procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
"""revset to select sample of repository
Hopefully this is useful to create interesting discovery cases.
"""
import collections
import random
from mercurial.i18n import _
from mercurial import (
registrar,
revset,
revsetlang,
smartset,
)
import sortedcontainers
SortedSet = sortedcontainers.SortedSet
revsetpredicate = registrar.revsetpredicate()
@revsetpredicate(b'subsetspec("<spec>")')
def subsetmarkerspec(repo, subset, x):
"""use a shorthand spec as used by search-discovery-case
Supported format are:
- "scratch-count-seed": not scratch(all(), count, "seed")
- "randomantichain-seed": ::randomantichain(all(), "seed")
- "rev-REV": "::REV"
"""
args = revsetlang.getargs(
x, 0, 1, _(b'subsetspec("spec") required an argument')
)
spec = revsetlang.getstring(args[0], _(b"spec should be a string"))
case = spec.split(b'-')
t = case[0]
if t == b'scratch':
spec_revset = b'not scratch(all(), %s, "%s")' % (case[1], case[2])
elif t == b'randomantichain':
spec_revset = b'::randomantichain(all(), "%s")' % case[1]
elif t == b'rev':
spec_revset = b'::%d' % case[1]
else:
assert False, spec
selected = repo.revs(spec_revset)
return selected & subset
@revsetpredicate(b'scratch(REVS, <count>, [seed])')
def scratch(repo, subset, x):
"""randomly remove <count> revision from the repository top
This subset is created by recursively picking changeset starting from the
heads. It can be summarized using the following algorithm::
selected = set()
for i in range(<count>):
unselected = repo.revs("not <selected>")
candidates = repo.revs("heads(<unselected>)")
pick = random.choice(candidates)
selected.add(pick)
"""
m = _(b"scratch expects revisions, count argument and an optional seed")
args = revsetlang.getargs(x, 2, 3, m)
if len(args) == 2:
x, n = args
rand = random
elif len(args) == 3:
x, n, seed = args
seed = revsetlang.getinteger(seed, _(b"seed should be a number"))
rand = random.Random(seed)
else:
assert False
n = revsetlang.getinteger(n, _(b"scratch expects a number"))
selected = set()
heads = SortedSet()
children_count = collections.defaultdict(lambda: 0)
parents = repo.changelog._uncheckedparentrevs
baseset = revset.getset(repo, smartset.fullreposet(repo), x)
baseset.sort()
for r in baseset:
heads.add(r)
p1, p2 = parents(r)
if p1 >= 0:
heads.discard(p1)
children_count[p1] += 1
if p2 >= 0:
heads.discard(p2)
children_count[p2] += 1
for h in heads:
assert children_count[h] == 0
selected = set()
for x in range(n):
if not heads:
break
pick = rand.choice(heads)
heads.remove(pick)
assert pick not in selected
selected.add(pick)
p1, p2 = parents(pick)
if p1 in children_count:
assert p1 in children_count
children_count[p1] -= 1
assert children_count[p1] >= 0
if children_count[p1] == 0:
assert p1 not in selected, (r, p1)
heads.add(p1)
if p2 in children_count:
assert p2 in children_count
children_count[p2] -= 1
assert children_count[p2] >= 0
if children_count[p2] == 0:
assert p2 not in selected, (r, p2)
heads.add(p2)
return smartset.baseset(selected) & subset
@revsetpredicate(b'randomantichain(REVS, [seed])')
def antichain(repo, subset, x):
"""Pick a random anti-chain in the repository
A antichain is a set of changeset where there isn't any element that is
either a descendant or ancestors of any other element in the set. In other
word, all the elements are independant. It can be summarized with the
following algorithm::
selected = set()
unselected = repo.revs('all()')
while unselected:
pick = random.choice(unselected)
selected.add(pick)
unselected -= repo.revs('::<pick> + <pick>::')
"""
args = revsetlang.getargs(
x, 1, 2, _(b"randomantichain expects revisions and an optional seed")
)
if len(args) == 1:
(x,) = args
rand = random
elif len(args) == 2:
x, seed = args
seed = revsetlang.getinteger(seed, _(b"seed should be a number"))
rand = random.Random(seed)
else:
assert False
cl = repo.changelog
# We already have cheap access to the parent mapping.
# However, we need to build a mapping of the children mapping
parents = repo.changelog._uncheckedparentrevs
children_map = collections.defaultdict(list)
for r in cl:
p1, p2 = parents(r)
if p1 >= 0:
children_map[p1].append(r)
if p2 >= 0:
children_map[p2].append(r)
children = children_map.__getitem__
selected = set()
undecided = SortedSet(cl)
while undecided:
# while there is "undecided content", we pick a random changeset X
# and we remove anything in `::X + X::` from undecided content
pick = rand.choice(undecided)
selected.add(pick)
undecided.remove(pick)
ancestors = set(p for p in parents(pick) if p in undecided)
descendants = set(c for c in children(pick) if c in undecided)
while ancestors:
current = ancestors.pop()
undecided.remove(current)
for p in parents(current):
if p in undecided:
ancestors.add(p)
while descendants:
current = descendants.pop()
undecided.remove(current)
for p in children(current):
if p in undecided:
ancestors.add(p)
return smartset.baseset(selected) & subset