pdo async query...

PDO_async_query.php

<?php
// Warning: this script is suspectible to https://bugs.php.net/bug.php?id=80523
// that bug was actually discovered with this class!


class AsyncQuery
{

    private $proc;

    private $stdout_handle;

    private $stderr_handle;

    private $ready = false;

    
    public function fetchAll(): array
    {
        $this->blockUntilReady();
        rewind($this->stdout_handle);
        $code = stream_get_contents($this->stdout_handle);
        // i want to use json_decode instead, but json can't handle binary data like "\x80"
        // but var_export() + eval() is both binary safe =/
        $ret = unserialize($code);
        return $ret;
    }

    public function blockUntilReady(): void
    {
        while (! $this->isReady()) {
            usleep(100 * 1000); // 100 ms / 0.1 seconds..
        }
    }

    public function isReady(): bool
    {
        if ($this->ready) {
            return true;
        }
        $status = proc_get_status($this->proc);
        if ($status["running"]) {
            return false;
        }
        $exitcode = $status["exitcode"];
        rewind($this->stderr_handle);
        $stderr = stream_get_contents($this->stderr_handle);
        if ($exitcode !== 0 || ! empty($stderr)) {
            throw new \RuntimeException("php query error, exitcode: {$exitcode} stderr: {$stderr}");
        }
        $this->ready = true;
        return true;
    }

    function __construct(string $query, string $pdo_dsn, string $username, string $password)
    {
        $code = '$db = new PDO(' . var_export($pdo_dsn, true) . "," . var_export($username, true) . ',' . var_export($password, true) . "," . var_export(array(
            \PDO::ATTR_EMULATE_PREPARES => false,
            \PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION,
            \PDO::ATTR_DEFAULT_FETCH_MODE => \PDO::FETCH_ASSOC
        ), true) . ");";
        $code .= 'echo serialize($db->query(';
        if (1 || ctype_print($query)) {
            $code .= var_export($query, true);
        } else {
            $code .= "hex2bin(" . var_export(bin2hex($query), true) . ")";
        }
        $code .= ")->fetchAll());";
        $cmd = 'php -r ' . escapeshellarg($code);
        $this->stdout_handle = tmpfile();
        $this->stderr_handle = tmpfile();
        $descriptorspecs = array(
            // we don't use stdin, but if none is created, the child inherit ours, we don't want that.
            // so we create a stdin for the child just to close it.
            0 => array(
                "pipe",
                "rb"
            ),
            1 => $this->stdout_handle,
            2 => $this->stderr_handle
        );
        $pipes = [];
        $this->proc = proc_open($cmd, $descriptorspecs, $pipes);
        fclose($pipes[0]);
        unset($pipes[0], $pipes);
    }

    private $clean = false;

    private function cleanup(): void
    {
        if ($this->clean) {
            return;
        }
        $this->clean = true;
        proc_close($this->proc);
        fclose($this->stdout_handle);
        fclose($this->stderr_handle);
    }

    function __destruct()
    {
        $this->cleanup();
    }
}