Enum mmtk::plan::AllocationSemantics

#[repr(i32)]
pub enum AllocationSemantics {
    Default = 0,
    Immortal = 1,
    Los = 2,
    Code = 3,
    ReadOnly = 4,
    LargeCode = 5,
    NonMoving = 6,
}

Allocation semantics that MMTk provides. Each allocation request requires a desired semantic for the object to allocate.

Variants

Default = 0

The default semantic. This means there is no specific requirement for the allocation. The actual semantic of the default will depend on the GC plan in use.

Immortal = 1

Immortal objects will not be reclaimed. MMTk still traces immortal objects, but will not reclaim the objects even if they are dead.

Los = 2

Large objects. It is usually desirable to allocate large objects specially. Large objects are allocated with page granularity and will not be moved. Each plan provides max_non_los_default_alloc_bytes (see crate::plan::PlanConstraints), which defines a threshold for objects that can be allocated with the default semantic. Any object that is larger than the threshold must be allocated with the Los semantic. This semantic may get removed and MMTk will transparently allocate into large object space for large objects.

Code = 3

Code objects have execution permission. Note that this is a place holder for now. Currently all the memory MMTk allocates has execution permission.

ReadOnly = 4

Read-only objects cannot be mutated once it is initialized. Note that this is a place holder for now. It does not provide read only semantic.

LargeCode = 5

Los + Code.

NonMoving = 6

Non moving objects will not be moved by GC.

Trait Implementations

impl Clone for AllocationSemantics

fn clone(&self) -> AllocationSemantics

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for AllocationSemantics

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Enum for AllocationSemantics

const LENGTH: usize = 7usize

Length of the enum.

fn from_usize(value: usize) -> Self

Takes an usize, and returns an element matching into_usize function.

fn into_usize(self) -> usize

Returns an unique identifier for a value within range of 0..Array::LENGTH.

impl<V> EnumArray<V> for AllocationSemantics

type Array = [V; 7]

Representation of an enum map for type V.

impl PartialEq for AllocationSemantics

fn eq(&self, other: &AllocationSemantics) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for AllocationSemantics

impl Eq for AllocationSemantics

impl StructuralPartialEq for AllocationSemantics