diff options
Diffstat (limited to 'pkgs/by-name/ri/river-mk-keymap/src/wayland/shm/slot.rs')
| -rw-r--r-- | pkgs/by-name/ri/river-mk-keymap/src/wayland/shm/slot.rs | 596 |
1 files changed, 596 insertions, 0 deletions
diff --git a/pkgs/by-name/ri/river-mk-keymap/src/wayland/shm/slot.rs b/pkgs/by-name/ri/river-mk-keymap/src/wayland/shm/slot.rs new file mode 100644 index 00000000..ab52c5f6 --- /dev/null +++ b/pkgs/by-name/ri/river-mk-keymap/src/wayland/shm/slot.rs @@ -0,0 +1,596 @@ +//! A pool implementation based on buffer slots + +use std::io; +use std::{ + os::unix::io::{AsRawFd, OwnedFd}, + sync::{ + atomic::{AtomicU8, AtomicUsize, Ordering}, + Arc, Mutex, Weak, + }, +}; + +use wayland_client::backend::protocol::Message; +use wayland_client::backend::{ObjectData, ObjectId}; +use wayland_client::{ + protocol::{wl_buffer, wl_shm, wl_surface}, + Proxy, +}; + +use crate::wayland::shm::raw::RawPool; +use crate::wayland::shm::CreatePoolError; + +#[derive(Debug, thiserror::Error)] +pub(crate) enum CreateBufferError { + /// Slot creation error. + #[error(transparent)] + Io(#[from] io::Error), + + /// Pool mismatch. + #[error("Incorrect pool for slot")] + PoolMismatch, + + /// Slot size mismatch + #[error("Requested buffer size is too large for slot")] + SlotTooSmall, +} + +#[derive(Debug, thiserror::Error)] +pub(crate) enum ActivateSlotError { + /// Buffer was already active + #[error("Buffer was already active")] + AlreadyActive, +} + +#[derive(Debug)] +pub(crate) struct SlotPool { + pub(crate) inner: RawPool, + free_list: Arc<Mutex<Vec<FreelistEntry>>>, +} + +#[derive(Debug)] +struct FreelistEntry { + offset: usize, + len: usize, +} + +/// A chunk of memory allocated from a [`SlotPool`] +/// +/// Retaining this object is only required if you wish to resize or change the buffer's format +/// without changing the contents of the backing memory. +#[derive(Debug)] +pub(crate) struct Slot { + inner: Arc<SlotInner>, +} + +#[derive(Debug)] +struct SlotInner { + free_list: Weak<Mutex<Vec<FreelistEntry>>>, + offset: usize, + len: usize, + active_buffers: AtomicUsize, + /// Count of all "real" references to this slot. This includes all Slot objects and any + /// [`BufferData`] object that is not in the DEAD state. When this reaches zero, the memory for + /// this slot will return to the [`free_list`]. It is not possible for it to reach zero and have a + /// Slot or Buffer referring to it. + all_refs: AtomicUsize, +} + +/// A wrapper around a [`wl_buffer::WlBuffer`] which has been allocated via a [`SlotPool`]. +/// +/// When this object is dropped, the buffer will be destroyed immediately if it is not active, or +/// upon the server's release if it is. +#[derive(Debug)] +pub(crate) struct Buffer { + inner: wl_buffer::WlBuffer, + height: i32, + stride: i32, + slot: Slot, +} + +/// [`ObjectData`] for the [`WlBuffer`] +#[derive(Debug)] +struct BufferData { + inner: Arc<SlotInner>, + state: AtomicU8, +} + +// These constants define the value of BufferData::state, since AtomicEnum does not exist. +impl BufferData { + /// Buffer is counted in [`active_buffers`] list; will return to INACTIVE on Release. + const ACTIVE: u8 = 0; + + /// Buffer is not counted in [`active_buffers`] list, but also has not been destroyed. + const INACTIVE: u8 = 1; + + /// Buffer is counted in [`active_buffers`] list; will move to DEAD on Release + const DESTROY_ON_RELEASE: u8 = 2; + + /// Buffer has been destroyed + const DEAD: u8 = 3; + + /// Value that is [`ORed`] on buffer release to transition to the next state + const RELEASE_SET: u8 = 1; + + /// Value that is [`ORed`] on buffer destroy to transition to the next state + const DESTROY_SET: u8 = 2; + + /// Call after successfully transitioning the state to DEAD + fn record_death(&self) { + drop(Slot { + inner: self.inner.clone(), + }); + } +} + +impl SlotPool { + pub(crate) fn new(len: usize, shm: &wl_shm::WlShm) -> Result<Self, CreatePoolError> { + let inner = RawPool::new(len, shm)?; + let free_list = Arc::new(Mutex::new(vec![FreelistEntry { + offset: 0, + len: inner.len(), + }])); + Ok(SlotPool { inner, free_list }) + } + + /// Create a new buffer in a new slot. + /// + /// This returns the buffer and the canvas. 