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2475.4.1
by Martin Pool
Start adding CountedLock class to partially replace LockableFiles |
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# Copyright (C) 2007 Canonical Ltd
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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"""Tests for bzrlib.counted_lock"""
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from bzrlib.counted_lock import CountedLock |
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from bzrlib.errors import ( |
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LockError, |
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ReadOnlyError, |
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)
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from bzrlib.tests import TestCase |
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class DummyLock(object): |
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"""Lock that just records what's been done to it."""
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def __init__(self): |
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self._calls = [] |
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self._lock_mode = None |
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def is_locked(self): |
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return self._lock_mode is not None |
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def lock_read(self): |
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self._assert_not_locked() |
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self._lock_mode = 'r' |
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self._calls.append('lock_read') |
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def lock_write(self): |
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self._assert_not_locked() |
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self._lock_mode = 'w' |
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self._calls.append('lock_write') |
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def unlock(self): |
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self._assert_locked() |
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self._lock_mode = None |
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self._calls.append('unlock') |
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def break_lock(self): |
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self._lock_mode = None |
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self._calls.append('break') |
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def _assert_locked(self): |
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if not self._lock_mode: |
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raise LockError("%s is not locked" % (self,)) |
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def _assert_not_locked(self): |
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if self._lock_mode: |
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raise LockError("%s is already locked in mode %r" % |
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(self, self._lock_mode)) |
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class TestDummyLock(TestCase): |
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def test_lock_initially_not_held(self): |
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l = DummyLock() |
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self.assertFalse(l.is_locked()) |
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def test_lock_not_reentrant(self): |
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# can't take the underlying lock twice
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l = DummyLock() |
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l.lock_read() |
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self.assertRaises(LockError, l.lock_read) |
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def test_detect_underlock(self): |
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l = DummyLock() |
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self.assertRaises(LockError, l.unlock) |
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def test_basic_locking(self): |
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# dummy lock works like a basic non reentrant lock
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real_lock = DummyLock() |
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self.assertFalse(real_lock.is_locked()) |
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# lock read and unlock
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real_lock.lock_read() |
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self.assertTrue(real_lock.is_locked()) |
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real_lock.unlock() |
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self.assertFalse(real_lock.is_locked()) |
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# lock write and unlock
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real_lock.lock_write() |
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self.assertTrue(real_lock.is_locked()) |
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real_lock.unlock() |
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self.assertFalse(real_lock.is_locked()) |
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# check calls
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self.assertEqual( |
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['lock_read', 'unlock', 'lock_write', 'unlock'], |
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real_lock._calls) |
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def test_break_lock(self): |
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l = DummyLock() |
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l.lock_write() |
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l.break_lock() |
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self.assertFalse(l.is_locked()) |
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self.assertEqual( |
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['lock_write', 'break'], |
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l._calls) |
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class TestCountedLock(TestCase): |
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def test_lock_unlock(self): |
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# Lock and unlock a counted lock
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real_lock = DummyLock() |
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l = CountedLock(real_lock) |
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self.assertFalse(l.is_locked()) |
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# can lock twice, although this isn't allowed on the underlying lock
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l.lock_read() |
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l.lock_read() |
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self.assertTrue(l.is_locked()) |
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# and release
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l.unlock() |
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self.assertTrue(l.is_locked()) |
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l.unlock() |
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self.assertFalse(l.is_locked()) |
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self.assertEquals( |
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['lock_read', 'unlock'], |
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real_lock._calls) |
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def test_unlock_not_locked(self): |
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real_lock = DummyLock() |
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l = CountedLock(real_lock) |
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self.assertRaises(LockError, l.unlock) |
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def test_read_lock_while_write_locked(self): |
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real_lock = DummyLock() |
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l = CountedLock(real_lock) |
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l.lock_write() |
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l.lock_read() |
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l.lock_write() |
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l.unlock() |
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l.unlock() |
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l.unlock() |
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self.assertFalse(l.is_locked()) |
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self.assertEquals( |
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['lock_write', 'unlock'], |
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real_lock._calls) |
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def test_write_lock_while_read_locked(self): |
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real_lock = DummyLock() |
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l = CountedLock(real_lock) |
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l.lock_read() |
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self.assertRaises(ReadOnlyError, l.lock_write) |
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self.assertRaises(ReadOnlyError, l.lock_write) |
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l.unlock() |
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self.assertFalse(l.is_locked()) |
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self.assertEquals( |
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['lock_read', 'unlock'], |
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real_lock._calls) |
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def test_break_lock(self): |
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real_lock = DummyLock() |
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l = CountedLock(real_lock) |
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l.lock_write() |
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l.lock_write() |
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self.assertTrue(real_lock.is_locked()) |
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l.break_lock() |
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self.assertFalse(l.is_locked()) |
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self.assertFalse(real_lock.is_locked()) |