revlog: use node tree (native code) for shortest() calculation
I want to rewrite revlog.shortest() to disambiguate only among hex
nodeids and then disambiguate the result with revnums at a higher
level (in scmutil). However, that would slow down `hg log -T
'{shortest(node,1)}\n'` from 5.0s to 6.8s, which I wasn't sure would
be acceptable. So this patch makes revlog.shortest() use the node tree
for finding the length of the shortest prefix that's unambiguous among
nodeids. Once that has been found, it makes it longer until it is also
not ambiguous with a revnum.
This speeds up `hg log -T '{shortest(node,1)}\n'` from 5.0s to 4.0s.
Differential Revision: https://phab.mercurial-scm.org/D3499
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__)