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authorCollin Winter <collinw@gmail.com>2009-05-25 05:43:30 (GMT)
committerCollin Winter <collinw@gmail.com>2009-05-25 05:43:30 (GMT)
commit5c9b02dffe1276d6383c1c088e7bcb0464df24e8 (patch)
tree4b49c63cef9086f2a13d379bb93a355a0de20ebb /Modules
parent94c65d9a8ff8ec56c2420f46a6622803f7f1b154 (diff)
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Merged revisions 72909 via svnmerge from
http://svn.python.org/projects/python/trunk Note that the performance improvement for the py3k branch is not as high as for trunk. ........ r72909 | collin.winter | 2009-05-24 21:34:39 -0700 (Sun, 24 May 2009) | 2 lines Issue 5670: special-case pickling of dicts. This nearly doubles the performance of dict pickling in cPickle. ........
Diffstat (limited to 'Modules')
-rw-r--r--Modules/_pickle.c90
1 files changed, 81 insertions, 9 deletions
diff --git a/Modules/_pickle.c b/Modules/_pickle.c
index 8adc136..30b1140 100644
--- a/Modules/_pickle.c
+++ b/Modules/_pickle.c
@@ -1699,6 +1699,69 @@ batch_dict(PicklerObject *self, PyObject *iter)
return -1;
}
+/* This is a variant of batch_dict() above that specializes for dicts, with no
+ * support for dict subclasses. Like batch_dict(), we batch up chunks of
+ * MARK key value ... key value SETITEMS
+ * opcode sequences. Calling code should have arranged to first create an
+ * empty dict, or dict-like object, for the SETITEMS to operate on.
+ * Returns 0 on success, -1 on error.
+ *
+ * Note that this currently doesn't work for protocol 0.
+ */
+static int
+batch_dict_exact(PicklerObject *self, PyObject *obj)
+{
+ PyObject *key = NULL, *value = NULL;
+ int i;
+ Py_ssize_t dict_size, ppos = 0;
+
+ static const char mark_op = MARK;
+ static const char setitem = SETITEM;
+ static const char setitems = SETITEMS;
+
+ assert(obj != NULL);
+ assert(self->proto > 0);
+
+ dict_size = PyDict_Size(obj);
+
+ /* Special-case len(d) == 1 to save space. */
+ if (dict_size == 1) {
+ PyDict_Next(obj, &ppos, &key, &value);
+ if (save(self, key, 0) < 0)
+ return -1;
+ if (save(self, value, 0) < 0)
+ return -1;
+ if (pickler_write(self, &setitem, 1) < 0)
+ return -1;
+ return 0;
+ }
+
+ /* Write in batches of BATCHSIZE. */
+ do {
+ i = 0;
+ if (pickler_write(self, &mark_op, 1) < 0)
+ return -1;
+ while (PyDict_Next(obj, &ppos, &key, &value)) {
+ if (save(self, key, 0) < 0)
+ return -1;
+ if (save(self, value, 0) < 0)
+ return -1;
+ if (++i == BATCHSIZE)
+ break;
+ }
+ if (pickler_write(self, &setitems, 1) < 0)
+ return -1;
+ if (PyDict_Size(obj) != dict_size) {
+ PyErr_Format(
+ PyExc_RuntimeError,
+ "dictionary changed size during iteration");
+ return -1;
+ }
+
+ } while (i == BATCHSIZE);
+ return 0;
+}
+
static int
save_dict(PicklerObject *self, PyObject *obj)
{
@@ -1733,15 +1796,24 @@ save_dict(PicklerObject *self, PyObject *obj)
if (len != 0) {
/* Save the dict items. */
- items = PyObject_CallMethod(obj, "items", "()");
- if (items == NULL)
- goto error;
- iter = PyObject_GetIter(items);
- Py_DECREF(items);
- if (iter == NULL)
- goto error;
- status = batch_dict(self, iter);
- Py_DECREF(iter);
+ if (PyDict_CheckExact(obj) && self->proto > 0) {
+ /* We can take certain shortcuts if we know this is a dict and
+ not a dict subclass. */
+ if (Py_EnterRecursiveCall(" while pickling an object") == 0) {
+ status = batch_dict_exact(self, obj);
+ Py_LeaveRecursiveCall();
+ }
+ } else {
+ items = PyObject_CallMethod(obj, "items", "()");
+ if (items == NULL)
+ goto error;
+ iter = PyObject_GetIter(items);
+ Py_DECREF(items);
+ if (iter == NULL)
+ goto error;
+ status = batch_dict(self, iter);
+ Py_DECREF(iter);
+ }
}
if (0) {