smuuf/primi

<?php

declare(strict_types=1);

namespace Smuuf\Primi\Helpers\Wrappers;

use \Smuuf\Primi\Tasks\TaskQueue;
use \Smuuf\Primi\Tasks\Emitters\PosixSignalTaskEmitter;

class CatchPosixSignalsWrapper extends AbstractWrapper {

    /**
     * Dictionary for tracking how many times this wrapper registered some
     * specific task queue (identified by its ID) to the POSIX signal handler.
     *
     * The task queue is registered before executing the wrapped function.
     * The queue is then unregistered after the most outer wrapper exits.
     *
     * This allows us to have nested 'catch signals' wrappers and at the same
     * time we don't keep the task queue referenced in `PosixSignalTaskEmitter`
     * if no longer necessary (so they can be garbage collected and we don't
     * risk memory leaks).
     *
     * @var array<string, int>
     */
    private static $level = [];

    /** Send Posix signal tasks to this queue. */
    private TaskQueue $tq;

    /** Unique ID for each TaskQueue instance. */
    private string $tqId;

    public function __construct(TaskQueue $tq) {
        $this->tq = $tq;
        $this->tqId = $tq->getId();
    }

    /**
     * @return mixed
     */
    public function executeBefore() {

        // If this is the first (outermost) context that uses this task queue,
        // register the queue from signal task emitter.
        if (empty(self::$level[$this->tqId])) {
            PosixSignalTaskEmitter::registerTaskQueue($this->tq);
            self::$level[$this->tqId] = 1;
        } else {
            self::$level[$this->tqId]++;
        }

    }

    public function executeAfter(): void {

        self::$level[$this->tqId]--;

        // If this was the last (outermost) context that uses this task queue,
        // unregister the queue from signal task emitter.
        if (self::$level[$this->tqId] === 0) {
            PosixSignalTaskEmitter::unregisterTaskQueue($this->tq);
        }

        unset($this->tq);

    }

}