<?php

namespace App\Service\Tracing;

use OpenTelemetry\API\Globals;
use OpenTelemetry\API\Trace\SpanInterface;
use OpenTelemetry\API\Trace\TracerInterface;

class Tracer
{
    protected TracerInterface $tracer;
    protected ?SpanInterface $lastSpan = null;
    protected ?SpanInterface $rootSpan = null;
    /**
     * @var array Span
     */
    protected array $spanMap = [];

    public function __construct()
    {
        $this->tracer = Globals::tracerProvider()
            ->getTracer('io.opentelemetry.contrib.php.laravel');
    }

    /**
     * 请查看 AppServiceProvider 注册为 scoped, 适用于 Octane
     * @return Tracer
     */
    public static function getInstance(): Tracer
    {
        return app(Tracer::class);
    }

    public function startRootSpan($name): void
    {
        $span = $this->startSpan($name);
        $this->rootSpan = $span;
    }

    public function startAndEndLastSpan($name): SpanInterface
    {
        $this->endLastSpan();
        return $this->startSpan($name);
    }

    public function startSpan($name): SpanInterface
    {
        $span = $this->tracer->spanBuilder($name)->startSpan();
        $this->spanMap[$name] = $span;
        $this->lastSpan = $span;
        return $span;
    }

    public function endRootSpan(): void
    {
        $this->endSpan($this->rootSpan);
    }

    /**
     * @return void 方便的 end 上一个 span
     */
    public function endLastSpan(): void
    {
        $this->endSpan($this->lastSpan);
    }

    public function endSpan(?SpanInterface $span): void
    {
        if (is_null($span)) {
            return;
        }

        $span->end();
    }
}

<?php

namespace App\Providers;

use App\Utils\Tracing\Tracer;
use Illuminate\Support\ServiceProvider;

class AppServiceProvider extends ServiceProvider
{
    /**
     * Register any application services.
     *
     * @return void
     */
    public function register()
    {
        // 整个生命周期只注册一次
        $this->app->scoped(Tracer::class, function () {
            return new Tracer();
        });
    }

    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot()
    {
        //
    }
}

<?php

namespace App\Http\Controllers;

use App\Service\Tracing;

class IndexAlbumsController extends Controller
{
    public function index()
    {
        $tracer = Tracer::getInstance();
        // 步骤0
        $tracer->startRootSpan('xxxx');
        
        // 步骤1
        $tracer->startSpan('s1');
        // 业务代码xxx
        // 结束步骤1, 并开启步骤2
        $tracer->startAndEndLastSpan('s2');
        // 业务代码xxx
        // 结束步骤2
        $tracer->endLastSpan();
        
        // 结束 root
        $tracer->endRootSpan();
    }
}

class BatchSpanProcessor {

    public function onEnd(ReadableSpanInterface $span): void
    {
        if ($this->closed) {
            return;
        }
        if (!$span->getContext()->isSampled()) {
            return;
        }

        if ($this->queueSize === $this->maxQueueSize) {
            $this->dropped++;

            return;
        }

        $this->queueSize++;
        $this->batch[] = $span->toSpanData();
        $this->nextScheduledRun ??= $this->clock->now() + $this->scheduledDelayNanos;

        if (count($this->batch) === $this->maxExportBatchSize) {
            $this->enqueueBatch();
        }
        if ($this->autoFlush) {
            // flush 
            $this->flush();
        }
    }
}