DUK_LOCAL void duk__sweep_stringtable(duk_heap *heap, duk_size_t *out_count_keep) {
duk_hstring *h;
duk_hstring *prev;
duk_uint32_t i;
#if defined(DUK_USE_DEBUG)
duk_size_t count_free = 0;
#endif
duk_size_t count_keep = 0;
DUK_DD(DUK_DDPRINT("duk__sweep_stringtable: %p", (void *) heap));
#if defined(DUK_USE_STRTAB_PTRCOMP)
if (heap->strtable16 == NULL) {
#else
if (heap->strtable == NULL) {
#endif
goto done;
}
for (i = 0; i < heap->st_size; i++) {
#if defined(DUK_USE_STRTAB_PTRCOMP)
h = DUK_USE_HEAPPTR_DEC16(heap->heap_udata, heap->strtable16[i]);
#else
h = heap->strtable[i];
#endif
prev = NULL;
while (h != NULL) {
duk_hstring *next;
next = h->hdr.h_next;
if (DUK_HEAPHDR_HAS_REACHABLE((duk_heaphdr *) h)) {
DUK_HEAPHDR_CLEAR_REACHABLE((duk_heaphdr *) h);
count_keep++;
prev = h;
} else {
#if defined(DUK_USE_DEBUG)
count_free++;
#endif
#if defined(DUK_USE_REFERENCE_COUNTING)
/* Non-zero refcounts should not happen for unreachable strings,
* because we refcount finalize all unreachable objects which
* should have decreased unreachable string refcounts to zero
* (even for cycles).
*/
DUK_ASSERT(DUK_HEAPHDR_GET_REFCOUNT((duk_heaphdr *) h) == 0);
#endif
/* deal with weak references first */
duk_heap_strcache_string_remove(heap, (duk_hstring *) h);
/* remove the string from the string table */
duk_heap_strtable_unlink_prev(heap, (duk_hstring *) h, (duk_hstring *) prev);
/* free inner references (these exist e.g. when external
* strings are enabled) and the struct itself.
*/
duk_free_hstring(heap, (duk_hstring *) h);
/* don't update 'prev'; it should be last string kept */
}
h = next;
}
}
done:
#if defined(DUK_USE_DEBUG)
DUK_D(DUK_DPRINT("mark-and-sweep sweep stringtable: %ld freed, %ld kept",
(long) count_free, (long) count_keep));
#endif
*out_count_keep = count_keep;
}
/*
* Sweep heap
*/
DUK_LOCAL void duk__sweep_heap(duk_heap *heap, duk_int_t flags, duk_size_t *out_count_keep) {
duk_heaphdr *prev; /* last element that was left in the heap */
duk_heaphdr *curr;
duk_heaphdr *next;
#if defined(DUK_USE_DEBUG)
duk_size_t count_free = 0;
duk_size_t count_finalize = 0;
duk_size_t count_rescue = 0;
#endif
duk_size_t count_keep = 0;
DUK_UNREF(flags);
DUK_DD(DUK_DDPRINT("duk__sweep_heap: %p", (void *) heap));
prev = NULL;
curr = heap->heap_allocated;
heap->heap_allocated = NULL;
while (curr) {
/* Strings and ROM objects are never placed on the heap allocated list. */
DUK_ASSERT(DUK_HEAPHDR_GET_TYPE(curr) != DUK_HTYPE_STRING);
DUK_ASSERT(!DUK_HEAPHDR_HAS_READONLY(curr));
next = DUK_HEAPHDR_GET_NEXT(heap, curr);
if (DUK_HEAPHDR_HAS_REACHABLE(curr)) {
/*
* Reachable object, keep
*/
DUK_DDD(DUK_DDDPRINT("sweep, reachable: %p", (void *) curr));
if (DUK_HEAPHDR_HAS_FINALIZABLE(curr)) {
/*
* If object has been marked finalizable, move it to the
* "to be finalized" work list. It will be collected on
* the next mark-and-sweep if it is still unreachable
* after running the finalizer.
*/
DUK_ASSERT(!DUK_HEAPHDR_HAS_FINALIZED(curr));
DUK_ASSERT(DUK_HEAPHDR_GET_TYPE(curr) == DUK_HTYPE_OBJECT);
DUK_DDD(DUK_DDDPRINT("object has finalizer, move to finalization work list: %p", (void *) curr));
#if defined(DUK_USE_DOUBLE_LINKED_HEAP)
if (heap->finalize_list) {
DUK_HEAPHDR_SET_PREV(heap, heap->finalize_list, curr);
}
DUK_HEAPHDR_SET_PREV(heap, curr, NULL);
#endif
DUK_HEAPHDR_SET_NEXT(heap, curr, heap->finalize_list);
DUK_ASSERT_HEAPHDR_LINKS(heap, curr);
heap->finalize_list = curr;
#if defined(DUK_USE_DEBUG)
count_finalize++;
#endif
} else {
/*
* Object will be kept; queue object back to heap_allocated (to tail)
*/
if (DUK_HEAPHDR_HAS_FINALIZED(curr)) {
/*
* Object's finalizer was executed on last round, and
* object has been happily rescued.
