محدودیت نرخ

/** Every pipeline below starts from the same two required options. */
$base = static fn(): PipelineBuilder => PipelineBuilder::profile('choosing', 'v1')
    ->partition('shop', 'prod', 'catalog-api')
    ->attemptTimeout(Duration::seconds(2), AttemptTimeoutRequirement::Cooperative);

$ok = static fn(): string => 'ok';
$context = static fn(CompiledPipeline $pipeline): ExecutionContext => $pipeline->newContext(Duration::seconds(30));

echo "-- 1. Rate limit: three algorithms, same builder call\n";
$algorithms = [
    'token bucket' => PipelineBuilder::tokenBucket(1, 1, Duration::seconds(3600)),
    'fixed window' => PipelineBuilder::fixedWindow(1, Duration::seconds(3600), FixedWindowAnchor::FirstHit),
    'sliding window' => PipelineBuilder::slidingWindow(1, Duration::seconds(3600)),
];
foreach ($algorithms as $name => $algorithm) {
    $pipeline = $base()->rateLimit($algorithm)->compileInMemory(ExceptionClassifier::create());
    $pipeline->execute($ok, $context($pipeline));
    try {
        $pipeline->execute($ok, $context($pipeline));
    } catch (AdmissionRejectedException | AdmissionDeferredException $e) {
        echo "{$name}: second call refused with {$e->reason()->value}\n";
    }
}

-- 1. Rate limit: three algorithms, same builder call
token bucket: second call refused with rate.exhausted
fixed window: second call refused with rate.exhausted
sliding window: second call refused with rate.exhausted

echo "-- 1. A retry is charged like a first attempt\n";
// A bucket of 3 units that does not refill within this script. The call may make up to 3 attempts.
$pipeline = PipelineBuilder::profile('rate-charges', 'v1')
    ->partition('shop', 'prod', 'catalog-api')
    ->attemptTimeout(Duration::seconds(2), AttemptTimeoutRequirement::Cooperative)
    ->retry(3, BackoffMode::Constant, Duration::milliseconds(5), Duration::milliseconds(5), JitterMode::None)
    ->retryBudget(10, 10, Duration::seconds(60), Duration::seconds(10))
    ->rateLimit(PipelineBuilder::tokenBucket(3, 1, Duration::seconds(3600)))
    ->compileInMemory(ExceptionClassifier::create()->retryOn(Hiccup::class));
$safety = static fn(): OperationSafety => OperationSafety::replayableRead(
    ReplaySafetyContract::forReadOnlyCallable('list-products', Duration::seconds(3600)),
);

$flaky = static function (AttemptContext $attempt): string {
    if ($attempt->dispatchedAttemptNumber < 3) {
        throw new Hiccup('try again');
    }

    return 'ok';
};
echo 'first operation: ', $pipeline->execute($flaky, $pipeline->newContext(Duration::seconds(30), $safety())), " (3 dispatches)\n";

$completion = $pipeline->executeDetailed($flaky, $pipeline->newContext(Duration::seconds(30), $safety()));
echo 'second operation: ', $completion->disposition->value, ', dispatched ', $completion->summary->dispatched, ', reason ', $completion->problem()?->code->value, "\n";

-- 1. A retry is charged like a first attempt
first operation: ok (3 dispatches)
second operation: rejected, dispatched 0, reason rate.exhausted

echo "-- 2. A cost above the capacity can never be admitted\n";
$tooCostly = PipelineBuilder::profile('rate-charges', 'v1')
    ->partition('shop', 'prod', 'catalog-api')
    ->attemptTimeout(Duration::seconds(2), AttemptTimeoutRequirement::Cooperative)
    ->rateLimit(PipelineBuilder::tokenBucket(2, 2, Duration::seconds(1)), cost: 3)
    ->compileInMemory(ExceptionClassifier::create());
try {
    $tooCostly->execute(static fn(): string => 'never runs', $tooCostly->newContext(Duration::seconds(30)));
} catch (ImpossibleAdmissionException $e) {
    echo get_class($e), ': ', $e->reason()->value, "\n";
} catch (AdmissionRejectedException | AdmissionDeferredException $e) {
    echo 'unexpected: ', get_class($e), "\n";
    exit(1);
}

-- 2. A cost above the capacity can never be admitted
Enaxon\Reqtide\Exception\ImpossibleAdmissionException: rate.cost_exceeds_capacity