public static function get_sizes() {
		$size_db    = self::get_database_size();
		$upload_dir = wp_get_upload_dir();

		/*
		 * We will be using the PHP max execution time to prevent the size calculations
		 * from causing a timeout. The default value is 30 seconds, and some
		 * hosts do not allow you to read configuration values.
		 */
		if ( function_exists( 'ini_get' ) ) {
			$max_execution_time = ini_get( 'max_execution_time' );
		}

		// The max_execution_time defaults to 0 when PHP runs from cli.
		// We still want to limit it below.
		if ( empty( $max_execution_time ) ) {
			$max_execution_time = 30;
		}

		if ( $max_execution_time > 20 ) {
			// If the max_execution_time is set to lower than 20 seconds, reduce it a bit to prevent
			// edge-case timeouts that may happen after the size loop has finished running.
			$max_execution_time -= 2;
		}

		// Go through the various installation directories and calculate their sizes.
		// No trailing slashes.
		$paths = array(
			'wordpress_size' => untrailingslashit( ABSPATH ),
			'themes_size'    => get_theme_root(),
			'plugins_size'   => WP_PLUGIN_DIR,
			'uploads_size'   => $upload_dir['basedir'],
		);

		$exclude = $paths;
		unset( $exclude['wordpress_size'] );
		$exclude = array_values( $exclude );

		$size_total = 0;
		$all_sizes  = array();

		// Loop over all the directories we want to gather the sizes for.
		foreach ( $paths as $name => $path ) {
			$dir_size = null; // Default to timeout.
			$results  = array(
				'path' => $path,
				'raw'  => 0,
			);

			if ( microtime( true ) - WP_START_TIMESTAMP < $max_execution_time ) {
				if ( 'wordpress_size' === $name ) {
					$dir_size = recurse_dirsize( $path, $exclude, $max_execution_time );
				} else {
					$dir_size = recurse_dirsize( $path, null, $max_execution_time );
				}
			}

			if ( false === $dir_size ) {
				// Error reading.
				$results['size']  = __( 'The size cannot be calculated. The directory is not accessible. Usually caused by invalid permissions.' );
				$results['debug'] = 'not accessible';

				// Stop total size calculation.
				$size_total = null;
			} elseif ( null === $dir_size ) {
				// Timeout.
				$results['size']  = __( 'The directory size calculation has timed out. Usually caused by a very large number of sub-directories and files.' );
				$results['debug'] = 'timeout while calculating size';

				// Stop total size calculation.
				$size_total = null;
			} else {
				if ( null !== $size_total ) {
					$size_total += $dir_size;
				}

				$results['raw']   = $dir_size;
				$results['size']  = size_format( $dir_size, 2 );
				$results['debug'] = $results['size'] . " ({$dir_size} bytes)";
			}

			$all_sizes[ $name ] = $results;
		}

		if ( $size_db > 0 ) {
			$database_size = size_format( $size_db, 2 );

			$all_sizes['database_size'] = array(
				'raw'   => $size_db,
				'size'  => $database_size,
				'debug' => $database_size . " ({$size_db} bytes)",
			);
		} else {
			$all_sizes['database_size'] = array(
				'size'  => __( 'Not available' ),
				'debug' => 'not available',
			);
		}

		if ( null !== $size_total && $size_db > 0 ) {
			$total_size    = $size_total + $size_db;
			$total_size_mb = size_format( $total_size, 2 );

			$all_sizes['total_size'] = array(
				'raw'   => $total_size,
				'size'  => $total_size_mb,
				'debug' => $total_size_mb . " ({$total_size} bytes)",
			);
		} else {
			$all_sizes['total_size'] = array(
				'size'  => __( 'Total size is not available. Some errors were encountered when determining the size of your installation.' ),
				'debug' => 'not available',
			);
		}

		return $all_sizes;
	}