[ovs-dev] [PATCH 1/2] Add optional C extension wrapper for Python JSON parsing
Terry Wilson
twilson at redhat.com
Tue May 10 02:40:22 UTC 2016
The pure Python in-tree JSON parser is *much* slower than the
in-tree C JSON parser. A local test parsing a 100Mb JSON file
showed the Python version taking 270 seconds. With the C wrapper,
it took 4 seconds.
The C extension will be used automatically if it can be built. If
the extension fails to build, a warning is displayed and the build
is restarted without the extension.
The Serializer class is replaced with Python's built-in
JSON library since the ability to process chunked data is not
needed in that case.
The extension should work with both Python 2.7 and Python 3.3+.
---
Makefile.am | 2 +-
python/automake.mk | 3 +
python/ovs/_json.c | 259 +++++++++++++++++++++++++++++++++++++++++++++++++++++
python/ovs/json.py | 11 +++
python/setup.py | 51 ++++++++++-
5 files changed, 323 insertions(+), 3 deletions(-)
create mode 100644 python/ovs/_json.c
diff --git a/Makefile.am b/Makefile.am
index 69dbe3d..8cb8523 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -251,7 +251,7 @@ config-h-check:
@cd $(srcdir); \
if test -e .git && (git --version) >/dev/null 2>&1 && \
git --no-pager grep -L '#include <config\.h>' `git ls-files | grep '\.c$$' | \
- grep -vE '^datapath|^lib/sflow|^third-party|^datapath-windows'`; \
+ grep -vE '^datapath|^lib/sflow|^third-party|^datapath-windows|^python'`; \
then \
echo "See above for list of violations of the rule that"; \
echo "every C source file must #include <config.h>."; \
diff --git a/python/automake.mk b/python/automake.mk
index dc62422..ecad39d 100644
--- a/python/automake.mk
+++ b/python/automake.mk
@@ -46,6 +46,9 @@ EXTRA_DIST += \
python/README.rst \
python/setup.py
+# C extension support.
+EXTRA_DIST += python/ovs/_json.c
+
PYFILES = $(ovs_pyfiles) python/ovs/dirs.py $(ovstest_pyfiles)
EXTRA_DIST += $(PYFILES)
PYCOV_CLEAN_FILES += $(PYFILES:.py=.py,cover)
diff --git a/python/ovs/_json.c b/python/ovs/_json.c
new file mode 100644
index 0000000..4f24823
--- /dev/null
+++ b/python/ovs/_json.c
@@ -0,0 +1,259 @@
+#include <openvswitch/lib/json.h>
+#include "Python.h"
+#include "structmember.h"
+
+#if PY_MAJOR_VERSION >= 3
+#define IS_PY3K
+#endif
+
+typedef struct {
+ PyObject_HEAD
+ struct json_parser *_parser;
+} json_ParserObject;
+
+static void
+Parser_dealloc(json_ParserObject *p)
+{
+ json_parser_abort(p->_parser);
+ Py_TYPE(p)->tp_free(p);
+}
+
+static PyObject *
+Parser_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
+{
+ json_ParserObject *self;
+ static char *kwlist[] = {"check_trailer", NULL};
+ PyObject *check_trailer = NULL;
+ int ct_int = 0;
+
+ if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|O", kwlist,
+ &check_trailer)) {
+ return NULL;
+ }
+
+ if (check_trailer != NULL) {
+ ct_int = PyObject_IsTrue(check_trailer);
+ if (ct_int < 0) {
+ return NULL;
+ } else if (ct_int) {
+ ct_int = JSPF_TRAILER;
+ }
+ }
+
+ self = (json_ParserObject *)type->tp_alloc(type, 0);
+ if (self != NULL) {
+ self->_parser = json_parser_create(ct_int);
+ }
+
+ return (PyObject *)self;
+}
+
+static PyObject *
+Parser_feed(json_ParserObject *self, PyObject *args)
+{
+ Py_ssize_t input_sz;
+ PyObject *input;
+ size_t rd;
+ char *input_str;
+
+ if (self->_parser == NULL) {
+ return NULL;
+ }
+
+ if (!PyArg_UnpackTuple(args, "input", 1, 1, &input)) {
+ return NULL;
+ }
+
+#ifdef IS_PY3K
