Add NullBackOff

Author: Aleksandr Denisyuk

docs/index.md

@@ -159,6 +159,7 @@ The following back-off decorators are available:
 - [ExponentialBackOff](../src/ExponentialBackOff.php)
 - [DecorrelatedBackOff](../src/DecorrelatedBackOff.php)
 - [ImmediatelyThrowableBackOff](../src/ImmediatelyThrowableBackOff.php)
+- [NullBackOff](../src/NullBackOff.php)
 
 ## Retry exceptions
 
@@ -168,6 +169,7 @@ Configure BackOff and ExceptionClassifier to retry your business logic when an e
 <?php
 
 use Orangesoft\BackOff\ExponentialBackOff;
+use Orangesoft\BackOff\NullBackOff;
 use Orangesoft\BackOff\Duration\Seconds;
 use Orangesoft\BackOff\Retry\ExceptionClassifier\ExceptionClassifier;
 use Orangesoft\BackOff\Retry\Retry;
@@ -184,6 +186,18 @@ $exceptionClassifier = new ExceptionClassifier([
 $retry = new Retry($backOff, $exceptionClassifier);
 ```
 
+If you don't need any back-off at all use NullBackOff which just count attempts:
+
+```php
+$backOff = new NullBackOff(maxAttempts: 3);
+
+$exceptionClassifier = new ExceptionClassifier([
+    \RuntimeException::class,
+]);
+
+$retry = new Retry($backOff, $exceptionClassifier);
+```
+
 Put the business logic in a callback function and call it:
 
 ```php

src/NullBackOff.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Orangesoft\BackOff;
+
+final class NullBackOff implements BackOffInterface
+{
+    public function __construct(
+        private int|float $maxAttempts = 3,
+    ) {
+    }
+
+    public function backOff(int $attempt, \Throwable $throwable): void
+    {
+        if ($attempt > $this->maxAttempts) {
+            throw $throwable;
+        }
+    }
+}

tests/NullBackOffTest.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Orangesoft\BackOff\Tests;
+
+use Orangesoft\BackOff\NullBackOff;
+use PHPUnit\Framework\TestCase;
+
+class NullBackOffTest extends TestCase
+{
+    public function testBackOff(): void
+    {
+        $nullBackOff = new NullBackOff(maxAttempts: 3);
+
+        $throwable = new \Exception();
+
+        $this->expectExceptionObject($throwable);
+
+        $nullBackOff->backOff(4, $throwable);
+    }
+}