# Copyright (C) 2007, 2008, 2009 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
"""Tests for bzrlib.counted_lock"""
from bzrlib.counted_lock import CountedLock
from bzrlib.errors import (
LockError,
LockNotHeld,
ReadOnlyError,
TokenMismatch,
)
from bzrlib.tests import TestCase
class DummyLock(object):
"""Lock that just records what's been done to it."""
def __init__(self):
self._calls = []
self._lock_mode = None
def is_locked(self):
return self._lock_mode is not None
def lock_read(self):
self._assert_not_locked()
self._lock_mode = 'r'
self._calls.append('lock_read')
def lock_write(self, token=None):
if token is not None:
if token == 'token':
# already held by this caller
return 'token'
else:
raise TokenMismatch()
self._assert_not_locked()
self._lock_mode = 'w'
self._calls.append('lock_write')
return 'token'
def unlock(self):
self._assert_locked()
self._lock_mode = None
self._calls.append('unlock')
def break_lock(self):
self._lock_mode = None
self._calls.append('break')
def _assert_locked(self):
if not self._lock_mode:
raise LockError("%s is not locked" % (self,))
def _assert_not_locked(self):
if self._lock_mode:
raise LockError("%s is already locked in mode %r" %
(self, self._lock_mode))
def validate_token(self, token):
if token == 'token':
# already held by this caller
return 'token'
elif token is None:
return
else:
raise TokenMismatch(token, 'token')
class TestDummyLock(TestCase):
def test_lock_initially_not_held(self):
l = DummyLock()
self.assertFalse(l.is_locked())
def test_lock_not_reentrant(self):
# can't take the underlying lock twice
l = DummyLock()
l.lock_read()
self.assertRaises(LockError, l.lock_read)
def test_detect_underlock(self):
l = DummyLock()
self.assertRaises(LockError, l.unlock)
def test_basic_locking(self):
# dummy lock works like a basic non reentrant lock
real_lock = DummyLock()
self.assertFalse(real_lock.is_locked())
# lock read and unlock
real_lock.lock_read()
self.assertTrue(real_lock.is_locked())
real_lock.unlock()
self.assertFalse(real_lock.is_locked())
# lock write and unlock
result = real_lock.lock_write()
self.assertEqual('token', result)
self.assertTrue(real_lock.is_locked())
real_lock.unlock()
self.assertFalse(real_lock.is_locked())
# check calls
self.assertEqual(
['lock_read', 'unlock', 'lock_write', 'unlock'],
real_lock._calls)
def test_break_lock(self):
l = DummyLock()
l.lock_write()
l.break_lock()
self.assertFalse(l.is_locked())
self.assertEqual(
['lock_write', 'break'],
l._calls)
class TestCountedLock(TestCase):
def test_read_lock(self):
# Lock and unlock a counted lock
real_lock = DummyLock()
l = CountedLock(real_lock)
self.assertFalse(l.is_locked())
# can lock twice, although this isn't allowed on the underlying lock
l.lock_read()
l.lock_read()
self.assertTrue(l.is_locked())
# and release
l.unlock()
self.assertTrue(l.is_locked())
l.unlock()
self.assertFalse(l.is_locked())
self.assertEquals(
['lock_read', 'unlock'],
real_lock._calls)
def test_unlock_not_locked(self):
real_lock = DummyLock()
l = CountedLock(real_lock)
self.assertRaises(LockNotHeld, l.unlock)
def test_read_lock_while_write_locked(self):
real_lock = DummyLock()
l = CountedLock(real_lock)
l.lock_write()
l.lock_read()
self.assertEquals('token', l.lock_write())
l.unlock()
l.unlock()
l.unlock()
self.assertFalse(l.is_locked())
self.assertEquals(
['lock_write', 'unlock'],
real_lock._calls)
def test_write_lock_while_read_locked(self):
real_lock = DummyLock()
l = CountedLock(real_lock)
l.lock_read()
self.assertRaises(ReadOnlyError, l.lock_write)
self.assertRaises(ReadOnlyError, l.lock_write)
l.unlock()
self.assertFalse(l.is_locked())
self.assertEquals(
['lock_read', 'unlock'],
real_lock._calls)
def test_write_lock_reentrant(self):
real_lock = DummyLock()
l = CountedLock(real_lock)
self.assertEqual('token', l.lock_write())
self.assertEqual('token', l.lock_write())
l.unlock()
l.unlock()
def test_reenter_with_token(self):
real_lock = DummyLock()
l1 = CountedLock(real_lock)
l2 = CountedLock(real_lock)
token = l1.lock_write()
self.assertEqual('token', token)
# now imagine that we lost that connection, but we still have the
# token...
del l1
# because we can supply the token, we can acquire the lock through
# another instance
self.assertTrue(real_lock.is_locked())
self.assertFalse(l2.is_locked())
self.assertEqual(token, l2.lock_write(token=token))
self.assertTrue(l2.is_locked())
self.assertTrue(real_lock.is_locked())
l2.unlock()
self.assertFalse(l2.is_locked())
self.assertFalse(real_lock.is_locked())
def test_break_lock(self):
real_lock = DummyLock()
l = CountedLock(real_lock)
l.lock_write()
l.lock_write()
self.assertTrue(real_lock.is_locked())
l.break_lock()
self.assertFalse(l.is_locked())
self.assertFalse(real_lock.is_locked())
# TODO: test get_physical_lock_status
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