contrib/chg/procutil.h

match: add visitchildrenset complement to visitdir

`visitdir(d)` lets a caller query whether the directory is part of the matcher.
It can receive a response of 'all' (yes, and all children, you can stop calling
visitdir now), False (no, and no children either), or True (yes, either
something in this directory or a child is part of the matcher).

`visitchildrenset(d)` augments that by instead of returning True, it returns a
list of items to actually investigate.  With this, code can be modified from:

    for f in self.all_items:
        if match.visitdir(self.dir + '/' + f):
            <do stuff>

to be:

    for f in self.all_items.intersect(match.visitchildrenset(self.dir)):
        <do stuff>

use of this function can provide significant performance improvements,
especially when using narrow (so that the matcher is much smaller than the stuff
we see on disk) and/or treemanifests (so that we can avoid loading manifests for
trees that aren't part of the matcher).

Differential Revision: https://phab.mercurial-scm.org/D4130

/*
 * Utilities about process handling - signal and subprocess (ex. pager)
 *
 * Copyright (c) 2011 Yuya Nishihara <[e-mail]>
 *
 * This software may be used and distributed according to the terms of the
 * GNU General Public License version 2 or any later version.
 */

#ifndef PROCUTIL_H_
#define PROCUTIL_H_

#include <unistd.h>

void restoresignalhandler(void);
void setupsignalhandler(pid_t pid, pid_t pgid);

pid_t setuppager(const char *pagercmd, const char *envp[]);
void waitpager(void);

#endif /* PROCUTIL_H_ */