mirror of
https://github.com/italicsjenga/vello.git
synced 2025-01-10 20:51:29 +11:00
657f219ce8
Reduce allocation of descriptor heaps. This change also enables clearing of buffers, as the handles are needed at command dispatch time. Also updates the tests to use clear_buffers on DX12. Looking forward to being able to get rid of the compute shader workaround on Metal. This is a followup on #125, and progress toward #95
82 lines
3 KiB
Rust
82 lines
3 KiB
Rust
// Copyright © 2021 piet-gpu developers.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those
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//! A simple best-fit allocator.
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use std::collections::{BTreeMap, BTreeSet};
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/// An allocator that tracks free ranges and returns best fit.
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pub struct BestFit {
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// map offset to size of free block
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free_by_ix: BTreeMap<u32, u32>,
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// size and offset
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free_by_size: BTreeSet<(u32, u32)>,
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}
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impl BestFit {
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pub fn new(size: u32) -> BestFit {
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let mut free_by_ix = BTreeMap::new();
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free_by_ix.insert(0, size);
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let mut free_by_size = BTreeSet::new();
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free_by_size.insert((size, 0));
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BestFit {
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free_by_ix,
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free_by_size,
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}
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}
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pub fn alloc(&mut self, size: u32) -> Option<u32> {
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let block = *self.free_by_size.range((size, 0)..).next()?;
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let ix = block.1;
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self.free_by_ix.remove(&ix);
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self.free_by_size.remove(&block);
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let fragment_size = block.0 - size;
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if fragment_size > 0 {
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let fragment_ix = ix + size;
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self.free_by_ix.insert(fragment_ix, fragment_size);
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self.free_by_size.insert((fragment_size, fragment_ix));
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}
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Some(ix)
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}
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pub fn free(&mut self, ix: u32, size: u32) {
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let next_ix = size + ix;
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if let Some((&prev_ix, &prev_size)) = self.free_by_ix.range(..ix).rev().next() {
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if prev_ix + prev_size == ix {
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self.free_by_size.remove(&(prev_size, prev_ix));
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if let Some(&next_size) = self.free_by_ix.get(&next_ix) {
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// consolidate with prev and next
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let new_size = prev_size + size + next_size;
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*self.free_by_ix.get_mut(&prev_ix).unwrap() = new_size;
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self.free_by_ix.remove(&next_ix);
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self.free_by_size.remove(&(next_size, next_ix));
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self.free_by_size.insert((new_size, prev_ix));
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} else {
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// consolidate with prev
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let new_size = prev_size + size;
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*self.free_by_ix.get_mut(&prev_ix).unwrap() = new_size;
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self.free_by_size.insert((new_size, prev_ix));
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}
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return;
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}
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}
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if let Some(&next_size) = self.free_by_ix.get(&next_ix) {
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// consolidate with next
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let new_size = size + next_size;
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self.free_by_ix.remove(&next_ix);
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self.free_by_ix.insert(ix, new_size);
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self.free_by_size.remove(&(next_size, next_ix));
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self.free_by_size.insert((new_size, ix));
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} else {
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// new isolated free block
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self.free_by_ix.insert(ix, size);
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self.free_by_size.insert((size, ix));
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}
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}
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}
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