Snippet #008 Using WordPress transients to cache data. https://since1979.dev/snippet-008-using-transients-to-cache-data/

maybe-cache.php

<?php
/**
 * Check if transient cache exist, else set it.
 *
 * Refactored by https://github.com/charmoney for PHP_CodeSniffer WordPress Standards compliance and WP_Error handling.
 *
 * @see https://since1979.dev/snippet-008-using-transients-to-cache-data/
 *
 * @uses get_transient() https://developer.wordpress.org/reference/functions/get_transient/
 * @uses is_callable() https://www.php.net/manual/en/function.is-callable.php
 * @uses wp_die() https://developer.wordpress.org/reference/functions/wp_die/
 * @uses call_user_func() https://www.php.net/manual/en/function.call-user-func.php
 * @uses set_transient() https://developer.wordpress.org/reference/functions/set_transient/
 *
 * @param string   $cache_key The name of the transient.
 * @param int      $time The transient timeout.
 * @param callable $callback The callback function.
 * @return mixed Cached data or WP_Error.
 */
function maybe_cache( string $cache_key = '', int $time = 7200, callable $callback = null ) {
	// Return cached data if possible.
	$cached_data = get_transient( $cache_key );
	if ( false !== $cached_data ) {
		return $cached_data;
	}

	// Invoke callback function if needed.
	if ( ! $callback || ! is_callable( $callback ) ) {
		wp_die( 'No valid callback function provided.' );
	}
	$data = call_user_func( $callback );

	// Cache anything except a \WP_Error.
	if ( ! is_wp_error( $data ) ) {
		set_transient( $cache_key, $data, $time );
	}

	return $data;
}