8ca1432b04
When a node start it does not have any information about cache temperature of other nodes in the cluster and it is hard (if not impossible) to make right guess. During cluster startup all nodes have cold caches, so there is no point to redirect reads to other nodes even though local cache it cold, but if only that node restarted than other nodes have populated cache and reads should be redirected. The node will get up-to-date information about other nodes caches, but only after receiving first reply, until then it does not have the information to make right decisions which may cause unwanted spikes immediately after restart. Having cache temperature in gossiper helps to solve the problem.
79 lines
2.9 KiB
C++
79 lines
2.9 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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/*
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* Modified by ScyllaDB
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* Copyright 2015 ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla 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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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "gms/application_state.hh"
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#include <seastar/core/sstring.hh>
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#include <ostream>
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#include <map>
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#include "seastarx.hh"
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namespace gms {
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static const std::map<application_state, sstring> application_state_names = {
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{application_state::STATUS, "STATUS"},
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{application_state::LOAD, "LOAD"},
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{application_state::SCHEMA, "SCHEMA"},
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{application_state::DC, "DC"},
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{application_state::RACK, "RACK"},
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{application_state::RELEASE_VERSION, "RELEASE_VERSION"},
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{application_state::REMOVAL_COORDINATOR, "REMOVAL_COORDINATOR"},
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{application_state::INTERNAL_IP, "INTERNAL_IP"},
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{application_state::RPC_ADDRESS, "RPC_ADDRESS"},
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{application_state::SEVERITY, "SEVERITY"},
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{application_state::NET_VERSION, "NET_VERSION"},
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{application_state::HOST_ID, "HOST_ID"},
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{application_state::TOKENS, "TOKENS"},
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{application_state::SUPPORTED_FEATURES, "SUPPORTED_FEATURES"},
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{application_state::CACHE_HITRATES, "CACHE_HITRATES"},
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};
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std::ostream& operator<<(std::ostream& os, const application_state& m) {
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auto it = application_state_names.find(m);
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if (it != application_state_names.end()) {
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os << application_state_names.at(m);
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} else {
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os << "UNKNOWN";
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}
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return os;
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}
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}
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