Source

File: wp-includes/class-wp-feed-cache-transient.php

public function __construct( $location, $filename, $extension ) {
		$this->name     = 'feed_' . $filename;
		$this->mod_name = 'feed_mod_' . $filename;

		$lifetime = $this->lifetime;
		/**
		 * Filters the transient lifetime of the feed cache.
		 *
		 * @since 2.8.0
		 *
		 * @param int    $lifetime Cache duration in seconds. Default is 43200 seconds (12 hours).
		 * @param string $filename Unique identifier for the cache object.
		 */
		$this->lifetime = apply_filters( 'wp_feed_cache_transient_lifetime', $lifetime, $filename );
	}