Action Pattern

Small, focused use case implementations.

Pattern

Each use case is encapsulated in an Action class:

class ReadCpuMetricsAction
{
    public function __construct(
        private CpuMetricsSource $source
    ) {}

    public function execute(): Result
    {
        return $this->source->read();
    }
}

Benefits

Single Responsibility

Each action does ONE thing:

• ReadCpuMetricsAction - Reads CPU metrics
• DetectEnvironmentAction - Detects environment
• ReadMemoryMetricsAction - Reads memory metrics

Easy Dependency Injection

$action = new ReadCpuMetricsAction(
    new RedisCachedCpuSource($redis)
);

$result = $action->execute();

Testable in Isolation

// Unit test with stub
$stub = $this->createStub(CpuMetricsSource::class);
$stub->method('read')->willReturn(Result::success($fakeCpu));

$action = new ReadCpuMetricsAction($stub);
$result = $action->execute();

$this->assertTrue($result->isSuccess());

Clear Boundaries

Actions define clear entry points:

• Input: Constructor dependencies
• Output: Result<T> from execute()
• Side effects: Explicit and documented

Implementation

All actions follow the same structure:

class SomeAction
{
    public function __construct(
        private SomeSource $source
    ) {}

    public function execute(): Result
    {
        // Thin orchestration - delegate to sources
        return $this->source->doSomething();
    }
}

Actions are thin orchestrators - they delegate actual work to sources/detectors/parsers.

Usage via Facade

The SystemMetrics facade uses actions internally:

class SystemMetrics
{
    public static function cpu(): Result
    {
        $action = new ReadCpuMetricsAction(
            SystemMetricsConfig::getCpuMetricsSource()
        );
        return $action->execute();
    }
}

Users typically use the facade, but can instantiate actions directly for dependency injection.

Available Actions

• DetectEnvironmentAction - Environment detection
• ReadCpuMetricsAction - CPU metrics
• ReadMemoryMetricsAction - Memory metrics
• ReadLoadAverageAction - Load average
• ReadUptimeAction - System uptime
• ReadStorageMetricsAction - Storage/disk metrics
• ReadNetworkMetricsAction - Network metrics
• ReadContainerMetricsAction - Container/cgroup metrics
• SystemOverviewAction - Complete system snapshot
• And more...

See API Reference for complete list.

Related Documentation

• Design Principles - Overall architecture
• Custom Implementations - Inject custom sources