exchange: support sorting URLs by client-side preferences
Not all bundles are appropriate for all clients. For example, someone
with a slow Internet connection may want to prefer bz2 bundles over gzip
bundles because they are smaller and don't take as long to transfer.
This is information that a server cannot know on its own. So, we invent
a mechanism for "preferring" server-advertised URLs based on their
attributes.
We could invent a negotiation between client and server where the client
sends its preferences and the sorting/filtering is done server-side.
However, this feels complex. We can avoid complicating the wire protocol
and exposing ourselves to backwards compatible concerns by performing
the sorting locally.
This patch defines a new config option for expressing preferred
attributes in server-advertised bundles.
At Mozilla, we leverage this feature so clients in fast data centers
prefer uncompressed bundles. (We advertise gzip bundles first because
that is a reasonable default.)
I consider this an advanced feature. I'm on the fence as to whether it
should be documented in `hg help config`.
import os
from mercurial import ui, commands, extensions
ignore = set(['highlight', 'win32text', 'factotum'])
if os.name != 'nt':
ignore.add('win32mbcs')
disabled = [ext for ext in extensions.disabled().keys() if ext not in ignore]
hgrc = open(os.environ["HGRCPATH"], 'w')
hgrc.write('[extensions]\n')
for ext in disabled:
hgrc.write(ext + '=\n')
hgrc.close()
u = ui.ui()
extensions.loadall(u)
globalshort = set()
globallong = set()
for option in commands.globalopts:
option[0] and globalshort.add(option[0])
option[1] and globallong.add(option[1])
for cmd, entry in commands.table.iteritems():
seenshort = globalshort.copy()
seenlong = globallong.copy()
for option in entry[1]:
if (option[0] and option[0] in seenshort) or \
(option[1] and option[1] in seenlong):
print "command '" + cmd + "' has duplicate option " + str(option)
seenshort.add(option[0])
seenlong.add(option[1])