0513f206d8
version_generator is a trivial class which keeps a global "version" counter, starting with 0 and counting up on a single Cassandra node. It is used by the gossip protocol to keep a version number for each piece of state information, so a remote node which gets two pieces of conflicting gossip can know which is the newer information. In Cassandra, the counter is an atomic integer. In our implementation, because there will be just a single gossiper per SMP machine, and the gossiper will run on a single CPU, it can be a regular integer. But this doesn't really help performance anyway (the version number changes rarely, so performance of this code is insignifcant). Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
37 lines
1.1 KiB
C++
37 lines
1.1 KiB
C++
/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. 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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* Modified by Cloudius Systems.
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* Copyright 2015 Cloudius Systems.
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*/
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#include "version_generator.hh"
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namespace gms {
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// In the original Cassandra code, version was an AtomicInteger.
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// For us, we run the gossiper on a single CPU, and don't need to use atomics.
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static int version = 0;
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int get_next_version()
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{
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return ++version;
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}
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} // namespace gms
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