Mercurial > hg
view tests/test-bdiff.py @ 36426:23d12524a202
http: drop custom http client logic
Eight and a half years ago, as my starter bug on code.google.com, I
investigated a mysterious "broken pipe" error from seemingly random
clients[0]. That investigation revealed a tragic story: the Python
standard library's httplib was (and remains) barely functional. During
large POSTs, if a server responds early with an error (even a
permission denied error!) the client only notices that the server
closed the connection and everything breaks. Such server behavior is
implicitly legal under RFC 2616 (the latest HTTP RFC as of when I was
last working on this), and my understanding is that later RFCs have
made it explicitly legal to respond early with any status code outside
the 2xx range.
I embarked, probably foolishly, on a journey to write a new http
library with better overall behavior. The http library appears to work
well in most cases, but it can get confused in the presence of
proxies, and it depends on select(2) which limits its utility if a lot
of file descriptors are open. I haven't touched the http library in
almost two years, and in the interim the Python community has
discovered a better way[1] of writing network code. In theory some day
urllib3 will have its own home-grown http library built on h11[2], or
we could do that. Either way, it's time to declare our current
confusingly-named "http2" client logic and move on. I do hope to
revisit this some day: it's still garbage that we can't even respond
with a 401 or 403 without reading the entire POST body from the
client, but the goalposts on writing a new http client library have
moved substantially. We're almost certainly better off just switching
to requests and eventually picking up their http fixes than trying to
live with something that realistically only we'll ever use. Another
approach would be to write an adapter so that Mercurial can use pycurl
if it's installed. Neither of those approaches seem like they should
be investigated prior to a release of Mercurial that works on Python
3: that's where the mindshare is going to be for any improvements to
the state of the http client art.
0: http://web.archive.org/web/20130501031801/http://code.google.com/p/support/issues/detail?id=2716
1: http://sans-io.readthedocs.io/
2: https://github.com/njsmith/h11
Differential Revision: https://phab.mercurial-scm.org/D2444
author | Augie Fackler <augie@google.com> |
---|---|
date | Sun, 25 Feb 2018 23:51:32 -0500 |
parents | 0c73634d0570 |
children | e05d7c71f209 |
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from __future__ import absolute_import, print_function import collections import struct import unittest from mercurial import ( mdiff, ) class diffreplace( collections.namedtuple('diffreplace', 'start end from_ to')): def __repr__(self): return 'diffreplace(%r, %r, %r, %r)' % self class BdiffTests(unittest.TestCase): def assert_bdiff_applies(self, a, b): d = mdiff.textdiff(a, b) c = a if d: c = mdiff.patches(a, [d]) self.assertEqual( c, b, ("bad diff+patch result from\n %r to\n " "%r: \nbdiff: %r\npatched: %r" % (a, b, d, c[:200]))) def