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xo-gc: + arena for object roots

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This commit is contained in:
Roland Conybeare 2026-01-03 13:53:21 -05:00
commit 8a2c89e9fd
4 changed files with 51 additions and 14 deletions
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9
xo-gc/include/xo/gc/DX1Collector.hpp
View file

@ -91,6 +91,9 @@ namespace xo {
/** storage for N object types requires 8*N bytes **/
std::size_t object_types_z_ = 2*1024*1024;
/** storage for N object roots requires 8*N bytes **/
std::size_t object_roots_z_ = 16*1024;
/** number of bits to represent generation **/
std::uint64_t gen_bits_ = 8;
@ -169,6 +172,7 @@ namespace xo {
std::string_view name() const { return config_.name_; }
const DArena * get_object_types() const noexcept { return &object_types_; }
const DArena * get_roots() const noexcept { return &roots_; }
const DArena * get_space(role r, generation g) const noexcept { return space_[r][g]; }
DArena * get_space(role r, generation g) noexcept { return space_[r][g]; }
DArena * from_space(generation g) noexcept { return get_space(role::from_space(), g); }
@ -308,6 +312,11 @@ namespace xo {
/** if > 0: need gc for all generations < gc_pending_upto_ **/
generation gc_pending_upto_;
/** (ab)using arena to get extensible list of root objects.
* For each root store one address (type obj<AGCObject>*)
**/
DArena roots_;
/** collector-managed memory here.
* - space_[1] is from-space
* - space_[0] is to-space

8
xo-gc/include/xo/gc/detail/RCollector.hpp
View file

@ -30,10 +30,16 @@ namespace xo {
bool is_type_installed(typeseq tseq) const noexcept { return O::iface()->is_type_installed(O::data(), tseq); }
bool install_type(const AGCObject & iface) { return O::iface()->install_type(O::data(), iface); }
void add_gc_root_poly(obj<AGCObject> * p_root) { O::iface()->add_gc_root(O::data(), p_root); }
void add_gc_root_poly(obj<AGCObject> * p_root) { O::iface()->add_gc_root_poly(O::data(), p_root); }
void request_gc(generation g) { O::iface()->request_gc(O::data(), g); }
void forward_inplace(AGCObject * lhs_iface, void ** lhs_data) { O::iface()->forward_inplace(O::data(), lhs_iface, lhs_data); }
/** add root @p p_root **/
template<typename DRepr>
void add_gc_root(obj<AGCObject, DRepr> * p_root) {
O::iface()->add_gc_root_poly(O::data(), (obj<AGCObject> *)p_root);
}
static bool _valid;
};

23
xo-gc/src/gc/DX1Collector.cpp
View file

@ -77,6 +77,13 @@ namespace xo {
.hugepage_z_ = page_z,
.store_header_flag_ = false});
roots_ = DArena::map(
ArenaConfig{
.name_ = "x1-object-roots",
.size_ = cfg.object_roots_z_,
.hugepage_z_ = page_z,
.store_header_flag_ = false});
for (uint32_t igen = 0, ngen = cfg.n_generation_; igen < ngen; ++igen) {
space_storage_[0][igen] = DArena::map(cfg.arena_config_);
space_storage_[1][igen] = DArena::map(cfg.arena_config_);
@ -119,7 +126,10 @@ namespace xo {
accumulate_total_aux(const DX1Collector & d,
size_t (DArena::* get_stat_fn)() const) noexcept
{
size_t z = (d.object_types_.*get_stat_fn)();
size_t z1 = (d.object_types_.*get_stat_fn)();
size_t z2 = (d.roots_.*get_stat_fn)();
size_t z3 = 0;
for (role ri : role::all()) {
for (generation gj{0}; gj < d.config_.n_generation_; ++gj) {
@ -127,11 +137,11 @@ namespace xo {
assert(arena);
z += (arena->*get_stat_fn)();
z3 += (arena->*get_stat_fn)();
}
}
return z;
return z1 + z2 + z3;
}
}
@ -231,7 +241,12 @@ namespace xo {
void
DX1Collector::add_gc_root_poly(obj<AGCObject> * p_root) noexcept
{
(void)p_root;
std::byte * mem
= roots_.alloc(typeseq::anon(),
sizeof(obj<AGCObject>*));
assert(mem);
*(obj<AGCObject> **)mem = p_root;
}
void

