slab*
ObjectCache::InitSlab(slab* slab, void* pages, size_t byteCount, uint32 flags)
{
TRACE_CACHE(this, "construct (%p, %p .. %p, %lu)", slab, pages,
((uint8*)pages) + byteCount, byteCount);
slab->pages = pages;
slab->count = slab->size = byteCount / object_size;
slab->free = NULL;
size_t spareBytes = byteCount - (slab->size * object_size);
if ((this->flags & CACHE_ALIGN_ON_SIZE) != 0) {
slab->offset = cache_color_cycle;
if (slab->offset > spareBytes)
cache_color_cycle = slab->offset = 0;
else
cache_color_cycle += kCacheColorPeriod;
} else
slab->offset = 0;
TRACE_CACHE(this, " %lu objects, %lu spare bytes, offset %lu",
slab->size, spareBytes, slab->offset);
uint8* data = ((uint8*)pages) + slab->offset;
CREATE_PARANOIA_CHECK_SET(slab, "slab");
for (size_t i = 0; i < slab->size; i++) {
status_t status = B_OK;
if (constructor)
status = constructor(cookie, data);
if (status != B_OK) {
data = ((uint8*)pages) + slab->offset;
for (size_t j = 0; j < i; j++) {
if (destructor)
destructor(cookie, data);
data += object_size;
}
DELETE_PARANOIA_CHECK_SET(slab);
return NULL;
}
_push(slab->free, object_to_link(data, object_size));
ADD_PARANOIA_CHECK(PARANOIA_SUSPICIOUS, slab,
&object_to_link(data, object_size)->next, sizeof(void*));
data += object_size;
}
return slab;
}
void
ObjectCache::ReturnObjectToSlab(slab* source, void* object, uint32 flags)
{
if (source == NULL) {
panic("object_cache: free'd object has no slab");
return;
}
ParanoiaChecker _(source);
uint8* data = (uint8*) object;
if (data < source->pages
|| data >= (uint8*) source->pages + source->size * object_size) {
panic("object_cache: free'd object does not belong to slab");
}
intptr_t objectOffset = data - source->offset - (uint8*) source->pages;
if (objectOffset % object_size != 0) {
panic("object_cache: returning a wrong pointer to a slab object");
}
object_link* link = object_to_link(object, object_size);
TRACE_CACHE(this, "returning %p (%p) to %p, %lu used (%lu empty slabs).",
object, link, source, source->size - source->count,
empty_count);
_push(source->free, link);
source->count++;
used_count--;
ADD_PARANOIA_CHECK(PARANOIA_SUSPICIOUS, source, &link->next, sizeof(void*));
if (source->count == source->size) {
partial.Remove(source);
if (empty_count < pressure
&& total_objects - used_count - source->size
>= min_object_reserve) {
empty_count++;
empty.Add(source);
} else {
ReturnSlab(source, flags);
}
} else if (source->count == 1) {
full.Remove(source);
partial.Add(source);
}
}
void
ObjectCache::ReturnObjectToSlab(slab* source, void* object, uint32 flags)
{
if (source == NULL) {
panic("object_cache: free'd object has no slab");
return;
}
ParanoiaChecker _(source);
object_link* link = object_to_link(object, object_size);
TRACE_CACHE(this, "returning %p (%p) to %p, %lu used (%lu empty slabs).",
object, link, source, source->size - source->count,
empty_count);
_push(source->free, link);
source->count++;
used_count--;
ADD_PARANOIA_CHECK(PARANOIA_SUSPICIOUS, source, &link->next, sizeof(void*));
if (source->count == source->size) {
partial.Remove(source);
if (empty_count < pressure
&& total_objects - used_count - source->size
>= min_object_reserve) {
empty_count++;
empty.Add(source);
} else {
ReturnSlab(source, flags);
}
} else if (source->count == 1) {
full.Remove(source);
partial.Add(source);
}
}