compression: introduce an official `zstd-revlog` requirement
This requirement supersedes `exp-compression-zstd`. However, we keep support for
the old requirement.
Strictly speaking, we do not need to add a new requirement, there are no logic
change making "new" repo incompatible with mercurial client using a version
that support `exp-compression-zstd`.
The choice to introduce a new requirement is motivated by the following:
* The previous requirement was explicitly "experimental". Using it by default
could confuse users.
* adding support for a hypothetical third compression engine will requires new
code, and will comes with its own requirement tool.
* We won't use it as the default for a while since I do not think we support
zstd on all platform. I can imagine we'll gain another (unrelated but on my
default) requirement by the time we turn this zstd by default.
--- a/mercurial/localrepo.py Tue Apr 16 15:10:16 2019 +0200
+++ b/mercurial/localrepo.py Wed Mar 27 18:27:03 2019 +0100
@@ -645,6 +645,8 @@
engine = util.compengines[name]
if engine.available() and engine.revlogheader():
supported.add(b'exp-compression-%s' % name)
+ if engine.name() == 'zstd':
+ supported.add(b'revlog-compression-zstd')
return supported
@@ -794,8 +796,13 @@
options[b'maxchainlen'] = maxchainlen
for r in requirements:
- if r.startswith(b'exp-compression-'):
- options[b'compengine'] = r[len(b'exp-compression-'):]
+ # we allow multiple compression engine requirement to co-exist because
+ # strickly speaking, revlog seems to support mixed compression style.
+ #
+ # The compression used for new entries will be "the last one"
+ prefix = r.startswith
+ if prefix('revlog-compression-') or prefix('exp-compression-'):
+ options[b'compengine'] = r.split('-', 2)[2]
options[b'zlib.level'] = ui.configint(b'storage', b'revlog.zlib.level')
if options[b'zlib.level'] is not None:
@@ -2943,7 +2950,9 @@
'compression engines'))
# zlib is the historical default and doesn't need an explicit requirement.
- if compengine != 'zlib':
+ elif compengine == 'zstd':
+ requirements.add('revlog-compression-zstd')
+ elif compengine != 'zlib':
requirements.add('exp-compression-%s' % compengine)
if scmutil.gdinitconfig(ui):
--- a/mercurial/upgrade.py Tue Apr 16 15:10:16 2019 +0200
+++ b/mercurial/upgrade.py Wed Mar 27 18:27:03 2019 +0100
@@ -325,10 +325,16 @@
@classmethod
def fromrepo(cls, repo):
+ # we allow multiple compression engine requirement to co-exist because
+ # strickly speaking, revlog seems to support mixed compression style.
+ #
+ # The compression used for new entries will be "the last one"
+ compression = 'zlib'
for req in repo.requirements:
- if req.startswith('exp-compression-'):
- return req.split('-', 2)[2]
- return 'zlib'
+ prefix = req.startswith
+ if prefix('revlog-compression-') or prefix('exp-compression-'):
+ compression = req.split('-', 2)[2]
+ return compression
@classmethod
def fromconfig(cls, repo):
--- a/tests/test-repo-compengines.t Tue Apr 16 15:10:16 2019 +0200
+++ b/tests/test-repo-compengines.t Wed Mar 27 18:27:03 2019 +0100
@@ -44,9 +44,9 @@
$ cd zstd
$ cat .hg/requires
dotencode
- exp-compression-zstd
fncache
generaldelta
+ revlog-compression-zstd
revlogv1
sparserevlog
store