perf: omit copying from ui.ferr to ui.fout for Mercurial earlier than 1.9 Before this patch, referring ui.ferr prevents perf.py from measuring performance with Mercurial earlier than 1.9 (or 4e1ccd4c2b6d), because ui.ferr isn't available in such Mercurial, even though there are some code paths for Mercurial earlier than 1.9 in perf.py. For example, setting "_prereadsize" attribute in perfindex() and perfnodelookup() is effective only with hg earlier than 1.8 (or 61c9bc3da402).

perf: define formatter locally for Mercurial earlier than 2.2 Before this patch, using ui.formatter() prevents perf.py from measuring performance with Mercurial earlier than 2.2 (or ae5f92e154d3), because ui.formatter() isn't available in such Mercurial, even though there are some code paths for Mercurial earlier than 2.2 in perf.py. For example, setting "_prereadsize" attribute in perfindex() and perfnodelookup() is effective only with hg earlier than 1.8 (or 61c9bc3da402). This patch defines formatter class locally, and use it instead of the value returned by ui.formatter(), if perf.py is used with Mercurial earlier than 2.2. In this case, we don't need to think about -T/--template option for formatter, because previous patch made -T/--template disabled for perf.py with Mercurial earlier than 3.2 (or 7a7eed5176a4).

perf: add functions to get vfs-like object for Mercurial earlier than 2.3 Before this patch, using svfs prevents perf.py from measuring performance of Mercurial earlier than 2.3 (or 7034365089bf), because svfs isn't available in such Mercurial, even though there are some code paths for Mercurial earlier than 2.3 in perf.py. For example, setting "_prereadsize" attribute in perfindex() and perfnodelookup() is effective only with hg earlier than 1.8 (or 61c9bc3da402). To get appropriate vfs-like object to access files under .hg/store, this patch adds getsvfs() (and also getvfs(), for future use). To avoid examining existence of attribute at each repetition while measuring performance, getsvfs() is invoked outside the function to be called repeatedly. This patch also adds check-perf-code.py an extra check entry to detect direct usage of repo.(vfs|svfs|opener|sopener) in perf.py.