borg/borg/testsuite/hashindex.py

import base64
import hashlib
import os
import struct
import tempfile
import zlib

import pytest
from ..hashindex import NSIndex, ChunkIndex
from .. import hashindex
from . import BaseTestCase


def H(x):
    # make some 32byte long thing that depends on x
    return bytes('%-0.32d' % x, 'ascii')


class HashIndexTestCase(BaseTestCase):

    def _generic_test(self, cls, make_value, sha):
        idx = cls()
        self.assert_equal(len(idx), 0)
        # Test set
        for x in range(100):
            idx[H(x)] = make_value(x)
        self.assert_equal(len(idx), 100)
        for x in range(100):
            self.assert_equal(idx[H(x)], make_value(x))
        # Test update
        for x in range(100):
            idx[H(x)] = make_value(x * 2)
        self.assert_equal(len(idx), 100)
        for x in range(100):
            self.assert_equal(idx[H(x)], make_value(x * 2))
        # Test delete
        for x in range(50):
            del idx[H(x)]
        self.assert_equal(len(idx), 50)
        idx_name = tempfile.NamedTemporaryFile()
        idx.write(idx_name.name)
        del idx
        # Verify file contents
        with open(idx_name.name, 'rb') as fd:
            self.assert_equal(hashlib.sha256(fd.read()).hexdigest(), sha)
        # Make sure we can open the file
        idx = cls.read(idx_name.name)
        self.assert_equal(len(idx), 50)
        for x in range(50, 100):
            self.assert_equal(idx[H(x)], make_value(x * 2))
        idx.clear()
        self.assert_equal(len(idx), 0)
        idx.write(idx_name.name)
        del idx
        self.assert_equal(len(cls.read(idx_name.name)), 0)

    def test_nsindex(self):
        self._generic_test(NSIndex, lambda x: (x, x),
                           'b96ec1ddabb4278cc92261ee171f7efc979dc19397cc5e89b778f05fa25bf93f')

    def test_chunkindex(self):
        self._generic_test(ChunkIndex, lambda x: (x, x, x),
                           '9d437a1e145beccc790c69e66ba94fc17bd982d83a401c9c6e524609405529d8')

    def test_resize(self):
        n = 2000  # Must be >= MIN_BUCKETS
        idx_name = tempfile.NamedTemporaryFile()
        idx = NSIndex()
        idx.write(idx_name.name)
        initial_size = os.path.getsize(idx_name.name)
        self.assert_equal(len(idx), 0)
        for x in range(n):
            idx[H(x)] = x, x
        idx.write(idx_name.name)
        self.assert_true(initial_size < os.path.getsize(idx_name.name))
        for x in range(n):
            del idx[H(x)]
        self.assert_equal(len(idx), 0)
        idx.write(idx_name.name)
        self.assert_equal(initial_size, os.path.getsize(idx_name.name))

    def test_iteritems(self):
        idx = NSIndex()
        for x in range(100):
            idx[H(x)] = x, x
        iterator = idx.iteritems()
        all = list(iterator)
        self.assert_equal(len(all), 100)
        # iterator is already exhausted by list():
        self.assert_raises(StopIteration, next, iterator)
        second_half = list(idx.iteritems(marker=all[49][0]))
        self.assert_equal(len(second_half), 50)
        self.assert_equal(second_half, all[50:])

    def test_chunkindex_merge(self):
        idx1 = ChunkIndex()
        idx1[H(1)] = 1, 100, 100
        idx1[H(2)] = 2, 200, 200
        idx1[H(3)] = 3, 300, 300
        # no H(4) entry
        idx2 = ChunkIndex()
        idx2[H(1)] = 4, 100, 100
        idx2[H(2)] = 5, 200, 200
        # no H(3) entry
        idx2[H(4)] = 6, 400, 400
        idx1.merge(idx2)
        assert idx1[H(1)] == (5, 100, 100)
        assert idx1[H(2)] == (7, 200, 200)
        assert idx1[H(3)] == (3, 300, 300)
        assert idx1[H(4)] == (6, 400, 400)

    def test_chunkindex_summarize(self):
        idx = ChunkIndex()
        idx[H(1)] = 1, 1000, 100
        idx[H(2)] = 2, 2000, 200
        idx[H(3)] = 3, 3000, 300

        size, csize, unique_size, unique_csize, unique_chunks, chunks = idx.summarize()
        assert size == 1000 + 2 * 2000 + 3 * 3000
        assert csize == 100 + 2 * 200 + 3 * 300
        assert unique_size == 1000 + 2000 + 3000
        assert unique_csize == 100 + 200 + 300
        assert chunks == 1 + 2 + 3
        assert unique_chunks == 3


class HashIndexRefcountingTestCase(BaseTestCase):
    def test_chunkindex_limit(self):
        idx = ChunkIndex()
        idx[H(1)] = ChunkIndex.MAX_VALUE - 1, 1, 2