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 + /// - `format`: the encoding format of the pixels. Using a format that was not + /// advertised to the `wl_shm` global by the server is a protocol error and will + /// terminate your connection. + /// + /// The [Slot] for this buffer will have exactly the size required for the data. It can be + /// accessed via [`Buffer::slot`] to create additional buffers that point to the same data. This + /// is required if you wish to change formats, buffer dimensions, or attach a canvas to + /// multiple surfaces. + /// + /// For more control over sizing, use [`Self::new_slot`] and [`Self::create_buffer_in`]. + pub(crate) fn create_buffer( + &mut self, + width: i32, + height: i32, + stride: i32, + format: wl_shm::Format, + ) -> Result<(Buffer, &mut [u8]), CreateBufferError> { + let len = (height as usize) * (stride as usize); + let slot = self.new_slot(len)?; + let buffer = self.create_buffer_in(&slot, width, height, stride, format)?; + let canvas = self.raw_data_mut(&slot); + Ok((buffer, canvas)) + } + + /// Get the bytes corresponding to a given slot or buffer if drawing to the slot is permitted. + /// + /// Returns `None` if there are active buffers in the slot or if the slot does not correspond + /// to this pool. + pub(crate) fn canvas(&mut self, key: &impl CanvasKey) -> Option<&mut [u8]> { + key.canvas(self) + } + + /// Returns the size, in bytes, of this pool. + #[allow(clippy::len_without_is_empty)] + pub(crate) fn len(&self) -> usize { + self.inner.len() + } + + /// Resizes the memory pool, notifying the server the pool has changed in size. + /// + /// This is an optimization; the pool automatically resizes when you allocate new slots. + pub(crate) fn resize(&mut self, size: usize) -> io::Result<()> { + let old_len = self.inner.len(); + self.inner.resize(size)?; + let new_len = self.inner.len(); + if old_len == new_len { + return Ok(()); + } + // add the new memory to the freelist + let mut free = self.free_list.lock().unwrap(); + if let Some(FreelistEntry { offset, len }) = free.last_mut() { + if *offset + *len == old_len { + *len += new_len - old_len; + return Ok(()); + } + } + free.push(FreelistEntry { + offset: old_len, + len: new_len - old_len, + }); + Ok(()) + } + + fn alloc(&mut self, size: usize) -> io::Result<usize> { + let mut free = self.free_list.lock().unwrap(); + for FreelistEntry { offset, len } in free.iter_mut() { + if *len >= size { + let rv = *offset; + *len -= size; + *offset += size; + return Ok(rv); + } + } + let mut rv = self.inner.len(); + let mut pop_tail = false; + if let Some(FreelistEntry { offset, len }) = free.last() { + if offset + len == self.inner.len() { + rv -= len; + pop_tail = true; + } + } + // resize like Vec::reserve, always at least doubling + let target = std::cmp::max(rv + size, self.inner.len() * 2); + self.inner.resize(target)?; + // adjust the end of the freelist here + if pop_tail { + free.pop(); + } + if target > rv + size { + free.push(FreelistEntry { + offset: rv + size, + len: target - rv - size, + }); + } + Ok(rv) + } + + fn free(free_list: &Mutex<Vec<FreelistEntry>>, mut offset: usize, mut len: usize) { + let mut free = free_list.lock().unwrap(); + let mut nf = Vec::with_capacity(free.len() + 1); + for &FreelistEntry { + offset: ioff, + len: ilen, + } in free.iter() + { + if ioff + ilen == offset { + offset = ioff; + len += ilen; + continue; + } + if ioff == offset + len { + len += ilen; + continue; + } + if ioff > offset + len && len != 0 { + nf.push(FreelistEntry { offset, len }); + len = 0; + } + if ilen != 0 { + nf.push(FreelistEntry { + offset: ioff, + len: ilen, + }); + } + } + if len != 0 { + nf.push(FreelistEntry { offset, len }); + } + *free = nf; + } + + /// Create a new slot with the given size in bytes. + pub(crate) fn new_slot(&mut self, mut len: usize) -> io::Result<Slot> { + len = (len + 63) & !63; + let offset = self.alloc(len)?; + + Ok(Slot { + inner: Arc::new(SlotInner { + free_list: Arc::downgrade(&self.free_list), + offset, + len, + active_buffers: AtomicUsize::new(0), + all_refs: AtomicUsize::new(1), + }), + }) + } + + /// Get the bytes corresponding to a given slot. + /// + /// Note: prefer using [`Self::canvas`], which will prevent drawing to a buffer that has not been + /// released by the server. + /// + /// Returns an empty buffer if the slot does not belong to this pool. + pub(crate) fn raw_data_mut(&mut self, slot: &Slot) -> &mut [u8] { + if