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Prevent an action for some amount of time. Hours, day, months, years, anything. Allows for multiple locks (e.g. 100/day) and clearing/releasing a lock just made. And it works just like it should, every single lock lasts exactly how long you specify and is taken atomically.

Installation

In application.config.php, add as follows:

'modules' => [..., 'IllchukLock', ...];

Import into your database data/illchuk_lock.sql:

CREATE TABLE IF NOT EXISTS `illchuk_lock` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT PRIMARY KEY,
  `key` varchar(255) NOT NULL UNIQUE KEY,
  `end_datetime` DATETIME NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
ALTER TABLE `illchuk_lock` ADD INDEX (`end_datetime`);

To Use

Either you get the lock or you don't.

// in controller
$locker = $this->getServiceLocator()->get('IllchukLock');

// term?
$term = new DateTimeUnit(2, 'weeks'); // or
$term = new DateTimeEnd(new DateTime('+2 weeks'));

if ($locker->takeLock('BiWeeklyReport', $term)) {
    // lock is taken atomically, made for 2 weeks: safe to do your work
}
else {
    // locked from before: leave it alone & perhaps try again later
}

/**
 * N.B. May throw \IllchukLock\Exception\PhantomLockException, when
 * lock is reported to be set but upon verification step is actually not.
 * This is truly exceptional and shouldn't be just thrown aside.
 */

Allow Multiple Locks

You can allow any number of locks e.g. 'lock1' => 5/hour, 'lock2' => 100/day. Here's how:

// copy IllchukLock.global.php to your config/autoload/
$locker = [
// ...
    'adapter_class' => 'IllchukLock\Adapter\DbMultiple', // was Adapter\Db
// ...
]
$regexCounts = [
    /**
     * E.g. You can create 3 'do-stuff' locks before the lock can't be taken.
     * Those not matching here are allowed the usual 1.
     */
    '/^do-stuff$/' => 3
];

// in controller
$locker = $this->getServiceLocator()->get('IllchukLock');
$locker->takeLock('do-stuff', new DateTimeUnit(1, 'day')); // YES
$locker->takeLock('do-stuff', new DateTimeUnit(1, 'day')); // YES
$locker->takeLock('do-stuff', new DateTimeUnit(1, 'day')); // YES
$locker->takeLock('do-stuff', new DateTimeUnit(1, 'day')); // FALSE
// ...
// A DAY LATER
$locker->takeLock('do-stuff', new DateTimeUnit(1, 'day')); // YES

Clearing Locks

$locker = $this->getServiceLocator()->get('IllchukLock');
$handle = $locker->takeLock('year-end', new DateTimeUnit(1, 'year')); // YES
$locker->takeLock('year-end', new DateTimeUnit(1, 'year')); // FALSE
if ($whoopsBackingOut) {
    $locker->clearLock($handle);
}
$locker->takeLock('year-end', new DateTimeUnit(1, 'year')); // YES

Lock with APC

For something more quick-n-dirty, use APC locking. This is adequate for short-term throttling with the usual caveats regarding APC persistence (e.g. some other part of your app might flush the entire cache, a PHP restart, out of memory).

N.B. If takeLock() fails, don't try to sleep() it out; that won't work for some reason to do with how apc_add() works. Instead, handle the no-lock condition then try again next request.

// copy illchuklock.global.php to your config/autoload/
$locker = [
// ...
    'adapter_class' => 'IllchukLock\Adapter\Apc', // was Adapter\Db
// ...
]

// from service manager
$locker = $container->get('IllchukLock');


// alternatively, a shortcut factory that doesn't require config
$locker = $container->get('illchuk_lock_apc');

illchuk / illchuk-locker

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