        # 5 is arbitray, any number of incref/decrefs shouldn't move it once it's limited
        for i in range(5):
            # first incref to move it to the limit
            refcount, *_ = idx.incref(H(1))
            assert refcount == ChunkIndex.MAX_VALUE
        for i in range(5):
            refcount, *_ = idx.decref(H(1))
            assert refcount == ChunkIndex.MAX_VALUE

    def _merge(self, refcounta, refcountb):
        def merge(refcount1, refcount2):
            idx1 = ChunkIndex()
            idx1[H(1)] = refcount1, 1, 2
            idx2 = ChunkIndex()
            idx2[H(1)] = refcount2, 1, 2
            idx1.merge(idx2)
            refcount, *_ = idx1[H(1)]
            return refcount
        result = merge(refcounta, refcountb)
        # check for commutativity
        assert result == merge(refcountb, refcounta)
        return result

    def test_chunkindex_merge_limit1(self):
        # Check that it does *not* limit at MAX_VALUE - 1
        # (MAX_VALUE is odd)
        half = ChunkIndex.MAX_VALUE // 2
        assert self._merge(half, half) == ChunkIndex.MAX_VALUE - 1

    def test_chunkindex_merge_limit2(self):
        # 3000000000 + 2000000000 > MAX_VALUE
        assert self._merge(3000000000, 2000000000) == ChunkIndex.MAX_VALUE

    def test_chunkindex_merge_limit3(self):
        # Crossover point: both addition and limit semantics will yield the same result
        half = ChunkIndex.MAX_VALUE // 2
        assert self._merge(half + 1, half) == ChunkIndex.MAX_VALUE

    def test_chunkindex_merge_limit4(self):
        # Beyond crossover, result of addition would be 2**31
        half = ChunkIndex.MAX_VALUE // 2
        assert self._merge(half + 2, half) == ChunkIndex.MAX_VALUE
        assert self._merge(half + 1, half + 1) == ChunkIndex.MAX_VALUE

    def test_chunkindex_add(self):
        idx1 = ChunkIndex()
        idx1.add(H(1), 5, 6, 7)
        assert idx1[H(1)] == (5, 6, 7)
        idx1.add(H(1), 1, 0, 0)
        assert idx1[H(1)] == (6, 6, 7)

    def test_incref_limit(self):
        idx1 = ChunkIndex()
        idx1[H(1)] = (ChunkIndex.MAX_VALUE, 6, 7)
        idx1.incref(H(1))
        refcount, *_ = idx1[H(1)]
        assert refcount == ChunkIndex.MAX_VALUE

    def test_decref_limit(self):
        idx1 = ChunkIndex()
        idx1[H(1)] = ChunkIndex.MAX_VALUE, 6, 7
        idx1.decref(H(1))
        refcount, *_ = idx1[H(1)]
        assert refcount == ChunkIndex.MAX_VALUE

    def test_decref_zero(self):
        idx1 = ChunkIndex()
        idx1[H(1)] = 0, 0, 0
        with pytest.raises(AssertionError):
            idx1.decref(H(1))

    def test_incref_decref(self):
        idx1 = ChunkIndex()
        idx1.add(H(1), 5, 6, 7)
        assert idx1[H(1)] == (5, 6, 7)
        idx1.incref(H(1))
        assert idx1[H(1)] == (6, 6, 7)
        idx1.decref(H(1))
        assert idx1[H(1)] == (5, 6, 7)

    def test_setitem_raises(self):
        idx1 = ChunkIndex()
        with pytest.raises(AssertionError):
            idx1[H(1)] = ChunkIndex.MAX_VALUE + 1, 0, 0

    def test_keyerror(self):
        idx = ChunkIndex()
        with pytest.raises(KeyError):
            idx.incref(H(1))
        with pytest.raises(KeyError):
            idx.decref(H(1))
        with pytest.raises(KeyError):
            idx[H(1)]
        with pytest.raises(OverflowError):
            idx.add(H(1), -1, 0, 0)


