view mercurial/diffhelpers.c @ 24407:dd01834a696f stable

annotate: reuse ancestry context when adjusting linkrev (issue4532)

The linkrev adjustment will likely do the same ancestry walking multiple time
so we already have an optional mechanism to take advantage of this. Since
2896f53509a7, linkrev adjustment was done lazily to prevent too bad performance
impact on rename computation. However, this laziness created a quadratic
situation in 'annotate'.

Mercurial repo: hg annotate mercurial/commands.py
before:   8.090
after:  36.300

Mozilla repo: hg annotate layout/generic/nsTextFrame.cpp
before:   1.190
after:  290.230


So we setup sharing of the ancestry context in the annotate case too. Linkrev
adjustment still have an impact but it a much more sensible one.

Mercurial repo: hg annotate mercurial/commands.py
before:  36.300
after:   10.230

Mozilla repo: hg annotate layout/generic/nsTextFrame.cpp
before: 290.230
after:    5.560

/*
 * diffhelpers.c - helper routines for mpatch
 *
 * Copyright 2007 Chris Mason <[e-mail]>
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License v2, incorporated herein by reference.
 */

#include <Python.h>
#include <stdlib.h>
#include <string.h>

#include "util.h"

static char diffhelpers_doc[] = "Efficient diff parsing";
static PyObject *diffhelpers_Error;


/* fixup the last lines of a and b when the patch has no newline at eof */
static void _fix_newline(PyObject *hunk, PyObject *a, PyObject *b)
{
	Py_ssize_t hunksz = PyList_Size(hunk);
	PyObject *s = PyList_GET_ITEM(hunk, hunksz-1);
	char *l = PyBytes_AsString(s);
	Py_ssize_t alen = PyList_Size(a);
	Py_ssize_t blen = PyList_Size(b);
	char c = l[0];
	PyObject *hline;
	Py_ssize_t sz = PyBytes_GET_SIZE(s);

	if (sz > 1 && l[sz-2] == '\r')
		/* tolerate CRLF in last line */
		sz -= 1;

	hline = PyBytes_FromStringAndSize(l, sz-1);
	if (!hline) {
		return;
	}

	if (c == ' ' || c == '+') {
		PyObject *rline = PyBytes_FromStringAndSize(l + 1, sz - 2);
		PyList_SetItem(b, blen-1, rline);
	}
	if (c == ' ' || c == '-') {
		Py_INCREF(hline);
		PyList_SetItem(a, alen-1, hline);
	}
	PyList_SetItem(hunk, hunksz-1, hline);
}

/* python callable form of _fix_newline */
static PyObject *
fix_newline(PyObject *self, PyObject *args)
{
	PyObject *hunk, *a, *b;
	if (!PyArg_ParseTuple(args, "OOO", &hunk, &a, &b))
		return NULL;
	_fix_newline(hunk, a, b);
	return Py_BuildValue("l", 0);
}

#if (PY_VERSION_HEX < 0x02050000)
static const char *addlines_format = "OOiiOO";
#else
static const char *addlines_format = "OOnnOO";
#endif

/*
 * read lines from fp into the hunk.  The hunk is parsed into two arrays
 * a and b.  a gets the old state of the text, b gets the new state
 * The control char from the hunk is saved when inserting into a, but not b
 * (for performance while deleting files)
 */
static PyObject *
addlines(PyObject *self, PyObject *args)
{

	PyObject *fp, *hunk, *a, *b, *x;
	Py_ssize_t i;
	Py_ssize_t lena, lenb;
	Py_ssize_t num;
	Py_ssize_t todoa, todob;
	char *s, c;
	PyObject *l;
	if (!PyArg_ParseTuple(args, addlines_format,
			      &fp, &hunk, &lena, &lenb, &a, &b))
		return NULL;

	while (1) {
		todoa = lena - PyList_Size(a);
		todob = lenb - PyList_Size(b);
		num = todoa > todob ? todoa : todob;
		if (num == 0)
		    break;
		for (i = 0; i < num; i++) {
			x = PyFile_GetLine(fp, 0);
			s = PyBytes_AsString(x);
			c = *s;
			if (strcmp(s, "\\ No newline at end of file\n") == 0) {
				_fix_newline(hunk, a, b);
				continue;
			}
			if (c == '\n') {
				/* Some patches may be missing the control char
				 * on empty lines. Supply a leading space. */
				Py_DECREF(x);
				x = PyBytes_FromString(" \n");
			}
			PyList_Append(hunk, x);
			if (c == '+') {
				l = PyBytes_FromString(s + 1);
				PyList_Append(b, l);
				Py_DECREF(l);
			} else if (c == '-') {
				PyList_Append(a, x);
			} else {
				l = PyBytes_FromString(s + 1);
				PyList_Append(b, l);
				Py_DECREF(l);
				PyList_Append(a, x);
			}
			Py_DECREF(x);
		}
	}
	return Py_BuildValue("l", 0);
}

/*
 * compare the lines in a with the lines in b.  a is assumed to have
 * a control char at the start of each line, this char is ignored in the
 * compare
 */
static PyObject *
testhunk(PyObject *self, PyObject *args)
{

	PyObject *a, *b;
	long bstart;
	Py_ssize_t alen, blen;
	Py_ssize_t i;
	char *sa, *sb;

	if (!PyArg_ParseTuple(args, "OOl", &a, &b, &bstart))
		return NULL;
	alen = PyList_Size(a);
	blen = PyList_Size(b);
	if (alen > blen - bstart || bstart < 0) {
		return Py_BuildValue("l", -1);
	}
	for (i = 0; i < alen; i++) {
		sa = PyBytes_AsString(PyList_GET_ITEM(a, i));
		sb = PyBytes_AsString(PyList_GET_ITEM(b, i + bstart));
		if (strcmp(sa + 1, sb) != 0)
			return Py_BuildValue("l", -1);
	}
	return Py_BuildValue("l", 0);
}

static PyMethodDef methods[] = {
	{"addlines", addlines, METH_VARARGS, "add lines to a hunk\n"},
	{"fix_newline", fix_newline, METH_VARARGS, "fixup newline counters\n"},
	{"testhunk", testhunk, METH_VARARGS, "test lines in a hunk\n"},
	{NULL, NULL}
};

#ifdef IS_PY3K
static struct PyModuleDef diffhelpers_module = {
	PyModuleDef_HEAD_INIT,
	"diffhelpers",
	diffhelpers_doc,
	-1,
	methods
};

PyMODINIT_FUNC PyInit_diffhelpers(void)
{
	PyObject *m;

	m = PyModule_Create(&diffhelpers_module);
	if (m == NULL)
		return NULL;

	diffhelpers_Error = PyErr_NewException("diffhelpers.diffhelpersError",
											NULL, NULL);
	Py_INCREF(diffhelpers_Error);
	PyModule_AddObject(m, "diffhelpersError", diffhelpers_Error);

	return m;
}
#else
PyMODINIT_FUNC
initdiffhelpers(void)
{
	Py_InitModule3("diffhelpers", methods, diffhelpers_doc);
	diffhelpers_Error = PyErr_NewException("diffhelpers.diffhelpersError",
	                                        NULL, NULL);
}
#endif