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.
$ . "$TESTDIR/helpers-testrepo.sh"
Testing that hghave does not crash when checking features
$ hghave --test-features 2>/dev/null
Testing hghave extensibility for third party tools
$ cat > hghaveaddon.py <<EOF
> import hghave
> @hghave.check("custom", "custom hghave feature")
> def has_custom():
> return True
> EOF
(invocation via run-tests.py)
$ cat > test-hghaveaddon.t <<EOF
> #require custom
> $ echo foo
> foo
> EOF
$ ( \
> testrepohgenv; \
> "$PYTHON" $TESTDIR/run-tests.py --with-hg=$HGTEST_REAL_HG -j 1 \
> $HGTEST_RUN_TESTS_PURE test-hghaveaddon.t \
> )
installed Mercurial in * seconds (glob) (?)
running 1 tests using 1 parallel processes
.
# Ran 1 tests, 0 skipped, 0 failed.
(invocation via command line)
$ unset TESTDIR
$ hghave custom
(terminate with exit code 2 at failure of importing hghaveaddon.py)
$ rm hghaveaddon.*
$ cat > hghaveaddon.py <<NO_CHECK_EOF
> importing this file should cause syntax error
> NO_CHECK_EOF
$ hghave custom
failed to import hghaveaddon.py from '.': invalid syntax (hghaveaddon.py, line 1)
[2]