fake the actual memory usage

Author: mlebkowski

src/Messenger/WorkerMemoryUsageSubscriber.php

@@ -7,9 +7,12 @@
 use Psr\Log\LoggerInterface;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
 use Symfony\Component\Messenger\Event\WorkerRunningEvent;
+use WonderNetwork\SlimKernel\System\RealSystem;
+use WonderNetwork\SlimKernel\System\System;
 
 final class WorkerMemoryUsageSubscriber implements EventSubscriberInterface {
     private int $memoryUsage;
+    private readonly System $system;
 
     /**
      * @return iterable<string,string>
@@ -23,12 +26,14 @@ public static function getSubscribedEvents(): iterable {
     public function __construct(
         private readonly LoggerInterface $logger,
         private readonly int $cutoff = 1024,
+        System $system = null,
     ) {
-        $this->memoryUsage = memory_get_usage();
+        $this->system = $system ?? new RealSystem();
+        $this->memoryUsage = $this->system->memoryUsage();
     }
 
     public function onWorkerRunning(): void {
-        $currentUsage = memory_get_usage();
+        $currentUsage = $this->system->memoryUsage();
 
         $difference = abs($this->memoryUsage - $currentUsage);
 

src/System/RealSystem.php

@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WonderNetwork\SlimKernel\System;
+
+final readonly class RealSystem implements System {
+    public function memoryUsage(): int {
+        return memory_get_usage();
+    }
+}

src/System/System.php

@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WonderNetwork\SlimKernel\System;
+
+interface System {
+    public function memoryUsage(): int;
+}

tests/Messenger/WorkerMemoryUsageSubscriberTest.php

@@ -7,31 +7,40 @@
 use Monolog\Handler\TestHandler;
 use Monolog\Logger;
 use PHPUnit\Framework\TestCase;
+use WonderNetwork\SlimKernel\System\FakeSystem;
 
 final class WorkerMemoryUsageSubscriberTest extends TestCase {
     public function testReportsAboveCutoff(): void {
         $buffer = new TestHandler();
         $logger = new Logger('some');
         $logger->pushHandler($buffer);
-        $memoryLeak = [];
 
-        $sut = new WorkerMemoryUsageSubscriber($logger, cutoff: 10 * 1024);
+        $system = new FakeSystem();
+
+        $sut = new WorkerMemoryUsageSubscriber(
+            logger: $logger,
+            cutoff: 10 * 1024,
+            system: $system,
+        );
         $sut->onWorkerRunning();
         self::assertEmpty($buffer->getRecords());
 
-        $memoryLeak[] = str_repeat(' ', 10 * 1024);
-        // triggers the first log
-        $sut->onWorkerRunning();
-        self::assertCount(1, $buffer->getRecords());
-        // the logs themselves take memory, so:
+        $system->setMemoryUsage(10 * 1024 - 1);
         $sut->onWorkerRunning();
-        self::assertCount(2, $buffer->getRecords());
-        // no more logs:
+        self::assertCount(0, $buffer->getRecords());
+
+        $system->setMemoryUsage(10 * 1024);
         $sut->onWorkerRunning();
+        self::assertCount(1, $buffer->getRecords());
+        self::assertSame([
+            'current' => '10 KB',
+            'sign' => '+',
+            'difference' => '10 KB',
+        ], $buffer->getRecords()[0]->context);
+
         $sut->onWorkerRunning();
+        $system->setMemoryUsage(12 * 1024);
         $sut->onWorkerRunning();
-        self::assertCount(2, $buffer->getRecords());
-
-        unset($memoryLeak);
+        self::assertCount(1, $buffer->getRecords());
     }
 }

tests/System/FakeSystem.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WonderNetwork\SlimKernel\System;
+
+final class FakeSystem implements System {
+    private int $memoryUsage = 0;
+
+    public function setMemoryUsage(int $memoryUsage): void {
+        $this->memoryUsage = $memoryUsage;
+    }
+
+    public function memoryUsage(): int {
+        return $this->memoryUsage;
+    }
+}