->_config->get_array( 'objectcache.redis.servers' ),
				'verify_tls_certificates' => $this->_config->get_boolean( 'objectcache.redis.verify_tls_certificates' ),
				'persistent' => $this->_config->get_boolean( 'objectcache.redis.persistent' ),
				'timeout' => $this->_config->get_integer( 'objectcache.redis.timeout' ),
				'retry_interval' => $this->_config->get_integer( 'objectcache.redis.retry_interval' ),
				'read_timeout' => $this->_config->get_integer( 'objectcache.redis.read_timeout' ),
				'dbid' => $this->_config->get_integer( 'objectcache.redis.dbid' ),
				'password' => $this->_config->get_string( 'objectcache.redis.password' )
			);
			break;

		default:
			$engineConfig = array();
		}

		$engineConfig['engine'] = $engine;
		return $engineConfig;
	}

	/**
	 * Returns cache object
	 *
	 * @param int|null $blog_id
	 * @param string  $group
	 * @return W3_Cache_Base
	 */
	function _get_cache( $blog_id = null, $group = '' ) {
		static $cache = array();

		if ( is_null( $blog_id ) && !in_array( $group, $this->global_groups ) )
			$blog_id = $this->_blog_id;
		elseif ( is_null( $blog_id ) )
			$blog_id = 0;

		if ( !isset( $cache[$blog_id] ) ) {
			$engine = $this->_config->get_string( 'objectcache.engine' );

			switch ( $engine ) {
			case 'memcached':
				$engineConfig = array(
					'servers' => $this->_config->get_array( 'objectcache.memcached.servers' ),
					'persistent' => $this->_config->get_boolean(
						'objectcache.memcached.persistent' ),
					'aws_autodiscovery' => $this->_config->get_boolean( 'objectcache.memcached.aws_autodiscovery' ),
					'username' => $this->_config->get_string( 'objectcache.memcached.username' ),
					'password' => $this->_config->get_string( 'objectcache.memcached.password' ),
					'binary_protocol' => $this->_config->get_boolean( 'objectcache.memcached.binary_protocol' )
				);
				break;

			case 'redis':
				$engineConfig = array(
					'servers' => $this->_config->get_array( 'objectcache.redis.servers' ),
					'verify_tls_certificates' => $this->_config->get_boolean( 'objectcache.redis.verify_tls_certificates' ),
					'persistent' => $this->_config->get_boolean( 'objectcache.redis.persistent' ),
					'timeout' => $this->_config->get_integer( 'objectcache.redis.timeout' ),
					'retry_interval' => $this->_config->get_integer( 'objectcache.redis.retry_interval' ),
					'read_timeout' => $this->_config->get_integer( 'objectcache.redis.read_timeout' ),
					'dbid' => $this->_config->get_integer( 'objectcache.redis.dbid' ),
					'password' => $this->_config->get_string( 'objectcache.redis.password' )
				);
				break;

			case 'file':
				$engineConfig = array(
					'section' => 'object',
					'locking' => $this->_config->get_boolean( 'objectcache.file.locking' ),
					'flush_timelimit' => $this->_config->get_integer( 'timelimit.cache_flush' )
				);
				break;

			default:
				$engineConfig = array();
			}
			$engineConfig['blog_id'] = $blog_id;
			$engineConfig['module'] = 'object';
			$engineConfig['host'] = Util_Environment::host();
			$engineConfig['instance_id'] = Util_Environment::instance_id();

			$cache[$blog_id] = Cache::instance( $engine, $engineConfig );
		}

		return $cache[$blog_id];
	}

	/**
	 * Check if caching allowed on init
	 *
	 * @return boolean
	 */
	function _can_cache() {
		/**
		 * Skip if disabled
		 */
		if ( !$this->_config->getf_boolean( 'objectcache.enabled' ) ) {
			$this->cache_reject_reason = 'objectcache.disabled';

			return false;
		}

		/**
		 * Check for DONOTCACHEOBJECT constant
		 */
		if ( defined( 'DONOTCACHEOBJECT' ) && DONOTCACHEOBJECT ) {
			$this->cache_reject_reason = 'DONOTCACHEOBJECT';

