зеркало из https://github.com/github/vitess-gh.git
80 строки
2.3 KiB
Python
80 строки
2.3 KiB
Python
# Copyright 2017 Google Inc.
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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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"""Helper methods to compare EventToken objects.
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"""
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MARIADB_FLAVOR = 'MariaDB'
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MYSQL_FLAVOR = 'MySQL56'
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def fresher(ev1, ev2):
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"""Returns a comparison of the tokens.
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If we can't figure it out, this method will return -1, meaning ev1
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is considered older in doubt.
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Args:
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ev1: the first event token.
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ev2: the second event token.
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Returns:
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value: a negative number of ev1<ev2, 0 if ev1 == ev2, a positive
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number if ev1>ev2.
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"""
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if ev1 is None or ev2 is None:
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# Either one is None, we don't know.
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return -1
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if ev1.timestamp != ev2.timestamp:
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# The timestamp is enough to set them apart.
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return ev1.timestamp - ev2.timestamp
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if ev1.shard and ev1.shard == ev2.shard:
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# They come from the same shard, we can parse them and compare.
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if not ev1.position or not ev2.position:
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# We do not know.
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return -1
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# Split them up.
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parts1 = ev1.position.split('/', 1)
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parts2 = ev2.position.split('/', 1)
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if len(parts1) != 2 or len(parts2) != 2:
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# This should never happen, but let's just handle it.
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return -1
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if parts1[0] != parts2[0]:
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# This should never happen, but let's just handle it.
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return -1
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pos1 = parts1[1]
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pos2 = parts2[1]
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if parts1[0] == MARIADB_FLAVOR:
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# Both GTIDSets should be of the form <domain>-<serverid>-<sequence>.
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# We just compare the sequence as int.
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parts1 = pos1.split('-', 2)
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parts2 = pos2.split('-', 2)
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if len(parts1) != 3 or len(parts2) != 3:
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# This should never happen, but let's just handle it.
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return -1
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return int(parts1[2]) - int(parts2[2])
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elif parts1[0] == MYSQL_FLAVOR:
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# Not implemented yet.
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pass
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# We do not know.
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return -1
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