Mercurial > hg
annotate mercurial/revlogutils/concurrency_checker.py @ 50896:b2b8c25f9462
hgwebmod: use sysstr to check for attribute presence
We do not need bytes here.
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
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date | Wed, 30 Aug 2023 13:28:09 +0200 |
parents | e9901d01d135 |
children | 1c5810ce737e |
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revlog: add a mechanism to verify expected file position before appending
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1 from ..i18n import _ |
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2 from .. import error |
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3 |
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4 |
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5 def get_checker(ui, revlog_name=b'changelog'): |
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6 """Get a function that checks file handle position is as expected. |
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7 |
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8 This is used to ensure that files haven't been modified outside of our |
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9 knowledge (such as on a networked filesystem, if `hg debuglocks` was used, |
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10 or writes to .hg that ignored locks happened). |
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11 |
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12 Due to revlogs supporting a concept of buffered, delayed, or diverted |
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13 writes, we're allowing the files to be shorter than expected (the data may |
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14 not have been written yet), but they can't be longer. |
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15 |
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16 Please note that this check is not perfect; it can't detect all cases (there |
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17 may be false-negatives/false-OKs), but it should never claim there's an |
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18 issue when there isn't (false-positives/false-failures). |
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19 """ |
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20 |
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21 vpos = ui.config(b'debug', b'revlog.verifyposition.' + revlog_name) |
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22 # Avoid any `fh.tell` cost if this isn't enabled. |
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23 if not vpos or vpos not in [b'log', b'warn', b'fail']: |
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24 return None |
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25 |
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26 def _checker(fh, fn, expected): |
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27 if fh.tell() <= expected: |
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28 return |
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29 |
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30 msg = _(b'%s: file cursor at position %d, expected %d') |
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31 # Always log if we're going to warn or fail. |
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32 ui.log(b'debug', msg + b'\n', fn, fh.tell(), expected) |
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33 if vpos == b'warn': |
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34 ui.warn((msg + b'\n') % (fn, fh.tell(), expected)) |
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35 elif vpos == b'fail': |
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36 raise error.RevlogError(msg % (fn, fh.tell(), expected)) |
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37 |
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38 return _checker |