Struct mmtk::policy::sft::EmptySpaceSFT

pub struct EmptySpaceSFT {}

An empty entry for SFT.

Trait Implementations

impl Debug for EmptySpaceSFT

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

Formats the value using the given formatter.

impl SFT for EmptySpaceSFT

fn name(&self) -> &str

The space name

fn is_live(&self, object: ObjectReference) -> bool

Is the object live, determined by the policy?

fn is_sane(&self) -> bool

Is the object sane? A policy should return false if there is any abnormality about object - the sanity checker will fail if an object is not sane.

fn pin_object(&self, _object: ObjectReference) -> bool

fn unpin_object(&self, _object: ObjectReference) -> bool

fn is_object_pinned(&self, _object: ObjectReference) -> bool

fn is_movable(&self) -> bool

Is the object movable, determined by the policy? E.g. the policy is non-moving, or the object is pinned.

fn is_in_space(&self, _object: ObjectReference) -> bool

Is the object managed by MMTk? For most cases, if we find the sft for an object, that means the object is in the space and managed by MMTk. However, for some spaces, like MallocSpace, we mark the entire chunk in the SFT table as a malloc space, but only some of the addresses in the space contain actual MMTk objects. So they need a further check.

fn is_mmtk_object(&self, _addr: Address) -> Option<ObjectReference>

Is addr a valid object reference to an object allocated in this space? This default implementation works for all spaces that use MMTk’s mapper to allocate memory. Some spaces, like MallocSpace, use third-party libraries to allocate memory. Such spaces needs to override this method.

fn find_object_from_internal_pointer( &self, _ptr: Address, _max_search_bytes: usize ) -> Option<ObjectReference>

fn initialize_object_metadata(&self, object: ObjectReference, _alloc: bool)

Initialize object metadata (in the header, or in the side metadata).

fn sft_trace_object( &self, _queue: &mut VectorObjectQueue, object: ObjectReference, _worker: GCWorkerMutRef<'_> ) -> ObjectReference

Trace objects through SFT. This along with SFTProcessEdges provides an easy way for most plans to trace objects without the need to implement any plan-specific code. However, tracing objects for some policies are more complicated, and they do not provide an implementation of this method. For example, mark compact space requires trace twice in each GC. Immix has defrag trace and fast trace.

fn get_forwarded_object( &self, _object: ObjectReference ) -> Option<ObjectReference>

Get forwarding pointer if the object is forwarded.

fn is_reachable(&self, object: ObjectReference) -> bool

Is the object reachable, determined by the policy? Note: Objects in ImmortalSpace may have is_live = true but are actually unreachable.