assert_bdiff(self, a, b): self.assert_bdiff_applies(a, b) self.assert_bdiff_applies(b, a) def test_bdiff_basic(self): cases = [ ("a\nc\n\n\n\n", "a\nb\n\n\n"), ("a\nb\nc\n", "a\nc\n"), ("", ""), ("a\nb\nc", "a\nb\nc"), ("a\nb\nc\nd\n", "a\nd\n"), ("a\nb\nc\nd\n", "a\nc\ne\n"), ("a\nb\nc\n", "a\nc\n"), ("a\n", "c\na\nb\n"), ("a\n", ""), ("a\n", "b\nc\n"), ("a\n", "c\na\n"), ("", "adjfkjdjksdhfksj"), ("", "ab"), ("", "abc"), ("a", "a"), ("ab", "ab"), ("abc", "abc"), ("a\n", "a\n"), ("a\nb", "a\nb"), ] for a, b in cases: self.assert_bdiff(a, b) def showdiff(self, a, b): bin = mdiff.textdiff(a, b) pos = 0 q = 0 actions = [] while pos < len(bin): p1, p2, l = struct.unpack(">lll", bin[pos:pos + 12]) pos += 12 if p1: actions.append(a[q:p1]) actions.append(diffreplace(p1, p2, a[p1:p2], bin[pos:pos + l])) pos += l q = p2 if q < len(a): actions.append(a[q:]) return actions def test_issue1295(self): cases = [ ("x\n\nx\n\nx\n\nx\n\nz\n", "x\n\nx\n\ny\n\nx\n\nx\n\nz\n", ['x\n\nx\n\n', diffreplace(6, 6, '', 'y\n\n'), 'x\n\nx\n\nz\n']), ("x\n\nx\n\nx\n\nx\n\nz\n", "x\n\nx\n\ny\n\nx\n\ny\n\nx\n\nz\n", ['x\n\nx\n\n', diffreplace(6, 6, '', 'y\n\n'), 'x\n\n', diffreplace(9, 9, '', 'y\n\n'), 'x\n\nz\n']), ] for old, new, want in cases: self.assertEqual(self.showdiff(old, new), want) def test_issue1295_varies_on_pure(self): # we should pick up abbbc. rather than bc.de as the longest match got = self.showdiff("a\nb\nb\nb\nc\n.\nd\ne\n.\nf\n", "a\nb\nb\na\nb\nb\nb\nc\n.\nb\nc\n.\nd\ne\nf\n") want_c = ['a\nb\nb\n', diffreplace(6, 6, '', 'a\nb\nb\nb\nc\n.\n'), 'b\nc\n.\nd\ne\n', diffreplace(16, 18, '.\n', ''), 'f\n'] want_pure = [diffreplace(0, 0, '', 'a\nb\nb\n'), 'a\nb\nb\nb\nc\n.\n', diffreplace(12, 12, '', 'b\nc\n.\n'), 'd\ne\n', diffreplace(16, 18, '.\n', ''), 'f\n'] self.assert_(got in (want_c, want_pure), 'got: %r, wanted either %r or %r' % ( got, want_c, want_pure)) def test_fixws(self): cases = [ (" \ta\r b\t\n", "ab\n", 1), (" \ta\r b\t\n", " a b\n", 0), ("", "", 1), ("", "", 0), ] for a, b, allws in cases: c = mdiff.fixws(a, allws) self.assertEqual( c, b, 'fixws(%r) want %r got %r (allws=%r)' % (a, b, c, allws)) def test_nice_diff_for_trivial_change(self): self.assertEqual(self.showdiff( ''.join('<%s\n-\n' % i for i in range(5)), ''.join('>%s\n-\n' % i for i in range(5))), [diffreplace(0, 3, '<0\n', '>0\n'), '-\n', diffreplace(5, 8, '<1\n', '>1\n'), '-\n', diffreplace(10, 13, '<2\n', '>2\n'), '-\n', diffreplace(15, 18, '<3\n', '>3\n'), '-\n', diffreplace(20, 23, '<4\n', '>4\n'), '-\n']) def test_prefer_appending(self): # 1 line to 3 lines self.assertEqual(self.showdiff('a\n', 'a\n' * 3), ['a\n', diffreplace(2, 2, '', 'a\na\n')]) # 1 line to 5 lines self.assertEqual(self.showdiff('a\n', 'a\n' * 5), ['a\n', diffreplace(2, 2, '', 'a\na\na\na\n')]) def test_prefer_removing_trailing(self): # 3 lines to 1 line self.assertEqual(self.showdiff('a\n' * 3, 'a\n'), ['a\n', diffreplace(2, 6, 'a\na\n', '')]) # 5 lines to 1 line self.assertEqual(self.showdiff('a\n' * 5, 'a\n'), ['a\n', diffreplace(2, 10, 'a\na\na\na\n', '')]) if __name__ == '__main__': import silenttestrunner silenttestrunner.main(__name__)