Mercurial > hg
annotate mercurial/txnutil.py @ 37290:cc5a040fe150
wireproto: syntax for encoding CBOR into frames
We just vendored a library for encoding and decoding the CBOR
data format. While the intent of that vendor was to support state
files, CBOR is really a nice data format. It is extensible and
compact.
I've been feeling dirty inventing my own data formats for
frame payloads. While custom formats can always beat out a generic
format, there is a cost to be paid in terms of implementation,
comprehension, etc. CBOR is compact enough that I'm not too
worried about efficiency loss. I think the benefits of using
a standardized format outweigh rolling our own formats. So
I plan to make heavy use of CBOR in the wire protocol going
forward.
This commit introduces support for encoding CBOR data in frame
payloads to our function to make a frame from a human string.
We do need to employ some low-level Python code in order to
evaluate a string as a Python expression. But other than that,
this should hopefully be pretty straightforward.
Unit tests for this function have been added.
Differential Revision: https://phab.mercurial-scm.org/D2948
author | Gregory Szorc <gregory.szorc@gmail.com> |
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date | Wed, 28 Mar 2018 15:05:39 -0700 |
parents | 206532700213 |
children | 2372284d9457 |
rev | line source |
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1 # txnutil.py - transaction related utilities |
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2 # |
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3 # Copyright FUJIWARA Katsunori <foozy@lares.dti.ne.jp> and others |
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4 # |
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5 # This software may be used and distributed according to the terms of the |
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6 # GNU General Public License version 2 or any later version. |
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7 |
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8 from __future__ import absolute_import |
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9 |
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10 import errno |
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11 |
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12 from . import ( |
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13 encoding, |
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14 ) |
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15 |
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16 def mayhavepending(root): |
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17 '''return whether 'root' may have pending changes, which are |
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18 visible to this process. |
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19 ''' |
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20 return root == encoding.environ.get('HG_PENDING') |
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21 |
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22 def trypending(root, vfs, filename, **kwargs): |
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23 '''Open file to be read according to HG_PENDING environment variable |
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24 |
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25 This opens '.pending' of specified 'filename' only when HG_PENDING |
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26 is equal to 'root'. |
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27 |
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28 This returns '(fp, is_pending_opened)' tuple. |
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29 ''' |
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30 if mayhavepending(root): |
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31 try: |
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32 return (vfs('%s.pending' % filename, **kwargs), True) |
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33 except IOError as inst: |
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34 if inst.errno != errno.ENOENT: |
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35 raise |
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36 return (vfs(filename, **kwargs), False) |