			return false;
		}

		return true;
	}

	/**
	 * Returns if we can cache, that condition can change in runtime
	 *
	 * @param unknown $group
	 * @return boolean
	 */
	function _check_can_cache_runtime( $group ) {
		//Need to be handled in wp admin as well as frontend
		if ( $this->_is_transient_group( $group ) )
			return true;

		if ( $this->_can_cache_dynamic != null )
			return $this->_can_cache_dynamic;

		if ( $this->_config->get_boolean( 'objectcache.enabled_for_wp_admin' ) ) {
			$this->_can_cache_dynamic = true;
		} else {
			if ( $this->_caching ) {
				if ( defined( 'WP_ADMIN' ) &&
					( !defined( 'DOING_AJAX' ) || !DOING_AJAX ) ) {
					$this->_can_cache_dynamic = false;
					$this->cache_reject_reason = 'WP_ADMIN defined';
					return $this->_can_cache_dynamic;
				}
			}
		}

		return $this->_caching;
	}

	private function _is_transient_group( $group ) {
		return in_array( $group, array( 'transient', 'site-transient' ) ) ;
	}

	public function w3tc_footer_comment( $strings ) {
		$reason = $this->get_reject_reason();
		$append = empty( $reason ) ? '' : sprintf( ' (%1$s)', $reason );

		$strings[] = sprintf(
			// translators: 1: Cache hits, 2: Cache total cache objects, 3: Engine anme, 4: Reason.
			__( 'Object Caching %1$d/%2$d objects using %3$s%4$s', 'w3-total-cache' ),
			$this->cache_hits,
			$this->cache_total,
			Cache::engine_name( $this->_config->get_string( 'objectcache.engine' ) ),
			$append
		);

		if ( $this->_config->get_boolean( 'objectcache.debug' ) ) {
			$strings[] = '';
			$strings[] = 'Object Cache debug info:';
			$strings[] = sprintf( "%s%s", str_pad( 'Caching: ', 20 ),
				( $this->_caching ? 'enabled' : 'disabled' ) );

			$strings[] = sprintf( "%s%d", str_pad( 'Total calls: ', 20 ), $this->cache_total );
			$strings[] = sprintf( "%s%d", str_pad( 'Cache hits: ', 20 ), $this->cache_hits );
			$strings[] = sprintf( "%s%.4f", str_pad( 'Total time: ', 20 ), $this->time_total );

			if ( $this->log_filehandle ) {
				fclose( $this->log_filehandle );
				$this->log_filehandle = false;
			}
		}

		return $strings;
	}

	public function w3tc_usage_statistics_of_request( $storage ) {
		$storage->counter_add( 'objectcache_get_total', $this->cache_total );
		$storage->counter_add( 'objectcache_get_hits', $this->cache_hits );
		$storage->counter_add( 'objectcache_sets', $this->cache_sets );
		$storage->counter_add( 'objectcache_flushes', $this->cache_flushes );
		$storage->counter_add( 'objectcache_time_ms', (int)($this->time_total * 1000) );
	}

	public function get_reject_reason() {
		if ( is_null( $this->cache_reject_reason ) )
			return '';
		return $this->_get_reject_reason_message( $this->cache_reject_reason );
	}

	/**
	 *
	 *
	 * @param unknown $key
	 * @return string|void
	 */
	private function _get_reject_reason_message( $key ) {
		if ( !function_exists( '__' ) )
			return $key;

		switch ( $key ) {
		case 'objectcache.disabled':
			return __( 'Object caching is disabled', 'w3-total-cache' );
		case 'DONOTCACHEOBJECT':
			return __( 'DONOTCACHEOBJECT constant is defined', 'w3-total-cache' );
		default:
			return '';
		}
	}



	private function log_call( $line ) {
		if ( !$this->log_filehandle ) {
			$filename = Util_Debug::log_filename( 'objectcache-calls' );
			$this->log_filehandle = fopen( $filename, 'a' );
		}

		fputcsv ( $this->log_filehandle, $line, "\t" );
	}
}