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Issue #23290: Optimize set_merge() for cases where the target is empty.

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(Contributed by Serhiy Storchaka.)
This commit is contained in:
Raymond Hettinger 2015-05-13 01:26:14 -07:00
parent eac503aeac
commit 1bd8d75be3
2 changed files with 43 additions and 10 deletions
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50
Objects/setobject.c
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@ -548,16 +548,16 @@ set_merge(PySetObject *so, PyObject *otherset)
{
PySetObject *other;
PyObject *key;
Py_hash_t hash;
Py_ssize_t i;
setentry *entry;
setentry *so_entry;
setentry *other_entry;
assert (PyAnySet_Check(so));
assert (PyAnySet_Check(otherset));
other = (PySetObject*)otherset;
if (other == so || other->used == 0)
/* a.update(a) or a.update({}); nothing to do */
/* a.update(a) or a.update(set()); nothing to do */
return 0;
/* Do one big resize at the start, rather than
* incrementally resizing as we insert new keys. Expect
@ -567,14 +567,44 @@ set_merge(PySetObject *so, PyObject *otherset)
if (set_table_resize(so, (so->used + other->used)*2) != 0)
return -1;
}
for (i = 0; i <= other->mask; i++) {
entry = &other->table[i];
key = entry->key;
hash = entry->hash;
if (key != NULL &&
key != dummy) {
so_entry = so->table;
other_entry = other->table;
/* If our table is empty, and both tables have the same size, and
there are no dummies to eliminate, then just copy the pointers. */
if (so->fill == 0 && so->mask == other->mask && other->fill == other->used) {
for (i = 0; i <= other->mask; i++, so_entry++, other_entry++) {
key = other_entry->key;
if (key != NULL) {
assert(so_entry->key == NULL);
Py_INCREF(key);
so_entry->key = key;
so_entry->hash = other_entry->hash;
}
}
so->fill = other->fill;
so->used = other->used;
return 0;
}
/* If our table is empty, we can use set_insert_clean() */
if (so->fill == 0) {
for (i = 0; i <= other->mask; i++, other_entry++) {
key = other_entry->key;
if (key != NULL && key != dummy) {
Py_INCREF(key);
set_insert_clean(so, key, other_entry->hash);
}
}
return 0;
}
/* We can't assure there are no duplicates, so do normal insertions */
for (i = 0; i <= other->mask; i++, other_entry++) {
key = other_entry->key;
if (key != NULL && key != dummy) {
Py_INCREF(key);
if (set_insert_key(so, key, hash) == -1) {
if (set_insert_key(so, key, other_entry->hash)) {
Py_DECREF(key);
return -1;
}