class HashIndexDataTestCase(BaseTestCase):
    # This bytestring was created with 1.0-maint at c2f9533
    HASHINDEX = b'eJzt0L0NgmAUhtHLT0LDEI6AuAEhMVYmVnSuYefC7AB3Aj9KNedJbnfyFne6P67P27w0EdG1Eac+Cm1ZybAsy7Isy7Isy7Isy7I' \
                b'sy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7Isy7LsL9nhc+cqTZ' \
                b'3XlO2Ys++Du5fX+l1/YFmWZVmWZVmWZVmWZVmWZVmWZVmWZVmWZVmWZVmWZVmWZVmWZVmWZVmWZVmWZVmWZVn2/+0O2rYccw=='

    def _serialize_hashindex(self, idx):
        with tempfile.TemporaryDirectory() as tempdir:
            file = os.path.join(tempdir, 'idx')
            idx.write(file)
            with open(file, 'rb') as f:
                return self._pack(f.read())

    def _deserialize_hashindex(self, bytestring):
        with tempfile.TemporaryDirectory() as tempdir:
            file = os.path.join(tempdir, 'idx')
            with open(file, 'wb') as f:
                f.write(self._unpack(bytestring))
            return ChunkIndex.read(file)

    def _pack(self, bytestring):
        return base64.b64encode(zlib.compress(bytestring))

    def _unpack(self, bytestring):
        return zlib.decompress(base64.b64decode(bytestring))

    def test_identical_creation(self):
        idx1 = ChunkIndex()
        idx1[H(1)] = 1, 2, 3
        idx1[H(2)] = 2**31 - 1, 0, 0
        idx1[H(3)] = 4294962296, 0, 0  # 4294962296 is -5000 interpreted as an uint32_t

        assert self._serialize_hashindex(idx1) == self.HASHINDEX

    def test_read_known_good(self):
        idx1 = self._deserialize_hashindex(self.HASHINDEX)
        assert idx1[H(1)] == (1, 2, 3)
        assert idx1[H(2)] == (2**31 - 1, 0, 0)
        assert idx1[H(3)] == (4294962296, 0, 0)

        idx2 = ChunkIndex()
        idx2[H(3)] = 2**32 - 123456, 6, 7
        idx1.merge(idx2)
        assert idx1[H(3)] == (ChunkIndex.MAX_VALUE, 0, 0)


def test_nsindex_segment_limit():
    idx = NSIndex()
    with pytest.raises(AssertionError):
        idx[H(1)] = NSIndex.MAX_VALUE + 1, 0
    assert H(1) not in idx
    idx[H(2)] = NSIndex.MAX_VALUE, 0
    assert H(2) in idx


def test_max_load_factor():
    assert NSIndex.MAX_LOAD_FACTOR < 1.0
    assert ChunkIndex.MAX_LOAD_FACTOR < 1.0


class IndexCorruptionTestCase(BaseTestCase):
    def test_bug_4829(self):

        from struct import pack

        def HH(x, y):
            # make some 32byte long thing that depends on x and y.
            # same x will mean a collision in the hashtable as bucket index is computed from
            # first 4 bytes. giving a specific x targets bucket index x.
            # y is to create different keys and does not go into the bucket index calculation.
            # so, same x + different y --> collision
            return pack('<IIQQQ', x, y, 0, 0, 0)  # 2 * 4 + 3 * 8 == 32

        idx = NSIndex()

        # create lots of colliding entries
        for y in range(700):  # stay below max load to not trigger resize
            idx[HH(0, y)] = (0, y)

        # assert idx.size() == 1031 * 40 + 18  # 1031 buckets + header

        # delete lots of the collisions, creating lots of tombstones
        for y in range(400):  # stay above min load to not trigger resize
            del idx[HH(0, y)]

        # create lots of colliding entries, within the not yet used part of the hashtable
        for y in range(330):  # stay below max load to not trigger resize
            # at y == 259 a resize will happen due to going beyond max EFFECTIVE load
            # if the bug is present, that element will be inserted at the wrong place.
            # and because it will be at the wrong place, it can not be found again.
            idx[HH(600, y)] = 600, y

        # now check if hashtable contents is as expected:

        assert [idx.get(HH(0, y)) for y in range(400, 700)] == [(0, y) for y in range(400, 700)]

        assert [HH(0, y) in idx for y in range(400)] == [False for y in range(400)]  # deleted entries

        # this will fail at HH(600, 259) if the bug is present.
        assert [idx.get(HH(600, y)) for y in range(330)] == [(600, y) for y in range(330)]