~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2009, 2011 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 OS Locks."""

from bzrlib import (

    debug,

    errors,

    lock,

    tests,

    )

from bzrlib.tests.scenarios import load_tests_apply_scenarios

load_tests = load_tests_apply_scenarios

class TestOSLock(tests.TestCaseInTempDir):

    scenarios = [(

        name, {

            'write_lock': write_lock,

            'read_lock': read_lock})

        for name, write_lock, read_lock in lock._lock_classes]

    read_lock = None

    write_lock = None

    def setUp(self):

        super(TestOSLock, self).setUp()

        self.build_tree(['a-lock-file'])

    def test_create_read_lock(self):

        r_lock = self.read_lock('a-lock-file')

        r_lock.unlock()

    def test_create_write_lock(self):

        w_lock = self.write_lock('a-lock-file')

        w_lock.unlock()

    def test_read_locks_share(self):

        r_lock = self.read_lock('a-lock-file')

        try:

            lock2 = self.read_lock('a-lock-file')

            lock2.unlock()

        finally:

            r_lock.unlock()

    def test_write_locks_are_exclusive(self):

        w_lock = self.write_lock('a-lock-file')

        try:

            self.assertRaises(errors.LockContention,

                              self.write_lock, 'a-lock-file')

        finally:

            w_lock.unlock()

    def test_read_locks_block_write_locks(self):

        r_lock = self.read_lock('a-lock-file')

        try:

            if lock.have_fcntl and self.write_lock is lock._fcntl_WriteLock:

                # With -Dlock, fcntl locks are properly exclusive

                debug.debug_flags.add('strict_locks')

                self.assertRaises(errors.LockContention,

                                  self.write_lock, 'a-lock-file')

                # But not without it

                debug.debug_flags.remove('strict_locks')

                try:

                    w_lock = self.write_lock('a-lock-file')

                except errors.LockContention:

                    self.fail('Unexpected success. fcntl read locks'

                              ' do not usually block write locks')

                else:

                    w_lock.unlock()

                    self.knownFailure('fcntl read locks don\'t'

                                      ' block write locks without -Dlock')

            else:

                self.assertRaises(errors.LockContention,

                                  self.write_lock, 'a-lock-file')

        finally:

            r_lock.unlock()

    def test_write_locks_block_read_lock(self):

        w_lock = self.write_lock('a-lock-file')

        try:

            if lock.have_fcntl and self.read_lock is lock._fcntl_ReadLock:

                # With -Dlock, fcntl locks are properly exclusive

                debug.debug_flags.add('strict_locks')

                self.assertRaises(errors.LockContention,

                                  self.read_lock, 'a-lock-file')

                # But not without it

                debug.debug_flags.remove('strict_locks')

                try:

                    r_lock = self.read_lock('a-lock-file')

                except errors.LockContention:

                    self.fail('Unexpected success. fcntl write locks'

                              ' do not usually block read locks')

                else:

                    r_lock.unlock()

                    self.knownFailure('fcntl write locks don\'t'

                                      ' block read locks without -Dlock')

            else:

                self.assertRaises(errors.LockContention,

                                  self.read_lock, 'a-lock-file')

        finally:

            w_lock.unlock()

    def test_temporary_write_lock(self):

        r_lock = self.read_lock('a-lock-file')

        try:

            status, w_lock = r_lock.temporary_write_lock()

            self.assertTrue(status)

            # This should block another write lock

            try:

                self.assertRaises(errors.LockContention,

                                  self.write_lock, 'a-lock-file')

            finally:

                r_lock = w_lock.restore_read_lock()

            # We should be able to take a read lock now

            r_lock2 = self.read_lock('a-lock-file')

            r_lock2.unlock()

        finally:

            r_lock.unlock()

    def test_temporary_write_lock_fails(self):

        r_lock = self.read_lock('a-lock-file')

        try:

            r_lock2 = self.read_lock('a-lock-file')

            try:

                status, w_lock = r_lock.temporary_write_lock()

                self.assertFalse(status)

                # Taking out the lock requires unlocking and locking again, so

                # we have to replace the original object

                r_lock = w_lock

            finally:

                r_lock2.unlock()

            # We should be able to take a read lock now

            r_lock2 = self.read_lock('a-lock-file')

            r_lock2.unlock()

        finally:

            r_lock.unlock()