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Diffstat (limited to 'crates/core/src/hive/group.rs')
| -rw-r--r-- | crates/core/src/hive/group.rs | 122 |
1 files changed, 0 insertions, 122 deletions
diff --git a/crates/core/src/hive/group.rs b/crates/core/src/hive/group.rs deleted file mode 100644 index 9217897..0000000 --- a/crates/core/src/hive/group.rs +++ /dev/null @@ -1,122 +0,0 @@ -//! An implementation of the individual memory blocks that make up a hive. - -use core::{ - mem::{self, ManuallyDrop}, - ptr::NonNull, -}; - -use crate::hive::skipfield; - -/// A type that may be either part of the free list or an element. -pub union Slot<T, Sk> -where - Sk: skipfield::SkipfieldType, -{ - /// An element of the [`Group`]. - element: ManuallyDrop<T>, - - /// A free list index. - free_list: FreeList<Sk>, -} - -/// The contents of a free list index. -/// -/// This uses the `packed` C representation to avoid any excess space. This is -/// not a problem in the general case as our type will only ever be `u16` or -/// `u8` unless an end-user overrides the skipfield type with a custom -/// implementation. -#[repr(C, packed)] -#[derive(Copy, Clone)] -#[cfg_attr(feature = "core-fmt", derive(Debug))] -pub struct FreeList<Sk> -where - Sk: skipfield::SkipfieldType, -{ - /// Index of the previous element in the free list. - pub previous: Sk, - - /// Index of the next element in the free list. - pub next: Sk, -} - -/// A doubly-linked `Group` of `T` with a skipfield type of `Sk`. -#[cfg_attr(feature = "core-fmt", derive(Debug))] -pub struct Group<T, Sk> -where - Sk: skipfield::SkipfieldType, -{ - /// Pointer to the start of the skipfield. - pub skipfield: Option<NonNull<Sk>>, - - /// Pointer to the next [`Group`]. - pub next: Option<NonNull<Group<T, Sk>>>, - - /// Pointer to element storage. - pub elements: Option<NonNull<Slot<T, Sk>>>, - - /// Pointer to the previous [`Group`]. - pub previous: Option<NonNull<Group<T, Sk>>>, - - /// Index of the last erased element in the group. - /// - /// The last erased element contains the index of the next, and so on. If - /// this is equal to the maximum value of the underlying integer type, - /// then the free list is considered to be empty. - pub free_list_head: Sk, - - /// Total number of elements this [`Group`] can hold. - pub capacity: Sk, - - /// Number of elements stored in this [`Group`]. - pub size: Sk, - - /// Pointer to the next [`Group`] with erased elements. - pub next_with_erasures: Option<NonNull<Group<T, Sk>>>, - - /// Pointer to the previous [`Group`] with erased elements. - pub previous_with_erasures: Option<NonNull<Group<T, Sk>>>, - - /// Number assigned to this group. - pub number: usize, -} - -impl<T, Sk> Group<T, Sk> -where - Sk: skipfield::SkipfieldType, -{ - /// Size of each individual element within a [`Group`] - pub const ELEMENT_ALLOCATION_SIZE: usize = - compute_element_allocation_size::<T, Sk>(); -} - -/// Helper function which computes the allocation size of elements -const fn compute_element_allocation_size<T, Sk>() -> usize { - let t_align = mem::align_of::<T>(); - let t_size = mem::size_of::<T>(); - let sk2_size = mem::size_of::<Sk>() * 2; - if t_align > t_size { - if sk2_size > t_align { - sk2_size - } else { - t_align - } - } else if sk2_size > t_size { - sk2_size - } else { - t_size - } -} - -#[cfg(all(test, feature = "core-error"))] -mod test { - use super::*; - - #[test] - fn validate_element_allocation_size() { - assert_eq!( - Group::<u32, u8>::ELEMENT_ALLOCATION_SIZE, - 4, - "element allocation size with T = u32, Sk = u8 is 4" - ); - } -} |
