revlog: move censor logic out of censor extension
The censor extension is doing very low-level things with revlogs.
It is fundamentally impossible for this logic to remain in the censor
extension while support multiple storage backends: we need each
storage backend to implement censor in its own storage-specific
way.
This commit effectively moves the revlog-specific censoring code to
be a method of revlogs themselves.
We've defined a new API on the file storage interface for censoring
an individual node. Even though the current censoring code doesn't
use it, the API requires a transaction instance because it logically
makes sense for storage backends to require an active transaction
(which implies a held write lock) in order to rewrite storage.
After this commit, the censor extension has been reduced to
boilerplate precondition checking before invoking the generic
storage API.
I tried to keep the code as similar as possible. But some minor
changes were made:
* We use self._io instead of instantiating a new revlogio instance.
* We compare self.version against REVLOGV0 instead of != REVLOGV1
because presumably all future revlog versions will support censoring.
* We use self.opener instead of going through repo.svfs (we don't have
a handle on the repo instance from a revlog).
* "revlog" dropped
* Replace "flog" with "self".
Differential Revision: https://phab.mercurial-scm.org/D4656
# A dummy extension that installs an hgweb command that throws an Exception.
from __future__ import absolute_import
from mercurial.hgweb import (
webcommands,
)
def raiseerror(web):
'''Dummy web command that raises an uncaught Exception.'''
# Simulate an error after partial response.
if 'partialresponse' in web.req.qsparams:
web.res.status = b'200 Script output follows'
web.res.headers[b'Content-Type'] = b'text/plain'
web.res.setbodywillwrite()
list(web.res.sendresponse())
web.res.getbodyfile().write(b'partial content\n')
raise AttributeError('I am an uncaught error!')
def extsetup(ui):
setattr(webcommands, 'raiseerror', raiseerror)
webcommands.__all__.append('raiseerror')