revisionbranchcache: fall back to slow path if starting readonly (issue4531)
Transitioning to Mercurial versions with revision branch cache could be slow as
long as all operations were readonly (revset queries) and the cache would be
populated but not written back.
Instead, fall back to using the consistently slow path when readonly and the
cache doesn't exist yet. That avoids the overhead of populating the cache
without writing it back.
If not readonly, it will still populate all missing entries initially. That
avoids repeated writing of the cache file with small updates, and it also makes
sure a fully populated cache available for the readonly operations.
$ cat > bundle2.py << EOF
> """A small extension to test bundle2 pushback parts.
> Current bundle2 implementation doesn't provide a way to generate those
> parts, so they must be created by extensions.
> """
> from mercurial import bundle2, pushkey, exchange, util
> def _newhandlechangegroup(op, inpart):
> """This function wraps the changegroup part handler for getbundle.
> It issues an additional b2x:pushkey part to send a new
> bookmark back to the client"""
> result = bundle2.handlechangegroup(op, inpart)
> if 'b2x:pushback' in op.reply.capabilities:
> params = {'namespace': 'bookmarks',
> 'key': 'new-server-mark',
> 'old': '',
> 'new': 'tip'}
> encodedparams = [(k, pushkey.encode(v)) for (k,v) in params.items()]
> op.reply.newpart('b2x:pushkey', mandatoryparams=encodedparams)
> else:
> op.reply.newpart('b2x:output', data='pushback not enabled')
> return result
> _newhandlechangegroup.params = bundle2.handlechangegroup.params
> bundle2.parthandlermapping['b2x:changegroup'] = _newhandlechangegroup
> EOF
$ cat >> $HGRCPATH <<EOF
> [ui]
> ssh = python "$TESTDIR/dummyssh"
> username = nobody <no.reply@example.com>
>
> [alias]
> tglog = log -G -T "{desc} [{phase}:{node|short}]"
> EOF
Set up server repository
$ hg init server
$ cd server
$ echo c0 > f0
$ hg commit -Am 0
adding f0
Set up client repository
$ cd ..
$ hg clone ssh://user@dummy/server client -q
$ cd client
Enable extension
$ cat >> $HGRCPATH <<EOF
> [extensions]
> bundle2=$TESTTMP/bundle2.py
> [experimental]
> bundle2-exp = True
> EOF
Without config
$ cd ../client
$ echo c1 > f1
$ hg commit -Am 1
adding f1
$ hg push
pushing to ssh://user@dummy/server
searching for changes
remote: pushback not enabled
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
$ hg bookmark
no bookmarks set
$ cd ../server
$ hg tglog
o 1 [public:2b9c7234e035]
|
@ 0 [public:6cee5c8f3e5b]
With config
$ cd ../client
$ echo '[experimental]' >> .hg/hgrc
$ echo 'bundle2.pushback = True' >> .hg/hgrc
$ echo c2 > f2
$ hg commit -Am 2
adding f2
$ hg push
pushing to ssh://user@dummy/server
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
$ hg bookmark
new-server-mark 2:0a76dfb2e179
$ cd ../server
$ hg tglog
o 2 [public:0a76dfb2e179]
|
o 1 [public:2b9c7234e035]
|
@ 0 [public:6cee5c8f3e5b]