Mercurial > hg
annotate mercurial/txnutil.py @ 37056:861e9d37e56e
wireproto: buffer output frames when in half duplex mode
Previously, when told that a response was ready, the server reactor
would instruct the caller to send frames immediately. This was OK
as an initial implementation. But it would not work for half-duplex
connections where the sender can't receive until all data has been
transmitted - such as httplib based clients.
In this commit, we teach the reactor that output frames should
be buffered until end of input is seen. This required a new
event to inform the reactor of end of input. The result from that
event will instruct the consumer to send all buffered frames.
The HTTP server is buffered by default.
This change effectively hides the complexity of buffering within
the reactor so that transports need not be concerned about it.
This helps keep the transports "dumb" and will make implementing
multiple requests-responses per atomic exchange (like an HTTP
request) much simpler.
Differential Revision: https://phab.mercurial-scm.org/D2860
author | Gregory Szorc <gregory.szorc@gmail.com> |
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date | Wed, 14 Mar 2018 14:01:16 -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) |