debugging wp_cron jobs with XDebug in Eclipse

Question

I use Eclipse for PHP Developers (Neon.3 Release (4.6.3) in case it matters) and XDebug when developing plugins/themes. It all works fine (i.e., I can set breakpoints in my plugin's code and step through it, etc).

However, I can't seem to get XDebug to stop at breakpoints in a function triggered by a 1-time WP_Cron job. For example, given the following:

add_action ('wpse_my_hook', 'wpse_my_cron_function') ;

function
wpse_my_function ()
{
    // schedule an immediate 1-time cron job
    wp_schedule_single_event (time (), 'wpse_my_hook', array ($some_data)) ;
}

function
wpse_my_cron_function ($some_data)
{
    $example = '' ; // set a breakpoint here

    // do something really cool :-)
}

and a breakpoint set at the 1st line in wpse_my_cron_function(), XDebug never stops there. I know the function is being called (because of mods that function makes to the DB).

Is there something I need to do in my XDebug setup in order to debug WP_Cron jobs or is it just not possible because of the way WP_Cron works?

Answer 1

I just found the answer to my question over on stackoverflow...and thought I'd copy the answer over here for future reference since WP folks are probably more likely to look here.

When WP_Cron fires a scheduled job it does so via a call to wp_remote_post(). The trick in that answer is to hook into cron_request and add the XDEBUG_SESSION_START=idekey query arg, as in

add_action ('cron_request', 'wpse_cron_add_xdebug_session_start', 10, 2) ;

function
wpse_cron_add_xdebug_session_start ($args, $doing_cron)
{
    $args['url'] = add_query_arg (array ('XDEBUG_SESSION_START' => 'ECLIPSE_DBGP'), $args['url']) ;

    return ($args) ;
}

That worked like a charm and I got my cron function debugged.

With my immediate need out of the way, I wanted a more general solution...one in which I didn't have to hard-code a specific IDE Key and this is what I came up with:

add_action ('cron_request', 'wpse_cron_add_xdebug_cookie', 10, 2) ;

/**
 * Allow debugging of wp_cron jobs
 *
 * @param array $cron_request_array
 * @param string $doing_wp_cron
 *
 * @return array $cron_request_array with the current XDEBUG_SESSION cookie added if set
 */
function
wpse_cron_add_xdebug_cookie ($cron_request_array, $doing_wp_cron)
{
    if (empty ($_COOKIE['XDEBUG_SESSION'])) {
        return ($cron_request_array) ;
        }

    if (empty ($cron_request_array['args']['cookies'])) {
        $cron_request_array['args']['cookies'] = array () ;
        }
    $cron_request_array['args']['cookies']['XDEBUG_SESSION'] = $_COOKIE['XDEBUG_SESSION'] ;

    return ($cron_request_array) ;
}

I hope this helps others who have the same problem.