bpo-36748: optimize TextIOWrapper.write() for ASCII string (GH-13002)

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Inada Naoki 2019-05-16 15:03:20 +09:00 committed by GitHub
parent 8a533ffb49
commit bfba8c373e
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 98 additions and 21 deletions

View File

@ -0,0 +1,3 @@
Optimized write buffering in C implementation of ``TextIOWrapper``. Writing
ASCII string to ``TextIOWrapper`` with ascii, latin1, or utf-8 encoding is
about 20% faster. Patch by Inada Naoki.

View File

@ -674,8 +674,8 @@ typedef struct
*/
PyObject *decoded_chars; /* buffer for text returned from decoder */
Py_ssize_t decoded_chars_used; /* offset into _decoded_chars for read() */
PyObject *pending_bytes; /* list of bytes objects waiting to be
written, or NULL */
PyObject *pending_bytes; // data waiting to be written.
// ascii unicode, bytes, or list of them.
Py_ssize_t pending_bytes_count;
/* snapshot is either NULL, or a tuple (dec_flags, next_input) where
@ -777,6 +777,15 @@ latin1_encode(textio *self, PyObject *text)
return _PyUnicode_AsLatin1String(text, PyUnicode_AsUTF8(self->errors));
}
// Return true when encoding can be skipped when text is ascii.
static inline int
is_asciicompat_encoding(encodefunc_t f)
{
return f == (encodefunc_t) ascii_encode
|| f == (encodefunc_t) latin1_encode
|| f == (encodefunc_t) utf8_encode;
}
/* Map normalized encoding names onto the specialized encoding funcs */
typedef struct {
@ -1489,21 +1498,62 @@ _io_TextIOWrapper_detach_impl(textio *self)
static int
_textiowrapper_writeflush(textio *self)
{
PyObject *pending, *b, *ret;
if (self->pending_bytes == NULL)
return 0;
pending = self->pending_bytes;
Py_INCREF(pending);
self->pending_bytes_count = 0;
Py_CLEAR(self->pending_bytes);
PyObject *pending = self->pending_bytes;
PyObject *b;
b = _PyBytes_Join(_PyIO_empty_bytes, pending);
if (PyBytes_Check(pending)) {
b = pending;
Py_INCREF(b);
}
else if (PyUnicode_Check(pending)) {
assert(PyUnicode_IS_ASCII(pending));
assert(PyUnicode_GET_LENGTH(pending) == self->pending_bytes_count);
b = PyBytes_FromStringAndSize(
PyUnicode_DATA(pending), PyUnicode_GET_LENGTH(pending));
if (b == NULL) {
return -1;
}
}
else {
assert(PyList_Check(pending));
b = PyBytes_FromStringAndSize(NULL, self->pending_bytes_count);
if (b == NULL) {
return -1;
}
char *buf = PyBytes_AsString(b);
Py_ssize_t pos = 0;
for (Py_ssize_t i = 0; i < PyList_GET_SIZE(pending); i++) {
PyObject *obj = PyList_GET_ITEM(pending, i);
char *src;
Py_ssize_t len;
if (PyUnicode_Check(obj)) {
assert(PyUnicode_IS_ASCII(obj));
src = PyUnicode_DATA(obj);
len = PyUnicode_GET_LENGTH(obj);
}
else {
assert(PyBytes_Check(obj));
if (PyBytes_AsStringAndSize(obj, &src, &len) < 0) {
Py_DECREF(b);
return -1;
}
}
memcpy(buf + pos, src, len);
pos += len;
}
assert(pos == self->pending_bytes_count);
}
self->pending_bytes_count = 0;
self->pending_bytes = NULL;
Py_DECREF(pending);
if (b == NULL)
return -1;
ret = NULL;
PyObject *ret;
do {
ret = PyObject_CallMethodObjArgs(self->buffer,
_PyIO_str_write, b, NULL);
@ -1566,16 +1616,23 @@ _io_TextIOWrapper_write_impl(textio *self, PyObject *text)
/* XXX What if we were just reading? */
if (self->encodefunc != NULL) {
b = (*self->encodefunc)((PyObject *) self, text);
if (PyUnicode_IS_ASCII(text) && is_asciicompat_encoding(self->encodefunc)) {
b = text;
Py_INCREF(b);
}
else {
b = (*self->encodefunc)((PyObject *) self, text);
}
self->encoding_start_of_stream = 0;
}
else
b = PyObject_CallMethodObjArgs(self->encoder,
_PyIO_str_encode, text, NULL);
Py_DECREF(text);
if (b == NULL)
return NULL;
if (!PyBytes_Check(b)) {
if (b != text && !PyBytes_Check(b)) {
PyErr_Format(PyExc_TypeError,
"encoder should return a bytes object, not '%.200s'",
Py_TYPE(b)->tp_name);
@ -1583,20 +1640,37 @@ _io_TextIOWrapper_write_impl(textio *self, PyObject *text)
return NULL;
}
Py_ssize_t bytes_len;
if (b == text) {
bytes_len = PyUnicode_GET_LENGTH(b);
}
else {
bytes_len = PyBytes_GET_SIZE(b);
}
if (self->pending_bytes == NULL) {
self->pending_bytes = PyList_New(0);
if (self->pending_bytes == NULL) {
self->pending_bytes_count = 0;
self->pending_bytes = b;
}
else if (!PyList_CheckExact(self->pending_bytes)) {
PyObject *list = PyList_New(2);
if (list == NULL) {
Py_DECREF(b);
return NULL;
}
self->pending_bytes_count = 0;
PyList_SET_ITEM(list, 0, self->pending_bytes);
PyList_SET_ITEM(list, 1, b);
self->pending_bytes = list;
}
if (PyList_Append(self->pending_bytes, b) < 0) {
else {
if (PyList_Append(self->pending_bytes, b) < 0) {
Py_DECREF(b);
return NULL;
}
Py_DECREF(b);
return NULL;
}
self->pending_bytes_count += PyBytes_GET_SIZE(b);
Py_DECREF(b);
self->pending_bytes_count += bytes_len;
if (self->pending_bytes_count > self->chunk_size || needflush ||
text_needflush) {
if (_textiowrapper_writeflush(self) < 0)