pathauditor: disable cache of audited paths by default (issue5628) The initial attempt was to discard cache when appropriate, but it appears to be error prone. We had to carefully inspect all places where audit() is called e.g. without actually updating filesystem, before removing files and directories, etc. So, this patch disables the cache of audited paths by default, and enables it only for the following cases: - short-lived auditor objects - repo.vfs, repo.svfs, and repo.cachevfs, which are managed directories and considered sort of append-only (a file/directory would never be replaced with a symlink) There would be more cacheable vfs objects (e.g. mq.queue.opener), but I decided not to inspect all of them in this patch. We can make them cached later. Benchmark result: - using old clone of http://selenic.com/repo/linux-2.6/ (38319 files) - on tmpfs - run HGRCPATH=/dev/null hg up -q --time tip && hg up -q null - try 4 times and take the last three results original: real 7.480 secs (user 1.140+22.760 sys 0.150+1.690) real 8.010 secs (user 1.070+22.280 sys 0.170+2.120) real 7.470 secs (user 1.120+22.390 sys 0.120+1.910) clearcache (the other series): real 7.680 secs (user 1.120+23.420 sys 0.140+1.970) real 7.670 secs (user 1.110+23.620 sys 0.130+1.810) real 7.740 secs (user 1.090+23.510 sys 0.160+1.940) enable cache only for vfs and svfs (this series): real 8.730 secs (user 1.500+25.190 sys 0.260+2.260) real 8.750 secs (user 1.490+25.170 sys 0.250+2.340) real 9.010 secs (user 1.680+25.340 sys 0.280+2.540) remove cache function at all (for reference): real 9.620 secs (user 1.440+27.120 sys 0.250+2.980) real 9.420 secs (user 1.400+26.940 sys 0.320+3.130) real 9.760 secs (user 1.530+27.270 sys 0.250+2.970)