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show: use consistent (and possibly shorter) node lengths...
show: use consistent (and possibly shorter) node lengths `hg show` makes heavy use of shortest() to limit the length of the node hash. For the "stack" and "work" views, you are often looking at multiple lines of similar output for "lines" of work. It is visually appeasing for things to vertically align. A naive use of {shortest(node, N)} could result in variable length nodes and for the first character of the description to vary by a column or two. We implement a function to determine the longest shortest prefix for a set of revisions. The new function is used to determine the printed node length for all `hg show` views. .. feature:: show: use consistent node length in views Our previous shortest node length of 5 was arbitrarily chosen. shortest() already does the work of ensuring that a partial node isn't ambiguous with an integer revision, which is our primary risk of a collision for very short nodes. It should be safe to go with the shortest node possible. Existing code is also optimized to handle nodes as short as 4. So, we decrease the minimum hash length from 5 to 4. We also add a test demonstrating that prefix collisions increase the node length. .. feature:: show: decrease minimum displayed hash length from 5 to 4 Differential Revision: https://phab.mercurial-scm.org/D558

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test-pathencode.py
204 lines | 6.3 KiB | text/x-python | PythonLexer
# This is a randomized test that generates different pathnames every
# time it is invoked, and tests the encoding of those pathnames.
#
# It uses a simple probabilistic model to generate valid pathnames
# that have proven likely to expose bugs and divergent behavior in
# different encoding implementations.
from __future__ import absolute_import, print_function
import binascii
import collections
import itertools
import math
import os
import random
import sys
import time
from mercurial import (
store,
)
validchars = set(map(chr, range(0, 256)))
alphanum = range(ord('A'), ord('Z'))
for c in '\0/':
validchars.remove(c)
winreserved = ('aux con prn nul'.split() +
['com%d' % i for i in xrange(1, 10)] +
['lpt%d' % i for i in xrange(1, 10)])
def casecombinations(names):
'''Build all case-diddled combinations of names.'''
combos = set()
for r in names:
for i in xrange(len(r) + 1):
for c in itertools.combinations(xrange(len(r)), i):
d = r
for j in c:
d = ''.join((d[:j], d[j].upper(), d[j + 1:]))
combos.add(d)
return sorted(combos)
def buildprobtable(fp, cmd='hg manifest tip'):
'''Construct and print a table of probabilities for path name
components. The numbers are percentages.'''
counts = collections.defaultdict(lambda: 0)
for line in os.popen(cmd).read().splitlines():
if line[-2:] in ('.i', '.d'):
line = line[:-2]
if line.startswith('data/'):
line = line[5:]
for c in line:
counts[c] += 1
for c in '\r/\n':
counts.pop(c, None)
t = sum(counts.itervalues()) / 100.0
fp.write('probtable = (')
for i, (k, v) in enumerate(sorted(counts.iteritems(), key=lambda x: x[1],
reverse=True)):
if (i % 5) == 0:
fp.write('\n ')
vt = v / t
if vt < 0.0005:
break
fp.write('(%r, %.03f), ' % (k, vt))
fp.write('\n )\n')
