Scaling Decision

Scaling Decision

Returned by ScalingEngine::evaluate() and dispatched in ScalingDecisionMade / SlaBreachPredicted events.

namespace Cbox\LaravelQueueAutoscale\Scaling;

readonly class ScalingDecision
{
    public function __construct(
        public string $connection,
        public string $queue,
        public int $currentWorkers,
        public int $targetWorkers,
        public string $reason,
        public ?float $predictedPickupTime = null,
        public int $slaTarget = 30,
        public ?CapacityCalculationResult $capacity = null,
        public ?SpawnCompensationConfiguration $spawnCompensation = null,
    ) {}

    public function shouldScaleUp(): bool;
    public function shouldScaleDown(): bool;
    public function shouldHold(): bool;
    public function workersToAdd(): int;
    public function workersToRemove(): int;
    public function action(): string;           // 'scale_up' | 'scale_down' | 'hold'
    public function isSlaBreachRisk(): bool;    // predictedPickupTime > slaTarget
}

There is no confidence property on ScalingDecision, or anywhere else in the package.

Do not confuse ScalingDecision::action() ('scale_up' | 'scale_down' | 'hold') with WorkersScaled::$action, which is always 'up' or 'down'.

CapacityCalculationResult

ScalingDecision::$capacity, in Cbox\LaravelQueueAutoscale\Scaling\DTOs:

readonly class CapacityCalculationResult
{
    public function __construct(
        public int $maxWorkersByCpu,
        public int $maxWorkersByMemory,
        public int $maxWorkersByConfig,
        public int $finalMaxWorkers,
        public string $limitingFactor,
        public array $details = [],
    ) {}

    public function cpuBreakdown(): CpuBreakdown;
    public function memoryBreakdown(): MemoryBreakdown;

    public function isCpuLimited(): bool;
    public function isMemoryLimited(): bool;
    public function isConfigLimited(): bool;
    public function getSummary(): string;
    public function getFormattedDetails(): array;
}

cpuBreakdown() and memoryBreakdown() return the same numbers as the nested cpu_details / memory_details entries of $details, as typed readonly objects — prefer them over indexing into the array. MemoryBreakdown also derives usedMb() and freeMb() from the percentage and total.

$cpu = $decision->capacity->cpuBreakdown();

$cpu->totalCores;             // float
$cpu->usableCores;            // float, total minus the reserve
$cpu->currentCpuPercent;      // float
$cpu->workerCpuCoreEstimate;  // float, cores one worker is assumed to occupy
$cpu->estimateSource;         // 'measured', 'config' or 'default'

limitingFactor values seen on a decision: cpu, memory, balanced, config, strategy, fuse, system_metrics_unavailable.