1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421
//! A pool implementation which automatically manage buffers.
//!
//! This pool is built on the [`RawPool`].
//!
//! The [`MultiPool`] takes a key which is used to identify buffers and tries to return the buffer associated to the key
//! if possible. If no buffer in the pool is associated to the key, it will create a new one.
//!
//! # Example
//!
//! ```rust
//! use smithay_client_toolkit::reexports::client::{
//! QueueHandle,
//! protocol::wl_surface::WlSurface,
//! protocol::wl_shm::Format,
//! };
//! use smithay_client_toolkit::shm::multi::MultiPool;
//!
//! struct WlFoo {
//! // The surface we'll draw on and the index of buffer associated to it
//! surface: (WlSurface, usize),
//! pool: MultiPool<(WlSurface, usize)>
//! }
//!
//! impl WlFoo {
//! fn draw(&mut self, qh: &QueueHandle<WlFoo>) {
//! let surface = &self.surface.0;
//! // We'll increment "i" until the pool can create a new buffer
//! // if there's no buffer associated with our surface and "i" or if
//! // a buffer with the obuffer associated with our surface and "i" is free for use.
//! //
//! // There's no limit to the amount of buffers we can allocate to our surface but since
//! // shm buffers are released fairly fast, it's unlikely we'll need more than double buffering.
//! for i in 0..2 {
//! self.surface.1 = i;
//! if let Ok((offset, buffer, slice)) = self.pool.create_buffer(
//! 100,
//! 100 * 4,
//! 100,
//! &self.surface,
//! Format::Argb8888,
//! ) {
//! /*
//! insert drawing code here
//! */
//! surface.attach(Some(buffer), 0, 0);
//! surface.commit();
//! // We exit the function after the draw.
//! return;
//! }
//! }
//! /*
//! If there's no buffer available we can for example request a frame callback
//! and trigger a redraw when it fires.
//! (not shown in this example)
//! */
//! }
//! }
//!
//! fn draw(slice: &mut [u8]) {
//! todo!()
//! }
//!
//! ```
//!
use std::borrow::Borrow;
use std::io;
use std::os::unix::io::OwnedFd;
use std::sync::{
atomic::{AtomicBool, Ordering},
Arc,
};
use wayland_client::{
protocol::{wl_buffer, wl_shm},
Proxy,
};
use crate::globals::ProvidesBoundGlobal;
use super::raw::RawPool;
use super::CreatePoolError;
#[derive(Debug, thiserror::Error)]
pub enum PoolError {
#[error("buffer is currently used")]
InUse,
#[error("buffer is overlapping another")]
Overlap,
#[error("buffer could not be found")]
NotFound,
}
/// This pool manages buffers associated with keys.
/// Only one buffer can be attributed to a given key.
#[derive(Debug)]
pub struct MultiPool<K> {
buffer_list: Vec<BufferSlot<K>>,
pub(crate) inner: RawPool,
}
#[derive(Debug, thiserror::Error)]
pub struct BufferSlot<K> {
free: Arc<AtomicBool>,
size: usize,
used: usize,
offset: usize,
buffer: Option<wl_buffer::WlBuffer>,
key: K,
}
impl<K> Drop for BufferSlot<K> {
fn drop(&mut self) {
self.destroy().ok();
}
}
impl<K> BufferSlot<K> {
pub fn destroy(&self) -> Result<(), PoolError> {
self.buffer.as_ref().ok_or(PoolError::NotFound).and_then(|buffer| {
self.free.load(Ordering::Relaxed).then(|| buffer.destroy()).ok_or(PoolError::InUse)
})
}
}
impl<K> MultiPool<K> {
pub fn new(shm: &impl ProvidesBoundGlobal<wl_shm::WlShm, 1>) -> Result<Self, CreatePoolError> {
Ok(Self { inner: RawPool::new(4096, shm)?, buffer_list: Vec::new() })
}
/// Resizes the memory pool, notifying the server the pool has changed in size.
