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allocator.rs
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allocator.rs
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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
use std::alloc::{self, Layout, LayoutError};
const DEFAULT_ALIGN_BYTES: usize = 4;
#[derive(PartialEq, Eq)]
pub struct Allocation {
layout: Layout,
ptr: *mut u8,
}
impl Allocation {
/// Allocates a chunk of memory of `size` bytes with optional alignment.
pub fn new(size: usize, align: Option<usize>) -> Result<Self, LayoutError> {
let alignment = align.unwrap_or(DEFAULT_ALIGN_BYTES);
let layout = Layout::from_size_align(size, alignment)?;
let ptr = unsafe { alloc::alloc(layout) };
if ptr.is_null() {
alloc::handle_alloc_error(layout);
}
Ok(Self { ptr, layout })
}
pub fn as_mut_ptr(&self) -> *mut u8 {
self.ptr
}
/// Returns the size of the Allocation in bytes.
pub fn size(&self) -> usize {
self.layout.size()
}
/// Returns the byte alignment of the Allocation.
pub fn align(&self) -> usize {
self.layout.align()
}
/// Returns a view of the Allocation.
pub fn as_slice(&self) -> &[u8] {
unsafe { std::slice::from_raw_parts(self.as_mut_ptr(), self.size()) }
}
/// Returns a mutable view of the Allocation.
pub fn as_mut_slice(&mut self) -> &mut [u8] {
unsafe { std::slice::from_raw_parts_mut(self.as_mut_ptr(), self.size()) }
}
}
impl Drop for Allocation {
fn drop(&mut self) {
unsafe {
alloc::dealloc(self.ptr, self.layout);
}
}
}