+ if ((input_str = PyUnicode_AsUTF8AndSize(input, &input_sz)) == NULL) {
+#else
+ if (PyString_AsStringAndSize(input, &input_str, &input_sz) < 0) {
+#endif
+ return NULL;
+ }
+
+ rd = json_parser_feed(self->_parser, input_str, (size_t)input_sz);
+
+#ifdef IS_PY3K
+ return PyLong_FromSize_t(rd);
+#else
+ return PyInt_FromSize_t(rd);
+#endif
+}
+
+static PyObject *
+Parser_is_done(json_ParserObject *self)
+{
+ if (self->_parser == NULL) {
+ return NULL;
+ }
+ return PyBool_FromLong(json_parser_is_done(self->_parser));
+}
+
+static PyObject *
+json_to_python(struct json *json)
+{
+ switch (json->type) {
+ case JSON_NULL: Py_RETURN_NONE;
+ case JSON_FALSE: Py_RETURN_FALSE;
+ case JSON_TRUE: Py_RETURN_TRUE;
+ case JSON_OBJECT: {
+ struct shash_node *node;
+ PyObject *dict = PyDict_New();
+
+ if (dict == NULL) {
+ return PyErr_NoMemory();
+ }
+ SHASH_FOR_EACH(node, json->u.object) {
+ PyObject *key = PyUnicode_FromString(node->name);
+ PyObject *val = json_to_python(node->data);
+
+ if (!(key && val) || PyDict_SetItem(dict, key, val)) {
+ Py_XDECREF(key);
+ Py_XDECREF(val);
+ Py_XDECREF(dict);
+ return NULL;
+ }
+
+ Py_XDECREF(key);
+ Py_XDECREF(val);
+ }
+ return dict;
+ }
+ case JSON_ARRAY: {
+ int i;
+ PyObject *arr = PyList_New(json->u.array.n);
+ if (arr == NULL) {
+ return PyErr_NoMemory();
+ }
+ for (i = 0; i < json->u.array.n; i++) {
+ PyObject *item = json_to_python(json->u.array.elems[i]);
+ if (!item || PyList_SetItem(arr, i, item)) {
+ Py_XDECREF(arr);
+ return NULL;
+ }
+ }
+ return arr;
+ }
+ case JSON_INTEGER:
+#ifdef IS_PY3K
+ return PyLong_FromLong((long)json->u.integer);
+#else
+ return PyInt_FromLong((long)json->u.integer);
+#endif
+
+ case JSON_REAL: return PyFloat_FromDouble(json->u.real);
+ case JSON_STRING: return PyUnicode_FromString(json->u.string);
+ default: return NULL;
+ }
+}
+
+static PyObject *
+Parser_finish(json_ParserObject *self)
+{
+ struct json *json;
+ PyObject *obj;
+
+ if (self->_parser == NULL) {
+ return NULL;
+ }
+
+ json = json_parser_finish(self->_parser);
+ self->_parser = NULL;
+ obj = json_to_python(json);
+ return obj;
+}
+
+static PyMethodDef Parser_methods[] = {
+ {"feed", (PyCFunction)Parser_feed, METH_VARARGS,
+ "Feed data to the parser and return the index of the last object."},
+ {"is_done", (PyCFunction)Parser_is_done, METH_NOARGS,
+ "Whether the parser has finished decoding an object."},
+ {"finish", (PyCFunction)Parser_finish, METH_NOARGS,
+ "Finish parsing and return Python object parsed."},
+ {NULL},
+};
+
+static PyTypeObject json_ParserType = {
+ PyVarObject_HEAD_INIT(NULL, 0)
+ "ovs._json.Parser", /*tp_name*/
+ sizeof(json_ParserObject), /*tp_basicsize*/
+ 0, /*tp_itemsize*/
+ (destructor)Parser_dealloc, /*tp_dealloc*/
+ 0, /*tp_print*/
+ 0, /*tp_getattr*/
+ 0, /*tp_setattr*/
+ 0, /*tp_compare*/
+ 0, /*tp_repr*/
+ 0, /*tp_as_number*/
+ 0, /*tp_as_sequence*/
+ 0, /*tp_as_mapping*/
+ 0, /*tp_hash */
+ 0, /*tp_call*/
+ 0, /*tp_str*/
+ 0, /*tp_getattro*/
+ 0, /*tp_setattro*/
+ 0, /*tp_as_buffer*/
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
+ "Parser objects", /* tp_doc */
+ 0, /* tp_traverse */
+ 0, /* tp_clear */
+ 0, /* tp_richcompare */
+ 0, /* tp_weaklistoffset */
+ 0, /* tp_iter */
+ 0, /* tp_iternext */
+ Parser_methods, /* tp_methods */
+ 0, /* tp_members */
+ 0, /* tp_getset */
+ 0, /* tp_base */
+ 0, /* tp_dict */
+ 0, /* tp_descr_get */
+ 0, /* tp_descr_set */
+ 0, /* tp_dictoffset */
