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<?php |
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|
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// allow-no-test-found: exercised by PermalinkCacheChainAlreadyArmedTest race and stale-owner scenarios. |
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|
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if (!defined('ABSPATH')) { |
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exit; |
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} |
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|
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require_once dirname(__DIR__) . '/core/ExclusiveOptionRow.php'; |
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|
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/** |
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* Serializes the permalink-cache hook probe with its WordPress cron write. |
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* |
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* WordPress de-duplicates scheduled events by hook and arguments. The cache |
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* chain changes its arguments on every link, so two callers that both inspect |
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* an empty cron store can otherwise both add a link. This claim makes that |
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* check-and-write critical section exclusive across PHP requests. |
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*/ |
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final class ABJ_404_Solution_PermalinkCacheScheduleLock { |
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|
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private const OPTION_NAME = 'abj404_permalink_cache_schedule_lock'; |
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|
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/** A killed request may delay, but never permanently wedge, the chain. */ |
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private const TTL_SECONDS = 180; |
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|
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/** |
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* @return string|null Exact owner value, or null while another live caller owns it. |
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* @phpstan-impure |
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*/ |
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public function acquire(): ?string { |
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$lockRow = $this->lockRow(); |
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$now = abj_clock()->now(); |
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$claimValue = ABJ_404_Solution_ExclusiveOptionRow::uniqueClaimValue( |
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(string)($now + self::TTL_SECONDS) |
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); |
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$claim = array('optionName' => self::OPTION_NAME, 'value' => $claimValue); |
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if ($lockRow->claim($claim)) { |
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return $claimValue; |
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} |
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|
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$existing = $lockRow->valueOf(self::OPTION_NAME); |
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$expiryPart = explode(':', $existing, 2)[0]; |
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$existingIsStale = $existing === '' || !is_numeric($expiryPart) || (int)$expiryPart <= $now; |
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if (!$existingIsStale) { |
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return null; |
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} |
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if ($existing !== '' && !$lockRow->releaseIfValueIs(array( |
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'optionName' => self::OPTION_NAME, |
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'value' => $existing, |
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))) { |
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return null; |
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} |
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|
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return $lockRow->claim($claim) ? $claimValue : null; |
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} |
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|
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/** Release only the exact claim this instance acquired. */ |
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public function release(string $claimValue): void { |
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$this->lockRow()->releaseIfValueIs(array( |
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'optionName' => self::OPTION_NAME, |
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'value' => $claimValue, |
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)); |
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} |
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|
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private function lockRow(): ABJ_404_Solution_ExclusiveOptionRow { |
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return new ABJ_404_Solution_ExclusiveOptionRow(); |
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} |
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} |
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|
