push: rework the computation of fallbackheads to be correct
The previous computation tried to be smart but ended up being wrong. This was
caught by phase movement test while reworking the phase discovery logic to be
faster.
The previous logic was failing to catch case where the pushed set was not based
on a common heads (i.e. when the discovery seemed to have "over discovered"
content, outside the pushed set)
In the following graph, `e` is a common head and we `hg push -r f`. We need to
detect `c` as a fallback heads and we previous failed to do so::
e
|
d f
|/
c
|
b
|
a
The performance impact of the change seems minimal. On the most impacted
repository at hand (mozilla-try), the slowdown seems mostly mixed in the
overall noise `hg push` but seems to be in the hundred of milliseconds order of
magnitude. When using rust, we seems to be a bit faster, probably because we
leverage more accelaratd internals.
I added a couple of performance related common for further investigation later
on.
import sys
import unittest
from mercurial.node import wdirrev
from mercurial.testing import revlog as revlogtesting
try:
from mercurial import rustext
rustext.__name__ # trigger immediate actual import
except ImportError:
rustext = None
else:
# this would fail already without appropriate ancestor.__package__
from mercurial.rustext.ancestor import (
AncestorsIterator,
LazyAncestors,
MissingAncestors,
)
from mercurial.rustext import dagop
try:
from mercurial.cext import parsers as cparsers
except ImportError:
cparsers = None
@unittest.skipIf(
rustext is None,
'The Rust version of the "ancestor" module is not available. It is needed'
' for this test.',
)
@unittest.skipIf(
rustext is None,
'The Rust or C version of the "parsers" module, which the "ancestor" module'
' relies on, is not available.',
)
class rustancestorstest(revlogtesting.RustRevlogBasedTestBase):
"""Test the correctness of binding to Rust code.
This test is merely for the binding to Rust itself: extraction of
Python variable, giving back the results etc.
It is not meant to test the algorithmic correctness of the operations
on ancestors it provides. Hence the very simple embedded index data is
good enough.
Algorithmic correctness is asserted by the Rust unit tests.
"""
def testiteratorrevlist(self):
idx = self.parserustindex()
# checking test assumption about the index binary data:
self.assertEqual(
{i: (r[5], r[6]) for i, r in enumerate(idx)},
{0: (-1, -1), 1: (0, -1), 2: (1, -1), 3: (2, -1)},
)
ait = AncestorsIterator(idx, [3], 0, True)
self.assertEqual([r for r in ait], [3, 2, 1, 0])
ait = AncestorsIterator(idx, [3], 0, False)
self.assertEqual([r for r in ait], [2, 1, 0])
def testlazyancestors(self):
idx = self.parserustindex()
start_count = sys.getrefcount(idx) # should be 2 (see Python doc)
self.assertEqual(
{i: (r[5], r[6]) for i, r in enumerate(idx)},
{0: (-1, -1), 1: (0, -1), 2: (1, -1), 3: (2, -1)},
)
lazy = LazyAncestors(idx, [3], 0, True)
# we have two more references to the index:
# - in its inner iterator for __contains__ and __bool__
# - in the LazyAncestors instance itself (to spawn new iterators)
self.assertEqual(sys.getrefcount(idx), start_count + 2)
self.assertTrue(2 in lazy)
self.assertTrue(bool(lazy))
self.assertEqual(list(lazy), [3, 2, 1, 0])
# a second time to validate that we spawn new iterators
self.assertEqual(list(lazy), [3, 2, 1, 0])
# now let's watch the refcounts closer
ait = iter(lazy)
self.assertEqual(sys.getrefcount(idx), start_count + 3)
del ait
self.assertEqual(sys.getrefcount(idx), start_count + 2)
del lazy
self.assertEqual(sys.getrefcount(idx), start_count)
# let's check bool for an empty one
self.assertFalse(LazyAncestors(idx, [0], 0, False))
def testmissingancestors(self):
idx = self.parserustindex()
missanc = MissingAncestors(idx, [1])
self.assertTrue(missanc.hasbases())
self.assertEqual(missanc.missingancestors([3]), [2, 3])
missanc.addbases({2})
self.assertEqual(missanc.bases(), {1, 2})
self.assertEqual(missanc.missingancestors([3]), [3])
self.assertEqual(missanc.basesheads(), {2})
def testmissingancestorsremove(self):
idx = self.parserustindex()
missanc = MissingAncestors(idx, [1])
revs = {0, 1, 2, 3}
missanc.removeancestorsfrom(revs)
self.assertEqual(revs, {2, 3})
def testrefcount(self):
idx = self.parserustindex()
start_count = sys.getrefcount(idx)
# refcount increases upon iterator init...
ait = AncestorsIterator(idx, [3], 0, True)
self.assertEqual(sys.getrefcount(idx), start_count + 1)
self.assertEqual(next(ait), 3)
# and decreases once the iterator is removed
del ait
self.assertEqual(sys.getrefcount(idx), start_count)
# and removing ref to the index after iterator init is no issue
ait = AncestorsIterator(idx, [3], 0, True)
del idx
self.assertEqual(list(ait), [3, 2, 1, 0])
# the index is not tracked by the GC, hence there is nothing more
# we can assert to check that it is properly deleted once its refcount
# drops to 0
def testgrapherror(self):
data = (
revlogtesting.data_non_inlined[: 64 + 27]
+ b'\xf2'
+ revlogtesting.data_non_inlined[64 + 28 :]
)
idx = self.parserustindex(data=data)
with self.assertRaises(rustext.GraphError) as arc:
AncestorsIterator(idx, [1], -1, False)
exc = arc.exception
self.assertIsInstance(exc, ValueError)
# rust-cpython issues appropriate str instances for Python 2 and 3
self.assertEqual(exc.args, ('ParentOutOfRange', 1))
def testwdirunsupported(self):
# trying to access ancestors of the working directory raises
idx = self.parserustindex()
with self.assertRaises(rustext.GraphError) as arc:
list(AncestorsIterator(idx, [wdirrev], -1, False))
exc = arc.exception
self.assertIsInstance(exc, ValueError)
# rust-cpython issues appropriate str instances for Python 2 and 3
self.assertEqual(exc.args, ('InvalidRevision', wdirrev))
def testheadrevs(self):
idx = self.parserustindex()
self.assertEqual(dagop.headrevs(idx, [1, 2, 3]), {3})
if __name__ == '__main__':
import silenttestrunner
silenttestrunner.main(__name__)