78 lines
2.0 KiB
Python
78 lines
2.0 KiB
Python
#
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# micro_indirect.py
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#
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# This source file is part of the FoundationDB open source project
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#
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# Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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import fdb
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fdb.api_version(300)
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class Workspace(object):
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def __init__(self, directory, db):
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self.dir = directory
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self.db = db
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def __enter__(self):
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return self.dir.create_or_open(self.db, (u'new',))
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def __exit__(self, *exc):
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self._update(self.db)
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@fdb.transactional
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def _update(self, tr):
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self.dir.remove(tr, (u'current'))
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self.dir.move(tr, (u'new'), (u'current'))
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@property
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def current(self):
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return self.dir.create_or_open(self.db, (u'current',))
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@fdb.transactional
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def clear_subspace(tr, subspace):
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tr.clear_range_startswith(subspace.key())
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@fdb.transactional
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def print_subspace(tr, subspace):
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for k, v in tr[subspace.range()]:
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print subspace.unpack(k), v
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def smoke_test():
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db = fdb.open()
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working_dir = fdb.directory.create_or_open(db, (u'working',))
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workspace = Workspace(working_dir, db)
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current = workspace.current
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clear_subspace(db, current)
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db[current[1]] = 'a'
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db[current[2]] = 'b'
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print "contents:"
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print_subspace(db, current)
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with workspace as newspace:
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clear_subspace(db, newspace)
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db[newspace[3]] = 'c'
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db[newspace[4]] = 'd'
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print "contents:"
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print_subspace(db, workspace.current)
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if __name__ == "__main__":
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smoke_test()
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