+ 0, /* tp_init */
+ 0, /* tp_alloc */
+ Parser_new, /* tp_new */
+};
+
+#ifdef IS_PY3K
+static struct PyModuleDef moduledef = {
+ PyModuleDef_HEAD_INIT,
+ "ovs._json", /* m_name */
+ "OVS JSON Parser module", /* m_doc */
+ 0, /* m_size */
+ 0, /* m_methods */
+ 0, /* m_slots */
+ 0, /* m_traverse */
+ 0, /* m_clear */
+ 0, /* m_free */
+};
+
+#define INITERROR return NULL
+# else /* !IS_PY3K */
+#define INITERROR return
+#endif
+
+PyMODINIT_FUNC
+#ifdef IS_PY3K
+PyInit__json(void)
+#else
+init_json(void)
+#endif
+{
+ PyObject *m;
+ if (PyType_Ready(&json_ParserType) < 0) {
+ INITERROR;
+ }
+
+#ifdef IS_PY3K
+ m = PyModule_Create(&moduledef);
+#else
+ m = Py_InitModule3("ovs._json", NULL, "OVS JSON Parser module");
+#endif
+
+ Py_INCREF(&json_ParserType);
+ PyModule_AddObject(m, "Parser", (PyObject *)&json_ParserType);
+#ifdef IS_PY3K
+ return m;
+#endif
+}
diff --git a/python/ovs/json.py b/python/ovs/json.py
index 42e697d..f1a6499 100644
--- a/python/ovs/json.py
+++ b/python/ovs/json.py
@@ -18,6 +18,11 @@ import sys
import six
from six.moves import range
+try:
+ import ovs._json
+except ImportError:
+ pass
+
__pychecker__ = 'no-stringiter'
escapes = {ord('"'): u"\\\"",
@@ -165,6 +170,12 @@ class Parser(object):
# Maximum height of parsing stack. #
MAX_HEIGHT = 1000
+ def __new__(cls, *args, **kwargs):
+ try:
+ return ovs._json.Parser(*args, **kwargs)
+ except NameError:
+ return super(Parser, cls).__new__(cls)
+
def __init__(self, check_trailer=False):
self.check_trailer = check_trailer
diff --git a/python/setup.py b/python/setup.py
index 49c8c4e..19c1f18 100644
--- a/python/setup.py
+++ b/python/setup.py
@@ -13,6 +13,10 @@
from __future__ import print_function
import sys
+from distutils.command.build_ext import build_ext
+from distutils.errors import CCompilerError, DistutilsExecError, \
+ DistutilsPlatformError
+
import setuptools
VERSION = "unknown"
@@ -25,8 +29,33 @@ except IOError:
file=sys.stderr)
sys.exit(-1)
+ext_errors = (CCompilerError, DistutilsExecError, DistutilsPlatformError)
+if sys.platform == 'win32':
+ ext_errors += (IOError, ValueError)
+
+
+class BuildFailed(Exception):
+ pass
+
+
+class try_build_ext(build_ext):
+ # This class allows C extension building to fail
+ # NOTE: build_ext is not a new-style class
+
+ def run(self):
+ try:
+ build_ext.run(self)
+ except DistutilsPlatformError:
+ raise BuildFailed()
-setuptools.setup(
+ def build_extension(self, ext):
+ try:
+ build_ext.build_extension(self, ext)
+ except ext_errors:
+ raise BuildFailed()
+
+
+setup_args = dict(
name='ovs',
description='Open vSwitch library',
version=VERSION,
@@ -46,5 +75,23 @@ setuptools.setup(
'Programming Language :: Python :: 2.7',
'Programming Language :: Python :: 3',
'Programming Language :: Python :: 3.4',
- ]
+ ],
+ ext_modules=[setuptools.Extension("ovs._json", sources=["ovs/_json.c"],
+ libraries=['openvswitch'])],
+ cmdclass={'build_ext': try_build_ext},
)
+
+try:
+ setuptools.setup(**setup_args)
+except BuildFailed:
+ BUILD_EXT_WARNING = ("WARNING: The C extension could not be compiled, "
+ "speedups are not enabled.")
+ print("*" * 75)
+ print(BUILD_EXT_WARNING)
+ print("Failure information, if any, is above.")
+ print("Retrying the build without the C extension.")
+ print("*" * 75)
+
+ del(setup_args['cmdclass'])
+ del(setup_args['ext_modules'])
+ setuptools.setup(**setup_args)
--
1.8.3.1
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