jam::heap::host Class Reference

Borrow a heap whose roots, barriers and reference policy belong to a host runtime. More...

Public Types
enum class	generation
	Select the arena for raw allocation or publication.

Public Member Functions
	host (heap &storage, std::size_t prefix) noexcept
	Reserve an identical guard in both fresh, fixed-size generations.
	~host () noexcept
	Release the capability after finishing its last collection.
void	publish (generation which, void *target, std::size_t skip, std::size_t count) const noexcept
	Publish one generation at a stable VM-owned address.
offset	allocate (generation which, std::size_t words) noexcept
	Allocate raw cells in either generation, preserving the tag bit. A host may subdivide the extent; scanner claims determine record boundaries.
void	begin (bool minor) noexcept
	Start a VM-owned marking epoch; the VM supplies barriers and weak policy.
template<class Trace> requires std::is_nothrow_invocable_v<Trace &, visitor &, offset>
void	trace (std::span< offset const > roots, Trace &&trace, std::size_t marker_limit=1, bool old_owners=false) noexcept
	Drain roots using jam's ordinary frontier and persistent worker pool.
bool	marked (offset at) const noexcept
	Exact collected-generation liveness; old objects are live during minors.
bool	prepare (bool promote=false) noexcept
	Freeze both forwarding tables after resolving all reference policies.
offset	forward (offset at) const noexcept
	Repair a root while original objects and both forwarding tables remain intact.
void	finish () noexcept
	Move with the original SIMD kernel and pack only after both moves finish.

Detailed Description

Borrow a heap whose roots, barriers and reference policy belong to a host runtime.

See hosting a runtime. One capability per heap; it must not outlive the heap. Ordinary Jam roots and collection are excluded.

Definition at line 1847 of file heap.ccm.

Constructor & Destructor Documentation

host()

jam::heap::host::host ( heap & storage, std::size_t prefix )

inlineexplicitnoexcept

Reserve an identical guard in both fresh, fixed-size generations.

Parameters

storage	Fresh heap borrowed for the capability lifetime.
prefix	Guard size in eight-byte cells, a positive native-page multiple.

Precondition

Sole host capability; no ordinary Jam allocations, roots or collection.

Definition at line 1861 of file heap.ccm.

Member Function Documentation

allocate()

offset jam::heap::host::allocate ( generation which, std::size_t words )

inlinenodiscardnoexcept

Allocate raw cells in either generation, preserving the tag bit. A host may subdivide the extent; scanner claims determine record boundaries.

Precondition

Positive extent fits the selected generation; no active collection.

Definition at line 1893 of file heap.ccm.

begin()

void jam::heap::host::begin ( bool minor )

inlinenoexcept

Start a VM-owned marking epoch; the VM supplies barriers and weak policy.

Precondition

No jam roots, weak registrations, remembered slots or active collection.

Definition at line 1899 of file heap.ccm.

finish()

void jam::heap::host::finish ( )

inlinenoexcept

Move with the original SIMD kernel and pack only after both moves finish.

Precondition

VM roots and old remembered fields have been repaired. Republish both aliases before resuming mutators. Majors need no combined-live-size fit in either generation.

Definition at line 1974 of file heap.ccm.

prepare()

bool jam::heap::host::prepare ( bool promote = false )

inlinenodiscardnoexcept

Freeze both forwarding tables after resolving all reference policies.

Returns

False if whole-nursery promotion does not fit. No forwarding is then visible; Retry without promotion in the same epoch; no further tracing is allowed. Majors retain both generations separately.

Definition at line 1943 of file heap.ccm.

publish()

void jam::heap::host::publish ( generation which, void * target, std::size_t skip, std::size_t count ) const

inlinenoexcept

Publish one generation at a stable VM-owned address.

Precondition

Fixed capacity, no shrink, stopped mutators; skip/count are page multiples. target corresponds to cell skip, not cell zero. The host owns the reservation.

Definition at line 1880 of file heap.ccm.

trace()

template<class Trace>
requires std::is_nothrow_invocable_v<Trace &, visitor &, offset>

void jam::heap::host::trace ( std::span< offset const > roots, Trace && trace, std::size_t marker_limit = 1, bool old_owners = false )

inlinenoexcept

Drain roots using jam's ordinary frontier and persistent worker pool.

Precondition

Marking phase; callbacks claim full objects before enumerating fields. marker_limit=1 keeps callbacks on the caller (e.g. a registered VM thread). old_owners admits dirty old source jobs in a minor; their targets remain young-only.

Definition at line 1921 of file heap.ccm.

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The documentation for this class was generated from the following file:

• heap.ccm