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<?php |
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|
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namespace SyncBasalam\Services\Api; |
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|
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defined('ABSPATH') || exit; |
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|
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/** |
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* Circuit Breaker for Basalam API requests. |
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* |
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* States: |
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* CLOSED - normal operation, requests pass through. |
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* OPEN - requests are blocked after too many consecutive failures. |
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* HALF_OPEN - one probe request is allowed after the cooldown period to test recovery. |
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* |
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* State is persisted in a single WordPress option so it survives across requests/cron jobs. |
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*/ |
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class CircuitBreaker |
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{ |
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const STATE_CLOSED = 'closed'; |
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const STATE_OPEN = 'open'; |
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const STATE_HALF_OPEN = 'half_open'; |
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|
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const OPTION_KEY = 'sync_basalam_circuit_breaker'; |
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|
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/** |
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* Request-local cache to avoid repeated DB reads when multiple API service |
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* instances are created in the same request lifecycle. |
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*/ |
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private static ?array $requestStateCache = null; |
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|
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/** Number of consecutive failures before the circuit opens. */ |
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private int $failureThreshold; |
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|
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/** Seconds to wait in OPEN state before moving to HALF_OPEN. */ |
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private int $recoveryTimeout; |
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|
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/** Seconds of inactivity in CLOSED state after which failure_count resets to 0. */ |
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private int $closedResetInterval; |
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|
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/** Seconds to wait before considering a HALF_OPEN probe stale. */ |
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private int $halfOpenProbeTimeout; |
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|
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private array $state; |
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|
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public function __construct( |
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int $failureThreshold = 10, |
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int $recoveryTimeout = 60, |
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int $closedResetInterval = 300, |
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?int $halfOpenProbeTimeout = null |
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) { |
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$this->failureThreshold = $failureThreshold; |
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$this->recoveryTimeout = $recoveryTimeout; |
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$this->closedResetInterval = $closedResetInterval; |
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$this->halfOpenProbeTimeout = $halfOpenProbeTimeout ?? $recoveryTimeout; |
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$this->state = $this->loadState(); |
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} |
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|
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/** |
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* Returns true when a request should be allowed through. |
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* Throws a CircuitBreakerOpenException when the circuit is OPEN. |
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*/ |
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public function isAllowed(): bool |
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{ |
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$currentState = $this->state['state']; |
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|
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if ($currentState === self::STATE_CLOSED) return true; |
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|
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if ($currentState === self::STATE_OPEN) { |
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if ($this->recoveryTimeoutElapsed()) { |
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$this->transitionTo(self::STATE_HALF_OPEN); |
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$currentState = self::STATE_HALF_OPEN; |
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} else { |
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throw new CircuitBreakerOpenException('سرویس باسلا� |
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� |
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وقتاً در دسترس نیست. لطفاً چند دقیقه دیگر تلاش کنید.', 503); |
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} |
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} |
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|
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if ($currentState === self::STATE_HALF_OPEN) { |
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if ($this->hasHalfOpenProbeInFlight() && !$this->halfOpenProbeExpired()) { |
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throw new CircuitBreakerOpenException('در حال بررسی اتصال � |
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جدد به باسلا� |
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هستی� |
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. لطفاً چند لحظه دیگر دوباره تلاش کنید.', 503); |
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} |
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|
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$this->state['probe_started_at'] = time(); |
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$this->saveState(); |
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|
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return true; |
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} |
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|
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return false; |
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} |
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|
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/** |
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* Records a successful request and resets the failure counter. |
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*/ |
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public function recordSuccess(): void |
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{ |
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$this->state['failure_count'] = 0; |
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$this->state['last_failure'] = null; |
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$this->transitionTo(self::STATE_CLOSED); |
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} |
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|
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/** |
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* Records a failed request and opens the circuit when the threshold is reached. |
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*/ |
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public function recordFailure(): void |
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{ |
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$this->state['failure_count']++; |
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$this->state['last_failure'] = time(); |
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$this->state['probe_started_at'] = null; |
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|
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if ($this->state['state'] === self::STATE_HALF_OPEN) { |
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$this->transitionTo(self::STATE_OPEN); |
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return; |
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} |
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|
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if ($this->state['failure_count'] >= $this->failureThreshold) { |
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$this->transitionTo(self::STATE_OPEN); |
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return; |
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} |
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|
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$this->saveState(); |
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} |
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|
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public function getState(): string |
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{ |
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return $this->state['state']; |
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} |
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|
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public function getFailureCount(): int |
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{ |
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return $this->state['failure_count']; |
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} |
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|
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public function getLastFailure(): ?int |
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{ |
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return empty($this->state['last_failure']) ? null : (int) $this->state['last_failure']; |
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} |
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|
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public function getSnapshot(): array |
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{ |
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return $this->state; |
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} |
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|
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public function reset(): void |
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{ |
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$this->state = $this->defaultState(); |
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$this->saveState(); |
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} |
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|
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private function recoveryTimeoutElapsed(): bool |
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{ |
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if (empty($this->state['last_failure'])) { |
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return true; |
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} |
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|
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return (time() - $this->state['last_failure']) >= $this->recoveryTimeout; |
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} |
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|
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private function hasHalfOpenProbeInFlight(): bool |
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{ |
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return !empty($this->state['probe_started_at']); |
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} |
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|
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private function halfOpenProbeExpired(): bool |
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{ |
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if (empty($this->state['probe_started_at'])) { |
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return true; |
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} |
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|
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return (time() - $this->state['probe_started_at']) >= $this->halfOpenProbeTimeout; |
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} |
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|
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private function transitionTo(string $newState): void |
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{ |
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if ($newState === self::STATE_CLOSED) { |
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$this->state = $this->defaultState(); |
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} else { |
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$this->state['state'] = $newState; |
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$this->state['probe_started_at'] = null; |
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} |
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|
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$this->saveState(); |
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} |
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|
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private function loadState(): array |
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{ |
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if (is_array(self::$requestStateCache)) { |
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$state = self::$requestStateCache; |
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} else { |
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$stored = get_option(self::OPTION_KEY, null); |
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|
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if (!is_array($stored)) { |
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$state = $this->defaultState(); |
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} else { |
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$state = array_merge($this->defaultState(), $stored); |
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} |
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|
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self::$requestStateCache = $state; |
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} |
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|
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if ( |
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$state['state'] === self::STATE_CLOSED && |
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$state['failure_count'] > 0 && |
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!empty($state['last_failure']) && |
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(time() - $state['last_failure']) >= $this->closedResetInterval |
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) { |
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$state['failure_count'] = 0; |
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$state['last_failure'] = null; |
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$state['probe_started_at'] = null; |
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update_option(self::OPTION_KEY, $state, false); |
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self::$requestStateCache = $state; |
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} |
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|
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if ( |
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$state['state'] === self::STATE_HALF_OPEN && |
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!empty($state['probe_started_at']) && |
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$this->halfOpenProbeExpired() |
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) { |
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$state['probe_started_at'] = null; |
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update_option(self::OPTION_KEY, $state, false); |
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self::$requestStateCache = $state; |
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} |
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|
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return $state; |
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} |
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|
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private function saveState(): void |
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{ |
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self::$requestStateCache = $this->state; |
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update_option(self::OPTION_KEY, $this->state, false); |
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} |
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|
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private function defaultState(): array |
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{ |
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return [ |
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'state' => self::STATE_CLOSED, |
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'failure_count' => 0, |
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'last_failure' => null, |
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'probe_started_at' => null, |
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]; |
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} |
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} |
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|
