revlog: introduce a mandatory `_writing` context to update revlog content
Before this change, various revlog methods where managing the opening and
closing of the revlog files manually and passing the file descriptor alors the
call path. To simplify the tracking of the write operation by a future docket,
we need something more organised. As a result, we introduce a `revlog._writing`
context manager that will wrap each revlog update operation. The file
descriptor are kept in the existing `revlog._writinghandles` parameter that
was already used by the `addgroup` logic.
All this change is internal to the revlog only, the "public" interface is not
affected. The `addrevision` and `addgroup` logic are still responsible for
setup up this context. However this new context give us multiple benefits:
* all writer use a same, unified, logic,
* this context is programmatically enforced,
* each write "session" as a clearly identified start and end.
The post-pull sidedata update logic is still doing writing by end and will be
adjusted in a later changesets.
This change affect the concurrency checker test, because register the state of
the file in the transaction sooner in `addrevision` (about as early as what
`addgroup` would do), so the abort is rollbacking the other commit. I don't want
to weaken the current main logic.
Differential Revision: https://phab.mercurial-scm.org/D10605
$ cat <<EOF >> $HGRCPATH
> [extensions]
> hooklib =
>
> [phases]
> publish = False
> EOF
$ hg init a
$ hg --cwd a debugbuilddag .
$ hg --cwd a phase --public 0
$ hg init b
$ cat <<EOF >> b/.hg/hgrc
> [hooks]
> pretxnclose-phase.enforce_draft_commits = \
> python:hgext.hooklib.enforce_draft_commits.hook
> EOF
$ hg --cwd b pull ../a
pulling from ../a
requesting all changes
adding changesets
adding manifests
adding file changes
error: pretxnclose-phase.enforce_draft_commits hook failed: New changeset 1ea73414a91b in phase 'public' rejected
transaction abort!
rollback completed
abort: New changeset 1ea73414a91b in phase 'public' rejected
[255]
$ hg --cwd a phase --force --draft 0
$ hg --cwd b pull ../a
pulling from ../a
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 0 changes to 0 files
new changesets 1ea73414a91b (1 drafts)
(run 'hg update' to get a working copy)
$ hg --cwd a phase --public 0
$ hg --cwd b pull ../a
pulling from ../a
searching for changes
no changes found
error: pretxnclose-phase.enforce_draft_commits hook failed: Phase change from 'draft' to 'public' for 1ea73414a91b rejected
abort: Phase change from 'draft' to 'public' for 1ea73414a91b rejected
[255]