tests/test-rust-revlog.py

revlog: add a C implementation of `headrevsdiff`

Python implementation of `headrevsdiff` can be very slow in the worst
case compared with the `heads` computation it replaces, since the
latter is done in C.

Even the average case of this Python implementation is still
noticeable in the profiles.

This patch makes the computation much much faster by doing it in C.

import struct
import unittest

from mercurial.node import hex

try:
    from mercurial import rustext

    rustext.__name__  # trigger immediate actual import
except ImportError:
    rustext = None
else:
    from mercurial.rustext import revlog

    # this would fail already without appropriate ancestor.__package__
    from mercurial.rustext.ancestor import LazyAncestors

from mercurial.testing import revlog as revlogtesting

header = struct.unpack(">I", revlogtesting.data_non_inlined[:4])[0]


@unittest.skipIf(
    rustext is None,
    "rustext module revlog relies on is not available",
)
class RustRevlogIndexTest(revlogtesting.RevlogBasedTestBase):
    def test_heads(self):
        idx = self.parseindex()
        rustidx = revlog.Index(revlogtesting.data_non_inlined, header)
        self.assertEqual(rustidx.headrevs(), idx.headrevs())

    def test_len(self):
        idx = self.parseindex()
        rustidx = revlog.Index(revlogtesting.data_non_inlined, header)
        self.assertEqual(len(rustidx), len(idx))

    def test_ancestors(self):
        rustidx = revlog.Index(revlogtesting.data_non_inlined, header)
        lazy = LazyAncestors(rustidx, [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.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])

        # let's check bool for an empty one
        self.assertFalse(LazyAncestors(rustidx, [0], 0, False))


@unittest.skipIf(
    rustext is None,
    "rustext module revlog relies on is not available",
)
class RustRevlogNodeTreeClassTest(revlogtesting.RustRevlogBasedTestBase):
    def test_standalone_nodetree(self):
        idx = self.parserustindex()
        nt = revlog.NodeTree(idx)
        for i in range(4):
            nt.insert(i)

        bin_nodes = [entry[7] for entry in idx]
        hex_nodes = [hex(n) for n in bin_nodes]

        for i, node in enumerate(hex_nodes):
            self.assertEqual(nt.prefix_rev_lookup(node), i)
            self.assertEqual(nt.prefix_rev_lookup(node[:5]), i)

        # all 4 revisions in idx (standard data set) have different
        # first nybbles in their Node IDs,
        # hence `nt.shortest()` should return 1 for them, except when
        # the leading nybble is 0 (ambiguity with NULL_NODE)
        for i, (bin_node, hex_node) in enumerate(zip(bin_nodes, hex_nodes)):
            shortest = nt.shortest(bin_node)
            expected = 2 if hex_node[0] == ord('0') else 1
            self.assertEqual(shortest, expected)
            self.assertEqual(nt.prefix_rev_lookup(hex_node[:shortest]), i)

        # test invalidation (generation poisoning) detection
        del idx[3]
        self.assertTrue(nt.is_invalidated())


if __name__ == '__main__':
    import silenttestrunner

    silenttestrunner.main(__name__)