///
/// The wl_shm protocol only allows the pool to be made bigger. If the new size is smaller than the
/// current size of the pool, this function will do nothing.
pub fn resize(&mut self, size: usize) -> io::Result<()> {
self.inner.resize(size)
}
/// Removes the buffer with the given key from the pool and rearranges the others.
pub fn remove<Q>(&mut self, key: &Q) -> Option<BufferSlot<K>>
where
Q: PartialEq,
K: std::borrow::Borrow<Q>,
{
self.buffer_list
.iter()
.enumerate()
.find(|(_, slot)| slot.key.borrow().eq(key))
.map(|(i, _)| i)
.map(|i| self.buffer_list.remove(i))
}
/// Insert a buffer into the pool.
///
/// The parameters are:
///
/// - `width`: the width of this buffer (in pixels)
/// - `height`: the height of this buffer (in pixels)
/// - `stride`: distance (in bytes) between the beginning of a row and the next one
/// - `key`: a borrowed form of the stored key type
/// - `format`: the encoding format of the pixels.
pub fn insert<Q>(
&mut self,
width: i32,
stride: i32,
height: i32,
key: &Q,
format: wl_shm::Format,
) -> Result<usize, PoolError>
where
K: Borrow<Q>,
Q: PartialEq + ToOwned<Owned = K>,
{
let mut offset = 0;
let mut found_key = false;
let size = (stride * height) as usize;
let mut index = Err(PoolError::NotFound);
for (i, buf_slot) in self.buffer_list.iter_mut().enumerate() {
if buf_slot.key.borrow().eq(key) {
found_key = true;
if buf_slot.free.load(Ordering::Relaxed) {
// Destroys the buffer if it's resized
if size != buf_slot.used {
if let Some(buffer) = buf_slot.buffer.take() {
buffer.destroy();
}
}
// Increases the size of the Buffer if it's too small and add 5% padding.
// It is possible this buffer overlaps the following but the else if
// statement prevents this buffer from being returned if that's the case.
buf_slot.size = buf_slot.size.max(size + size / 20);
index = Ok(i);
} else {
index = Err(PoolError::InUse);
}
// If a buffer is resized, it is likely that the followings might overlap
} else if offset > buf_slot.offset {
// When the buffer is free, it's safe to shift it because we know the compositor won't try to read it.
if buf_slot.free.load(Ordering::Relaxed) {
if offset != buf_slot.offset {
if let Some(buffer) = buf_slot.buffer.take() {
buffer.destroy();
}
}
buf_slot.offset = offset;
} else {
// If one of the overlapping buffers is busy, then no buffer can be returned because it could result in a data race.
index = Err(PoolError::InUse);
}
} else if found_key {
break;
}
let size = (buf_slot.size + 63) & !63;
offset += size;
}
if !found_key {
if let Err(err) = index {
return self
.dyn_resize(offset, width, stride, height, key.to_owned(), format)
.map(|_| self.buffer_list.len() - 1)
.ok_or(err);
}
}
index
}
/// Retreives the buffer associated with the given key.
///
/// The parameters are:
///
/// - `width`: the width of this buffer (in pixels)
/// - `height`: the height of this buffer (in pixels)
/// - `stride`: distance (in bytes) between the beginning of a row and the next one
/// - `key`: a borrowed form of the stored key type
/// - `format`: the encoding format of the pixels.
pub fn get<Q>(
&mut self,
width: i32,
stride: i32,
height: i32,
key: &Q,
format: wl_shm::Format,
) -> Option<(usize, &wl_buffer::WlBuffer, &mut [u8])>
where
Q: PartialEq,
K: std::borrow::Borrow<Q>,
{
let len = self.inner.len();
let size = (stride * height) as usize;
let buf_slot =
self.buffer_list.iter_mut().find(|buf_slot| buf_slot.key.borrow().eq(key))?;
if buf_slot.size >= size {
return None;
}
buf_slot.used = size;
let offset = buf_slot.offset;
if buf_slot.buffer.is_none() {
if offset + size > len {
self.inner.resize(offset + size + size / 20).ok()?;
}
let free = Arc::new(AtomicBool::new(true));
let data = BufferObjectData { free: free.clone() };
let buffer = self.inner.create_buffer_raw(
offset as i32,
width,
height,
stride,
format,
Arc::new(data),
);
buf_slot.free = free;
buf_slot.buffer = Some(buffer);
}
let buf = buf_slot.buffer.as_ref()?;
buf_slot.free.store(false, Ordering::Relaxed);
Some((offset, buf, &mut self.inner.mmap()[offset..][..size]))
}
/// Returns the buffer associated with the given key and its offset (usize) in the mempool.