25
xo-object2/utest/X1Collector.test.cpp
View file

@ -98,7 +98,13 @@ namespace ut {
REQUIRE(otypes->reserved() >= cfg.object_types_z_);
REQUIRE(otypes->reserved() < cfg.object_types_z_ + otypes->page_z_);
DArena * from_0 = gc.get_space(role::from_space(), generation{0});
const DArena * roots = gc.get_roots();
REQUIRE(roots != nullptr);
REQUIRE(roots->reserved() >= cfg.object_roots_z_);
REQUIRE(roots->reserved() < cfg.object_roots_z_ + roots->page_z_);
const DArena * from_0 = gc.get_space(role::from_space(), generation{0});
REQUIRE(from_0 != nullptr);
REQUIRE(from_0->reserved() >= tc.tenured_z_);
@ -106,7 +112,7 @@ namespace ut {
REQUIRE(from_0->reserved() % from_0->page_z_ == 0);
REQUIRE(from_0->allocated() == 0);
DArena * from_1 = gc.get_space(role::from_space(), generation{1});
const DArena * from_1 = gc.get_space(role::from_space(), generation{1});
REQUIRE(from_1 != nullptr);
REQUIRE(from_1->reserved() == from_0->reserved());
@ -118,22 +124,22 @@ namespace ut {
REQUIRE(to_0->reserved() == from_0->reserved());
REQUIRE(to_0->allocated() == 0);
DArena * to_1 = gc.get_space(role::to_space(), generation{1});
const DArena * to_1 = gc.get_space(role::to_space(), generation{1});
REQUIRE(to_1 != nullptr);
REQUIRE(to_1->reserved() == to_0->reserved());
REQUIRE(to_1->allocated() == 0);
DArena * from_2 = gc.get_space(role::from_space(), generation{2});
const DArena * from_2 = gc.get_space(role::from_space(), generation{2});
REQUIRE(from_2 == nullptr);
DArena * to_2 = gc.get_space(role::to_space(), generation{2});
const DArena * to_2 = gc.get_space(role::to_space(), generation{2});
REQUIRE(to_2 == nullptr);
REQUIRE(gc.reserved_total()
== otypes->reserved() + 4 * from_0->reserved());
== otypes->reserved() + roots->reserved() + 4 * from_0->reserved());
}
/* attempt allocation */
@ -147,18 +153,17 @@ namespace ut {
ok = c_o.is_type_installed(typeseq::id<DFloat>());
REQUIRE(ok);
ok = c_o.is_type_installed(typeseq::id<DList>());
REQUIRE(ok);
DFloat * x0 = DFloat::make(gc_o, 3.1415927);
auto x0_o = with_facet<AGCObject>::mkobj(x0);
c_o.add_gc_root(&x0_o);
REQUIRE(to_0->allocated() == sizeof(AllocHeader) + sizeof(DFloat));
DList * l0 = DList::list(gc_o, x0_o);
auto l0_o = with_facet<AGCObject>::mkobj(l0);
c_o.add_gc_root(&l0_o);
REQUIRE(to_0->allocated() == (sizeof(AllocHeader) + sizeof(DFloat)
+ sizeof(AllocHeader) + sizeof(DList)));
@ -195,6 +200,8 @@ namespace ut {
/* no GC roots, so GC is trivial */
c_o.request_gc(generation{1});
} catch (std::exception & ex) {
std::cerr << "caught exception: " << ex.what() << std::endl;
REQUIRE(false);