*/
DUK_ASSERT(!DUK_HEAPHDR_HAS_FINALIZABLE(curr));
DUK_ASSERT(DUK_HEAPHDR_GET_TYPE(curr) == DUK_HTYPE_OBJECT);
DUK_DD(DUK_DDPRINT("object rescued during mark-and-sweep finalization: %p", (void *) curr));
#if defined(DUK_USE_DEBUG)
count_rescue++;
#endif
} else {
/*
* Plain, boring reachable object.
*/
DUK_DD(DUK_DDPRINT("keep object: %!iO", curr));
count_keep++;
}
if (!heap->heap_allocated) {
heap->heap_allocated = curr;
}
if (prev) {
DUK_HEAPHDR_SET_NEXT(heap, prev, curr);
}
#if defined(DUK_USE_DOUBLE_LINKED_HEAP)
DUK_HEAPHDR_SET_PREV(heap, curr, prev);
#endif
DUK_ASSERT_HEAPHDR_LINKS(heap, prev);
DUK_ASSERT_HEAPHDR_LINKS(heap, curr);
prev = curr;
}
DUK_HEAPHDR_CLEAR_REACHABLE(curr);
DUK_HEAPHDR_CLEAR_FINALIZED(curr);
DUK_HEAPHDR_CLEAR_FINALIZABLE(curr);
DUK_ASSERT(!DUK_HEAPHDR_HAS_REACHABLE(curr));
DUK_ASSERT(!DUK_HEAPHDR_HAS_FINALIZED(curr));
DUK_ASSERT(!DUK_HEAPHDR_HAS_FINALIZABLE(curr));
curr = next;
} else {
/*
* Unreachable object, free
*/
DUK_DDD(DUK_DDDPRINT("sweep, not reachable: %p", (void *) curr));
#if defined(DUK_USE_REFERENCE_COUNTING)
/* Non-zero refcounts should not happen because we refcount
* finalize all unreachable objects which should cancel out
* refcounts (even for cycles).
*/
DUK_ASSERT(DUK_HEAPHDR_GET_REFCOUNT(curr) == 0);
#endif
DUK_ASSERT(!DUK_HEAPHDR_HAS_FINALIZABLE(curr));
if (DUK_HEAPHDR_HAS_FINALIZED(curr)) {
DUK_DDD(DUK_DDDPRINT("finalized object not rescued: %p", (void *) curr));
}
/* Note: object cannot be a finalizable unreachable object, as
* they have been marked temporarily reachable for this round,
* and are handled above.
*/
#if defined(DUK_USE_DEBUG)
count_free++;
#endif
/* weak refs should be handled here, but no weak refs for
* any non-string objects exist right now.
*/
/* free object and all auxiliary (non-heap) allocs */
duk_heap_free_heaphdr_raw(heap, curr);
curr = next;
}
}
if (prev) {
DUK_HEAPHDR_SET_NEXT(heap, prev, NULL);
}
DUK_ASSERT_HEAPHDR_LINKS(heap, prev);
#if defined(DUK_USE_DEBUG)
DUK_D(DUK_DPRINT("mark-and-sweep sweep objects (non-string): %ld freed, %ld kept, %ld rescued, %ld queued for finalization",
(long) count_free, (long) count_keep, (long) count_rescue, (long) count_finalize));
#endif
*out_count_keep = count_keep;
}
static void duk__sweep_heap(duk_heap *heap, duk_int_t flags, duk_size_t *out_count_keep) {
duk_heaphdr *prev; /* last element that was left in the heap */
duk_heaphdr *curr;
duk_heaphdr *next;
#ifdef DUK_USE_DEBUG
duk_size_t count_free = 0;
duk_size_t count_finalize = 0;
duk_size_t count_rescue = 0;
#endif
duk_size_t count_keep = 0;
DUK_UNREF(flags);
DUK_DD(DUK_DDPRINT("duk__sweep_heap: %p", (void *) heap));
prev = NULL;
curr = heap->heap_allocated;
heap->heap_allocated = NULL;
while (curr) {
/* strings are never placed on the heap allocated list */
DUK_ASSERT(DUK_HEAPHDR_GET_TYPE(curr) != DUK_HTYPE_STRING);
next = DUK_HEAPHDR_GET_NEXT(curr);
if (DUK_HEAPHDR_HAS_REACHABLE(curr)) {
/*
* Reachable object, keep
*/
DUK_DDD(DUK_DDDPRINT("sweep, reachable: %p", (void *) curr));
if (DUK_HEAPHDR_HAS_FINALIZABLE(curr)) {
/*
* If object has been marked finalizable, move it to the
* "to be finalized" work list. It will be collected on
* the next mark-and-sweep if it is still unreachable
* after running the finalizer.
