mercurial/util.h

store: implement fncache basic path encoding in C

(This is not yet enabled; it will be turned on in a followup patch.)

The path encoding performed by fncache is complex and (perhaps
surprisingly) slow enough to negatively affect the overall performance
of Mercurial.

For a short path (< 120 bytes), the Python code can be reduced to a fairly
tractable state machine that either determines that nothing needs to be
done in a single pass, or performs the encoding in a second pass.

For longer paths, we avoid the more complicated hashed encoding scheme
for now, and fall back to Python.

Raw performance: I measured in a repo containing 150,000 files in its tip
manifest, with a median path name length of 57 bytes, and 95th percentile
of 96 bytes.

In this repo, the Python code takes 3.1 seconds to encode all path
names, while the hybrid C-and-Python code (called from Python) takes
0.21 seconds, for a speedup of about 14.

Across several other large repositories, I've measured the speedup from
the C code at between 26x and 40x.

For path names above 120 bytes where we must fall back to Python for
hashed encoding, the speedup is about 1.7x.  Thus absolute performance
will depend strongly on the characteristics of a particular repository.

/*
 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 */

/* Backports from 2.6 */
#if PY_VERSION_HEX < 0x02060000

#define Py_TYPE(ob) (ob)->ob_type
#define Py_SIZE(ob) (ob)->ob_size
#define PyVarObject_HEAD_INIT(type, size) PyObject_HEAD_INIT(type) size,

/* Shamelessly stolen from bytesobject.h */
#define PyBytesObject PyStringObject
#define PyBytes_Type PyString_Type

#define PyBytes_Check PyString_Check
#define PyBytes_CheckExact PyString_CheckExact
#define PyBytes_CHECK_INTERNED PyString_CHECK_INTERNED
#define PyBytes_AS_STRING PyString_AS_STRING
#define PyBytes_GET_SIZE PyString_GET_SIZE
#define Py_TPFLAGS_BYTES_SUBCLASS Py_TPFLAGS_STRING_SUBCLASS

#define PyBytes_FromStringAndSize PyString_FromStringAndSize
#define PyBytes_FromString PyString_FromString
#define PyBytes_FromFormatV PyString_FromFormatV
#define PyBytes_FromFormat PyString_FromFormat
#define PyBytes_Size PyString_Size
#define PyBytes_AsString PyString_AsString
#define PyBytes_Repr PyString_Repr
#define PyBytes_Concat PyString_Concat
#define PyBytes_ConcatAndDel PyString_ConcatAndDel
#define _PyBytes_Resize _PyString_Resize
#define _PyBytes_Eq _PyString_Eq
#define PyBytes_Format PyString_Format
#define _PyBytes_FormatLong _PyString_FormatLong
#define PyBytes_DecodeEscape PyString_DecodeEscape
#define _PyBytes_Join _PyString_Join
#define PyBytes_Decode PyString_Decode
#define PyBytes_Encode PyString_Encode
#define PyBytes_AsEncodedObject PyString_AsEncodedObject
#define PyBytes_AsEncodedString PyString_AsEncodedString
#define PyBytes_AsDecodedObject PyString_AsDecodedObject
#define PyBytes_AsDecodedString PyString_AsDecodedString
#define PyBytes_AsStringAndSize PyString_AsStringAndSize
#define _PyBytes_InsertThousandsGrouping _PyString_InsertThousandsGrouping

#endif /* PY_VERSION_HEX */

#if (PY_VERSION_HEX < 0x02050000)
/* Definitions to get compatibility with python 2.4 and earlier which
   does not have Py_ssize_t. See also PEP 353.
   Note: msvc (8 or earlier) does not have ssize_t, so we use Py_ssize_t.
*/
typedef int Py_ssize_t;
typedef Py_ssize_t (*lenfunc)(PyObject *);
typedef PyObject *(*ssizeargfunc)(PyObject *, Py_ssize_t);
#define PyInt_FromSsize_t PyInt_FromLong

#if !defined(PY_SSIZE_T_MIN)
#define PY_SSIZE_T_MAX INT_MAX
#define PY_SSIZE_T_MIN INT_MIN
#endif
#endif

#ifdef _WIN32
#ifdef _MSC_VER
/* msvc 6.0 has problems */
#define inline __inline
typedef unsigned char uint8_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

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 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;
}

#endif /* _HG_UTIL_H_ */