concurrency_checker.py
38 lines
| 1.5 KiB
| text/x-python
|
PythonLexer
Kyle Lippincott
|
r47349 | 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 | ||||