~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2006 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 the (un)lock interfaces on all working tree implemenations."""

import sys

from bzrlib import (

    branch,

    errors,

    lockdir,

    )

from bzrlib.tests import TestSkipped

from bzrlib.tests.per_workingtree import TestCaseWithWorkingTree

class TestWorkingTreeLocking(TestCaseWithWorkingTree):

    def test_trivial_lock_read_unlock(self):

        """Locking and unlocking should work trivially."""

        wt = self.make_branch_and_tree('.')

        self.assertFalse(wt.is_locked())

        self.assertFalse(wt.branch.is_locked())

        wt.lock_read()

        try:

            self.assertTrue(wt.is_locked())

            self.assertTrue(wt.branch.is_locked())

        finally:

            wt.unlock()

        self.assertFalse(wt.is_locked())

        self.assertFalse(wt.branch.is_locked())

    def test_trivial_lock_write_unlock(self):

        """Locking for write and unlocking should work trivially."""

        wt = self.make_branch_and_tree('.')

        self.assertFalse(wt.is_locked())

        self.assertFalse(wt.branch.is_locked())

        wt.lock_write()

        try:

            self.assertTrue(wt.is_locked())

            self.assertTrue(wt.branch.is_locked())

        finally:

            wt.unlock()

        self.assertFalse(wt.is_locked())

        self.assertFalse(wt.branch.is_locked())

    def test_trivial_lock_tree_write_unlock(self):

        """Locking for tree write is ok when the branch is not locked."""

        wt = self.make_branch_and_tree('.')

        self.assertFalse(wt.is_locked())

        self.assertFalse(wt.branch.is_locked())

        wt.lock_tree_write()

        try:

            self.assertTrue(wt.is_locked())

            self.assertTrue(wt.branch.is_locked())

        finally:

            wt.unlock()

        self.assertFalse(wt.is_locked())

        self.assertFalse(wt.branch.is_locked())

    def test_trivial_lock_tree_write_branch_read_locked(self):

        """It is ok to lock_tree_write when the branch is read locked."""

        wt = self.make_branch_and_tree('.')

        self.assertFalse(wt.is_locked())

        self.assertFalse(wt.branch.is_locked())

        wt.branch.lock_read()

        try:

            wt.lock_tree_write()

        except errors.ReadOnlyError:

            # When ReadOnlyError is raised, it indicates that the

            # workingtree shares its lock with the branch, which is what

            # the git/hg/bzr0.6 formats do.

            # in this case, no lock should have been taken - but the tree

            # will have been locked because they share a lock. Unlocking

            # just the branch should make everything match again correctly.

            wt.branch.unlock()

            self.assertFalse(wt.is_locked())

            self.assertFalse(wt.branch.is_locked())

            return

        try:

            self.assertTrue(wt.is_locked())

            self.assertTrue(wt.branch.is_locked())

        finally:

            wt.unlock()

        self.assertFalse(wt.is_locked())

        self.assertTrue(wt.branch.is_locked())

        wt.branch.unlock()

    def _test_unlock_with_lock_method(self, methodname):

        """Create a tree and then test its unlocking behaviour.

        :param methodname: The lock method to use to establish locks.

        """

        if sys.platform == "win32":

            raise TestSkipped("don't use oslocks on win32 in unix manner")

        # This helper takes a write lock on the source tree, then opens a

        # second copy and tries to grab a read lock. This works on Unix and is

        # a reasonable way to detect when the file is actually written to, but

        # it won't work (as a test) on Windows. It might be nice to instead

        # stub out the functions used to write and that way do both less work

        # and also be able to execute on Windows.

        self.thisFailsStrictLockCheck()

        # when unlocking the last lock count from tree_write_lock,

        # the tree should do a flush().

        # we test that by changing the inventory using set_root_id

        tree = self.make_branch_and_tree('tree')

        # prepare for a series of changes that will modify the

        # inventory

        getattr(tree, methodname)()

        # note that we dont have a try:finally here because of two reasons:

        # firstly there will only be errors reported if the test fails, and

        # when it fails thats ok as long as the test suite cleanup still works,

        # which it will as the lock objects are released (thats where the

        # warning comes from.  Secondly, it is hard in this test to be

        # sure that we've got the right interactions between try:finally

        # and the lock/unlocks we are doing.

        getattr(tree, methodname)()

        # this should really do something within the public api

        # e.g. mkdir('foo') but all the mutating methods at the

        # moment trigger inventory writes and thus will not

        # let us trigger a read-when-dirty situation.

        old_root = tree.get_root_id()

        tree.set_root_id('new-root')

        # to detect that the inventory is written by unlock, we

        # first check that it was not written yet.

        # TODO: This requires taking a read lock while we are holding the above

        #       write lock, which shouldn't actually be possible

        reference_tree = tree.bzrdir.open_workingtree()

        self.assertEqual(old_root, reference_tree.get_root_id())

        # now unlock the second held lock, which should do nothing.

        tree.unlock()

        reference_tree = tree.bzrdir.open_workingtree()

        self.assertEqual(old_root, reference_tree.get_root_id())

        # unlocking the first lock we took will now flush.

        tree.unlock()

        # and check it was written using another reference tree

        reference_tree = tree.bzrdir.open_workingtree()

        self.assertEqual('new-root', reference_tree.get_root_id())

    def test_unlock_from_tree_write_lock_flushes(self):

        self._test_unlock_with_lock_method("lock_tree_write")

    def test_unlock_from_write_lock_flushes(self):

        self._test_unlock_with_lock_method("lock_write")

    def test_unlock_branch_failures(self):

        """If the branch unlock fails the tree must still unlock."""

