Let OPcache cache files written after startup with BREF_LOOP_MAX

src/FunctionRuntime/Main.php

@@ -17,6 +17,12 @@ public static function run(): void
     {
         ColdStartTracker::init();
 
+        // OPcache doesn't cache files modified less than 2 seconds before the request started, and with BREF_LOOP_MAX
+        // the request starts with the process: files written later (e.g. compiled views) would never be cached
+        if (getenv('BREF_LOOP_MAX') > 1 && get_cfg_var('opcache.file_update_protection') === false) {
+            ini_set('opcache.file_update_protection', '0');
+        }
+
         LazySecretsLoader::loadSecretEnvironmentVariables();
 
         Bref::events()->beforeStartup();

tests/FunctionRuntime/MainTest.php

@@ -0,0 +1,53 @@
+<?php declare(strict_types=1);
+
+namespace Bref\Test\FunctionRuntime;
+
+use Bref\FunctionRuntime\Main;
+use Bref\Test\RuntimeTestCase;
+
+class MainTest extends RuntimeTestCase
+{
+    public function setUp(): void
+    {
+        parent::setUp();
+
+        $_SERVER['LAMBDA_TASK_ROOT'] = __DIR__ . '/../Runtime/Fixtures';
+        putenv('_HANDLER=foo.php');
+    }
+
+    public function tearDown(): void
+    {
+        unset($_SERVER['LAMBDA_TASK_ROOT']);
+        putenv('_HANDLER');
+        putenv('BREF_LOOP_MAX');
+        ini_restore('opcache.file_update_protection');
+
+        parent::tearDown();
+    }
+
+    public function test BREF_LOOP_MAX disables OPcache file update protection()
+    {
+        putenv('BREF_LOOP_MAX=100');
+
+        try {
+            Main::run();
+        } catch (\Throwable) {
+            // Needed because `run()` is an infinite loop and will fail eventually
+        }
+
+        $this->assertSame('0', ini_get('opcache.file_update_protection'));
+    }
+
+    public function test OPcache settings are unchanged without BREF_LOOP_MAX()
+    {
+        $fileUpdateProtection = ini_get('opcache.file_update_protection');
+
+        try {
+            Main::run();
+        } catch (\Throwable) {
+            // Needed because `run()` is an infinite loop and will fail eventually
+        }
+
+        $this->assertSame($fileUpdateProtection, ini_get('opcache.file_update_protection'));
+    }
+}