awslabs_aws-crt-php/lib/AWS/CRT/NativeResource.php

<?php

/**
 * Base class for all native resources, tracks all outstanding resources
 * and provides basic leak checking
 */
abstract class NativeResource {
    protected static $crt = null;
    protected static $resources = [];
    protected $native = null;

    function __construct() {
        if (is_null(self::$crt)) {
            try {
                self::$crt = new CRT();
            } catch (Exception $e) {
                echo 'Exception while loading CRT: ', $e->getMessage(), "\n";
            }
        }

        self::$resources[spl_object_hash($this)] = 1;
    }

    protected function acquire($handle) {
        $this->native = $handle;
    }

    protected function release() {
        $this->native = null;
    }

    function __destruct() {
        // Should have been destroyed and released by derived resource
        assert($this->native == null);
        unset(self::$resources[spl_object_hash($this)]);
    }
}