slot.inner.free_list.as_ptr() == Arc::as_ptr(&self.free_list) { + &mut self.inner.mmap()[slot.inner.offset..][..slot.inner.len] + } else { + &mut [] + } + } + + /// Create a new buffer corresponding to a slot. + /// + /// 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 + /// - `format`: the encoding format of the pixels. Using a format that was not + /// advertised to the `wl_shm` global by the server is a protocol error and will + /// terminate your connection + pub(crate) fn create_buffer_in( + &mut self, + slot: &Slot, + width: i32, + height: i32, + stride: i32, + format: wl_shm::Format, + ) -> Result<Buffer, CreateBufferError> { + let offset = slot.inner.offset as i32; + let len = (height as usize) * (stride as usize); + if len > slot.inner.len { + return Err(CreateBufferError::SlotTooSmall); + } + + if slot.inner.free_list.as_ptr() != Arc::as_ptr(&self.free_list) { + return Err(CreateBufferError::PoolMismatch); + } + + let slot = slot.clone(); + // take a ref for the BufferData, which will be destroyed by BufferData::record_death + slot.inner.all_refs.fetch_add(1, Ordering::Relaxed); + let data = Arc::new(BufferData { + inner: slot.inner.clone(), + state: AtomicU8::new(BufferData::INACTIVE), + }); + let buffer = self + .inner + .create_buffer_raw(offset, width, height, stride, format, data); + Ok(Buffer { + inner: buffer, + height, + stride, + slot, + }) + } +} + +impl Clone for Slot { + fn clone(&self) -> Self { + let inner = self.inner.clone(); + inner.all_refs.fetch_add(1, Ordering::Relaxed); + Slot { inner } + } +} + +impl Drop for Slot { + fn drop(&mut self) { + if self.inner.all_refs.fetch_sub(1, Ordering::Relaxed) == 1 { + if let Some(free_list) = self.inner.free_list.upgrade() { + SlotPool::free(&free_list, self.inner.offset, self.inner.len); + } + } + } +} + +impl Drop for SlotInner { + fn drop(&mut self) { + debug_assert_eq!(*self.all_refs.get_mut(), 0); + } +} + +/// A helper trait for [`SlotPool::canvas`]. +pub(crate) trait CanvasKey { + fn canvas<'pool>(&self, pool: &'pool mut SlotPool) -> Option<&'pool mut [u8]>; +} + +impl Slot { + /// Return true if there are buffers referencing this slot whose contents are being accessed + /// by the server. + pub(crate) fn has_active_buffers(&self) -> bool { + self.inner.active_buffers.load(Ordering::Relaxed) != 0 + } + + /// Returns the size, in bytes, of this slot. + #[allow(clippy::len_without_is_empty)] + pub(crate) fn len(&self) -> usize { + self.inner.len + } + + /// Get the bytes corresponding to a given slot if drawing to the slot is permitted. + /// + /// Returns `None` if there are active buffers in the slot or if the slot does not correspond + /// to this pool. + pub(crate) fn canvas<'pool>(&self, pool: &'pool mut SlotPool) -> Option<&'pool mut [u8]> { + if self.has_active_buffers() { + return None; + } + if self.inner.free_list.as_ptr() == Arc::as_ptr(&pool.free_list) { + Some(&mut pool.inner.mmap()[self.inner.offset..][..self.inner.len]) + } else { + None + } + } +} + +impl CanvasKey for Slot { + fn canvas<'pool>(&self, pool: &'pool mut SlotPool) -> Option<&'pool mut [u8]> { + self.canvas(pool) + } +} + +impl Buffer { + /// Attach a buffer to a surface. + /// + /// This marks the slot as active until the server releases the buffer, which will happen + /// automatically assuming the surface is committed without attaching a different buffer. + /// + /// Note: if you need to ensure that [`canvas()`](Buffer::canvas) calls never return data that + /// could be attached to a surface in a multi-threaded client, make this call while you have + /// exclusive access to the corresponding [`SlotPool`]. + pub(crate) fn attach_to(&self, surface: &wl_surface::WlSurface) -> Result<(), ActivateSlotError> { + self.activate()?; + surface.attach(Some(&self.inner), 0, 0); + Ok(()) + } + + /// Get the inner buffer. + pub(crate) fn wl_buffer(&self) -> &wl_buffer::WlBuffer { + &self.inner + } + + pub(crate) fn height(&self) -> i32 { + self.height + } + + pub(crate) fn stride(&self) -> i32 { + self.stride + } + + fn data(&self) -> Option<&BufferData> { + self.inner.object_data()?.downcast_ref() + } + + /// Get the bytes corresponding to this buffer if drawing is permitted. + /// + /// This may be smaller than the canvas associated with the slot. + pub(crate) fn canvas<'pool>(&self, pool: &'pool mut