tests/test-parseindex2.py

documentation: add some internals documentation about bid merge

This is an important algorithm that was only documented on the wiki so far.

Some update to the algorithm (and associated doc) is to expected in the future
since the bid merge algorithm is bug-ridden when it comes to file deletion comes
to play.

Differential Revision: https://phab.mercurial-scm.org/D8711

"""This unit test primarily tests parsers.parse_index2().

It also checks certain aspects of the parsers module as a whole.
"""

from __future__ import absolute_import, print_function

import struct
import subprocess
import sys
import unittest

from mercurial.node import (
    nullid,
    nullrev,
)
from mercurial import (
    node as nodemod,
    policy,
    pycompat,
)

parsers = policy.importmod('parsers')

# original python implementation
def gettype(q):
    return int(q & 0xFFFF)


def offset_type(offset, type):
    return int(int(offset) << 16 | type)


indexformatng = ">Qiiiiii20s12x"


def py_parseindex(data, inline):
    s = 64
    cache = None
    index = []
    nodemap = {nullid: nullrev}
    n = off = 0

    l = len(data) - s
    append = index.append
    if inline:
        cache = (0, data)
        while off <= l:
            e = struct.unpack(indexformatng, data[off : off + s])
            nodemap[e[7]] = n
            append(e)
            n += 1
            if e[1] < 0:
                break
            off += e[1] + s
    else:
        while off <= l:
            e = struct.unpack(indexformatng, data[off : off + s])
            nodemap[e[7]] = n
            append(e)
            n += 1
            off += s

    e = list(index[0])
    type = gettype(e[0])
    e[0] = offset_type(0, type)
    index[0] = tuple(e)

    return index, cache


data_inlined = (
    b'\x00\x01\x00\x01\x00\x00\x00\x00\x00\x00\x01\x8c'
    b'\x00\x00\x04\x07\x00\x00\x00\x00\x00\x00\x15\x15\xff\xff\xff'
    b'\xff\xff\xff\xff\xff\xebG\x97\xb7\x1fB\x04\xcf\x13V\x81\tw\x1b'
    b'w\xdduR\xda\xc6\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
    b'x\x9c\x9d\x93?O\xc30\x10\xc5\xf7|\x8a\xdb\x9a\xa8m\x06\xd8*\x95'
    b'\x81B\xa1\xa2\xa2R\xcb\x86Pd\x9a\x0b5$vd_\x04\xfd\xf6\x9c\xff@'
    b'\x11!\x0b\xd9\xec\xf7\xbbw\xe7gG6\xad6\x04\xdaN\xc0\x92\xa0$)'
    b'\xb1\x82\xa2\xd1%\x16\xa4\x8b7\xa9\xca\xd4-\xb2Y\x02\xfc\xc9'
    b'\xcaS\xf9\xaeX\xed\xb6\xd77Q\x02\x83\xd4\x19\xf5--Y\xea\xe1W'
    b'\xab\xed\x10\xceR\x0f_\xdf\xdf\r\xe1,\xf5\xf0\xcb\xf5 \xceR\x0f'
    b'_\xdc\x0e\x0e\xc3R\x0f_\xae\x96\x9b!\x9e\xa5\x1e\xbf\xdb,\x06'
    b'\xc7q\x9a/\x88\x82\xc3B\xea\xb5\xb4TJ\x93\xb6\x82\x0e\xe16\xe6'
    b'KQ\xdb\xaf\xecG\xa3\xd1 \x01\xd3\x0b_^\xe8\xaa\xa0\xae\xad\xd1'
    b'&\xbef\x1bz\x08\xb0|\xc9Xz\x06\xf6Z\x91\x90J\xaa\x17\x90\xaa'
    b'\xd2\xa6\x11$5C\xcf\xba#\xa0\x03\x02*2\x92-\xfc\xb1\x94\xdf\xe2'
    b'\xae\xb8\'m\x8ey0^\x85\xd3\x82\xb4\xf0`:\x9c\x00\x8a\xfd\x01'
    b'\xb0\xc6\x86\x8b\xdd\xae\x80\xf3\xa9\x9fd\x16\n\x00R%\x1a\x06'
    b'\xe9\xd8b\x98\x1d\xf4\xf3+\x9bf\x01\xd8p\x1b\xf3.\xed\x9f^g\xc3'
    b'^\xd9W81T\xdb\xd5\x04sx|\xf2\xeb\xd6`%?x\xed"\x831\xbf\xf3\xdc'
    b'b\xeb%gaY\xe1\xad\x9f\xb9f\'1w\xa9\xa5a\x83s\x82J\xb98\xbc4\x8b'
    b'\x83\x00\x9f$z\xb8#\xa5\xb1\xdf\x98\xd9\xec\x1b\x89O\xe3Ts\x9a4'
    b'\x17m\x8b\xfc\x8f\xa5\x95\x9a\xfc\xfa\xed,\xe5|\xa1\xfe\x15\xb9'
    b'\xbc\xb2\x93\x1f\xf2\x95\xff\xdf,\x1a\xc5\xe7\x17*\x93Oz:>\x0e'
)

