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author | Collin Winter <collinw@gmail.com> | 2009-05-25 05:43:30 (GMT) |
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committer | Collin Winter <collinw@gmail.com> | 2009-05-25 05:43:30 (GMT) |
commit | 5c9b02dffe1276d6383c1c088e7bcb0464df24e8 (patch) | |
tree | 4b49c63cef9086f2a13d379bb93a355a0de20ebb /Modules | |
parent | 94c65d9a8ff8ec56c2420f46a6622803f7f1b154 (diff) | |
download | cpython-5c9b02dffe1276d6383c1c088e7bcb0464df24e8.zip cpython-5c9b02dffe1276d6383c1c088e7bcb0464df24e8.tar.gz cpython-5c9b02dffe1276d6383c1c088e7bcb0464df24e8.tar.bz2 |
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.
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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.
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Diffstat (limited to 'Modules')
-rw-r--r-- | Modules/_pickle.c | 90 |
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) { |