Mercurial > hg
view tests/test-pathencode.py @ 18040:fe8caf28d580
strip: make query to get new bookmark target cheaper
The current query to get the new bookmark target for stripped revisions
involves multiple walks up the DAG, and is really expensive, taking over 2.5
seconds on a repository with over 400,000 changesets even if just one
changeset is being stripped.
A slightly simplified version of the current query is
max(heads(::<tostrip> - <tostrip>))
We make two observations here.
1. For any set s, max(heads(s)) == max(s). That is because revision numbers
define a topological order, so that the element with the highest revision
number in s will not have any children in s.
2. For any set s, max(::s - s) == max(parents(s) - s). In other words, the
ancestor of s with the highest revision number not in s is a parent of one
of the revs in s. Why? Because if it were an ancestor but not a parent of s,
it would have a descendant that would be a parent of s. This descendant
would have a higher revision number, leading to a contradiction.
Combining these two observations, we rewrite the revset query as
max(parents(<tostrip>) - <tostrip>)
The time complexity is now linear in the number of changesets being stripped.
For the above repository, the query now takes 0.1 seconds when one changeset
is stripped. This speeds up operations that use repair.strip, like the rebase
and strip commands.
author | Siddharth Agarwal <sid0@fb.com> |
---|---|
date | Wed, 05 Dec 2012 14:33:15 -0800 |
parents | f945caa5e963 |
children | 8ceabb34f1cb |
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# 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 behaviour in # different encoding implementations. from mercurial import parsers from mercurial import store import binascii, itertools, math, os, random, sys, time import collections if sys.version_info[:2] < (2, 6): sys.exit(0) def hybridencode(path): return store._hybridencode(path, True) 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] while l <= k: 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(): x, k = 0, mink 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): hybridencode(p) 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) 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()