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Viewing changes to bzrlib/tests/test_counted_lock.py

  • Committer: Canonical.com Patch Queue Manager
  • Date: 2008-10-31 04:39:04 UTC
  • mfrom: (3565.6.16 switch_nick)
  • Revision ID: pqm@pqm.ubuntu.com-20081031043904-52fnbfrloojemvcc
(mbp) branch nickname documentation

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bzrlib/tests/test_counted_lock.py
 
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# Copyright (C) 2007, 2008 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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    LockNotHeld,
 
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    ReadOnlyError,
 
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    TokenMismatch,
 
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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, token=None):
 
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        if token not in (None, 'token'):
 
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            raise TokenMismatch(token, 'token')
 
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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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        return 'token'
 
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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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    def validate_token(self, token):
 
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        if token == 'token':
 
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            # already held by this caller
 
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            return 'token'
 
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        elif token is None:
 
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            return
 
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        else:
 
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            raise TokenMismatch(token, 'token')
 
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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(LockNotHeld, 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())