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Semaphore Laravel Package
symfony/semaphore
Symfony Semaphore Component provides semaphores for coordinating access to shared resources across processes and threads. Use it to enforce mutual exclusion, limit concurrency, and prevent race conditions via an easy, reusable API.
Symfony Semaphore Component
Frequently asked questions about Semaphore
- How do I install Symfony Semaphore in a Laravel project?
- Use Composer to install the package with `composer require symfony/semaphore`. No additional Laravel-specific setup is required—it integrates directly with the Symfony service container. For Redis-backed semaphores, ensure the `predis/predis` or `phpredis` package is installed for optimal performance.
- Can Symfony Semaphore work with Laravel Queues or Horizon?
- Yes, it’s ideal for queue coordination. Wrap job execution in semaphores to prevent race conditions, e.g., `Semaphore::acquire('job-lock'); dispatch(new ProcessPaymentJob()); Semaphore::release('job-lock');`. Works seamlessly with Laravel’s queue workers and Horizon.
- What Laravel versions does Symfony Semaphore support?
- The component requires PHP 8.1+ (v7.x) or 8.4+ (v8.x), which aligns with Laravel 9+ and 10+. For Laravel 8.x, you’ll need to upgrade PHP or use filesystem/DBAL backends, though Redis is recommended for production.
- How do I configure Symfony Semaphore for Redis in Laravel?
- Configure Redis via Symfony’s `SemaphoreFactory` with a DSN like `redis://127.0.0.1:6379`. In Laravel, bind the factory to the container in `config/app.php` under `providers`. Example: `$factory = new SemaphoreFactory(new RedisClient($dsn));`
- What happens if a semaphore lock times out or fails?
- Locks auto-release after the configured timeout (default: 30 seconds). If the backing store fails (e.g., Redis downtime), locks may persist until recovery. Use `try-finally` blocks to ensure `release()` is called, or set a short timeout for critical sections.
- Can I use Symfony Semaphore for tenant-aware rate limiting?
- Yes, create unique semaphore keys per tenant (e.g., `tenant:{id}-stripe-calls`). Set a permit limit (e.g., 5) to enforce concurrent access. Example: `Semaphore::acquire('tenant:123-stripe', 5, 60)` for 5 concurrent calls with a 60-second window.
- Is Symfony Semaphore thread-safe for Laravel’s CLI commands?
- Yes, it’s designed for concurrent environments. Protect long-running CLI commands (e.g., `artisan migrate`) by acquiring a semaphore before execution. Example: `Semaphore::acquire('migration-lock');` to block concurrent migrations.
- What are the alternatives to Symfony Semaphore in Laravel?
- Alternatives include Redis `SETNX` (less reliable), database `SELECT ... FOR UPDATE`, or Laravel’s native `flock()` (filesystem-only). Symfony Semaphore stands out for its cross-process reliability, Redis/DBAL support, and built-in timeouts, reducing deadlock risks.
- How do I test Symfony Semaphore in Laravel unit tests?
- Use an in-memory backend (e.g., `SemaphoreFactory` with a mock store) or Redis for integration tests. Avoid filesystem backends in CI/CD due to race conditions. Example: `$factory = new SemaphoreFactory(new InMemoryStore());` for deterministic testing.
- Can Symfony Semaphore handle distributed locks across multiple servers?
- Yes, Redis-backed semaphores work across clusters. For high availability, use Redis Sentinel or Cluster mode (v7.2.4+). Validate DSN configurations (e.g., `redis+cluster://`) in staging to avoid connection failures. Fallback to filesystem/DBAL if Redis is unavailable.
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