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# Copyright (C) 2007 Canonical Ltd
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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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# 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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# 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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"""Tests for Branch.revision_history."""
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from bzrlib import branch
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from bzrlib.tests.branch_implementations.test_branch import TestCaseWithBranch
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class TestRevisionHistoryCaching(TestCaseWithBranch):
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"""Tests for the caching of branches' revision_history.
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When locked, branches should avoid regenerating or rereading
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revision_history by caching the last value of it. This is safe because
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the branch is locked, so nothing can change the revision_history
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When not locked, obviously the revision_history will need to be regenerated
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We test if revision_history is using the cache by instrumenting the branch's
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_gen_revision_history method, which is called by Branch.revision_history if
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the branch does not have a cache of the revision history.
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def get_instrumented_branch(self):
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"""Get a branch and monkey patch it to log calls to
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_gen_revision_history.
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:returns: a tuple of (the branch, list that calls will be logged to)
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branch = self.get_branch()
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real_gen_revision_history = branch._gen_revision_history
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def fake_gen_revision_history():
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calls.append('_gen_revision_history')
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return real_gen_revision_history()
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branch._gen_revision_history = fake_gen_revision_history
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def test_revision_history_when_unlocked(self):
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"""Repeated calls to revision history will call _gen_revision_history
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each time when the branch is not locked.
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branch, calls = self.get_instrumented_branch()
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# Repeatedly call revision_history.
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branch.revision_history()
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branch.revision_history()
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['_gen_revision_history', '_gen_revision_history'], calls)
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def test_revision_history_when_locked(self):
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"""Repeated calls to revision history will only call
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_gen_revision_history once while the branch is locked.
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branch, calls = self.get_instrumented_branch()
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# Lock the branch, then repeatedly call revision_history.
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branch.revision_history()
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branch.revision_history()
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self.assertEqual(['_gen_revision_history'], calls)
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def test_set_revision_history_when_locked(self):
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"""When the branch is locked, calling set_revision_history should cache
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the revision history so that a later call to revision_history will not
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need to call _gen_revision_history.
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branch, calls = self.get_instrumented_branch()
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# Lock the branch, set the revision history, then repeatedly call
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branch.set_revision_history([])
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branch.revision_history()
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self.assertEqual([], calls)
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def test_set_revision_history_when_unlocked(self):
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"""When the branch is not locked, calling set_revision_history will not
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cause the revision history to be cached.
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branch, calls = self.get_instrumented_branch()
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# Lock the branch, set the revision history, then repeatedly call
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branch.set_revision_history([])
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branch.revision_history()
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self.assertEqual(['_gen_revision_history'], calls)
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def test_set_last_revision_info_when_locked(self):
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"""When the branch is locked, calling set_last_revision_info should
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cache the last revision info so that a later call to last_revision_info
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will not need the revision_history. Thus the branch will not to call
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_gen_revision_history in this situation.
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a_branch, calls = self.get_instrumented_branch()
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# Lock the branch, set the last revision info, then call
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# last_revision_info.
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a_branch.lock_write()
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a_branch.set_last_revision_info(0, None)
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a_branch.last_revision_info()
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self.assertEqual([], calls)
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def test_set_last_revision_info_uncaches_revision_history_for_format6(self):
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"""On format 6 branches, set_last_revision_info invalidates the revision
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if not isinstance(self.branch_format, branch.BzrBranchFormat6):
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a_branch, calls = self.get_instrumented_branch()
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# Lock the branch, cache the revision history.
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a_branch.lock_write()
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a_branch.revision_history()
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# Set the last revision info, clearing the cache.
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a_branch.set_last_revision_info(0, None)
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a_branch.revision_history()
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self.assertEqual(['_gen_revision_history'], calls)
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def test_cached_revision_history_not_accidentally_mutable(self):
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"""When there's a cached version of the history, revision_history
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returns a copy of the cached data so that callers cannot accidentally
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branch = self.get_branch()
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# Lock the branch, then repeatedly call revision_history, mutating the
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# The first time the data returned will not be in the cache.
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history = branch.revision_history()
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history.append('one')
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# The second time the data comes from the cache.
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history = branch.revision_history()
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history.append('two')
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# The revision_history() should still be unchanged, even though
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# we've mutated the return values from earlier calls.
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self.assertEqual([], branch.revision_history())
added
removed
bzrlib/tests/branch_implementations/test_revision_history.py
