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
        );
    }
}

Hello, I am using a phpmailer.
if a user uploads a material, it sends notices to other users email and i used the phpmailer.
it is working. but when there is an error occurs, it shows an error, i don't want the user to see the error but the code to retrying sending the message.
i need help on how i should integrate your code in it.
or should i post my code here.
`
foreach($result as $row){
$email = $row['email'];
$full_name = $row['full_name'];
$stu_email = $row['stu_email'];
$stu_name = $row['stu_name'];
// Import PHPMailer classes into the global namespace
// These must be at the top of your script, not inside a function
require '../vendor/autoload.php';

          $mail = new PHPMailer(true);          // Passing `true` enables exceptions
          try {
              //Server settings
              
              // $mail->isSMTP();                              // Set mailer to use SMTP
              $mail->SMTPDebug = 2;                       // Enable verbose debug output
              $mail->SMTPAuth = true;                  // Enable SMTP authentication
              $mail->SMTPSecure = 'tls';     // Enable TLS encryption, `tls` also accepted
              $mail->Host = 'smtp.gmail.com';  // Specify main and backup SMTP servers
              $mail->Port = 587; // TCP port to connect to 465 or 587 Use ssl / 465 or tls/ 587; 
              $mail->Mailer = "smtp";
              $mail->Username = '[email protected]';                 // SMTP username
              $mail->Password = 'ucnote@2018';                           // SMTP password
              
              //Recipients
              $mail->setFrom("[email protected]", "UcNOTE");
              $mail->addAddress($stu_email, $stu_name);     // Add a recipient
              // $mail->addAddress('[email protected]');               // Name is optional
              $mail->addReplyTo($email, $full_name);
              // $mail->addCC('[email protected]');
              // $mail->addBCC('[email protected]');

              //Attachments
              // $mail->addAttachment('/var/tmp/file.tar.gz');         // Add attachments
              // $mail->addAttachment('/tmp/image.jpg', 'new.jpg');    // Optional name

              //Content
              $mail->isHTML(true);                                  // Set email format to HTML
              $mail->Subject = $full_name."  uploaded an assignment.";
              $mail->Body    = $message;
              // $mail->AltBody = 'This is the body in plain text for non-HTML mail clients';

              $mail->send();
                          //     echo 'Message has been sent';
          } catch (Exception $e) {
              echo 'Message could not be sent. Mailer Error';
          }
         }

`

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