outgoing: rework the handling of the `missingroots` case to be faster
The previous implementation was slow, to the point it was taking a significant
amount of `hg bundle --type none-streamv2` call. We rework the code to compute
the same value much faster, making the operation disappear from the `hg bundle
--type none-streamv2` profile. Someone would remark that producing a streamclone
does not requires an `outgoing` object. However that is a matter for another
day. There is other user of `missingroots` (non stream `hg bundle` call for
example), and they will also benefit from this rework.
We implement an old TODO in the process, directly computing the missing and
common attribute as we have most element at hand already.
### benchmark.name = hg.command.bundle
# bin-env-vars.hg.flavor = default
# bin-env-vars.hg.py-re2-module = default
# benchmark.variants.revs = all
# benchmark.variants.type = none-streamv2
## data-env-vars.name = heptapod-public-2024-03-25-zstd-sparse-revlog
before: 7.750458
after: 6.665565 (-14.00%, -1.08)
## data-env-vars.name = mercurial-public-2024-03-22-zstd-sparse-revlog
before: 0.700229
after: 0.496050 (-29.16%, -0.20)
## data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog
before: 346.508952
after: 316.749699 (-8.59%, -29.76)
## data-env-vars.name = pypy-2024-03-22-zstd-sparse-revlog
before: 3.401700
after: 2.915810 (-14.28%, -0.49)
## data-env-vars.name = tryton-public-2024-03-22-zstd-sparse-revlog
before: 1.870798
after: 1.461583 (-21.87%, -0.41)
note: this whole `missingroots` of outgoing has a limited number of callers and
could likely be replace by something simpler (like taking an explicit
"missing_revs" set for example). However this is a wider change and we focus on
a small impact, quick rework that does not change the API for now.
# 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.
import binascii
import collections
import itertools
import math
import os
import random
import sys
import time
from mercurial import (
pycompat,
store,
)
validchars = set(map(pycompat.bytechr, range(0, 256)))
alphanum = range(ord('A'), ord('Z'))
for c in (b'\0', b'/'):
validchars.remove(c)
winreserved = (
b'aux con prn nul'.split()
+ [b'com%d' % i for i in range(1, 10)]
+ [b'lpt%d' % i for i in range(1, 10)]
)
def casecombinations(names):
'''Build all case-diddled combinations of names.'''
combos = set()
for r in names:
for i in range(len(r) + 1):
for c in itertools.combinations(range(len(r)), i):
d = r
for j in c:
d = b''.join((d[:j], d[j : j + 1].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.values()) / 100.0
fp.write('probtable = (')
for i, (k, v) in enumerate(
sorted(counts.items(), 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 = (
(b't', 9.828),
(b'e', 9.042),
(b's', 8.011),
(b'a', 6.801),
(b'i', 6.618),
(b'g', 5.053),
(b'r', 5.030),
(b'o', 4.887),
(b'p', 4.363),
(b'n', 4.258),
(b'l', 3.830),
(b'h', 3.693),
(b'_', 3.659),
(b'.', 3.377),
(b'm', 3.194),
(b'u', 2.364),
(b'd', 2.296),
(b'c', 2.163),
(b'b', 1.739),
(b'f', 1.625),
(b'6', 0.666),
(b'j', 0.610),
(b'y', 0.554),
(b'x', 0.487),
(b'w', 0.477),
(b'k', 0.476),
(b'v', 0.473),
(b'3', 0.336),
(b'1', 0.335),
(b'2', 0.326),
(b'4', 0.310),
(b'5', 0.305),
(b'9', 0.302),
(b'8', 0.300),
(b'7', 0.299),
(b'q', 0.298),
(b'0', 0.250),
(b'z', 0.223),
(b'-', 0.118),
(b'C', 0.095),
(b'T', 0.087),
(b'F', 0.085),
(b'B', 0.077),
(b'S', 0.076),
(b'P', 0.076),
(b'L', 0.059),
(b'A', 0.058),
(b'N', 0.051),
(b'D', 0.049),
(b'M', 0.046),
(b'E', 0.039),
(b'I', 0.035),
(b'R', 0.035),
(b'G', 0.028),
(b'U', 0.026),
(b'W', 0.025),
(b'O', 0.017),
(b'V', 0.015),
(b'H', 0.013),
(b'Q', 0.011),
(b'J', 0.007),
(b'K', 0.005),
(b'+', 0.004),
(b'X', 0.003),
(b'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(b'.hg .i .d'.split())
# The last component of a path, before a slash or at the end of a name.
lasttable = resttable + (
(lambda rng: b'', 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 b''.join(ps)
def makepath(rng, j, k):
'''Construct a complete pathname.'''
return (
b'data/'
+ b'/'.join(makepart(rng, k) for _ in range(j))
+ rng.choice([b'.d', b'.i'])
)
def genpath(rng, count):
'''Generate random pathnames with gradually increasing lengths.'''
mink, maxk = 1, 4096
def steps():
for i in range(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 = int(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 = int(binascii.hexlify(os.urandom(16)), 16)
except AttributeError:
seed = int(time.time() * 1000)
rng = random.Random(seed)
if runtests(rng, seed, count):
sys.exit(1)
if __name__ == '__main__':
main()