Added serializable MemoryUsage recording object

src/Helper/MemoryUsage.php

@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Scoutapm\Helper;
+
+use JsonSerializable;
+use function memory_get_peak_usage;
+use function memory_get_usage;
+
+final class MemoryUsage implements JsonSerializable
+{
+    /** @var int */
+    private $bytesAllocated;
+
+    /** @var int */
+    private $bytesUsed;
+
+    /** @var int */
+    private $peakBytesAllocated;
+
+    /** @var int */
+    private $peakBytesUsed;
+
+    private function __construct()
+    {
+        $this->bytesAllocated     = memory_get_usage(true);
+        $this->bytesUsed          = memory_get_usage(false);
+        $this->peakBytesAllocated = memory_get_peak_usage(true);
+        $this->peakBytesUsed      = memory_get_peak_usage(false);
+    }
+
+    public static function record() : self
+    {
+        return new self();
+    }
+
+    /**
+     * @return int[]|array<string, int>
+     *
+     * @psalm-return array{allocated: int, used: int, peak_allocated: int, peak_used: int}
+     */
+    public function jsonSerialize() : array
+    {
+        return [
+            'allocated' => $this->bytesAllocated,
+            'used' => $this->bytesUsed,
+            'peak_allocated' => $this->peakBytesAllocated,
+            'peak_used' => $this->peakBytesUsed,
+        ];
+    }
+}

tests/Unit/Helper/MemoryUsageTest.php

@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Scoutapm\UnitTests\Helper;
+
+use PHPUnit\Framework\TestCase;
+use Scoutapm\Helper\MemoryUsage;
+
+/** @covers \Scoutapm\Helper\MemoryUsage */
+final class MemoryUsageTest extends TestCase
+{
+    public function testMemoryUsageCanBeRecorded() : void
+    {
+        $usage = MemoryUsage::record()->jsonSerialize();
+
+        self::assertArrayHasKey('allocated', $usage);
+        self::assertArrayHasKey('used', $usage);
+        self::assertArrayHasKey('peak_allocated', $usage);
+        self::assertArrayHasKey('peak_used', $usage);
+
+        self::assertIsInt($usage['allocated']);
+        self::assertIsInt($usage['used']);
+        self::assertIsInt($usage['peak_allocated']);
+        self::assertIsInt($usage['peak_used']);
+
+        self::assertGreaterThan(0, $usage['allocated']);
+        self::assertGreaterThan(0, $usage['used']);
+        self::assertGreaterThan(0, $usage['peak_allocated']);
+        self::assertGreaterThan(0, $usage['peak_used']);
+    }
+}