BIF_RETTYPE lists_reverse_2(BIF_ALIST_2)
{
/* Handle legal and illegal non-lists quickly. */
if (is_nil(BIF_ARG_1)) {
BIF_RET(BIF_ARG_2);
} else if (is_not_list(BIF_ARG_1)) {
BIF_ERROR(BIF_P, BADARG);
}
/* We build the reversal on the unused part of the heap if possible to save
* us the trouble of having to figure out the list size. We fall back to
* lists_reverse_alloc when we run out of space. */
if (HeapWordsLeft(BIF_P) > 8) {
return lists_reverse_onheap(BIF_P, BIF_ARG_1, BIF_ARG_2);
}
return lists_reverse_alloc(BIF_P, BIF_ARG_1, BIF_ARG_2);
}
static void grow(Process *p)
{
unsigned int i,j;
unsigned int steps = p->dictionary->homeSize / 5;
Eterm l1,l2;
Eterm l;
Eterm *hp;
unsigned int pos;
unsigned int homeSize;
int needed = 0;
ProcDict *pd;
#ifdef DEBUG
Eterm *hp_limit;
#endif
HDEBUGF(("grow: steps = %d", steps));
if (steps == 0)
steps = 1;
/* Dont grow over MAX_HASH */
if ((MAX_HASH - steps) <= HASH_RANGE(p->dictionary)) {
return;
}
/*
* Calculate total number of heap words needed, and garbage collect
* if necessary.
*/
pd = p->dictionary;
pos = pd->splitPosition;
homeSize = pd->homeSize;
for (i = 0; i < steps; ++i) {
if (pos == homeSize) {
homeSize *= 2;
pos = 0;
}
l = ARRAY_GET(pd, pos);
pos++;
if (is_not_tuple(l)) {
while (l != NIL) {
needed += 2;
l = TCDR(l);
}
}
}
if (HeapWordsLeft(p) < needed) {
BUMP_REDS(p, erts_garbage_collect(p, needed, 0, 0));
}
#ifdef DEBUG
hp_limit = p->htop + needed;
#endif
/*
* Now grow.
*/
for (i = 0; i < steps; ++i) {
ProcDict *pd = p->dictionary;
if (pd->splitPosition == pd->homeSize) {
pd->homeSize *= 2;
pd->splitPosition = 0;
}
pos = pd->splitPosition;
++pd->splitPosition; /* For the hashes */
l = ARRAY_GET(pd, pos);
if (is_tuple(l)) {
if (pd_hash_value(pd, tuple_val(l)[1]) != pos) {
array_put(&(p->dictionary), pos +
p->dictionary->homeSize, l);
array_put(&(p->dictionary), pos, NIL);
}
} else {
l2 = NIL;
l1 = l;
for (j = 0; l1 != NIL; l1 = TCDR(l1))
j += 2;
hp = HeapOnlyAlloc(p, j);
while (l != NIL) {
if (pd_hash_value(pd, tuple_val(TCAR(l))[1]) == pos)
l1 = CONS(hp, TCAR(l), l1);
else
l2 = CONS(hp, TCAR(l), l2);
hp += 2;
l = TCDR(l);
}
if (l1 != NIL && TCDR(l1) == NIL)
l1 = TCAR(l1);
if (l2 != NIL && TCDR(l2) == NIL)
l2 = TCAR(l2);
ASSERT(hp <= hp_limit);
/* After array_put pd is no longer valid */
array_put(&(p->dictionary), pos, l1);
array_put(&(p->dictionary), pos +
p->dictionary->homeSize, l2);
}
}
#ifdef HARDDEBUG
dictionary_dump(p->dictionary,CERR);
#endif
}
static void shrink(Process *p, Eterm* ret)
{
unsigned int range = HASH_RANGE(p->dictionary);
unsigned int steps = (range*3) / 10;
Eterm hi, lo, tmp;
unsigned int i;
Eterm *hp;
#ifdef DEBUG
Eterm *hp_limit;
#endif
if (range - steps < INITIAL_SIZE) {
steps = range - INITIAL_SIZE;
}
for (i = 0; i < steps; ++i) {
ProcDict *pd = p->dictionary;
if (pd->splitPosition == 0) {
pd->homeSize /= 2;
pd->splitPosition = pd->homeSize;
}
--(pd->splitPosition);
hi = ARRAY_GET(pd, (pd->splitPosition + pd->homeSize));
lo = ARRAY_GET(pd, pd->splitPosition);
if (hi != NIL) {
if (lo == NIL) {
array_put(&(p->dictionary), pd->splitPosition, hi);
} else {
int needed = 4;
if (is_list(hi) && is_list(lo)) {
needed = 2*erts_list_length(hi);
}
if (HeapWordsLeft(p) < needed) {
BUMP_REDS(p, erts_garbage_collect(p, needed, ret, 1));