        # The public interface for WorkingTree requires a branch, but

        # does not require that the working tree use the branch - its

        # implementation specific how the WorkingTree, Branch, and Repository

        # hang together.

        # in order to test that implementations which *do* unlock via the branch

        # do so correctly, we unlock the branch after locking the working tree.

        # The next unlock on working tree should trigger a LockNotHeld exception

        # from the branch object, which must be exposed to the caller. To meet

        # our object model - where locking a tree locks its branch, and

        # unlocking a branch does not unlock a working tree, *even* for

        # all-in-one implementations like bzr 0.6, git, and hg, implementations

        # must have some separate counter for each object, so our explicit

        # unlock should trigger some error on all implementations, and

        # requiring that to be LockNotHeld seems reasonable.

        #

        # we use this approach rather than decorating the Branch, because the

        # public interface of WorkingTree does not permit altering the branch

        # object - and we cannot tell which attribute might allow us to

        # backdoor-in and change it reliably. For implementation specific tests

        # we can do such skullduggery, but not for interface specific tests.

        # And, its simpler :)

        wt = self.make_branch_and_tree('.')

        self.assertFalse(wt.is_locked())

        self.assertFalse(wt.branch.is_locked())

        wt.lock_write()

        self.assertTrue(wt.is_locked())

        self.assertTrue(wt.branch.is_locked())

        # manually unlock the branch, preparing a LockNotHeld error.

        wt.branch.unlock()

        # the branch *may* still be locked here, if its an all-in-one

        # implementation because there is a single lock object with three

        # references on it, and unlocking the branch only drops this by two

        self.assertRaises(errors.LockNotHeld, wt.unlock)

        # but now, the tree must be unlocked

        self.assertFalse(wt.is_locked())

        # and the branch too.

        self.assertFalse(wt.branch.is_locked())

    def test_failing_to_lock_branch_does_not_lock(self):

        """If the branch cannot be locked, dont lock the tree."""

        # Many implementations treat read-locks as non-blocking, but some

        # treat them as blocking with writes.. Accordingly we test this by

        # opening the branch twice, and locking the branch for write in the

        # second instance.  Our lock contract requires separate instances to

        # mutually exclude if a lock is exclusive at all: If we get no error

        # locking, the test still passes.

        wt = self.make_branch_and_tree('.')

        branch_copy = branch.Branch.open('.')

        branch_copy.lock_write()

        try:

            try:

                wt.lock_read()

            except errors.LockError:

                # any error here means the locks are exclusive in some

                # manner

                self.assertFalse(wt.is_locked())

                self.assertFalse(wt.branch.is_locked())

                return

            else:

                # no error - the branch allows read locks while writes

                # are taken, just pass.

                wt.unlock()

        finally:

            branch_copy.unlock()

    def test_failing_to_lock_write_branch_does_not_lock(self):

        """If the branch cannot be write locked, dont lock the tree."""

        # all implementations of branch are required to treat write

        # locks as blocking (compare to repositories which are not required

        # to do so).

        # Accordingly we test this by opening the branch twice, and locking the

        # branch for write in the second instance.  Our lock contract requires

        # separate instances to mutually exclude.

        wt = self.make_branch_and_tree('.')

        branch_copy = branch.Branch.open('.')

        branch_copy.lock_write()

        try:

            try:

                self.assertRaises(errors.LockError, wt.lock_write)

                self.assertFalse(wt.is_locked())

                self.assertFalse(wt.branch.is_locked())

            finally:

                if wt.is_locked():

                    wt.unlock()

        finally:

            branch_copy.unlock()

    def test_failing_to_lock_tree_write_branch_does_not_lock(self):

        """If the branch cannot be read locked, dont lock the tree."""

        # Many implementations treat read-locks as non-blocking, but some

        # treat them as blocking with writes.. Accordingly we test this by

        # opening the branch twice, and locking the branch for write in the

        # second instance.  Our lock contract requires separate instances to

        # mutually exclude if a lock is exclusive at all: If we get no error

        # locking, the test still passes.

        wt = self.make_branch_and_tree('.')

        branch_copy = branch.Branch.open('.')

        branch_copy.lock_write()

        try:

            try:

                wt.lock_tree_write()

            except errors.LockError:

                # any error here means the locks are exclusive in some

                # manner

                self.assertFalse(wt.is_locked())

                self.assertFalse(wt.branch.is_locked())

                return

            else:

                # no error - the branch allows read locks while writes

                # are taken, just pass.

                wt.unlock()

        finally:

            branch_copy.unlock()