///
/// The parameters are:
///
/// - `width`: the width of this buffer (in pixels)
/// - `height`: the height of this buffer (in pixels)
/// - `stride`: distance (in bytes) between the beginning of a row and the next one
/// - `key`: a borrowed form of the stored key type
/// - `format`: the encoding format of the pixels.
///
/// The offset can be used to determine whether or not a buffer was moved in the mempool
/// and by consequence if it should be damaged partially or fully.
pub fn create_buffer<Q>(
&mut self,
width: i32,
stride: i32,
height: i32,
key: &Q,
format: wl_shm::Format,
) -> Result<(usize, &wl_buffer::WlBuffer, &mut [u8]), PoolError>
where
K: Borrow<Q>,
Q: PartialEq + ToOwned<Owned = K>,
{
let index = self.insert(width, stride, height, key, format)?;
self.get_at(index, width, stride, height, format)
}
/// Retreives the buffer at the given index.
fn get_at(
&mut self,
index: usize,
width: i32,
stride: i32,
height: i32,
format: wl_shm::Format,
) -> Result<(usize, &wl_buffer::WlBuffer, &mut [u8]), PoolError> {
let len = self.inner.len();
let size = (stride * height) as usize;
let buf_slot = self.buffer_list.get_mut(index).ok_or(PoolError::NotFound)?;
if size > buf_slot.size {
return Err(PoolError::Overlap);
}
buf_slot.used = size;
let offset = buf_slot.offset;
if buf_slot.buffer.is_none() {
if offset + size > len {
self.inner.resize(offset + size + size / 20).map_err(|_| PoolError::Overlap)?;
}
let free = Arc::new(AtomicBool::new(true));
let data = BufferObjectData { free: free.clone() };
let buffer = self.inner.create_buffer_raw(
offset as i32,
width,
height,
stride,
format,
Arc::new(data),
);
buf_slot.free = free;
buf_slot.buffer = Some(buffer);
}
buf_slot.free.store(false, Ordering::Relaxed);
let buf = buf_slot.buffer.as_ref().unwrap();
Ok((offset, buf, &mut self.inner.mmap()[offset..][..size]))
}
/// Calcule the offet and size of a buffer based on its stride.
fn offset(&self, mut offset: i32, stride: i32, height: i32) -> (usize, usize) {
// bytes per pixel
let size = stride * height;
// 5% padding.
offset += offset / 20;
offset = (offset + 63) & !63;
(offset as usize, size as usize)
}
#[allow(clippy::too_many_arguments)]
/// Resizes the pool and appends a new buffer.
fn dyn_resize(
&mut self,
offset: usize,
width: i32,
stride: i32,
height: i32,
key: K,
format: wl_shm::Format,
) -> Option<()> {
let (offset, size) = self.offset(offset as i32, stride, height);
if self.inner.len() < offset + size {
self.resize(offset + size + size / 20).ok()?;
}
let free = Arc::new(AtomicBool::new(true));
let data = BufferObjectData { free: free.clone() };
let buffer = self.inner.create_buffer_raw(
offset as i32,
width,
height,
stride,
format,
Arc::new(data),
);
self.buffer_list.push(BufferSlot {
offset,
used: 0,
free,
buffer: Some(buffer),
size,
key,
});
Some(())
}
}
struct BufferObjectData {
free: Arc<AtomicBool>,
}
impl wayland_client::backend::ObjectData for BufferObjectData {
fn event(
self: Arc<Self>,
_backend: &wayland_backend::client::Backend,
msg: wayland_backend::protocol::Message<wayland_backend::client::ObjectId, OwnedFd>,
) -> Option<Arc<dyn wayland_backend::client::ObjectData>> {
debug_assert!(wayland_client::backend::protocol::same_interface(
msg.sender_id.interface(),
wl_buffer::WlBuffer::interface()
));
debug_assert!(msg.opcode == 0);
// wl_buffer only has a single event: wl_buffer.release
self.free.store(true, Ordering::Relaxed);
None
}
fn destroyed(&self, _: wayland_backend::client::ObjectId) {}
}