# A table of character frequencies (as percentages), gleaned by
# looking at filelog names from a real-world, very large repo.
probtable = (
('t', 9.828), ('e', 9.042), ('s', 8.011), ('a', 6.801), ('i', 6.618),
('g', 5.053), ('r', 5.030), ('o', 4.887), ('p', 4.363), ('n', 4.258),
('l', 3.830), ('h', 3.693), ('_', 3.659), ('.', 3.377), ('m', 3.194),
('u', 2.364), ('d', 2.296), ('c', 2.163), ('b', 1.739), ('f', 1.625),
('6', 0.666), ('j', 0.610), ('y', 0.554), ('x', 0.487), ('w', 0.477),
('k', 0.476), ('v', 0.473), ('3', 0.336), ('1', 0.335), ('2', 0.326),
('4', 0.310), ('5', 0.305), ('9', 0.302), ('8', 0.300), ('7', 0.299),
('q', 0.298), ('0', 0.250), ('z', 0.223), ('-', 0.118), ('C', 0.095),
('T', 0.087), ('F', 0.085), ('B', 0.077), ('S', 0.076), ('P', 0.076),
('L', 0.059), ('A', 0.058), ('N', 0.051), ('D', 0.049), ('M', 0.046),
('E', 0.039), ('I', 0.035), ('R', 0.035), ('G', 0.028), ('U', 0.026),
('W', 0.025), ('O', 0.017), ('V', 0.015), ('H', 0.013), ('Q', 0.011),
('J', 0.007), ('K', 0.005), ('+', 0.004), ('X', 0.003), ('Y', 0.001),
)
for c, _ in probtable:
validchars.remove(c)
validchars = list(validchars)
def pickfrom(rng, table):
c = 0
r = rng.random() * sum(i[1] for i in table)
for i, p in table:
c += p
if c >= r:
return i
reservedcombos = casecombinations(winreserved)
# The first component of a name following a slash.
firsttable = (
(lambda rng: pickfrom(rng, probtable), 90),
(lambda rng: rng.choice(validchars), 5),
(lambda rng: rng.choice(reservedcombos), 5),
)
# Components of a name following the first.
resttable = firsttable[:-1]
# Special suffixes.
internalsuffixcombos = casecombinations('.hg .i .d'.split())
# The last component of a path, before a slash or at the end of a name.
lasttable = resttable + (
(lambda rng: '', 95),
(lambda rng: rng.choice(internalsuffixcombos), 5),
)
def makepart(rng, k):
'''Construct a part of a pathname, without slashes.'''
p = pickfrom(rng, firsttable)(rng)
l = len(p)
ps = [p]
maxl = rng.randint(1, k)
while l < maxl:
p = pickfrom(rng, resttable)(rng)
l += len(p)
ps.append(p)
ps.append(pickfrom(rng, lasttable)(rng))
return ''.join(ps)
def makepath(rng, j, k):
'''Construct a complete pathname.'''
return ('data/' + '/'.join(makepart(rng, k) for _ in xrange(j)) +
rng.choice(['.d', '.i']))
def genpath(rng, count):
'''Generate random pathnames with gradually increasing lengths.'''
mink, maxk = 1, 4096
def steps():
for i in xrange(count):
yield mink + int(round(math.sqrt((maxk - mink) * float(i) / count)))
for k in steps():
x = rng.randint(1, k)
y = rng.randint(1, k)
yield makepath(rng, x, y)
def runtests(rng, seed, count):
nerrs = 0
for p in genpath(rng, count):
h = store._pathencode(p) # uses C implementation, if available
r = store._hybridencode(p, True) # reference implementation in Python
if h != r:
if nerrs == 0:
print('seed:', hex(seed)[:-1], file=sys.stderr)
print("\np: '%s'" % p.encode("string_escape"), file=sys.stderr)
print("h: '%s'" % h.encode("string_escape"), file=sys.stderr)
print("r: '%s'" % r.encode("string_escape"), file=sys.stderr)
nerrs += 1
return nerrs
def main():
import getopt
# Empirically observed to take about a second to run
count = 100
seed = None
opts, args = getopt.getopt(sys.argv[1:], 'c:s:',
['build', 'count=', 'seed='])
for o, a in opts:
if o in ('-c', '--count'):
count = int(a)
elif o in ('-s', '--seed'):
seed = long(a, base=0) # accepts base 10 or 16 strings
elif o == '--build':
buildprobtable(sys.stdout,
'find .hg/store/data -type f && '
'cat .hg/store/fncache 2>/dev/null')
sys.exit(0)
if seed is None:
try:
seed = long(binascii.hexlify(os.urandom(16)), 16)
except AttributeError:
seed = long(time.time() * 1000)
rng = random.Random(seed)
if runtests(rng, seed, count):
sys.exit(1)
if __name__ == '__main__':
main()