data_non_inlined = (
    b'\x00\x00\x00\x01\x00\x00\x00\x00\x00\x01D\x19'
    b'\x00\x07e\x12\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff'
    b'\xff\xff\xff\xff\xd1\xf4\xbb\xb0\xbe\xfc\x13\xbd\x8c\xd3\x9d'
    b'\x0f\xcd\xd9;\x8c\x07\x8cJ/\x00\x00\x00\x00\x00\x00\x00\x00\x00'
    b'\x00\x00\x00\x00\x00\x00\x01D\x19\x00\x00\x00\x00\x00\xdf\x00'
    b'\x00\x01q\x00\x00\x00\x01\x00\x00\x00\x01\x00\x00\x00\x00\xff'
    b'\xff\xff\xff\xc1\x12\xb9\x04\x96\xa4Z1t\x91\xdfsJ\x90\xf0\x9bh'
    b'\x07l&\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
    b'\x00\x01D\xf8\x00\x00\x00\x00\x01\x1b\x00\x00\x01\xb8\x00\x00'
    b'\x00\x01\x00\x00\x00\x02\x00\x00\x00\x01\xff\xff\xff\xff\x02\n'
    b'\x0e\xc6&\xa1\x92\xae6\x0b\x02i\xfe-\xe5\xbao\x05\xd1\xe7\x00'
    b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01F'
    b'\x13\x00\x00\x00\x00\x01\xec\x00\x00\x03\x06\x00\x00\x00\x01'
    b'\x00\x00\x00\x03\x00\x00\x00\x02\xff\xff\xff\xff\x12\xcb\xeby1'
    b'\xb6\r\x98B\xcb\x07\xbd`\x8f\x92\xd9\xc4\x84\xbdK\x00\x00\x00'
    b'\x00\x00\x00\x00\x00\x00\x00\x00\x00'
)


def parse_index2(data, inline):
    index, chunkcache = parsers.parse_index2(data, inline)
    return list(index), chunkcache


def importparsers(hexversion):
    """Import mercurial.parsers with the given sys.hexversion."""
    # The file parsers.c inspects sys.hexversion to determine the version
    # of the currently-running Python interpreter, so we monkey-patch
    # sys.hexversion to simulate using different versions.
    code = (
        "import sys; sys.hexversion=%s; "
        "import mercurial.cext.parsers" % hexversion
    )
    cmd = "python -c \"%s\"" % code
    # We need to do these tests inside a subprocess because parser.c's
    # version-checking code happens inside the module init function, and
    # when using reload() to reimport an extension module, "The init function
    # of extension modules is not called a second time"
    # (from http://docs.python.org/2/library/functions.html?#reload).
    p = subprocess.Popen(
        cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT
    )
    return p.communicate()  # returns stdout, stderr


def hexfailmsg(testnumber, hexversion, stdout, expected):
    try:
        hexstring = hex(hexversion)
    except TypeError:
        hexstring = None
    return (
        "FAILED: version test #%s with Python %s and patched "
        "sys.hexversion %r (%r):\n Expected %s but got:\n-->'%s'\n"
        % (
            testnumber,
            sys.version_info,
            hexversion,
            hexstring,
            expected,
            stdout,
        )
    )


