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4088c0a7f3
Automated register all functions with below naming convention by iterating through the symbols: void DB::registerXXX(DB::FunctionFactory &)
48 lines
1.1 KiB
C++
48 lines
1.1 KiB
C++
#include "FunctionsConsistentHashing.h"
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#include <Functions/FunctionFactory.h>
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namespace DB
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{
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namespace
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{
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/// Code from https://arxiv.org/pdf/1406.2294.pdf
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inline int32_t JumpConsistentHash(uint64_t key, int32_t num_buckets)
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{
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int64_t b = -1, j = 0;
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while (j < num_buckets)
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{
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b = j;
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key = key * 2862933555777941757ULL + 1;
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j = static_cast<int64_t>((b + 1) * (static_cast<double>(1LL << 31) / static_cast<double>((key >> 33) + 1)));
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}
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return static_cast<int32_t>(b);
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}
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struct JumpConsistentHashImpl
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{
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static constexpr auto name = "jumpConsistentHash";
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using HashType = UInt64;
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using ResultType = Int32;
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using BucketsType = ResultType;
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static constexpr auto max_buckets = static_cast<UInt64>(std::numeric_limits<BucketsType>::max());
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static inline ResultType apply(UInt64 hash, BucketsType n)
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{
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return JumpConsistentHash(hash, n);
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}
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};
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using FunctionJumpConsistentHash = FunctionConsistentHashImpl<JumpConsistentHashImpl>;
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}
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REGISTER_FUNCTION(JumpConsistentHash)
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{
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factory.registerFunction<FunctionJumpConsistentHash>();
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}
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}
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