*/
DUK_ASSERT(!DUK_HEAPHDR_HAS_FINALIZED(curr));
DUK_ASSERT(DUK_HEAPHDR_GET_TYPE(curr) == DUK_HTYPE_OBJECT);
DUK_DDD(DUK_DDDPRINT("object has finalizer, move to finalization work list: %p", (void *) curr));
#ifdef DUK_USE_DOUBLE_LINKED_HEAP
if (heap->finalize_list) {
DUK_HEAPHDR_SET_PREV(heap->finalize_list, curr);
}
DUK_HEAPHDR_SET_PREV(curr, NULL);
#endif
DUK_HEAPHDR_SET_NEXT(curr, heap->finalize_list);
heap->finalize_list = curr;
#ifdef DUK_USE_DEBUG
count_finalize++;
#endif
} else {
/*
* Object will be kept; queue object back to heap_allocated (to tail)
*/
if (DUK_HEAPHDR_HAS_FINALIZED(curr)) {
/*
* Object's finalizer was executed on last round, and
* object has been happily rescued.
*/
DUK_ASSERT(!DUK_HEAPHDR_HAS_FINALIZABLE(curr));
DUK_ASSERT(DUK_HEAPHDR_GET_TYPE(curr) == DUK_HTYPE_OBJECT);
DUK_DD(DUK_DDPRINT("object rescued during mark-and-sweep finalization: %p", (void *) curr));
#ifdef DUK_USE_DEBUG
count_rescue++;
#endif
} else {
/*
* Plain, boring reachable object.
*/
count_keep++;
}
if (!heap->heap_allocated) {
heap->heap_allocated = curr;
}
if (prev) {
DUK_HEAPHDR_SET_NEXT(prev, curr);
}
#ifdef DUK_USE_DOUBLE_LINKED_HEAP
DUK_HEAPHDR_SET_PREV(curr, prev);
#endif
prev = curr;
}
DUK_HEAPHDR_CLEAR_REACHABLE(curr);
DUK_HEAPHDR_CLEAR_FINALIZED(curr);
DUK_HEAPHDR_CLEAR_FINALIZABLE(curr);
DUK_ASSERT(!DUK_HEAPHDR_HAS_REACHABLE(curr));
DUK_ASSERT(!DUK_HEAPHDR_HAS_FINALIZED(curr));
DUK_ASSERT(!DUK_HEAPHDR_HAS_FINALIZABLE(curr));
curr = next;
} else {
/*
* Unreachable object, free
*/
DUK_DDD(DUK_DDDPRINT("sweep, not reachable: %p", (void *) curr));
#if defined(DUK_USE_REFERENCE_COUNTING)
/* Non-zero refcounts should not happen because we refcount
* finalize all unreachable objects which should cancel out
* refcounts (even for cycles).
*/
DUK_ASSERT(DUK_HEAPHDR_GET_REFCOUNT(curr) == 0);
#endif
DUK_ASSERT(!DUK_HEAPHDR_HAS_FINALIZABLE(curr));
if (DUK_HEAPHDR_HAS_FINALIZED(curr)) {
DUK_DDD(DUK_DDDPRINT("finalized object not rescued: %p", (void *) curr));
}
/* Note: object cannot be a finalizable unreachable object, as
* they have been marked temporarily reachable for this round,
* and are handled above.
*/
#ifdef DUK_USE_DEBUG
count_free++;
#endif
/* weak refs should be handled here, but no weak refs for
* any non-string objects exist right now.
*/
/* free object and all auxiliary (non-heap) allocs */
duk_heap_free_heaphdr_raw(heap, curr);
curr = next;
}
}
if (prev) {
DUK_HEAPHDR_SET_NEXT(prev, NULL);
}
#ifdef DUK_USE_DEBUG
DUK_D(DUK_DPRINT("mark-and-sweep sweep objects (non-string): %d freed, %d kept, %d rescued, %d queued for finalization",
(int) count_free, (int) count_keep, (int) count_rescue, (int) count_finalize));
#endif
*out_count_keep = count_keep;
}
