PHP code example of antikirra / probability

    
        
<?php
require_once('vendor/autoload.php');

/* Start to develop here. Best regards https://php-download.com/ */

    

antikirra / probability example snippets

use function Antikirra\probability;

// Random execution - 30% chance to log debug info
if (probability(0.3)) {
    error_log("Debug: processing request #{$requestId}");
}

// Deterministic execution - same user always gets same experience
if (probability(0.5, "new_checkout_user_{$userId}")) {
    return renderNewCheckout();
}

// Gradual rollout - increase from 10% to 100% over time
if (probability(0.1, "feature_ai_search_user_{$userId}")) {
    enableAISearch();
}

probability(0.25); // 25% chance, different result each time

probability(0.25, 'unique_key'); // Same result for same key

function probability(float $probability, string $key = ''): bool

// 15% random chance
probability(0.15);

// Deterministic 30% for user with id 123
probability(0.30, "user_123");

// Combining feature and user for unique distribution
probability(0.25, "feature_checkout_user_123");

// ❌ Bad - too generic
probability(0.5, "test");

// ✅ Good - specific and unique
probability(0.5, "homepage_redesign_user_$userId");

// ❌ Bad - same users get all features
if (probability(0.2, $userId)) { /* feature A */ }
if (probability(0.2, $userId)) { /* feature B */ }

// ✅ Good - different user groups per feature
if (probability(0.2, "feature_a_$userId")) { /* feature A */ }
if (probability(0.2, "feature_b_$userId")) { /* feature B */ }

// For high-frequency operations, use very small probabilities
if (probability(0.001)) { // 0.1% - suitable for millions of requests
    $metrics->record($data);
}

namespace App\Http\Middleware;

use Closure;
use function Antikirra\probability;

class FeatureFlag
{
    public function handle($request, Closure $next, $feature, $percentage)
    {
        $userId = $request->user()?->id ?? $request->ip();
        $key = "{$feature}_user_{$userId}";

        if (!probability((float)$percentage, $key)) {
            abort(404); // Feature not enabled for this user
        }

        return $next($request);
    }
}

// Usage in routes:
// Route::get('/beta', ...)->middleware('feature:beta_dashboard,0.1');

use function Antikirra\probability;
use Psr\Log\LoggerInterface;

class DatabaseQueryLogger
{
    public function __construct(
        private LoggerInterface $logger,
        private float $samplingRate = 0.01 // 1% of queries
    ) {}

    public function logQuery(string $sql, float $duration): void
    {
        // Random sampling - no need for deterministic behavior
        if (!probability($this->samplingRate)) {
            return;
        }

        $this->logger->info('Query executed', [
            'sql' => $sql,
            'duration' => $duration,
            'sampled' => true
        ]);
    }
}

use function Antikirra\probability;

function show_homepage_variant() {
    $user_id = get_current_user_id() ?: $_SERVER['REMOTE_ADDR'];
    $key = "homepage_redesign_user_{$user_id}";

    // 50% of users see new design, consistently
    if (probability(0.5, $key)) {
        get_template_part('homepage', 'new');
    } else {
        get_template_part('homepage', 'classic');
    }
}

use function Antikirra\probability;

class ApiRateLimiter
{
    public function allowRequest(User $user, string $endpoint): bool
    {
        $limits = [
            'free' => 0.1,    // 10% of requests allowed
            'basic' => 0.5,   // 50% of requests allowed
            'premium' => 1.0  // 100% of requests allowed
        ];

        $probability = $limits[$user->tier] ?? 0;
        $key = "api_{$endpoint}_{$user->id}_" . date('YmdH'); // Hourly bucket

        return probability($probability, $key);
    }
}

// ❌ This will differ between users
probability(0.5, $userId); // If $userId is different

// ✅ This will be consistent for same user
probability(0.5, "feature_x_user_{$userId}");

// Week 1: 10% rollout
if (probability(0.1, "feature_x_user_{$userId}")) { ... }

// Week 2: 50% rollout (feature_x_user_{$userId}")) { ... }