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* Improve a variable name: entry0 --> table.

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* Give set_lookkey_string() a fast alternate path when no dummy entries
  are present.
* Have set_swap_bodies() reset the hash field to -1 whenever either of
  bodies is not a frozenset.  Maintains the invariant of regular sets
  always having -1 in the hash field; otherwise, any mutation would make
  the hash value invalid.
* Use an entry pointer to simplify the code in frozenset_hash().
This commit is contained in:
Raymond Hettinger 2005-08-05 17:19:54 +00:00
parent a9d9936d10
commit a580c47c6d
1 changed files with 58 additions and 39 deletions
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97
Objects/setobject.c
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@ -46,7 +46,7 @@ set_lookkey(PySetObject *so, PyObject *key, register long hash)
register unsigned int perturb;
register setentry *freeslot;
register unsigned int mask = so->mask;
setentry *entry0 = so->table;
setentry *table = so->table;
register setentry *entry;
register int restore_error;
register int checked_error;
@ -55,7 +55,7 @@ set_lookkey(PySetObject *so, PyObject *key, register long hash)
PyObject *startkey;
i = hash & mask;
entry = &entry0[i];
entry = &table[i];
if (entry->key == NULL || entry->key == key)
return entry;
@ -74,7 +74,7 @@ set_lookkey(PySetObject *so, PyObject *key, register long hash)
cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
if (cmp < 0)
PyErr_Clear();
if (entry0 == so->table && entry->key == startkey) {
if (table == so->table && entry->key == startkey) {
if (cmp > 0)
goto Done;
}
@ -93,7 +93,7 @@ set_lookkey(PySetObject *so, PyObject *key, register long hash)
least likely outcome, so test for that last. */
for (perturb = hash; ; perturb >>= PERTURB_SHIFT) {
i = (i << 2) + i + perturb + 1;
entry = &entry0[i & mask];
entry = &table[i & mask];
if (entry->key == NULL) {
if (freeslot != NULL)
entry = freeslot;
@ -114,7 +114,7 @@ set_lookkey(PySetObject *so, PyObject *key, register long hash)
cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
if (cmp < 0)
PyErr_Clear();
if (entry0 == so->table && entry->key == startkey) {
if (table == so->table && entry->key == startkey) {
if (cmp > 0)
break;
}
@ -153,7 +153,7 @@ set_lookkey_string(PySetObject *so, PyObject *key, register long hash)
register unsigned int perturb;
register setentry *freeslot;
register unsigned int mask = so->mask;
setentry *entry0 = so->table;
setentry *table = so->table;
register setentry *entry;
/* Make sure this function doesn't have to handle non-string keys,
@ -165,31 +165,47 @@ set_lookkey_string(PySetObject *so, PyObject *key, register long hash)
return set_lookkey(so, key, hash);
}
i = hash & mask;
entry = &entry0[i];
entry = &table[i];
if (entry->key == NULL || entry->key == key)
return entry;
if (entry->key == dummy)
freeslot = entry;
else {
if (so->fill != so->used) {
if (entry->key == dummy)
freeslot = entry;
else {
if (entry->hash == hash && _PyString_Eq(entry->key, key))
return entry;
freeslot = NULL;
}
/* In the loop, key == dummy is by far (factor of 100s) the
least likely outcome, so test for that last. */
for (perturb = hash; ; perturb >>= PERTURB_SHIFT) {
i = (i << 2) + i + perturb + 1;
entry = &table[i & mask];
if (entry->key == NULL)
return freeslot == NULL ? entry : freeslot;
if (entry->key == key
|| (entry->hash == hash
&& entry->key != dummy
&& _PyString_Eq(entry->key, key)))
return entry;
if (entry->key == dummy && freeslot == NULL)
freeslot = entry;
}
} else {
/* Simplified loop that can assume are no dummy entries */
if (entry->hash == hash && _PyString_Eq(entry->key, key))
return entry;
freeslot = NULL;
}
/* In the loop, key == dummy is by far (factor of 100s) the
least likely outcome, so test for that last. */
for (perturb = hash; ; perturb >>= PERTURB_SHIFT) {
i = (i << 2) + i + perturb + 1;
entry = &entry0[i & mask];
if (entry->key == NULL)
return freeslot == NULL ? entry : freeslot;
if (entry->key == key
|| (entry->hash == hash
&& entry->key != dummy
&& _PyString_Eq(entry->key, key)))
return entry;
if (entry->key == dummy && freeslot == NULL)
freeslot = entry;
for (perturb = hash; ; perturb >>= PERTURB_SHIFT) {
i = (i << 2) + i + perturb + 1;
entry = &table[i & mask];
if (entry->key == NULL)
return entry;
if (entry->key == key
|| (entry->hash == hash
&& _PyString_Eq(entry->key, key)))
return entry;
}
}
}
@ -377,10 +393,8 @@ set_clear_internal(PySetObject *so)
setentry small_copy[PySet_MINSIZE];
#ifdef Py_DEBUG
int i, n;
#endif
assert (PyAnySet_Check(so));
#ifdef Py_DEBUG
n = so->mask + 1;
i = 0;
#endif
@ -841,7 +855,13 @@ set_swap_bodies(PySetObject *a, PySetObject *b)
memcpy(b->smalltable, tab, sizeof(tab));
}
h = a->hash; a->hash = b->hash; b->hash = h;
if (PyType_IsSubtype(a->ob_type, &PyFrozenSet_Type) &&
PyType_IsSubtype(b->ob_type, &PyFrozenSet_Type)) {
h = a->hash; a->hash = b->hash; b->hash = h;
} else {
a->hash = -1;
b->hash = -1;
}
}
static int
@ -1301,19 +1321,18 @@ static long
frozenset_hash(PyObject *self)
{
PySetObject *so = (PySetObject *)self;
long hash = 1927868237L;
int i, j;
long h, hash = 1927868237L;
setentry *entry;
int i;
if (so->hash != -1)
return so->hash;
hash *= set_len(self) + 1;
for (i=0, j=so->used ; j ; j--, i++) {
setentry *entry;
long h;
while ((entry = &so->table[i])->key == NULL || entry->key==dummy)
i++;
entry = &so->table[0];
for (i=so->used ; i ; entry++, i--) {
while (entry->key == NULL || entry->key==dummy)
entry++;
/* Work to increase the bit dispersion for closely spaced hash
values. The is important because some use cases have many
combinations of a small number of elements with nearby