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<?php |
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|
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declare(strict_types=1); |
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|
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namespace malkusch\lock\util; |
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use malkusch\lock\mutex\Mutex; |
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|
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/** |
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* The double-checked locking pattern. |
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* |
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* You should not instantiate this class directly. Use |
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* {@link \malkusch\lock\mutex\Mutex::check()}. |
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* |
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* @author Markus Malkusch <markus@malkusch.de> |
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* @link bitcoin:1P5FAZ4QhXCuwYPnLZdk3PJsqePbu1UDDA Donations |
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* @license WTFPL |
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*/ |
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class DoubleCheckedLocking |
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{ |
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/** |
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* @var \malkusch\lock\mutex\Mutex The mutex. |
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*/ |
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private $mutex; |
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|
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/** |
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* @var callable The check. |
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*/ |
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private $check; |
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|
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/** |
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* Constructs a new instance of the DoubleCheckedLocking pattern. |
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* |
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* @param \malkusch\lock\mutex\Mutex $mutex Provides methods for exclusive |
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* code execution. |
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* @param callable $check Callback that decides if the lock should be |
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* acquired and if the critical code callback should be executed after |
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* acquiring the lock. |
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*/ |
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public function __construct(Mutex $mutex, callable $check) |
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{ |
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$this->mutex = $mutex; |
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$this->check = $check; |
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} |
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|
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/** |
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* Executes a synchronized callback only after the check callback passes |
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* before and after acquiring the lock. |
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* |
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* If then returns boolean boolean false, the check did not pass before or |
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* after acquiring the lock. A boolean false can also be returned from the |
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* critical code callback to indicate that processing did not occure or has |
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* failed. It is up to the user to decide the last point. |
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* |
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* @param callable $code The critical code callback. |
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* @throws \Exception The execution callback or the check threw an |
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* exception. |
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* @throws \malkusch\lock\exception\LockAcquireException The mutex could not |
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* be acquired. |
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* @throws \malkusch\lock\exception\LockReleaseException The mutex could not |
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* be released. |
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* @throws \malkusch\lock\exception\ExecutionOutsideLockException Some code |
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* has been executed outside of the lock. |
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* @return mixed Boolean false if check did not pass or mixed for what ever |
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* the critical code callback returns. |
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*/ |
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public function then(callable $code) |
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{ |
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if (!\call_user_func($this->check)) { |
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return false; |
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} |
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|
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return $this->mutex->synchronized(function () use ($code) { |
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if (!\call_user_func($this->check)) { |
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return false; |
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} |
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|
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return $code(); |
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}); |
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} |
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} |
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