From f851c6ce90e1f6266aa53c6a4befba4d9ac34e74 Mon Sep 17 00:00:00 2001
From: Christoph Wurst <christoph@winzerhof-wurst.at>
Date: Fri, 20 Jan 2023 16:56:25 +0100
Subject: [PATCH] feat(dev-manual): Document performance optimizations with
 class loaders

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>
---
 .../digging_deeper/classloader.rst            | 25 ++++++++++++++++++-
 .../digging_deeper/performance.rst            |  5 ++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/developer_manual/digging_deeper/classloader.rst b/developer_manual/digging_deeper/classloader.rst
index 463e17bc3..540e0a47a 100644
--- a/developer_manual/digging_deeper/classloader.rst
+++ b/developer_manual/digging_deeper/classloader.rst
@@ -10,7 +10,7 @@ The classloader is provided by Nextcloud and loads all your classes automaticall
 PSR-4 autoloading
 -----------------
 
-Nextcloud uses a PSR-4 autoloader. The namespace **\\OCA\\MyApp**
+Nextcloud uses a  :ref:`PSR-0 autoloader<psr4>`. The namespace **\\OCA\\MyApp**
 is mapped to :file:`/apps/myapp/lib/`. Afterwards normal PSR-4 rules apply, so
 a folder is a namespace section in the same casing and the class name matches
 the file name.
@@ -32,3 +32,26 @@ info.xml in the following way:
 
 A second PSR-4 root is available when running tests. **\\OCA\\MyApp\\Tests** is
 thereby mapped to :file:`/apps/myapp/tests/`.
+
+.. _app-custom-classloader:
+
+Replacing Nextcloud's autoloader
+--------------------------------
+
+Nextcloud's autoloader for apps is flexible and robust but not always the fastest. You can improve the loading speed of your app by shipping and optimizing a Composer class loader with the app.
+
+First of all, familiarize yourself with the `Composer autoloader optimization options <https://getcomposer.org/doc/articles/autoloader-optimization.md>`_ and how they work. (Authoritative) class maps are a good fit for Nextcloud apps.
+
+Once Composer is set up and class maps have been dumped, you can replace the generic Nextcloud class loader with the Composer class loader. This is done by placing a file at `composer/autoload.php`. If Nextcloud finds this file for an app, no generic class loader will be registered. The following contents will wire the file to Composer's generated ``autoloader.php`` file:
+
+.. code-block:: php
+  :caption: composer/autoload.php
+
+  <?php
+
+  declare(strict_types=1);
+
+  require_once __DIR__ . '/../vendor/autoload.php';
+
+
+.. note:: Make sure the auto loader is generated at release time and all files are included in the release tarball
diff --git a/developer_manual/digging_deeper/performance.rst b/developer_manual/digging_deeper/performance.rst
index e3e6907cd..331cf99a2 100644
--- a/developer_manual/digging_deeper/performance.rst
+++ b/developer_manual/digging_deeper/performance.rst
@@ -8,6 +8,11 @@ This document introduces some common considerations and tips on improving perfor
 
 .. note::**Tips welcome**: More tips and ideas on performance are very welcome!
 
+PHP Performance
+---------------
+
+* Autoloader: Consider using an :ref:`optimized class loader<app-custom-classloader>`. The application code does not have to change for this optimization.
+
 Database performance
 --------------------