mercurial/exewrapper.c

encoding: add fast-path for ASCII uppercase.

This copies the performance hack from encoding.lower (c481761033bd).

The case-folding logic that kicks in on case-insensitive filesystems
hits encoding.upper hard: with a repository with 75k files, the
timings went from

  hg perfstatus
  ! wall 3.156000 comb 3.156250 user 1.625000 sys 1.531250 (best of 3)

to

  hg perfstatus
  ! wall 2.390000 comb 2.390625 user 1.078125 sys 1.312500 (best of 5)

This is a 24% decrease. For comparison, Mercurial 2.0 gives:

  hg perfstatus
  ! wall 2.172000 comb 2.171875 user 0.984375 sys 1.187500 (best of 5)

so we're only 10% slower than before we added the extra case-folding
logic.

The same decrease is seen when executing 'hg status' as normal, where
we go from:

  hg status --time
  time: real 4.322 secs (user 2.219+0.000 sys 2.094+0.000)

to

  hg status --time
  time: real 3.307 secs (user 1.750+0.000 sys 1.547+0.000)

/*
 exewrapper.c - wrapper for calling a python script on Windows

 Copyright 2012 Adrian Buehlmann <[e-mail]> and others

 This software may be used and distributed according to the terms of the
 GNU General Public License version 2 or any later version.
*/

#include <Python.h>
#include <windows.h>


#ifdef __GNUC__
int strcat_s(char *d, size_t n, const char *s)
{
	return !strncat(d, s, n);
}
#endif


static char pyscript[MAX_PATH + 10];

int main(int argc, char *argv[])
{
	char *dot;
	int ret;
	int i;
	int n;
	char **pyargv;
	WIN32_FIND_DATA fdata;
	HANDLE hfind;
	const char *err;

	if (GetModuleFileName(NULL, pyscript, sizeof(pyscript)) == 0)
	{
		err = "GetModuleFileName failed";
		goto bail;
	}

	dot = strrchr(pyscript, '.');
	if (dot == NULL) {
		err = "malformed module filename";
		goto bail;
	}
	*dot = 0; /* cut trailing ".exe" */

	hfind = FindFirstFile(pyscript, &fdata);
	if (hfind != INVALID_HANDLE_VALUE) {
		/* pyscript exists, close handle */
		FindClose(hfind);
	} else {
		/* file pyscript isn't there, take <pyscript>exe.py */
		strcat_s(pyscript, sizeof(pyscript), "exe.py");
	}

	/*
	Only add the pyscript to the args, if it's not already there. It may
	already be there, if the script spawned a child process of itself, in
	the same way as it got called, that is, with the pyscript already in
	place. So we optionally accept the pyscript as the first argument
	(argv[1]), letting our exe taking the role of the python interpreter.
	*/
	if (argc >= 2 && strcmp(argv[1], pyscript) == 0) {
		/*
		pyscript is already in the args, so there is no need to copy
		the args and we can directly call the python interpreter with
		the original args.
		*/
		return Py_Main(argc, argv);
	}

	/*
	Start assembling the args for the Python interpreter call. We put the
	name of our exe (argv[0]) in the position where the python.exe
	canonically is, and insert the pyscript next.
	*/
	pyargv = malloc((argc + 5) * sizeof(char*));
	if (pyargv == NULL) {
		err = "not enough memory";
		goto bail;
	}
	n = 0;
	pyargv[n++] = argv[0];
	pyargv[n++] = pyscript;

	/* copy remaining args from the command line */
	for (i = 1; i < argc; i++)
		pyargv[n++] = argv[i];
	/* argv[argc] is guaranteed to be NULL, so we forward that guarantee */
	pyargv[n] = NULL;

	ret = Py_Main(n, pyargv); /* The Python interpreter call */

	free(pyargv);
	return ret;

bail:
	fprintf(stderr, "abort: %s\n", err);
	return 255;
}