# Miscellaneous

## Sign the Android APK from CI

The [Github Actions Workflow](https://github.com/minetest/minetest/actions?query=workflow%3Aandroid+event%3Apush)
automatically produces an APK for each architecture.
Before installing them onto a device they however need to be signed.

This requires an installation of the Android SDK and `adb`.
```bash
.../android-sdk/build-tools/30.0.3/apksigner sign --ks ~/.android/debug.keystore \
	app-arm64-v8a-release-unsigned.apk
# Enter 'android' (without quotes) when asked for a password
```

Note that the `debug.keystore` will not exist if you have never compiled an
Android app on your system (probably).

After that installing it will work:
```bash
adb install -r -d ./app-arm64-v8a-release-unsigned.apk
```

## How to get debug output from Minetest on Android

In case debug.txt isn't enough (e.g. when debugging a crash), you can get debug
output using logcat:

`adb logcat -s 'Minetest:*' '*:F'`

Note that you can do this even *after* the app has crashed,
since Android keeps an internal buffer.

A segmentation fault for example looks like this:

```
01-10 17:20:22.215 19308 20560 F libc    : Fatal signal 6 (SIGABRT), code -1 (SI_QUEUE) in tid 20560 (MinetestNativeT), pid 19308 (netest.minetest)
01-10 17:20:22.287 20576 20576 F DEBUG   : *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
01-10 17:20:22.287 20576 20576 F DEBUG   : Build fingerprint: '...'
01-10 17:20:22.287 20576 20576 F DEBUG   : Revision: '4'
01-10 17:20:22.287 20576 20576 F DEBUG   : ABI: 'arm64'
01-10 17:20:22.288 20576 20576 F DEBUG   : Timestamp: 2024-01-10 17:20:22+0100
01-10 17:20:22.288 20576 20576 F DEBUG   : pid: 19308, tid: 20560, name: MinetestNativeT  >>> net.minetest.minetest <<<
01-10 17:20:22.288 20576 20576 F DEBUG   : uid: 10385
01-10 17:20:22.288 20576 20576 F DEBUG   : signal 6 (SIGABRT), code -1 (SI_QUEUE), fault addr --------
[ ... more information follows ... ]
```

## Profiling Minetest on Linux

We will be using a tool called "perf", which you can get by installing `perf` or `linux-perf` or `linux-tools-common`.

For best results build Minetest and Irrlicht with debug symbols
(`-DCMAKE_BUILD_TYPE=RelWithDebInfo` or `-DCMAKE_BUILD_TYPE=Debug`).

Run the client (or server) like this and do whatever you wanted to test:
```bash
perf record -z --call-graph dwarf -- ./bin/minetest
```

This will leave a file called "perf.data".

You can open this file with perf built-in tools but much more interesting
is the visualization using a GUI tool: **[Hotspot](https://github.com/KDAB/hotspot)**.
It will give you flamegraphs, per-thread, per-function views and much more.