retry.php

<?php

// util
$constant = function ($value) {
    return function ($_) use ($value) {
        return $value;
    };
};

$lessThan = function ($right) {
    return function ($left) use ($right) {
        return $left < $right;
    };
};

$linear = function ($ms) {
    return function ($n) use ($ms) {
        return $n * $ms;
    };
};

$exponential = function ($ms) {
    return function ($n) use ($ms) {
        return pow(2, $n - 1) * $ms;
    };
};





// implementation
$retry = function ($allowAttempt, $backoff, $supportsException, $fn) {
    $attempt = 0;

    while (true) {
        if ($attempt > 0) {
            usleep($backoff($attempt) * 1000);
        }

        try {
            return $fn();
        } catch (\Exception $exception) {
            if (!$supportsException($exception)) {
                throw $exception;
            }

            if (!$allowAttempt(++$attempt)) {
                throw new \Exception('Max attempts');
            }
        }
    }
};





// test
$result = $retry(
    $lessThan(5),
    $linear(2000),
    $constant(true),
    function () {
        if (rand(0, 2)) {
            var_dump('has exception');
            throw new \Exception('random error');
        } else {
            var_dump('has result');
            return 'hello world';
        }
    }
);

var_dump($result);