lockfree_object_pool/
linear_page.rs

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1use crate::page::{Page, PageId};
2use std::ptr;
3use std::sync::atomic::{AtomicPtr, Ordering};
4
5pub struct LinearPage<T> {
6    page: Page<T>,
7    next: AtomicPtr<LinearPage<T>>,
8}
9
10impl<T> LinearPage<T> {
11    #[inline]
12    pub fn new<I>(init: I) -> Self
13    where
14        I: Fn() -> T,
15    {
16        Self {
17            page: Page::new(init),
18            next: AtomicPtr::new(ptr::null_mut()),
19        }
20    }
21
22    #[inline]
23    pub fn get_or_create_next<I>(&self, init: I) -> &Self
24    where
25        I: Fn() -> T,
26    {
27        let mut current = self.next.load(Ordering::Relaxed);
28        if current.is_null() {
29            let new = Box::into_raw(Box::new(LinearPage::<T>::new(init)));
30            match self
31                .next
32                .compare_exchange(current, new, Ordering::SeqCst, Ordering::Relaxed)
33            {
34                Ok(_) => {
35                    current = new;
36                }
37                Err(x) => {
38                    unsafe {
39                        // SAFETY: new was been allocated by Box::new
40                        drop(Box::from_raw(new))
41                    };
42                    current = x;
43                }
44            }
45        }
46        unsafe {
47            // SAFETY: there are no mutable references to current
48            current.as_ref().unwrap()
49        }
50    }
51
52    #[inline]
53    pub fn alloc<I>(&self, init: I) -> (&Page<T>, PageId)
54    where
55        I: Fn() -> T + Clone,
56    {
57        let mut linear_page = self;
58        loop {
59            match linear_page.page.alloc() {
60                Some(id) => {
61                    return (&linear_page.page, id);
62                }
63                None => {
64                    linear_page = linear_page.get_or_create_next(init.clone());
65                }
66            };
67        }
68    }
69}
70
71impl<T> Drop for LinearPage<T> {
72    #[inline]
73    fn drop(&mut self) {
74        let current = self.next.load(Ordering::Relaxed);
75        if !current.is_null() {
76            unsafe {
77                // SAFETY: current was allocated with Box::new
78                drop(Box::from_raw(current))
79            };
80        }
81    }
82}
lockfree_object_pool/linear_page.rs

lockfree_object_pool/
linear_page.rs
