nodemap: gate the feature behind a new requirement
Now that the feature is working smoothly, a question was still open, should we
gate the feature behind a new requirement or just treat it as a cache to be
warmed by those who can and ignored by other.
The advantage of using the cache approach is a transparent upgrade/downgrade
story, making the feature easier to move to. However having out of date cache
can come with a significant performance hit for process who expect an up to
date cache but found none. In this case the file needs to be stored under
`.hg/cache`.
The "requirement" approach guarantee that the persistent nodemap is up to date.
However, it comes with a less flexible activation story since an explicite
upgrade is required. In this case the file can be stored in `.hg/store`.
This wiki page is relevant to this questions:
https://www.mercurial-scm.org/wiki/ComputedIndexPlan
So which one should we take? Another element came into plan, the persistent
nodemap use the `add` method of the transaction, it is used to keep track of a
file content before a transaction in case we need to rollback it back. It turns
out that the `transaction.add` API does not support file stored anywhere than
`.hg/store`. Making it support file stored elsewhere is possible, require a
change in on disk transaction format. Updating on disk file requires…
introducing a new requirements.
As a result, we pick the second option "gating the persistent nodemap behind a
new requirements".
Differential Revision: https://phab.mercurial-scm.org/D8417
#require test-repo
$ . "$TESTDIR/helpers-testrepo.sh"
Sanity check check-config.py
$ cat > testfile.py << EOF
> # Good
> foo = ui.config('ui', 'username')
> # Missing
> foo = ui.config('ui', 'doesnotexist')
> # Missing different type
> foo = ui.configint('ui', 'missingint')
> # Missing with default value
> foo = ui.configbool('ui', 'missingbool1', default=True)
> foo = ui.configbool('ui', 'missingbool2', False)
> # Inconsistent values for defaults.
> foo = ui.configint('ui', 'intdefault', default=1)
> foo = ui.configint('ui', 'intdefault', default=42)
> # Can suppress inconsistent value error
> foo = ui.configint('ui', 'intdefault2', default=1)
> # inconsistent config: ui.intdefault2
> foo = ui.configint('ui', 'intdefault2', default=42)
> EOF
$ cat > files << EOF
> mercurial/helptext/config.txt
> $TESTTMP/testfile.py
> EOF
$ cd "$TESTDIR"/..
$ "$PYTHON" contrib/check-config.py < $TESTTMP/files
foo = ui.configint('ui', 'intdefault', default=42)
conflict on ui.intdefault: ('int', '42') != ('int', '1')
at $TESTTMP/testfile.py:12:
undocumented: ui.doesnotexist (str)
undocumented: ui.intdefault (int) [42]
undocumented: ui.intdefault2 (int) [42]
undocumented: ui.missingbool1 (bool) [True]
undocumented: ui.missingbool2 (bool)
undocumented: ui.missingint (int)
New errors are not allowed. Warnings are strongly discouraged.
$ testrepohg files "set:(**.py or **.txt) - tests/**" | sed 's|\\|/|g' |
> "$PYTHON" contrib/check-config.py