revlog: move censor logic into main revlog class
Previously, the revlog class implemented dummy methods for
various censor-related functionality. Revision censoring was
(and will continue to be) only possible on filelog instances.
So filelog implemented these methods to perform something
reasonable.
A problem with implementing censoring on filelog is that
it assumes filelog is a revlog. Upcoming work to formalize
the filelog interface will make this not true.
Furthermore, the censoring logic is security-sensitive. I
think action-at-a-distance with custom implementation of core
revlog APIs in derived classes is a bit dangerous. I think at
a minimum the censor logic should live in revlog.py.
I was tempted to created a "censored revlog" class that
basically pulled these methods out of filelog. But, I wasn't
a huge fan of overriding core methods in child classes. A
reason to do that would be performance. However, the censoring
code only comes into play when:
* hash verification fails
* delta generation
* applying deltas from changegroups
The new code is conditional on an instance attribute. So the
overhead for running the censored code when the revlog isn't
censorable is an attribute lookup. All of these operations are
at least a magnitude slower than a Python attribute lookup. So
there shouldn't be a performance concern.
Differential Revision: https://phab.mercurial-scm.org/D3151
# In most cases, the mercurial repository can be read by the bundled hg, but
# that isn't always true because third-party extensions may change the store
# format, for example. In which case, the system hg installation is used.
#
# We want to use the hg version being tested when interacting with the test
# repository, and the system hg when interacting with the mercurial source code
# repository.
#
# The mercurial source repository was typically orignally cloned with the
# system mercurial installation, and may require extensions or settings from
# the system installation.
if [ -n $HGTESTEXTRAEXTENSIONS ]; then
for extension in $HGTESTEXTRAEXTENSIONS; do
extraoptions="$extraoptions --config extensions.$extension=!"
done
fi
syshg () {
(
syshgenv
exec hg "$@"
)
}
# Revert the environment so that running "hg" runs the system hg
# rather than the test hg installation.
syshgenv () {
. "$HGTEST_RESTOREENV"
HGPLAIN=1
export HGPLAIN
}
# The test-repo is a live hg repository which may have evolution markers
# created, e.g. when a ~/.hgrc enabled evolution.
#
# Tests may be run using a custom HGRCPATH, which do not enable evolution
# markers by default.
#
# If test-repo includes evolution markers, and we do not enable evolution
# markers, hg will occasionally complain when it notices them, which disrupts
# tests resulting in sporadic failures.
#
# Since we aren't performing any write operations on the test-repo, there's
# no harm in telling hg that we support evolution markers, which is what the
# following lines for the hgrc file do:
cat >> "$HGRCPATH" << EOF
[experimental]
evolution = createmarkers
EOF
# Use the system hg command if the bundled hg can't read the repository with
# no warning nor error.
if [ -n "`hg id -R "$TESTDIR/.." 2>&1 >/dev/null`" ]; then
alias testrepohg=syshg
alias testrepohgenv=syshgenv
else
alias testrepohg="hg $extraoptions"
alias testrepohgenv=:
fi