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use crate::lock::{rank, Mutex};
/// A pool of free [`wgpu_hal::CommandEncoder`]s, owned by a `Device`.
///
/// Each encoder in this list is in the "closed" state.
///
/// Since a raw [`CommandEncoder`][ce] is itself a pool for allocating
/// raw [`CommandBuffer`][cb]s, this is a pool of pools.
///
/// [`wgpu_hal::CommandEncoder`]: hal::CommandEncoder
/// [ce]: hal::CommandEncoder
/// [cb]: hal::Api::CommandBuffer
pub(crate) struct CommandAllocator {
free_encoders: Mutex<Vec<Box<dyn hal::DynCommandEncoder>>>,
}
impl CommandAllocator {
pub(crate) fn new() -> Self {
Self {
free_encoders: Mutex::new(rank::COMMAND_ALLOCATOR_FREE_ENCODERS, Vec::new()),
}
}
/// Return a fresh [`wgpu_hal::CommandEncoder`] in the "closed" state.
///
/// If we have free encoders in the pool, take one of those. Otherwise,
/// create a new one on `device`.
///
/// [`wgpu_hal::CommandEncoder`]: hal::CommandEncoder
pub(crate) fn acquire_encoder(
&self,
device: &dyn hal::DynDevice,
queue: &dyn hal::DynQueue,
) -> Result<Box<dyn hal::DynCommandEncoder>, hal::DeviceError> {
let mut free_encoders = self.free_encoders.lock();
match free_encoders.pop() {
Some(encoder) => Ok(encoder),
None => unsafe {
let hal_desc = hal::CommandEncoderDescriptor { label: None, queue };
device.create_command_encoder(&hal_desc)
},
}
}
/// Add `encoder` back to the free pool.
pub(crate) fn release_encoder(&self, encoder: Box<dyn hal::DynCommandEncoder>) {
let mut free_encoders = self.free_encoders.lock();
free_encoders.push(encoder);
}
}