view mercurial/cext/util.h @ 37968:0304f22497fa

revlog: use node tree (native code) for shortest() calculation

I want to rewrite revlog.shortest() to disambiguate only among hex
nodeids and then disambiguate the result with revnums at a higher
level (in scmutil). However, that would slow down `hg log -T
'{shortest(node,1)}\n'` from 5.0s to 6.8s, which I wasn't sure would
be acceptable. So this patch makes revlog.shortest() use the node tree
for finding the length of the shortest prefix that's unambiguous among
nodeids. Once that has been found, it makes it longer until it is also
not ambiguous with a revnum.

This speeds up `hg log -T '{shortest(node,1)}\n'` from 5.0s to 4.0s.

Differential Revision: https://phab.mercurial-scm.org/D3499

/*
 util.h - utility functions for interfacing with the various python APIs.

 This software may be used and distributed according to the terms of
 the GNU General Public License, incorporated herein by reference.
*/

#ifndef _HG_UTIL_H_
#define _HG_UTIL_H_

#include "compat.h"

#if PY_MAJOR_VERSION >= 3
#define IS_PY3K
#endif

/* helper to switch things like string literal depending on Python version */
#ifdef IS_PY3K
#define PY23(py2, py3) py3
#else
#define PY23(py2, py3) py2
#endif

/* clang-format off */
typedef struct {
	PyObject_HEAD
	char state;
	int mode;
	int size;
	int mtime;
} dirstateTupleObject;
/* clang-format on */

extern PyTypeObject dirstateTupleType;
#define dirstate_tuple_check(op) (Py_TYPE(op) == &dirstateTupleType)

#ifndef MIN
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#endif
/* VC9 doesn't include bool and lacks stdbool.h based on my searching */
#if defined(_MSC_VER) || __STDC_VERSION__ < 199901L
#define true 1
#define false 0
typedef unsigned char bool;
#else
#include <stdbool.h>
#endif

static inline PyObject *_dict_new_presized(Py_ssize_t expected_size)
{
	/* _PyDict_NewPresized expects a minused parameter, but it actually
	   creates a dictionary that's the nearest power of two bigger than the
	   parameter. For example, with the initial minused = 1000, the
	   dictionary created has size 1024. Of course in a lot of cases that
	   can be greater than the maximum load factor Python's dict object
	   expects (= 2/3), so as soon as we cross the threshold we'll resize
	   anyway. So create a dictionary that's at least 3/2 the size. */
	return _PyDict_NewPresized(((1 + expected_size) / 2) * 3);
}

#endif /* _HG_UTIL_H_ */