// Free n objects from a span s back into the central free list c.
// Called during sweep.
// Returns true if the span was returned to heap.
bool
runtime_MCentral_FreeSpan(MCentral *c, MSpan *s, int32 n, MLink *start, MLink *end)
{
int32 size;
runtime_lock(c);
// Move to nonempty if necessary.
if(s->freelist == nil) {
runtime_MSpanList_Remove(s);
runtime_MSpanList_Insert(&c->nonempty, s);
}
// Add the objects back to s's free list.
end->next = s->freelist;
s->freelist = start;
s->ref -= n;
c->nfree += n;
if(s->ref != 0) {
runtime_unlock(c);
return false;
}
// s is completely freed, return it to the heap.
size = runtime_class_to_size[c->sizeclass];
runtime_MSpanList_Remove(s);
s->needzero = 1;
s->freelist = nil;
c->nfree -= (s->npages << PageShift) / size;
runtime_unlock(c);
runtime_unmarkspan((byte*)(s->start<<PageShift), s->npages<<PageShift);
runtime_MHeap_Free(&runtime_mheap, s, 0);
return true;
}
// Return s to the heap. s must be unused (s->ref == 0). Unlocks c.
static void
MCentral_ReturnToHeap(MCentral *c, MSpan *s)
{
int32 size;
size = runtime_class_to_size[c->sizeclass];
runtime_MSpanList_Remove(s);
s->needzero = 1;
s->freelist = nil;
if(s->ref != 0)
runtime_throw("ref wrong");
c->nfree -= (s->npages << PageShift) / size;
runtime_unlock(&c->lock);
runtime_unmarkspan((byte*)(s->start<<PageShift), s->npages<<PageShift);
runtime_MHeap_Free(&runtime_mheap, s, 0);
}
// Helper: free one object back into the central free list.
static void
MCentral_Free(MCentral *c, void *v)
{
MSpan *s;
MLink *p;
int32 size;
// Find span for v.
s = runtime_MHeap_Lookup(&runtime_mheap, v);
if(s == nil || s->ref == 0)
runtime_throw("invalid free");
// Move to nonempty if necessary.
if(s->freelist == nil) {
runtime_MSpanList_Remove(s);
runtime_MSpanList_Insert(&c->nonempty, s);
}
// Add v back to s's free list.
p = v;
p->next = s->freelist;
s->freelist = p;
c->nfree++;
// If s is completely freed, return it to the heap.
if(--s->ref == 0) {
size = runtime_class_to_size[c->sizeclass];
runtime_MSpanList_Remove(s);
runtime_unmarkspan((byte*)(s->start<<PageShift), s->npages<<PageShift);
*(uintptr*)(s->start<<PageShift) = 1; // needs zeroing
s->freelist = nil;
c->nfree -= (s->npages << PageShift) / size;
runtime_unlock(c);
runtime_MHeap_Free(&runtime_mheap, s, 0);
runtime_lock(c);
}
}
