mmtk/policy/
gc_work.rs

1/// Used to identify the trace if a policy has different kinds of traces. For example, defrag vs fast trace for Immix,
2/// mark vs forward trace for mark compact.
3pub(crate) type TraceKind = u8;
4
5pub const DEFAULT_TRACE: u8 = u8::MAX;
6pub const TRACE_KIND_TRANSITIVE_PIN: u8 = DEFAULT_TRACE - 1;
7
8use crate::plan::ObjectQueue;
9use crate::scheduler::GCWorker;
10use crate::util::copy::CopySemantics;
11
12use crate::util::ObjectReference;
13
14use crate::vm::VMBinding;
15
16/// This trait defines policy-specific behavior for tracing objects.
17/// The procedural macro #[derive(PlanTraceObject)] will generate code
18/// that uses this trait. We expect any policy to implement this trait.
19/// For the sake of performance, the implementation
20/// of this trait should mark methods as `[inline(always)]`.
21pub trait PolicyTraceObject<VM: VMBinding> {
22    /// Trace object in the policy. If the policy copies objects, we should
23    /// expect `copy` to be a `Some` value.
24    fn trace_object<Q: ObjectQueue, const KIND: TraceKind>(
25        &self,
26        queue: &mut Q,
27        object: ObjectReference,
28        copy: Option<CopySemantics>,
29        worker: &mut GCWorker<VM>,
30    ) -> ObjectReference;
31
32    /// Policy-specific post-scan-object hook.  It is called after scanning
33    /// each object in this space.
34    fn post_scan_object(&self, _object: ObjectReference) {
35        // Do nothing.
36    }
37
38    /// Return whether the policy moves objects.
39    fn may_move_objects<const KIND: TraceKind>() -> bool;
40}
mmtk/policy/gc_work.rs

mmtk/policy/
gc_work.rs
