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#!/usr/bin/env python
#
# Public Domain 2014-present MongoDB, Inc.
# Public Domain 2008-2014 WiredTiger, Inc.
#
# This is free and unencumbered software released into the public domain.
#
# Anyone is free to copy, modify, publish, use, compile, sell, or
# distribute this software, either in source code form or as a compiled
# binary, for any purpose, commercial or non-commercial, and by any
# means.
#
# In jurisdictions that recognize copyright laws, the author or authors
# of this software dedicate any and all copyright interest in the
# software to the public domain. We make this dedication for the benefit
# of the public at large and to the detriment of our heirs and
# successors. We intend this dedication to be an overt act of
# relinquishment in perpetuity of all present and future rights to this
# software under copyright law.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.
import wiredtiger, wttest
from wtscenario import make_scenarios
# test_rollback_to_stable24.py
# Exercise a recno-counting bug in column store.
#
# Prior to August 2021 a cell for which there's a pending stable update was counted (in the
# column-store RTS code) as having RLE count 1 regardless of what the actual count was.
#
# In order to exploit this we have to do janky things with timestamps, but I think they're
# allowable.
#
# Construct a cell with RLE count of 3 by writing 3 copies of aaaaaa at timestamp 10.
# Then at the next key write bbbbbb at timestamp 10 and cccccc at timestamp 50.
# Evict the page to reconcile it and produce the RLE cell.
#
# Then post an update to the first key of the RLE cell at timestamp 30 (to dddddd), and roll
# back to 40.
#
# Reading at 40, we should at that point see dddddd and two aaaaaa's followed by bbbbbb, but
# with the bad counting we get a key error on the second key.
#
# This happens because it goes to process key 4 but thinks it's on key 2; it finds that it
# needs to roll back the value it's looking at (the cccccc from timestamp 50) but because it
# thinks it's on key to it asks the history store for key 2 and finds nothing. (The bbbbbb
# from timestamp 10 is in the history store, but under key 4; there's nothing in the history
# store for key 2.) So it issues a tombstone, and issues it for key 2, so key 2 improperly
# disappears.
#
# Run this test on rows as well as columns to help make sure the test itself is valid (and
# stays so over time...)
class test_rollback_to_stable24(wttest.WiredTigerTestCase):
session_config = 'isolation=snapshot'
conn_config = 'in_memory=false'
key_format_values = [
('column', dict(key_format='r')),
('integer_row', dict(key_format='i')),
]
scenarios = make_scenarios(key_format_values)
def test_rollback_to_stable24(self):
# Create a table without logging.
uri = "table:rollback_to_stable24"
format = 'key_format={},value_format=S'.format(self.key_format)
self.session.create(uri, format + ', log=(enabled=false)')
# Pin oldest timestamp to 10.
self.conn.set_timestamp('oldest_timestamp=' + self.timestamp_str(10))
# Start stable timestamp at 10.
self.conn.set_timestamp('stable_timestamp=' + self.timestamp_str(10))
value_a = "aaaaa" * 100
value_b = "bbbbb" * 100
value_c = "ccccc" * 100
value_d = "ddddd" * 100
s = self.conn.open_session()
cursor = s.open_cursor(uri)
# Write some keys at time 10.
s.begin_transaction()
cursor[1] = value_a
cursor[2] = value_a
cursor[3] = value_a
cursor[4] = value_b
s.commit_transaction('commit_timestamp=' + self.timestamp_str(10))
# Update key 4 at time 50.
s.begin_transaction()
cursor[4] = value_c
s.commit_transaction('commit_timestamp=' + self.timestamp_str(50))
cursor.close()
# Evict the page to force reconciliation.
evict_cursor = self.session.open_cursor(uri, None, "debug=(release_evict)")
s.begin_transaction()
# Search the key to evict it.
v = evict_cursor[1]
self.assertEqual(v, value_a)
self.assertEqual(evict_cursor.reset(), 0)
s.rollback_transaction()
evict_cursor.close()
# Now update key 1 at time 30.
cursor = s.open_cursor(uri)
s.begin_transaction()
cursor[1] = value_d
s.commit_transaction('commit_timestamp=' + self.timestamp_str(30))
cursor.close()
# Roll back to 40.
self.conn.set_timestamp('stable_timestamp=' + self.timestamp_str(40))
self.conn.rollback_to_stable()
# Now read at 40.
cursor = s.open_cursor(uri)
s.begin_transaction('read_timestamp=' + self.timestamp_str(40))
self.assertEqual(cursor[1], value_d)
self.assertEqual(cursor[2], value_a)
self.assertEqual(cursor[3], value_a)
self.assertEqual(cursor[4], value_b)
s.rollback_transaction()
cursor.close()
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