Rate Limiter Generator

Rate Limiter Generator

Creates Rate Limiter pattern infrastructure for request throttling and API protection.

When to Use

Component Characteristics

RateLimiterInterface

• Common interface for all algorithms
• Check and consume methods
• Remaining capacity queries

Algorithms

• Token Bucket: Smooth rate limiting with burst capacity
• Sliding Window: Time-based with sliding window log
• Fixed Window: Simple time-based counter

RateLimitResult

• Contains allowed/​denied status
• Provides retry-after information
• Generates HTTP headers

---

Generation Process

Step 1: Generate Core Components

Path: src/​Infrastructure/​Resilience/​RateLimiter/

1. RateLimiterInterface.php — Common interface
2. RateLimitResult.php — Result value object with headers
3. RateLimitExceededException.php — Exception with retry info
4. StorageInterface.php — Storage abstraction

Step 2: Choose and Generate Algorithm

Choose based on use case:

1. TokenBucketRateLimiter.php — For APIs with burst allowance
2. SlidingWindowRateLimiter.php — For strict per-time limits
3. FixedWindowRateLimiter.php — For simple rate limiting

Step 3: Generate Storage

1. RedisStorage.php — Production storage with TTL

Step 4: Generate Tests

1. {Algorithm}RateLimiterTest.php — Algorithm tests
2. RateLimitResultTest.php — Result value object tests

---

File Placement

---

Naming Conventions

---

Quick Template Reference

RateLimiterInterface

interface RateLimiterInterface
{
    public function attempt(string $key, int $tokens = 1): RateLimitResult;
    public function getRemainingTokens(string $key): int;
    public function getRetryAfter(string $key): ?int;
    public function reset(string $key): void;
}

RateLimitResult

final readonly class RateLimitResult
{
    public static function allowed(int $remaining, int $limit, \DateTimeImmutable $resetsAt): self;
    public static function denied(int $limit, int $retryAfter, \DateTimeImmutable $resetsAt): self;
    public function isAllowed(): bool;
    public function isDenied(): bool;
    public function toHeaders(): array; // X-RateLimit-* headers
}

---

Usage Example

// Create limiter
$limiter = new TokenBucketRateLimiter(
    capacity: 100,
    refillRate: 10.0, // 10 tokens per second
    clock: $clock,
    storage: new RedisStorage($redis)
);

// Check limit
$result = $limiter->attempt('user:123');

if ($result->isDenied()) {
    throw new RateLimitExceededException(
        key: 'user:123',
        limit: $result->limit,
        retryAfterSeconds: $result->retryAfterSeconds
    );
}

// Add headers to response
foreach ($result->toHeaders() as $name => $value) {
    $response = $response->withHeader($name, (string) $value);
}

---

Algorithm Comparison

---

Anti-patterns to Avoid

---

References

For complete PHP templates and examples, see:

• references/​templates.md — All algorithm implementations
• references/​examples.md — Middleware example and tests