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Viewing changes to bzrlib/tests/test_counted_lock.py

  • Committer: thitipong at ndrsolution
  • Date: 2011-11-14 06:31:02 UTC
  • Revision ID: thitipong@ndrsolution.com-20111114063102-9obte3yfi2azku7d
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bzrlib/tests/test_counted_lock.py
 
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# Copyright (C) 2007, 2008, 2009 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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 is not None:
 
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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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            else:
 
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                raise TokenMismatch()
 
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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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83
 
 
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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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        result = real_lock.lock_write()
 
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        self.assertEqual('token', result)
 
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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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129
 
 
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class TestCountedLock(TestCase):
 
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    def test_read_lock(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):
 
156
        real_lock = DummyLock()
 
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        l = CountedLock(real_lock)
 
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        l.lock_write()
 
159
        l.lock_read()
 
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        self.assertEquals('token', 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_write_lock_reentrant(self):
 
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        real_lock = DummyLock()
 
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        l = CountedLock(real_lock)
 
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        self.assertEqual('token', l.lock_write())
 
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        self.assertEqual('token', l.lock_write())
 
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        l.unlock()
 
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        l.unlock()
 
188
 
 
189
    def test_reenter_with_token(self):
 
190
        real_lock = DummyLock()
 
191
        l1 = CountedLock(real_lock)
 
192
        l2 = CountedLock(real_lock)
 
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        token = l1.lock_write()
 
194
        self.assertEqual('token', token)
 
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        # now imagine that we lost that connection, but we still have the
 
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        # token...
 
197
        del l1
 
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        # because we can supply the token, we can acquire the lock through
 
199
        # another instance
 
200
        self.assertTrue(real_lock.is_locked())
 
201
        self.assertFalse(l2.is_locked())
 
202
        self.assertEqual(token, l2.lock_write(token=token))
 
203
        self.assertTrue(l2.is_locked())
 
204
        self.assertTrue(real_lock.is_locked())
 
205
        l2.unlock()
 
206
        self.assertFalse(l2.is_locked())
 
207
        self.assertFalse(real_lock.is_locked())
 
208
 
 
209
    def test_break_lock(self):
 
210
        real_lock = DummyLock()
 
211
        l = CountedLock(real_lock)
 
212
        l.lock_write()
 
213
        l.lock_write()
 
214
        self.assertTrue(real_lock.is_locked())
 
215
        l.break_lock()
 
216
        self.assertFalse(l.is_locked())
 
217
        self.assertFalse(real_lock.is_locked())
 
218
 
 
219
    # TODO: test get_physical_lock_status