branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
/*
* Utility functions
*
* Copyright (c) 2011 Yuya Nishihara <yuya@tcha.org>
*
* This software may be used and distributed according to the terms of the
* GNU General Public License version 2 or any later version.
*/
#ifndef UTIL_H_
#define UTIL_H_
#ifdef __GNUC__
#define PRINTF_FORMAT_ __attribute__((format(printf, 1, 2)))
#define UNUSED_ __attribute__((unused))
#else
#define PRINTF_FORMAT_
#define UNUSED_
#endif
void abortmsg(const char *fmt, ...) PRINTF_FORMAT_;
void abortmsgerrno(const char *fmt, ...) PRINTF_FORMAT_;
void enablecolor(void);
void enabledebugmsg(void);
void debugmsg(const char *fmt, ...) PRINTF_FORMAT_;
void fchdirx(int dirfd);
void fsetcloexec(int fd);
void *mallocx(size_t size);
void *reallocx(void *ptr, size_t size);
int runshellcmd(const char *cmd, const char *envp[], const char *cwd);
#endif /* UTIL_H_ */