Fcalva/cyclone
1
0
Fork 0
mirror of https://github.com/justinethier/cyclone.git synced 2025-07-16 17:27:33 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

Added comments around trace/alloc/clear colors

Browse source
This commit is contained in:
Justin Ethier 2018-07-18 13:14:45 -04:00
parent df27292e6d
commit 91c67aee8b
1 changed files with 12 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
gc.c
View file

@ -1624,6 +1624,13 @@ gc_heap *gc_sweep(gc_heap * h, int heap_type, gc_thread_data *thd)
} }
#endif #endif
// Use the object's mark to determine if we keep it.
// Need to check for both colors because:
// - Objects that are either newly-allocated or recently traced are given
// the alloc color, and we need to keep them.
// - If the collector is currently tracing, objects not traced yet will
// have the trace/clear color. We need to keep any of those to make sure
// the collector has a chance to trace the entire heap.
if (//mark(p) != markColor && if (//mark(p) != markColor &&
mark(p) != thd->gc_alloc_color && mark(p) != thd->gc_alloc_color &&
mark(p) != thd->gc_trace_color) { //gc_color_clear) mark(p) != thd->gc_trace_color) { //gc_color_clear)
@ -2113,6 +2120,11 @@ void gc_mark_gray(gc_thread_data * thd, object obj)
// From what I can tell, no other thread would be modifying // From what I can tell, no other thread would be modifying
// either object type or mark. Both should be stable once the object is placed // either object type or mark. Both should be stable once the object is placed
// into the heap, with the collector being the only thread that changes marks. // into the heap, with the collector being the only thread that changes marks.
//
// Note when marking we check for both clear and purple to prevent against
// timing issues when incrementing colors and since if we ever reach a
// purple object during tracing we would want to mark it.
// TODO: revisit if checking for gc_color_purple is truly necessary here and elsewhere.
if (is_object_type(obj) && (mark(obj) == gc_color_clear || if (is_object_type(obj) && (mark(obj) == gc_color_clear ||
mark(obj) == gc_color_purple)) { // TODO: sync?? mark(obj) == gc_color_purple)) { // TODO: sync??
// Place marked object in a buffer to avoid repeated scans of the heap. // Place marked object in a buffer to avoid repeated scans of the heap.