Purpose

The cron-task registry. Sibling plugins register their scheduled tasks by appending entries to the array passed through this filter. The mam_setcron_processor AJAX endpoint (pinged by FastCron on every tick) walks the registry and dispatches tasks whose schedule matches “now”.

25+ subscribers across mam-suite-hold and the use-case plugins.

Signature

$crons = apply_filters( 'mam_cron_manager', array $crons );

Returns: array — the augmented map.

Cron entry shape

array(
    'my_plugin_nightly_sync' => array(
        'title'      => 'Nightly Sync',
        'expression' => '0 2 * * *',          // standard cron syntax
        'callback'   => 'my_plugin_nightly_sync_action',
    ),
    // ...
)

The cron id (the key) is the dispatch handle. It must be unique site-wide.

Example: register a cron

add_filter( 'mam_cron_manager', function ( array $crons ): array {

    $crons['my_plugin_nightly_sync'] = array(
        'title'      => 'My Plugin: Nightly Sync',
        'expression' => '0 2 * * *',
        'callback'   => 'my_plugin_nightly_sync_action',
    );

    return $crons;
} );

// The callback registered against the dispatch hook (cron id):
function my_plugin_nightly_sync_action( $unused = array() ) {
    // do the work
    // return value is discarded
}
add_filter( 'my_plugin_nightly_sync', 'my_plugin_nightly_sync_action' );

⚠️ Note: per-cron callbacks are invoked via apply_filters( $cron_id, array() ), not do_action. This is for return-value compatibility with older callbacks. Treat your return value as discarded.

How dispatch works

mam_setcron_manager::mam_setcron_processor():

On every FastCron tick (typically every 1–5 minutes):

  1. Resolve current time + timezone (wp_timezone_string())
  2. $crons = apply_filters('mam_cron_manager', array());
  3. For each cron entry:
       - Evaluate `expression` against "now"
       - If schedule matches: apply_filters($cron_id, array())

Multiple crons matching the same tick run serially.

Cron expression gotchas

• Standard 5-field cron syntax. Minute / hour / day-of-month / month / day-of-week.
• Time zone matters. The processor uses wp_timezone_string(). A site set to Asia/Kolkata (+05:30) evaluates expressions in IST.
• Off-set zones (e.g., +05:30) fall back through two timezone_name_from_abbr attempts. Failed lookups silently fall through to UTC. Use named timezones where possible.
• FastCron’s resolution is the real ceiling — if FastCron pings every 5 minutes, a * * * * * cron runs every 5 minutes, not every minute.

Common cron tasks

Gotchas

• Cron id must be unique. Two plugins registering the same id produce dispatch ambiguity; the second registration overwrites the first.
• apply_filters not do_action. Return values are discarded; this is for compat with old callbacks.
• No retry semantics. A failed cron callback isn’t retried until the next tick that matches its expression.
• Long-running callbacks block other crons on the same tick. Keep work short or move to a queue + drain pattern.
• Time-zone resolution can silently fall through to UTC for offset-style timezones.
• FastCron must be configured for crons to fire — see Integration: FastCron.

Related articles

• Integration: FastCron
• Notification queue and cron
• Recipe: Register a scheduled cron task

Metadata