diff options
Diffstat (limited to 'dwl/dwl-patches/patches/hot-reload/README.md')
| -rwxr-xr-x | dwl/dwl-patches/patches/hot-reload/README.md | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/dwl/dwl-patches/patches/hot-reload/README.md b/dwl/dwl-patches/patches/hot-reload/README.md new file mode 100755 index 0000000..e387ca4 --- /dev/null +++ b/dwl/dwl-patches/patches/hot-reload/README.md @@ -0,0 +1,110 @@ +### Description +Enables hot-reloading of dwl; meaning almost all logic can be changed at runtime. +This obviously requires some black magic so for now there's a glibc 2.0 or later +dependency to this. +In particular this allows for every option in config.h to be changed at runtime. + +#### Reloading +To reload rebuild dwl.so, perhaps reinstall it and then run trigger reload function (bound to Mod+Shift+R by default). +This currently calls `notify-send` in order to inform you of a reloading taking place. +So in short: +1. make changes to `config.h` or `dwl.c` +2. run `make` to rebuild dwl.so +3. run `sudo make install` to reinstall dwl + + +#### Limitations +Reloading the compositor will replace all functionality except for `main`, `setup`, `run` and the reload logic. +Note that you're responsible yourself for reloading ressources like fonts, which may only get acquired once. +A lot of components of dwl will also only get run on a trigger (the tiling for example). +So not every change will be immediate. +Furthermore, any patch adding more global state to dwl cannot currently be reloaded properly since +we keep state in the cold part. These patches will still work and their functionality will (hopefully) be +reloadable but you will need to restart the compositor once. + +#### Notes +##### reduce compile errors +This patch triggers `-Wpedantic` a bunch (I don't think there's a way around this, `dlsym` yields `void*` pointers to functions). +This will show a lot of warnings but cause no errors. +So you may want to disable this compile option in order to get readable compiler output. +##### runtime dependencies +This does depend on you having a notification daemon like `dunst` or `mako` running as well as +having `notify-send` installed in order for the compositor to inform you of the reload. + + +#### How? +Most of all dwl functionality is moved into a shared object file `dwl.so`, which can be reloaded at runtime. + +#### How do I make this work with other patches? +Most patches should already put everything in more or less the correct place but if they don't, then here is +where you learn how to fix it. + +The concept itself is quite simple. We compile dwl.c twice once normally and once with the `HOT` macro defined. +The first run will yield the executable and the second will yield a shared object file to be reloaded at runtime. +From the cold part there are some newly available macros: +> symbol names are written as-is, never as string literals +* `TSYM(T, s)` dynamically loads the symbol `s` with type `T` from the shared object file use this if you need to call functions in the cold part (i.e. the `setup` function). +* `CSYM(T, v)` dynamically accesses the value of the symbol `v` of type `T` from the shared object. Use this to query values from config.h for example. +* `LISTEN_GLOBAL(E, L)` is similar to the `LISTEN` macro. `E` is an event and `L` the name of a global +listener. Current implementation is a bit messy and I may fix it if someone bothers me about it. +* `UNLISTEN(L)` takes a listener and unregisteres it. This is important for reloading. + +When adding new code there are some considerations to be made. Since dwl decorates all symbols with `static` by default, we cannot access them as-is. +C's macro system is a bit too powerful though and we use this to our advantage. We will repeatedly define and +undefine a macro called `static` in order to replace the `static` keyword inside some sections. +This allows us to do less refactoring and preserve a lot of the original patch compatability since we're only +strategically adding lines. We're tring to be as minimally invasive as we can. +As a general guide: +* global state should be global for the cold part and `extern` in the cold part meaning it should be inside a block like this: + ```C + #ifdef HOT + #define static extern + #else + #define static + #endif + ... // your global variables go here + #undef static + ``` +* function declarations should be visible in the hot part but not included in the cold part meaning they should be enclosed like this: + ```C + #ifdef HOT + #define static + ... // your function declarations go here + #undef static + #endif + ``` +* static data like the event handler structs in the current `main` branch are a bit more difficult but we will let them reside inside the hot part. +Thus, we enclose them the same way we do functions: + ```C + #ifdef HOT + #define static + ... // your struct wl_listener event handlers go here + #undef static + #endif + ``` +* function definitions should go in the hot part, so they need to be inside a big block like this: + ```C + #ifdef HOT + ... // function definitions here + #endif +* enfore use of the `LISTEN_GLOBAL` and `UNLISTEN` macros (I know this sucks but what can I do, I need to get +access to the callbacks somehow). So you want + * `wl_list_remove(listener.link)` to become `UNLISTEN(listener)` and + * `wl_signal_add(event, global_listener)` to become `LISTEN_GLOBAL(event, global_listener)`. +* Make sure that any patch you're using also uses static everywhere. +* If a patch adds any config variables that are accessed in the cold part (i.e. probably `setup`), +then you'll have to manually remove the `static` keyword from them. + +Note that usually you do not have to create the big `#ifdef` blocks yourself. +There is for example already a huge `#ifdef HOT`-delimited codeblock at the bottom +of dwl.c where all the function definitions go. + +If you have any troubles, feel free to reach out. + +### Download +- [0.7](/dwl/dwl-patches/raw/branch/main/patches/hot-reload/hot-reload-0.7.patch) +- [main 2025-05-30](/dwl/dwl-patches/raw/branch/main/patches/hot-reload/hot-reload.patch) +- find the repo for the patch [here](/Sivecano/dwl/src/branch/hot-reload) +### Authors +- [Sivecano](https://codeberg.org/Sivecano) +- Sérécano at [dwl Discord](https://discord.gg/jJxZnrGPWN) |