hi = pd->data[(pd->splitPosition + pd->homeSize)];
lo = pd->data[pd->splitPosition];
}
#ifdef DEBUG
hp_limit = p->htop + needed;
#endif
if (is_tuple(lo)) {
if (is_tuple(hi)) {
hp = HeapOnlyAlloc(p, 4);
tmp = CONS(hp, hi, NIL);
hp += 2;
array_put(&(p->dictionary), pd->splitPosition,
CONS(hp,lo,tmp));
hp += 2;
ASSERT(hp <= hp_limit);
} else { /* hi is a list */
hp = HeapOnlyAlloc(p, 2);
array_put(&(p->dictionary), pd->splitPosition,
CONS(hp, lo, hi));
hp += 2;
ASSERT(hp <= hp_limit);
}
} else { /* lo is a list */
if (is_tuple(hi)) {
hp = HeapOnlyAlloc(p, 2);
array_put(&(p->dictionary), pd->splitPosition,
CONS(hp, hi, lo));
hp += 2;
ASSERT(hp <= hp_limit);
} else { /* Two lists */
hp = HeapOnlyAlloc(p, needed);
for (tmp = hi; tmp != NIL; tmp = TCDR(tmp)) {
lo = CONS(hp, TCAR(tmp), lo);
hp += 2;
}
ASSERT(hp <= hp_limit);
array_put(&(p->dictionary), pd->splitPosition, lo);
}
}
}
}
array_put(&(p->dictionary), (pd->splitPosition + pd->homeSize), NIL);
}
if (HASH_RANGE(p->dictionary) <= (p->dictionary->size / 4)) {
array_shrink(&(p->dictionary), (HASH_RANGE(p->dictionary) * 3) / 2);
}
}
static Eterm pd_hash_put(Process *p, Eterm id, Eterm value)
{
unsigned int hval;
Eterm *hp;
Eterm tpl;
Eterm old;
Eterm tmp;
int needed;
int i = 0;
#ifdef DEBUG
Eterm *hp_limit;
#endif
if (p->dictionary == NULL) {
/* Create it */
array_put(&(p->dictionary), INITIAL_SIZE - 1, NIL);
p->dictionary->homeSize = INITIAL_SIZE;
}
hval = pd_hash_value(p->dictionary, id);
old = ARRAY_GET(p->dictionary, hval);
/*
* Calculate the number of heap words needed and garbage
* collect if necessary. (Might be a slight overestimation.)
*/
needed = 3; /* {Key,Value} tuple */
if (is_boxed(old)) {
/*
* We don't want to compare keys twice, so we'll always
* reserve the space for two CONS cells.
*/
needed += 2+2;
} else if (is_list(old)) {
i = 0;
for (tmp = old; tmp != NIL && !EQ(tuple_val(TCAR(tmp))[1], id); tmp = TCDR(tmp)) {
++i;
}
if (is_nil(tmp)) {
i = -1;
needed += 2;
} else {
needed += 2*(i+1);
}
}
if (HeapWordsLeft(p) < needed) {
Eterm root[3];
root[0] = id;
root[1] = value;
root[2] = old;
BUMP_REDS(p, erts_garbage_collect(p, needed, root, 3));
id = root[0];
value = root[1];
old = root[2];
}
#ifdef DEBUG
hp_limit = p->htop + needed;
#endif
/*
* Create the {Key,Value} tuple.
*/
hp = HeapOnlyAlloc(p, 3);
tpl = TUPLE2(hp, id, value);
/*
* Update the dictionary.
*/
if (is_nil(old)) {
array_put(&(p->dictionary), hval, tpl);
++(p->dictionary->numElements);
} else if (is_boxed(old)) {
ASSERT(is_tuple(old));
if (EQ(tuple_val(old)[1],id)) {
array_put(&(p->dictionary), hval, tpl);
return tuple_val(old)[2];
} else {
hp = HeapOnlyAlloc(p, 4);
tmp = CONS(hp, old, NIL);
hp += 2;
++(p->dictionary->numElements);
array_put(&(p->dictionary), hval, CONS(hp, tpl, tmp));
hp += 2;
ASSERT(hp <= hp_limit);
}
} else if (is_list(old)) {
if (i == -1) {
/*
* New key. Simply prepend the tuple to the beginning of the list.
*/
hp = HeapOnlyAlloc(p, 2);
array_put(&(p->dictionary), hval, CONS(hp, tpl, old));
hp += 2;
ASSERT(hp <= hp_limit);
++(p->dictionary->numElements);
} else {
/*
* i = Number of CDRs to skip to reach the changed element in the list.
*
* Replace old value in list. To avoid pointers from the old generation
* to the new, we must rebuild the list from the beginning up to and
* including the changed element.
