AgentSkillsCN

symfony-7-4-semaphore

Symfony 7.4 Semaphore组件参考文档，用于限制并发量与控制资源访问。触发器包括：Semaphore、并发限制、加权信号量、Redis信号量、SemaphoreFactory、SemaphoreInterface、RedisStore、acquire、release、速率限制、并发进程。

SKILL.md
--- frontmatter
name: "symfony-7-4-semaphore"
description: "Symfony 7.4 Semaphore component for concurrency limiting and resource access control. Triggers on: Semaphore, concurrency limiting, weighted semaphore, Redis semaphore, SemaphoreFactory, SemaphoreInterface, RedisStore, acquire, release, rate limiting, concurrent processes."

Symfony 7.4 Semaphore Component

Overview

The Symfony Semaphore component manages semaphores - mechanisms to control concurrent access to shared resources. Unlike locks (which allow only one process), semaphores allow multiple processes to access a resource simultaneously, up to a configurable limit.

Quick Reference

Installation

bash
composer require symfony/semaphore

Basic Usage

php
use Symfony\Component\Semaphore\SemaphoreFactory;
use Symfony\Component\Semaphore\Store\RedisStore;

// Setup Redis store
$redis = new Redis();
$redis->connect('127.0.0.1');
$store = new RedisStore($redis);
$factory = new SemaphoreFactory($store);

// Create semaphore: resource name + max concurrent processes
$semaphore = $factory->createSemaphore('pdf-generation', 2);

// Acquire and use
if ($semaphore->acquire()) {
    try {
        // Only up to 2 processes can be here simultaneously
        $this->generatePdf();
    } finally {
        $semaphore->release();
    }
}

Key Interfaces

Class/InterfacePurpose
SemaphoreFactoryCreates semaphore instances
SemaphoreInterfaceContract for semaphore operations
RedisStoreRedis-backed persistence
PersistingStoreInterfaceContract for storage backends

acquire() vs release()

php
$semaphore->acquire();  // Returns true if acquired, false if limit reached
$semaphore->release();  // Releases the semaphore (also auto-releases on destruction)

Disable Auto-Release (for cross-request locking)

php
$semaphore = $factory->createSemaphore(
    'resource-name',
    2,
    300.0,  // TTL in seconds
    false   // Disable auto-release
);

Common Use Cases

  • •Rate limiting: Control concurrent access to expensive operations
  • •Resource management: Limit concurrent database connections or API calls
  • •Batch processing: Control parallelism in background jobs
  • •Invoice generation: Limit concurrent PDF generations

Full Documentation