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https://github.com/scylladb/scylladb.git
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1f88d103a8
When performing a range query, we want to iterate over shards, running the query on each shard in order until the query range is exhausted or we have the right number of rows. To be able to do this, introduce token_for_next_shard(), which allows us to determine the boundary between shards. It is a sort-of inverse to shard_of(), in that shard_of(token_for_next_range(t)) == shard_of(t) + 1
82 lines
2.9 KiB
C++
82 lines
2.9 KiB
C++
/*
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* Copyright (C) 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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#pragma once
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#include "i_partitioner.hh"
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#include "bytes.hh"
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#include "sstables/key.hh"
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namespace dht {
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class byte_ordered_partitioner final : public i_partitioner {
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unsigned _shard_count;
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public:
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byte_ordered_partitioner(unsigned shard_count = smp::count) : _shard_count(shard_count) {}
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virtual const sstring name() { return "org.apache.cassandra.dht.ByteOrderedPartitioner"; }
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virtual token get_token(const schema& s, partition_key_view key) override {
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auto&& legacy = key.legacy_form(s);
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return token(token::kind::key, bytes(legacy.begin(), legacy.end()));
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}
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virtual token get_token(const sstables::key_view& key) override {
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auto v = bytes_view(key);
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if (v.empty()) {
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return minimum_token();
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}
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return token(token::kind::key, bytes(v.begin(), v.end()));
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}
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virtual token get_random_token() override;
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virtual bool preserves_order() override { return true; }
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virtual std::map<token, float> describe_ownership(const std::vector<token>& sorted_tokens) override;
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virtual data_type get_token_validator() override { return bytes_type; }
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virtual int tri_compare(const token& t1, const token& t2) const override {
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return compare_unsigned(t1._data, t2._data);
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}
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virtual token midpoint(const token& t1, const token& t2) const;
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virtual sstring to_sstring(const dht::token& t) const override {
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if (t._kind == dht::token::kind::before_all_keys) {
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return sstring();
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} else {
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return to_hex(t._data);
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}
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}
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virtual dht::token from_sstring(const sstring& t) const override {
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if (t.empty()) {
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return minimum_token();
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} else {
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auto data = from_hex(t);
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return token(token::kind::key, bytes(data.begin(), data.end()));
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}
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}
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virtual dht::token from_bytes(bytes_view bytes) const override {
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if (bytes.empty()) {
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return minimum_token();
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} else {
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return token(token::kind::key, bytes);
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}
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}
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virtual unsigned shard_of(const token& t) const override;
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virtual token token_for_next_shard(const token& t) const override;
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};
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}
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