*/
Eterm nlist;
int j;
hp = HeapOnlyAlloc(p, (i+1)*2);
/* Find the list element to change. */
for (j = 0, nlist = old; j < i; j++, nlist = TCDR(nlist)) {
;
}
ASSERT(EQ(tuple_val(TCAR(nlist))[1], id));
nlist = TCDR(nlist); /* Unchanged part of list. */
/* Rebuild list before the updated element. */
for (tmp = old; i-- > 0; tmp = TCDR(tmp)) {
nlist = CONS(hp, TCAR(tmp), nlist);
hp += 2;
}
ASSERT(EQ(tuple_val(TCAR(tmp))[1], id));
/* Put the updated element first in the new list. */
nlist = CONS(hp, tpl, nlist);
hp += 2;
ASSERT(hp <= hp_limit);
array_put(&(p->dictionary), hval, nlist);
return tuple_val(TCAR(tmp))[2];
}
} else {
#ifdef DEBUG
erts_fprintf(stderr,
"Process dictionary for process %T is broken, trying to "
"display term found in line %d:\n"
"%T\n", p->common.id, __LINE__, old);
#endif
erl_exit(1, "Damaged process dictionary found during put/2.");
}
if (HASH_RANGE(p->dictionary) <= p->dictionary->numElements) {
grow(p);
}
return am_undefined;
}
BIF_RETTYPE lists_reverse_2(BIF_ALIST_2)
{
Eterm list;
Eterm tmp_list;
Eterm result;
Eterm* hp;
Uint n;
int max_iter;
/*
* Handle legal and illegal non-lists quickly.
*/
if (is_nil(BIF_ARG_1)) {
BIF_RET(BIF_ARG_2);
} else if (is_not_list(BIF_ARG_1)) {
error:
BIF_ERROR(BIF_P, BADARG);
}
/*
* First use the rest of the remaning heap space.
*/
list = BIF_ARG_1;
result = BIF_ARG_2;
hp = HEAP_TOP(BIF_P);
n = HeapWordsLeft(BIF_P) / 2;
while (n != 0 && is_list(list)) {
Eterm* pair = list_val(list);
result = CONS(hp, CAR(pair), result);
list = CDR(pair);
hp += 2;
n--;
}
HEAP_TOP(BIF_P) = hp;
if (is_nil(list)) {
BIF_RET(result);
}
/*
* Calculate length of remaining list (up to a suitable limit).
*/
max_iter = CONTEXT_REDS * 40;
n = 0;
tmp_list = list;
while (max_iter-- > 0 && is_list(tmp_list)) {
tmp_list = CDR(list_val(tmp_list));
n++;
}
if (is_not_nil(tmp_list) && is_not_list(tmp_list)) {
goto error;
}
/*
* Now do one HAlloc() and continue reversing.
*/
hp = HAlloc(BIF_P, 2*n);
while (n != 0 && is_list(list)) {
Eterm* pair = list_val(list);
result = CONS(hp, CAR(pair), result);
list = CDR(pair);
hp += 2;
n--;
}
if (is_nil(list)) {
BIF_RET(result);
} else {
BUMP_ALL_REDS(BIF_P);
BIF_TRAP2(bif_export[BIF_lists_reverse_2], BIF_P, list, result);
}
}
static BIF_RETTYPE append(Process* p, Eterm A, Eterm B)
{
Eterm list;
Eterm copy;
Eterm last;
Eterm* hp = NULL;
Sint i;
list = A;
if (is_nil(list)) {
BIF_RET(B);
}
if (is_not_list(list)) {
BIF_ERROR(p, BADARG);
}
/* optimistic append on heap first */
if ((i = HeapWordsLeft(p) / 2) < 4) {
goto list_tail;
}
hp = HEAP_TOP(p);
copy = last = CONS(hp, CAR(list_val(list)), make_list(hp+2));
list = CDR(list_val(list));
hp += 2;
i -= 2; /* don't use the last 2 words (extra i--;) */
while(i-- && is_list(list)) {
Eterm* listp = list_val(list);
last = CONS(hp, CAR(listp), make_list(hp+2));
list = CDR(listp);
hp += 2;
}
/* A is proper and B is NIL return A as-is, don't update HTOP */
if (is_nil(list) && is_nil(B)) {
BIF_RET(A);
}
if (is_nil(list)) {
HEAP_TOP(p) = hp;
CDR(list_val(last)) = B;
BIF_RET(copy);
}
list_tail:
if ((i = erts_list_length(list)) < 0) {
BIF_ERROR(p, BADARG);
}
/* remaining list was proper and B is NIL */
if (is_nil(B)) {
BIF_RET(A);
}
if (hp) {
/* Note: fall through case, already written
* on the heap.
* The last 2 words of the heap is not written yet
*/
Eterm *hp_save = hp;
ASSERT(i != 0);
HEAP_TOP(p) = hp + 2;
if (i == 1) {
hp[0] = CAR(list_val(list));
hp[1] = B;
BIF_RET(copy);
}
hp = HAlloc(p, 2*(i - 1));
last = CONS(hp_save, CAR(list_val(list)), make_list(hp));
} else {
hp = HAlloc(p, 2*i);
copy = last = CONS(hp, CAR(list_val(list)), make_list(hp+2));
hp += 2;
}
list = CDR(list_val(list));
i--;
ASSERT(i > -1);
while(i--) {
Eterm* listp = list_val(list);
last = CONS(hp, CAR(listp), make_list(hp+2));
list = CDR(listp);
hp += 2;
}
CDR(list_val(last)) = B;
BIF_RET(copy);
}
