WordPress Bulk process users on hourly cron event

bulk-users-hourly-cron.php

<?php

/**
 * Check expiration date for a set of users.
 *
 * @return string
 */
function dtl_course_expiry_check( $debug = false ) {
	// option to start over when used manually via query string
	if ( isset($_REQUEST['startover']) ) update_option( 'dtl-ce-user-index', 0, false );
	
	// Pluggable required for get_user_count to work.
	// Sometimes it was undefined, not sure why. Maybe fixed already but just in case
	if ( !function_exists('wp_get_current_user')) {
		include_once(ABSPATH . "wp-includes/pluggable.php");
	}
	
	// total number of users
	$count = count_users();
	$total_users = $count['total_users'];
	
	// get cached number of users per query. this resets at the end of each batch, see below.
	$users_per_query = (int) get_option( 'dtl-ce-users-per-query' );
	if ( !$users_per_query ) $users_per_query = 20;
	
	// user index to start at from the database. 
	// this is like pagination but uses an offset like in MySQL
	// so $user_index = 2 means the query will start at the third user.
	$user_index = (int) get_option( 'dtl-ce-user-index' );
	if ( !$user_index ) $user_index = 0;
	
	// start over if the user index exceeds the total number of users
	if ( $user_index > $total_users ) $user_index = 0;
	
	// when we're starting at the beginning, process the completed "batch"
	// this means we finished, and are starting over.
	if ( $user_index === 0 ) {
		$last_batch_start_time = get_option( 'dtl-ce-batch-start-time' );
		$last_batch_end_time = time();
		$last_batch_emails_sent = get_option( 'dtl-ce-batch-emails-sent' );
		
		$last_batch = array(
			'start' => $last_batch_start_time,
			'end' => $last_batch_end_time,
			'time_diff' => $last_batch_start_time ? human_time_diff( $last_batch_start_time, $last_batch_end_time ) : "N/A first run",
			'emails_sent' => $last_batch_emails_sent,
		);
		
		// debug to see when cron triggers via email response
		/*
		$complete_time_local = get_date_from_gmt( date('Y-m-d H:i:s', $last_batch['end']), 'F jS, Y H:i' );
		
		wp_mail(
			'[email protected]',
			'BLI Debug - Course Expiry Batch Completed ' . date('H:i:s'),
			'Hi myself, a batch is finished processing. ' . "\n\n<br>\n\n" . '<p>The process took '. $last_batch['time_diff'] . ' and ' . $last_batch['emails_sent'] . ' email(s) were sent. The process completed on ' . $complete_time_local . '.</p>'
		);
		 */
	
		// to process all users daily this number should be X, where:
		// X = ( total users / queries per day )
		// For hourly cron with 1000 users:
		// X = ( 1000 / 24 )
		// X = 41.6 users per hour
		$queries_per_day = 24; // 24 = hourly, 1 = daily, etc.
		
		// this would give 42 users per query with the above example
		$users_per_query = ceil( $total_users / $queries_per_day ); 
		update_option( 'dtl-ce-users-per-query', $users_per_query, false );
		
		// save the duration of the last batch
		update_option( 'dtl-ce-last-batch', $last_batch, false );
		
		// save the start time for this batch
		update_option( 'dtl-ce-batch-start-time', time(), false );
		
		// reset email sent counter for this new batch
		update_option( 'dtl-ce-batch-emails-sent', 0, false );
	}
	
	// search for users who haven't been checked
	$args = array(
		// this many users
		'number' => $users_per_query,
		
		// starting at this position
		'offset' => $user_index,

		// order by, doesn't actually matter
		'orderby' => 'ID',
		'order' => 'ASC',
	);
	
	// get users
	$users = new WP_User_Query( $args );
	
	// if no users were returned, start over by setting the user index beyond total users.
	// this will reset to 0 on the next iteration, going into "if ( $user_index === 0 )" above.
	if ( empty($users->get_results()) ) {
		update_option( 'dtl-ce-user-index', $total_users + 1 );
		return dtl_course_expiry_check( $debug );
	}
	
	// loop through users
	foreach( $users->get_results() as $user ) {
		// do something with WP_User $user or int $user->ID
		
		// increase the user index
		$user_index++;
	}
	
	// save the user index so we can continue from where we left off next cron event
	update_option( 'dtl-ce-user-index', $user_index, false );
	
	// save the current progress
	update_option( 'dtl-ce-current-progress', $user_index / $total_users, false );
	
	if ( $debug ) {
		// debugging stuff
		ob_start();
		echo '<pre>';
		
		echo '$total_users: ', $total_users, '<br>';
		echo '$users_per_query: ', $users_per_query, '<br>';
		echo '$user_index: ', $user_index, '<br>';
		echo 'progress: ', round(100 * (get_option('dtl-ce-current-progress')), 2), '%<br>';
		
		echo '$args: <br>';
		var_dump($args);
		
		echo '$users this query: ', count($users->get_results()), '<br>';
	
		echo '$users display names: <br>';
	
		foreach( $users->get_results() as $u ) {
			if ( !$u instanceof  WP_User ) continue;
			echo "\t", $u->get('display_name'), ' (#', $u->get('ID'), ')<br>';
		}
	
		echo 'this batch duration: <br>';
		var_dump( human_time_diff( get_option('dtl-ce-batch-start-time'), time() ) );
		
		echo 'last batch: <br>';
		var_dump( get_option('dtl-ce-last-batch') );
		
		echo '</pre>';
	}
}
// run this function during our scheduled cron event
add_action( 'wp_cron_dtl_course_expiry_check', 'dtl_course_expiry_check' );

// allow to run manually in the browser, with debug mode, by adding ?manual_expiry_check
if ( isset($_GET['manual_expiry_check']) ) {
	add_action( 'init', function() {
		dtl_course_expiry_check( true ); // true = debug
		exit;
	} );
}

// Schedule an event every hour to handle cron events
function dtlce_start_cron() {
	if ( !wp_next_scheduled ( 'wp_cron_dtl_course_expiry_check' ) ) {
		wp_schedule_event(time(), 'hourly', 'wp_cron_dtl_course_expiry_check');
	}
}
register_activation_hook( __FILE__, 'dtlce_start_cron' );

// Clear the scheduled cron event if plugin gets deactivated
function dtlce_clear_cron() {
	wp_clear_scheduled_hook('wp_cron_dtl_course_expiry_check');
}
register_deactivation_hook( __FILE__, 'dtlce_clear_cron' );