def makehex(major, minor, micro):
    return int("%x%02x%02x00" % (major, minor, micro), 16)


class parseindex2tests(unittest.TestCase):
    def assertversionokay(self, testnumber, hexversion):
        stdout, stderr = importparsers(hexversion)
        self.assertFalse(
            stdout, hexfailmsg(testnumber, hexversion, stdout, 'no stdout')
        )

    def assertversionfail(self, testnumber, hexversion):
        stdout, stderr = importparsers(hexversion)
        # We include versionerrortext to distinguish from other ImportErrors.
        errtext = b"ImportError: %s" % pycompat.sysbytes(
            parsers.versionerrortext
        )
        self.assertIn(
            errtext,
            stdout,
            hexfailmsg(
                testnumber,
                hexversion,
                stdout,
                expected="stdout to contain %r" % errtext,
            ),
        )

    def testversiondetection(self):
        """Check the version-detection logic when importing parsers."""
        # Only test the version-detection logic if it is present.
        try:
            parsers.versionerrortext
        except AttributeError:
            return
        info = sys.version_info
        major, minor, micro = info[0], info[1], info[2]
        # Test same major-minor versions.
        self.assertversionokay(1, makehex(major, minor, micro))
        self.assertversionokay(2, makehex(major, minor, micro + 1))
        # Test different major-minor versions.
        self.assertversionfail(3, makehex(major + 1, minor, micro))
        self.assertversionfail(4, makehex(major, minor + 1, micro))
        self.assertversionfail(5, "'foo'")

    def testbadargs(self):
        # Check that parse_index2() raises TypeError on bad arguments.
        with self.assertRaises(TypeError):
            parse_index2(0, True)

    def testparseindexfile(self):
        # Check parsers.parse_index2() on an index file against the
        # original Python implementation of parseindex, both with and
        # without inlined data.

        want = py_parseindex(data_inlined, True)
        got = parse_index2(data_inlined, True)
        self.assertEqual(want, got)  # inline data

        want = py_parseindex(data_non_inlined, False)
        got = parse_index2(data_non_inlined, False)
        self.assertEqual(want, got)  # no inline data

        ix = parsers.parse_index2(data_inlined, True)[0]
        for i, r in enumerate(ix):
            if r[7] == nullid:
                i = -1
            try:
                self.assertEqual(
                    ix[r[7]],
                    i,
                    'Reverse lookup inconsistent for %r' % nodemod.hex(r[7]),
                )
            except TypeError:
                # pure version doesn't support this
                break

    def testminusone(self):
        want = (0, 0, 0, -1, -1, -1, -1, nullid)
        index, junk = parsers.parse_index2(data_inlined, True)
        got = index[-1]
        self.assertEqual(want, got)  # inline data

        index, junk = parsers.parse_index2(data_non_inlined, False)
        got = index[-1]
        self.assertEqual(want, got)  # no inline data

    def testdelitemwithoutnodetree(self):
        index, _junk = parsers.parse_index2(data_non_inlined, False)

        def hexrev(rev):
            if rev == nullrev:
                return b'\xff\xff\xff\xff'
            else:
                return nodemod.bin('%08x' % rev)

        def appendrev(p1, p2=nullrev):
            # node won't matter for this test, let's just make sure
            # they don't collide. Other data don't matter either.
            node = hexrev(p1) + hexrev(p2) + b'.' * 12
            index.append((0, 0, 12, 1, 34, p1, p2, node))

        appendrev(4)
        appendrev(5)
        appendrev(6)
        self.assertEqual(len(index), 7)

        del index[1:-1]

        # assertions that failed before correction
        self.assertEqual(len(index), 1)  # was 4
        headrevs = getattr(index, 'headrevs', None)
        if headrevs is not None:  # not implemented in pure
            self.assertEqual(index.headrevs(), [0])  # gave ValueError


if __name__ == '__main__':
    import silenttestrunner

    silenttestrunner.main(__name__)