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Commit 29dd37a4 authored by Augie Fackler's avatar Augie Fackler
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bdiff: write a native version of splitnewlines

./hg perfunidiff mercurial/manifest.py 0 --count 500 --profile before:
! wall 0.309280 comb 0.350000 user 0.290000 sys 0.060000 (best of 32)

./hg perfunidiff mercurial/manifest.py 0 --count 500 --profile after:
! wall 0.241572 comb 0.260000 user 0.240000 sys 0.020000 (best of 39)

so it's about 20% faster. I hate Python. I wish we could usefully
write this in Rust, but it doesn't look like that's realistic without
using the cpython crate, which I'd still like to avoid.

Differential Revision: https://phab.mercurial-scm.org/D1973
parent 4f3e9895
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......@@ -180,9 +180,57 @@
return result ? result : PyErr_NoMemory();
}
static bool sliceintolist(PyObject *list, Py_ssize_t destidx,
const char *source, Py_ssize_t len)
{
PyObject *sliced = PyBytes_FromStringAndSize(source, len);
if (sliced == NULL)
return false;
PyList_SET_ITEM(list, destidx, sliced);
return true;
}
static PyObject *splitnewlines(PyObject *self, PyObject *args)
{
const char *text;
Py_ssize_t nelts = 0, size, i, start = 0;
PyObject *result = NULL;
if (!PyArg_ParseTuple(args, "s#", &text, &size)) {
goto abort;
}
if (!size) {
return PyList_New(0);
}
/* This loops to size-1 because if the last byte is a newline,
* we don't want to perform a split there. */
for (i = 0; i < size - 1; ++i) {
if (text[i] == '\n') {
++nelts;
}
}
if ((result = PyList_New(nelts + 1)) == NULL)
goto abort;
nelts = 0;
for (i = 0; i < size - 1; ++i) {
if (text[i] == '\n') {
if (!sliceintolist(result, nelts++, text + start,
i - start + 1))
goto abort;
start = i + 1;
}
}
if (!sliceintolist(result, nelts++, text + start, size - start))
goto abort;
return result;
abort:
Py_XDECREF(result);
return NULL;
}
static char mdiff_doc[] = "Efficient binary diff.";
static PyMethodDef methods[] = {
{"bdiff", bdiff, METH_VARARGS, "calculate a binary diff\n"},
{"blocks", blocks, METH_VARARGS, "find a list of matching lines\n"},
{"fixws", fixws, METH_VARARGS, "normalize diff whitespaces\n"},
......@@ -183,9 +231,11 @@
static char mdiff_doc[] = "Efficient binary diff.";
static PyMethodDef methods[] = {
{"bdiff", bdiff, METH_VARARGS, "calculate a binary diff\n"},
{"blocks", blocks, METH_VARARGS, "find a list of matching lines\n"},
{"fixws", fixws, METH_VARARGS, "normalize diff whitespaces\n"},
{"splitnewlines", splitnewlines, METH_VARARGS,
"like str.splitlines, but only split on newlines\n"},
{NULL, NULL},
};
......@@ -189,7 +239,7 @@
{NULL, NULL},
};
static const int version = 1;
static const int version = 2;
#ifdef IS_PY3K
static struct PyModuleDef bdiff_module = {
......
......@@ -29,16 +29,7 @@
patches = mpatch.patches
patchedsize = mpatch.patchedsize
textdiff = bdiff.bdiff
def splitnewlines(text):
'''like str.splitlines, but only split on newlines.'''
lines = [l + '\n' for l in text.split('\n')]
if lines:
if lines[-1] == '\n':
lines.pop()
else:
lines[-1] = lines[-1][:-1]
return lines
splitnewlines = bdiff.splitnewlines
class diffopts(object):
'''context is the number of context lines
......
......@@ -71,7 +71,7 @@
# keep in sync with "version" in C modules
_cextversions = {
(r'cext', r'base85'): 1,
(r'cext', r'bdiff'): 1,
(r'cext', r'bdiff'): 2,
(r'cext', r'diffhelpers'): 1,
(r'cext', r'mpatch'): 1,
(r'cext', r'osutil'): 3,
......
......@@ -90,3 +90,13 @@
text = re.sub('[ \t\r]+', ' ', text)
text = text.replace(' \n', '\n')
return text
def splitnewlines(text):
'''like str.splitlines, but only split on newlines.'''
lines = [l + '\n' for l in text.split('\n')]
if lines:
if lines[-1] == '\n':
lines.pop()
else:
lines[-1] = lines[-1][:-1]
return lines
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