~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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""Tests for the (un)lock interfaces on all working tree implemenations."""

import bzrlib.branch as branch

import bzrlib.errors as errors

from bzrlib.tests.workingtree_implementations 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_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()