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* Every function in its own file, part 6 [#CLICKHOUSE-2] * Every function in its own file, part 6 [#CLICKHOUSE-2] * Every function in its own file, part 6 [#CLICKHOUSE-2]
92 lines
2.9 KiB
C++
92 lines
2.9 KiB
C++
#pragma once
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#include <Functions/domain.h>
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#include <common/find_symbols.h>
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namespace DB
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{
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struct ExtractFirstSignificantSubdomain
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{
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static size_t getReserveLengthForElement() { return 10; }
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static void execute(const Pos data, const size_t size, Pos & res_data, size_t & res_size, Pos * out_domain_end = nullptr)
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{
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res_data = data;
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res_size = 0;
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Pos tmp;
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size_t domain_length;
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ExtractDomain<true>::execute(data, size, tmp, domain_length);
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if (domain_length == 0)
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return;
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if (out_domain_end)
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*out_domain_end = tmp + domain_length;
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/// cut useless dot
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if (tmp[domain_length - 1] == '.')
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--domain_length;
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res_data = tmp;
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res_size = domain_length;
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auto begin = tmp;
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auto end = begin + domain_length;
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const char * last_3_periods[3]{};
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auto pos = find_first_symbols<'.'>(begin, end);
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while (pos < end)
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{
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last_3_periods[2] = last_3_periods[1];
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last_3_periods[1] = last_3_periods[0];
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last_3_periods[0] = pos;
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pos = find_first_symbols<'.'>(pos + 1, end);
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}
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if (!last_3_periods[0])
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return;
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if (!last_3_periods[1])
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{
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res_size = last_3_periods[0] - begin;
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return;
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}
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if (!last_3_periods[2])
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last_3_periods[2] = begin - 1;
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size_t size_of_second_subdomain_plus_period = last_3_periods[0] - last_3_periods[1];
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if (size_of_second_subdomain_plus_period == 4 || size_of_second_subdomain_plus_period == 3)
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{
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/// We will key by four bytes that are either ".xyz" or ".xy.".
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UInt32 key = unalignedLoad<UInt32>(last_3_periods[1]);
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/// NOTE: assuming little endian.
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/// NOTE: does the compiler generate SIMD code?
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/// NOTE: for larger amount of cases we can use a perfect hash table (see 'gperf' as an example).
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if ( key == '.' + 'c' * 0x100U + 'o' * 0x10000U + 'm' * 0x1000000U
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|| key == '.' + 'n' * 0x100U + 'e' * 0x10000U + 't' * 0x1000000U
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|| key == '.' + 'o' * 0x100U + 'r' * 0x10000U + 'g' * 0x1000000U
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|| key == '.' + 'b' * 0x100U + 'i' * 0x10000U + 'z' * 0x1000000U
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|| key == '.' + 'g' * 0x100U + 'o' * 0x10000U + 'v' * 0x1000000U
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|| key == '.' + 'm' * 0x100U + 'i' * 0x10000U + 'l' * 0x1000000U
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|| key == '.' + 'e' * 0x100U + 'd' * 0x10000U + 'u' * 0x1000000U
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|| key == '.' + 'c' * 0x100U + 'o' * 0x10000U + '.' * 0x1000000U)
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{
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res_data += last_3_periods[2] + 1 - begin;
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res_size = last_3_periods[1] - last_3_periods[2] - 1;
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return;
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}
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}
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res_data += last_3_periods[1] + 1 - begin;
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res_size = last_3_periods[0] - last_3_periods[1] - 1;
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}
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};
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}
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