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# Copyright (C) 2007 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
"""Tests for OS level locks."""
from bzrlib import (
errors,
osutils,
)
from bzrlib.tests.per_lock import TestCaseWithLock
class TestLock(TestCaseWithLock):
def setUp(self):
super(TestLock, self).setUp()
self.build_tree(['a-file'])
def test_read_lock(self):
"""Smoke test for read locks."""
a_lock = self.read_lock('a-file')
self.addCleanup(a_lock.unlock)
# The lock file should be opened for reading
txt = a_lock.f.read()
self.assertEqual('contents of a-file\n', txt)
def test_create_if_needed_read(self):
"""We will create the file if it doesn't exist yet."""
a_lock = self.read_lock('other-file')
self.addCleanup(a_lock.unlock)
txt = a_lock.f.read()
self.assertEqual('', txt)
def test_create_if_needed_write(self):
"""We will create the file if it doesn't exist yet."""
a_lock = self.write_lock('other-file')
self.addCleanup(a_lock.unlock)
txt = a_lock.f.read()
self.assertEqual('', txt)
a_lock.f.seek(0)
a_lock.f.write('foo\n')
a_lock.f.seek(0)
txt = a_lock.f.read()
self.assertEqual('foo\n', txt)
def test_readonly_file(self):
"""If the file is readonly, we can take a read lock.
But we shouldn't be able to take a write lock.
"""
osutils.make_readonly('a-file')
# Make sure the file is read-only (on all platforms)
self.assertRaises(IOError, open, 'a-file', 'rb+')
a_lock = self.read_lock('a-file')
a_lock.unlock()
self.assertRaises(errors.LockFailed, self.write_lock, 'a-file')
def test_write_lock(self):
"""Smoke test for write locks."""
a_lock = self.write_lock('a-file')
self.addCleanup(a_lock.unlock)
# You should be able to read and write to the lock file.
txt = a_lock.f.read()
self.assertEqual('contents of a-file\n', txt)
# Win32 requires that you call seek() when switching between a read
# operation and a write operation.
a_lock.f.seek(0, 2)
a_lock.f.write('more content\n')
a_lock.f.seek(0)
txt = a_lock.f.read()
self.assertEqual('contents of a-file\nmore content\n', txt)
def test_multiple_read_locks(self):
"""You can take out more than one read lock on the same file."""
a_lock = self.read_lock('a-file')
self.addCleanup(a_lock.unlock)
b_lock = self.read_lock('a-file')
self.addCleanup(b_lock.unlock)
def test_multiple_write_locks_exclude(self):
"""Taking out more than one write lock should fail."""
a_lock = self.write_lock('a-file')
self.addCleanup(a_lock.unlock)
# Taking out a lock on a locked file should raise LockContention
self.assertRaises(errors.LockContention, self.write_lock, 'a-file')
def _disabled_test_read_then_write_excludes(self):
"""If a file is read-locked, taking out a write lock should fail."""
a_lock = self.read_lock('a-file')
self.addCleanup(a_lock.unlock)
# Taking out a lock on a locked file should raise LockContention
self.assertRaises(errors.LockContention, self.write_lock, 'a-file')
def test_read_unlock_write(self):
"""Make sure that unlocking allows us to lock write"""
a_lock = self.read_lock('a-file')
a_lock.unlock()
a_lock = self.write_lock('a-file')
a_lock.unlock()
# TODO: jam 20070319 fcntl read locks are not currently fully
# mutually exclusive with write locks. This will be fixed
# in the next release.
def _disabled_test_write_then_read_excludes(self):
"""If a file is write-locked, taking out a read lock should fail.
The file is exclusively owned by the write lock, so we shouldn't be
able to take out a shared read lock.
"""
a_lock = self.write_lock('a-file')
self.addCleanup(a_lock.unlock)
# Taking out a lock on a locked file should raise LockContention
self.assertRaises(errors.LockContention, self.read_lock, 'a-file')
# TODO: jam 20070319 fcntl write locks are not currently fully
# mutually exclusive with read locks. This will be fixed
# in the next release.
def _disabled_test_write_unlock_read(self):
"""If we have removed the write lock, we can grab a read lock."""
a_lock = self.write_lock('a-file')
a_lock.unlock()
a_lock = self.read_lock('a-file')
a_lock.unlock()
def _disabled_test_multiple_read_unlock_write(self):
"""We can only grab a write lock if all read locks are done."""
a_lock = b_lock = c_lock = None
try:
a_lock = self.read_lock('a-file')
b_lock = self.read_lock('a-file')
self.assertRaises(errors.LockContention, self.write_lock, 'a-file')
a_lock.unlock()
a_lock = None
self.assertRaises(errors.LockContention, self.write_lock, 'a-file')
b_lock.unlock()
b_lock = None
c_lock = self.write_lock('a-file')
c_lock.unlock()
c_lock = None
finally:
# Cleanup as needed
if a_lock is not None:
a_lock.unlock()
if b_lock is not None:
b_lock.unlock()
if c_lock is not None:
c_lock.unlock()
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