view mercurial/util.h @ 29304:5e32852fa4bd

revset: make filteredset.__nonzero__ respect the order of the filteredset

This fix allows __nonzero__ to respect the direction of iteration of the
whole filteredset. Here's the case when it matters. Imagine that we have a
very large repository and we want to execute a command like:

    $ hg log --rev '(tip:0) and user(ikostia)' --limit 1

(we want to get the latest commit by me).

Mercurial will evaluate a filteredset lazy data structure, an
instance of the filteredset class, which will know that it has to iterate
in a descending order (isdescending() will return True if called). This
means that when some code iterates over the instance of this filteredset,
the 'and user(ikostia)' condition will be first checked on the latest
revision, then on the second latest and so on, allowing Mercurial to
print matches as it founds them. However, cmdutil.getgraphlogrevs
contains the following code:

    revs = _logrevs(repo, opts)
    if not revs:
        return revset.baseset(), None, None

The "not revs" expression is evaluated by calling filteredset.__nonzero__,
which in its current implementation will try to iterate the filteredset
in ascending order until it finds a revision that matches the 'and user(..'
condition. If the condition is only true on late revisions, a lot of
useless iterations will be done. These iterations could be avoided if
__nonzero__ followed the order of the filteredset, which in my opinion
is a sensible thing to do here.

The problem gets even worse when instead of 'user(ikostia)' some more
expensive check is performed, like grepping the commit diff.


I tested this fix on a very large repo where tip is my commit and my very
first commit comes fairly late in the revision history. Results of timing
of the above command on that very large repo.

-with my fix:
real    0m1.795s
user    0m1.657s
sys     0m0.135s

-without my fix:
real    1m29.245s
user    1m28.223s
sys     0m0.929s

I understand that this is a very specific kind of problem that presents
itself very rarely, only on very big repositories and with expensive
checks and so on. But I don't see any disadvantages to this kind of fix
either.

/*
 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_

#if PY_MAJOR_VERSION >= 3

#define IS_PY3K
#define PyInt_FromLong PyLong_FromLong
#define PyInt_AsLong PyLong_AsLong

/*
 Mapping of some of the python < 2.x PyString* functions to py3k's PyUnicode.

 The commented names below represent those that are present in the PyBytes
 definitions for python < 2.6 (below in this file) that don't have a direct
 implementation.
*/

#define PyStringObject PyUnicodeObject
#define PyString_Type PyUnicode_Type

#define PyString_Check PyUnicode_Check
#define PyString_CheckExact PyUnicode_CheckExact
#define PyString_CHECK_INTERNED PyUnicode_CHECK_INTERNED
#define PyString_AS_STRING PyUnicode_AsLatin1String
#define PyString_GET_SIZE PyUnicode_GET_SIZE

#define PyString_FromStringAndSize PyUnicode_FromStringAndSize
#define PyString_FromString PyUnicode_FromString
#define PyString_FromFormatV PyUnicode_FromFormatV
#define PyString_FromFormat PyUnicode_FromFormat
/* #define PyString_Size PyUnicode_GET_SIZE */
/* #define PyString_AsString */
/* #define PyString_Repr */
#define PyString_Concat PyUnicode_Concat
#define PyString_ConcatAndDel PyUnicode_AppendAndDel
#define _PyString_Resize PyUnicode_Resize
/* #define _PyString_Eq */
#define PyString_Format PyUnicode_Format
/* #define _PyString_FormatLong */
/* #define PyString_DecodeEscape */
#define _PyString_Join PyUnicode_Join
#define PyString_Decode PyUnicode_Decode
#define PyString_Encode PyUnicode_Encode
#define PyString_AsEncodedObject PyUnicode_AsEncodedObject
#define PyString_AsEncodedString PyUnicode_AsEncodedString
#define PyString_AsDecodedObject PyUnicode_AsDecodedObject
#define PyString_AsDecodedString PyUnicode_AsDecodedUnicode
/* #define PyString_AsStringAndSize */
#define _PyString_InsertThousandsGrouping _PyUnicode_InsertThousandsGrouping

#endif /* PY_MAJOR_VERSION */

#ifdef _WIN32
#ifdef _MSC_VER
/* msvc 6.0 has problems */
#define inline __inline
typedef signed char int8_t;
typedef short int16_t;
typedef long int32_t;
typedef __int64 int64_t;
typedef unsigned char uint8_t;
typedef unsigned short uint16_t;
typedef unsigned long uint32_t;
typedef unsigned __int64 uint64_t;
#else
#include <stdint.h>
#endif
#else
/* not windows */
#include <sys/types.h>
#if defined __BEOS__ && !defined __HAIKU__
#include <ByteOrder.h>
#else
#include <arpa/inet.h>
#endif
#include <inttypes.h>
#endif

#if defined __hpux || defined __SUNPRO_C || defined _AIX
#define inline
#endif

#ifdef __linux
#define inline __inline
#endif

typedef struct {
	PyObject_HEAD
	char state;
	int mode;
	int size;
	int mtime;
} dirstateTupleObject;

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

static inline uint32_t getbe32(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;

	return ((d[0] << 24) |
		(d[1] << 16) |
		(d[2] << 8) |
		(d[3]));
}

static inline int16_t getbeint16(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;

	return ((d[0] << 8) |
		(d[1]));
}

static inline uint16_t getbeuint16(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;

	return ((d[0] << 8) |
		(d[1]));
}

static inline void putbe32(uint32_t x, char *c)
{
	c[0] = (x >> 24) & 0xff;
	c[1] = (x >> 16) & 0xff;
	c[2] = (x >> 8) & 0xff;
	c[3] = (x) & 0xff;
}

static inline double getbefloat64(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;
	double ret;
	int i;
	uint64_t t = 0;
	for (i = 0; i < 8; i++) {
		t = (t<<8) + d[i];
	}
	memcpy(&ret, &t, sizeof(t));
	return ret;
}

/* This should be kept in sync with normcasespecs in encoding.py. */
enum normcase_spec {
	NORMCASE_LOWER = -1,
	NORMCASE_UPPER = 1,
	NORMCASE_OTHER = 0
};

#define MIN(a, b) (((a)<(b))?(a):(b))
/* 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

#endif /* _HG_UTIL_H_ */