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xo-alloc: try to make commit happen at start of GC cycle

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This commit is contained in:
Roland Conybeare 2025-08-26 13:36:18 -04:00
commit 6c7b13e443
4 changed files with 77 additions and 48 deletions
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8
include/xo/alloc/ArenaAlloc.hpp
View file

@ -54,13 +54,15 @@ namespace xo {
return std::make_pair(lo_, free_ptr_);
}
/** Reset to empty state **/
void reset(std::size_t /*z_ignored*/) { this->clear(); }
/** Reset to empty state; provision at least @p need_z bytes of (committed) space **/
void reset(std::size_t need_z);
void capture_object_statistics(capture_phase phase,
ObjectStatistics * p_dest) const;
/** expand available (i.e. committed) space to size @p z **/
/** expand available (i.e. committed) space to size at least @p z
* In practice will round up to a multiple of @ref page_z_
**/
bool expand(std::size_t z);
// inherited from IAlloc...

27
include/xo/alloc/GC.hpp
View file

@ -33,12 +33,16 @@ namespace xo {
struct Config {
/** initial size in bytes for youngest (Nursery) generation.
* GC allocates two nursery spaces of this size.
* Will allocate more space as needed
* This number represents reserved address space.
* pages are committed on demand.
* Initial committment will be up to @ref incr_gc_threshold_
**/
std::size_t initial_nursery_z_ = 0;
/** initial size in bytes for oldest (Tenured) generation.
* GC allocates two tenured spaces of this size
* Will allocate more space as needed
* GC allocates two tenured spaces of this size.
* This number represents reserved address space.
* pages are committed on demand.
* Initial committment will be up to @ref full_gc_threshold_
**/
std::size_t initial_tenured_z_ = 0;
/** trigger incremental GC after this many bytes allocated in nursery **/
@ -158,6 +162,8 @@ namespace xo {
bool is_gc_enabled() const { return gc_enabled_ == 0; }
/** true iff GC has been requested **/
bool is_gc_pending() const { return incr_gc_pending_ || full_gc_pending_; }
/** true iff full GC pending **/
bool is_full_gc_pending() const { return full_gc_pending_; }
/** true during (and only during) a GC cycle **/
bool gc_in_progress() const { return runstate_.in_progress(); }
/** @return reserved size of Nursery to-space **/
@ -170,6 +176,10 @@ namespace xo {
std::size_t nursery_after_checkpoint() const;
/** @return allocated memory range for nursery **/
std::pair<const std::byte *, const std::byte *> nursery_span(role role) const;
/** @return nursery bytes used in from-space
* (only interesting during GC copy phase, e.g. during scope of a GcCopyCallback call)
**/
std::size_t nursery_from_allocated() const;
/** @return reserved size of Tenured to-space **/
std::size_t tenured_to_reserved() const;
/** @return committed size of Tenured to-space **/
@ -186,19 +196,19 @@ namespace xo {
* and allocated size of that generation
* @p role chooses between to-space and from-space
**/
std::tuple<generation_result, std::size_t, std::size_t> location_of(role role, const void * x) const;
std::tuple<generation_result, std::size_t, std::size_t, std::size_t> location_of(role role, const void * x) const;
/** @return generation to which object at @p x belongs,
* location relative to base address for @p x,
* and allocated size of generation
**/
std::tuple<generation_result,std::size_t,std::size_t> tospace_location_of(const void * x) const;
std::tuple<generation_result, std::size_t, std::size_t, std::size_t> tospace_location_of(const void * x) const;
/** @return generation that contains @p x, given it's in from-space **/
generation_result fromspace_generation_of(const void * x) const;
/** @return generation to which object at @p x belongs,
* location relative to base address for @p x,
* and allocated size of generation
**/
std::tuple<generation_result,std::size_t,std::size_t> fromspace_location_of(const void * x) const;
std::tuple<generation_result, std::size_t, std::size_t, std::size_t> fromspace_location_of(const void * x) const;
/** true iff from-space contains @p x **/
bool fromspace_contains(const void * x) const;
/** @return free pointer for generation @p gen, i.e. nursery or tenured space **/
@ -215,7 +225,10 @@ namespace xo {
* Intended for GC visualization.
**/
CallbackId add_gc_copy_callback(up<GcCopyCallback> fn);
/** request garbage collection. **/
/** request garbage collection.
* If GC currently disabled, collection will be deferred until the next time GC
* is in an enabled state. See @ref disable_gc and @ref enable_gc
**/
void request_gc(generation g);
/** disable garbage collection until matching call to @ref enable_gc.
*