A retry function for PHP.

test.retry.php

<?php
require_once dirname(__FILE__) . '/../lib/simpletest/autorun.php';

function retry($f, $delay = 10, $retries = 3)
{
    try {
        return $f();
    } catch (Exception $e) {
        if ($retries > 0) {
            sleep($delay);
            return retry($f, $delay, $retries - 1);
        } else {
            throw $e;
        }
    }
}

class RetryTest extends UnitTestCase
{
    function testRetryWithNoExceptions()
    {
        $name = "Bob";
        $result = retry(
            function () use ($name) {
                return $name . "!";
            },
            0.1
        );

        $this->assertEqual("Bob!", $result);
    }

    function testRetryWithException()
    {
        $fail = true;
        $result = retry(
            function () use (&$fail) {
                if ($fail) {
                    $fail = false;
                    throw new Exception("Boom!");
                } else {
                    return "Woo!";
                }
            },
            0.1
        );

        $this->assertEqual("Woo!", $result);
    }

    function testRetryTriesTheExpectedNumberOfTimes()
    {
        $count = 0;
        try {
            retry(
                function () use (&$count) {
                    $count += 1;
                    throw new Exception("Boom!");
                },
                0.1
            );
        } catch (Exception $e) {
        }

        $this->assertEqual(4, $count);
    }

    function testRetryWithConstantFailure()
    {
        $this->expectException(new PatternExpectation("/I will never work./"));
        $result = retry(
            function () {
                throw new Exception("I will never work.");
            },
            0.1
        );
    }
}

FYI, Laravel has a retry() helper for this. (code)