Check if a WordPress cron event is firing and show a notice if not

wp-check-cron-event-firing.php

<?php

/* 
Usecase: 

You might have an important task within your plugin/theme that requires WP CRON working flawlessly. If a user website has little traffic, WP CRON is turned off via wp_config.php, or there is an issue with WP CRON; your scheduled task will not fire. 

The code below allows you to set a value in minutes after which a notice(or whatever else you might want to happen) would appear in the user admin dashboard.

Users can permanently dismiss the notice.

prefix_cron_job is the hook for your scheduled task.

Change instances of "prefix" to suit your plugin/theme.
*/

function prefix_cron_event_status_notice() {
    
    		$user_id = get_current_user_id();

		if ( get_user_meta( $user_id, 'prefix-cron-event-status-notice-dismissed' ) ) {
			return;
		}

		$prefix_next_task_hit = wp_next_scheduled( 'prefix_cron_job' );
		$prefix_current_time = time();

		// if sharing not started cron event will not be present
		if ( ! $prefix_next_task_hit ) {
			return;
		}
	
		$prefix_cron_elapsed_time = ( $prefix_current_time - $prefix_next_task_hit ) / 60;
        	$prefix_cron_elapsed_time = absint( $prefix_cron_elapsed_time );

		// default: 60 minutes
		$prefix_cron_event_excess_elapsed_time = apply_filters( 'prefix_cron_event_excess_elapsed_time', 60 );
    
        	// if it's been more >= 60 minutes since the event was due to fire
		if ( $prefix_cron_elapsed_time >= $prefix_cron_event_excess_elapsed_time ) {

			?>
			<div class="notice notice-error">
				<?php echo sprintf( __( '%1$s%2$sYour Plugin/Theme Name:%3$s There might be an issue preventing Plugin/Theme Name from [performing important task]. See %4$shere for solutions.%5$s%6$s%7$s', 'plugin-theme-text-domain' ), '<p>', '<b>', '</b>', '<a href="https://example.com/docs/how-to-create-true-cron-for-wp" target="_blank">', '</a>', '<a style="float: right;" href="?prefix-cron-event-status-notice-dismissed">Dismiss</a>', '</p>' ); ?>

			</div>
			<?php

		}
add_action('admin_notices', 'prefix_cron_event_status_notice');


function prefix_dismiss_prefix_event_not_firing_notice() {

		$user_id = get_current_user_id();
		if ( isset( $_GET['prefix-cron-event-status-notice-dismissed'] ) ) {
			add_user_meta( $user_id, 'prefix-cron-event-status-notice-dismissed', 'true', true );
		}

	}
 add_action('admin_init', 'prefix_dismiss_prefix_event_not_firing_notice');