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<?php |
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|
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namespace Yoast\WP\SEO\Helpers; |
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|
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use Yoast\WP\SEO\Exceptions\Locking\Lock_Timeout_Exception; |
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use Yoast\WP\SEO\Expiring_Store\Application\Expiring_Store; |
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|
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/** |
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* Distributed exclusive lock backed by the expiring store. |
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* |
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* Acquires a network-scoped lock in the expiring store table, executes the |
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* callback, and releases the lock in a finally block. |
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* |
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* The lock has a TTL so that it self-expires if the owning process crashes without |
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* releasing it. Other processes retry with a configurable delay between attempts. |
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*/ |
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class Lock_Helper { |
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|
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/** |
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* The expiring store. |
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* |
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* @var Expiring_Store |
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*/ |
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private $store; |
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|
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/** |
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* The constructor. |
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* |
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* @param Expiring_Store $store The expiring store. |
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*/ |
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public function __construct( Expiring_Store $store ) { |
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$this->store = $store; |
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} |
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|
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/** |
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* Acquires a lock, executes the callback, and releases the lock. |
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* |
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* @template T |
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* |
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* @param string $lock_key The lock key. |
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* @param callable(): T $callback The callback to execute while holding the lock. |
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* @param int $ttl_in_seconds The lock TTL in seconds. Defaults to 30. |
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* @param int $max_attempts The maximum number of acquisition attempts. Defaults to 5. |
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* @param int $retry_delay_microseconds The delay between attempts in microseconds. Defaults to 20000 (20ms). |
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* |
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* @return T The callback's return value. |
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* @throws Lock_Timeout_Exception When the lock cannot be acquired within the allowed attempts. |
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*/ |
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public function execute( string $lock_key, callable $callback, int $ttl_in_seconds = 30, int $max_attempts = 5, int $retry_delay_microseconds = 20_000 ) { |
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$this->acquire( $lock_key, $ttl_in_seconds, $max_attempts, $retry_delay_microseconds ); |
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|
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try { |
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return $callback(); |
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} |
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finally { |
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$this->store->delete_for_multisite( $lock_key ); |
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} |
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} |
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|
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/** |
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* Attempts to acquire the lock with retries. |
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* |
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* @param string $lock_key The lock key. |
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* @param int $ttl_in_seconds The lock TTL in seconds. |
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* @param int $max_attempts The maximum number of attempts. |
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* @param int $retry_delay_microseconds The delay between attempts in microseconds. |
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* |
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* @return void |
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* @throws Lock_Timeout_Exception When all attempts are exhausted. |
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*/ |
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private function acquire( string $lock_key, int $ttl_in_seconds, int $max_attempts, int $retry_delay_microseconds ): void { |
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for ( $attempt = 1; $attempt <= $max_attempts; $attempt++ ) { |
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if ( $this->store->persist_if_absent_for_multisite( $lock_key, true, $ttl_in_seconds ) ) { |
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return; |
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} |
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|
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if ( $attempt < $max_attempts ) { |
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\usleep( $retry_delay_microseconds ); |
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} |
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} |
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|
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// phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped -- This is an exception message, not output. |
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throw new Lock_Timeout_Exception( $lock_key, $max_attempts ); |
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} |
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} |
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|
