tags-fnode-cache: skip building a changectx in getfnode
Building a changectx object is costly, doing it just to retrieve the revision
number is suboptimal. Directly fetching the revision number from the changelog
provide a sizeable speedup to `hg debugupdatecache`.
### data-env-vars.name = mercurial-2018-08-01-zstd-sparse-revlog
# benchmark.name = debug-update-cache
# benchmark.variants.pre-state = warm
before: 0.213229 seconds
after: 0.165577 seconds (-22.35%)
# data-env-vars.name = mercurial-filtered-2019-11-22-zstd-sparse-revlog
before: 1.200383 seconds
after: 1.071618 seconds (-10.73%)
# data-env-vars.name = mozilla-central-2018-08-01-zstd-sparse-revlog
before: 1.465735 seconds
after: 0.923128 seconds (-37.02%)
# data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog
before: 6.511771 seconds
after: 4.507316 seconds (-30.78%)
# data-env-vars.name = netbeans-2018-08-01-zstd-sparse-revlog
before: 1.023007 seconds
after: 0.645026 seconds (-36.95%)
# data-env-vars.name = pypy-2018-08-01-zstd-sparse-revlog
before: 0.381141 seconds
after: 0.268654 seconds (-29.51%)
cHg
===
A fast client for Mercurial command server running on Unix.
Install:
$ make
$ make install
Usage:
$ chg help # show help of Mercurial
$ alias hg=chg # replace hg command
$ chg --kill-chg-daemon # terminate background server
Environment variables:
Although cHg tries to update environment variables, some of them cannot be
changed after spawning the server. The following variables are specially
handled:
* configuration files are reloaded automatically by default.
* CHGHG or HG specifies the path to the hg executable spawned as the
background command server.
The following variables are available for testing:
* CHGDEBUG enables debug messages.
* CHGSOCKNAME specifies the socket path of the background cmdserver.
* CHGTIMEOUT specifies how many seconds chg will wait before giving up
connecting to a cmdserver. If it is 0, chg will wait forever. Default: 60
Build environment variables:
* HGPATH: the path to the hg executable to call when CHGHG and HG are not set,
instead of "hg"
* HGPATHREL=1: when CHGHG and HG are not set, the hg executable will be ./hg
relative to the chg executable. Only works on linux, falls back to "hg"
otherwise.