SlotPool) -> Option<&'pool mut [u8]> { + let len = (self.height as usize) * (self.stride as usize); + if self.slot.inner.active_buffers.load(Ordering::Relaxed) != 0 { + return None; + } + if self.slot.inner.free_list.as_ptr() == Arc::as_ptr(&pool.free_list) { + Some(&mut pool.inner.mmap()[self.slot.inner.offset..][..len]) + } else { + None + } + } + + /// Get the slot corresponding to this buffer. + pub(crate) fn slot(&self) -> Slot { + self.slot.clone() + } + + /// Manually mark a buffer as active. + /// + /// An active buffer prevents drawing on its slot until a Release event is received or until + /// manually deactivated. + pub(crate) fn activate(&self) -> Result<(), ActivateSlotError> { + let data = self.data().expect("UserData type mismatch"); + + // This bitwise AND will transition INACTIVE -> ACTIVE, or do nothing if the buffer was + // already ACTIVE. No other ordering is required, as the server will not send a Release + // until we send our attach after returning Ok. + match data + .state + .fetch_and(!BufferData::RELEASE_SET, Ordering::Relaxed) + { + BufferData::INACTIVE => { + data.inner.active_buffers.fetch_add(1, Ordering::Relaxed); + Ok(()) + } + BufferData::ACTIVE => Err(ActivateSlotError::AlreadyActive), + _ => unreachable!("Invalid state in BufferData"), + } + } + + /// Manually mark a buffer as inactive. + /// + /// This should be used when the buffer was manually marked as active or when a buffer was + /// attached to a surface but not committed. Calling this function on a buffer that was + /// committed to a surface risks making the surface contents undefined. + pub(crate) fn deactivate(&self) -> Result<(), ActivateSlotError> { + let data = self.data().expect("UserData type mismatch"); + + // Same operation as the Release event, but we know the Buffer was not dropped. + match data + .state + .fetch_or(BufferData::RELEASE_SET, Ordering::Relaxed) + { + BufferData::ACTIVE => { + data.inner.active_buffers.fetch_sub(1, Ordering::Relaxed); + Ok(()) + } + BufferData::INACTIVE => Err(ActivateSlotError::AlreadyActive), + _ => unreachable!("Invalid state in BufferData"), + } + } +} + +impl CanvasKey for Buffer { + fn canvas<'pool>(&self, pool: &'pool mut SlotPool) -> Option<&'pool mut [u8]> { + self.canvas(pool) + } +} + +impl Drop for Buffer { + fn drop(&mut self) { + if let Some(data) = self.data() { + match data + .state + .fetch_or(BufferData::DESTROY_SET, Ordering::Relaxed) + { + BufferData::ACTIVE => { + // server is using the buffer, let ObjectData handle the destroy + } + BufferData::INACTIVE => { + data.record_death(); + self.inner.destroy(); + } + _ => unreachable!("Invalid state in BufferData"), + } + } + } +} + +impl ObjectData for BufferData { + fn event( + self: Arc<Self>, + handle: &wayland_client::backend::Backend, + msg: Message<ObjectId, OwnedFd>, + ) -> Option<Arc<dyn ObjectData>> { + debug_assert!(wayland_client::backend::protocol::same_interface( + msg.sender_id.interface(), + wl_buffer::WlBuffer::interface() + )); + debug_assert!(msg.opcode == 0); + + match self + .state + .fetch_or(BufferData::RELEASE_SET, Ordering::Relaxed) + { + BufferData::ACTIVE => { + self.inner.active_buffers.fetch_sub(1, Ordering::Relaxed); + } + BufferData::INACTIVE => { + // possible spurious release, or someone called deactivate incorrectly + eprintln!("Unexpected WlBuffer::Release on an inactive buffer"); + } + BufferData::DESTROY_ON_RELEASE => { + self.record_death(); + self.inner.active_buffers.fetch_sub(1, Ordering::Relaxed); + + // The Destroy message is identical to Release message (no args, same ID), so just reply + handle + .send_request(msg.map_fd(|x| x.as_raw_fd()), None, None) + .expect("Unexpected invalid ID"); + } + BufferData::DEAD => { + // no-op, this object is already unusable + } + _ => unreachable!("Invalid state in BufferData"), + } + + None + } + + fn destroyed(&self, _: ObjectId) {} +} + +impl Drop for BufferData { + fn drop(&mut self) { + let state = *self.state.get_mut(); + if state == BufferData::ACTIVE || state == BufferData::DESTROY_ON_RELEASE { + // Release the active-buffer count + self.inner.active_buffers.fetch_sub(1, Ordering::Relaxed); + } + + if state != BufferData::DEAD { + // nobody has ever transitioned state to DEAD, so we are responsible for freeing the + // extra reference + self.record_death(); + } + } +} |