Mercurial > hg
view mercurial/revlogutils/concurrency_checker.py @ 47387:75e1104f23a2
revlog: use dedicated code for reading sidedata
We are about to introduce a new, dedicated, file to store sidedata. Before doing so, we make sidedata reading go through different code as reading data chunk. This will simplify some of the complexity of the next changesets.
The reading is very simple right now and will need some improvement later to
reuse some of the caching strategy we use for the data file.
Differential Revision: https://phab.mercurial-scm.org/D10785
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
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date | Thu, 27 May 2021 04:09:30 +0200 |
parents | e9901d01d135 |
children |
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from ..i18n import _ from .. import error def get_checker(ui, revlog_name=b'changelog'): """Get a function that checks file handle position is as expected. This is used to ensure that files haven't been modified outside of our knowledge (such as on a networked filesystem, if `hg debuglocks` was used, or writes to .hg that ignored locks happened). Due to revlogs supporting a concept of buffered, delayed, or diverted writes, we're allowing the files to be shorter than expected (the data may not have been written yet), but they can't be longer. Please note that this check is not perfect; it can't detect all cases (there may be false-negatives/false-OKs), but it should never claim there's an issue when there isn't (false-positives/false-failures). """ vpos = ui.config(b'debug', b'revlog.verifyposition.' + revlog_name) # Avoid any `fh.tell` cost if this isn't enabled. if not vpos or vpos not in [b'log', b'warn', b'fail']: return None def _checker(fh, fn, expected): if fh.tell() <= expected: return msg = _(b'%s: file cursor at position %d, expected %d') # Always log if we're going to warn or fail. ui.log(b'debug', msg + b'\n', fn, fh.tell(), expected) if vpos == b'warn': ui.warn((msg + b'\n') % (fn, fh.tell(), expected)) elif vpos == b'fail': raise error.RevlogError(msg % (fn, fh.tell(), expected)) return _checker