mirror of
https://github.com/ClickHouse/ClickHouse.git
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114 lines
4.2 KiB
C++
114 lines
4.2 KiB
C++
//Copyright (c) 2011-2012 Mail.RU
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//Copyright (c) 2011-2012 Maksim Kalinchenko
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//Copyright (c) 2012 Sokolov Yura aka funny-falcon
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//
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//MIT License
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//
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//Permission is hereby granted, free of charge, to any person obtaining
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//a copy of this software and associated documentation files (the
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//"Software"), to deal in the Software without restriction, including
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//without limitation the rights to use, copy, modify, merge, publish,
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//distribute, sublicense, and/or sell copies of the Software, and to
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//permit persons to whom the Software is furnished to do so, subject to
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//the following conditions:
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//
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//The above copyright notice and this permission notice shall be
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//included in all copies or substantial portions of the Software.
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//
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//THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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//EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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//MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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//NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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//LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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//OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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//WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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#include <stdexcept>
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#define L 0xFFFFFFFF
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static unsigned int L27_38[] = {L / 27, L / 28, L / 29, L / 30, L / 31, L / 32,
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L / 33, L / 34, L / 35, L / 36, L / 37, L / 38,
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L / 39, L / 40, L / 41, L / 42, L / 43, L / 44,
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L / 45, L / 46, L / 47, L / 48, L / 49, L / 50,
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L / 51, L / 52, L / 53, L / 54, L / 55, L / 56,
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L / 57, L / 58, L / 59, L / 60, L / 61, L / 62
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};
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static unsigned int LL27_38[] = {L/(26*27), L/(27*28), L/(28*29), L/(29*30), L/(30*31), L/(31*32),
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L/(32*33), L/(33*34), L/(34*35), L/(35*36), L/(36*37), L/(37*38),
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L/(38*39), L/(39*40), L/(40*41), L/(41*42), L/(42*43), L/(43*44),
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L/(44*45), L/(45*46), L/(46*47), L/(47*48), L/(48*49), L/(49*50),
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L/(50*51), L/(51*52), L/(52*53), L/(53*54), L/(54*55), L/(55*56),
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L/(56*57), L/(57*58), L/(58*59), L/(59*60), L/(60*61), L/(61*62)
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};
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unsigned int sumburConsistentHash(unsigned int hashed_int, unsigned int capacity)
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{
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unsigned int h = hashed_int;
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unsigned int capa = capacity;
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unsigned int part, n, i, c;
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if (capa == 0)
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throw std::runtime_error("Sumbur is not applicable to empty cluster");
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part = L / capa;
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if (L - h < part) return 0;
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n = 1;
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do {
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if (h >= L / 2) h -= L / 2;
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else {
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n = 2;
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if (L / 2 - h < part) return 1;
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}
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if (capa == 2) return 1;
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#define curslice(i) (L / (i * (i - 1)))
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#define unroll(i) \
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if (curslice(i) <= h) h -= curslice(i); \
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else { \
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h += curslice(i) * (i - n - 1); \
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n = i; \
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if (L / i - h < part) return n-1; \
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} \
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if (capa == i) return (n-1)
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unroll(3); unroll(4); unroll(5);
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unroll(6); unroll(7); unroll(8);
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unroll(9); unroll(10); unroll(11);
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unroll(12); unroll(13); unroll(14);
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unroll(15); unroll(16); unroll(17);
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unroll(18); unroll(19); unroll(20);
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unroll(21); unroll(22); unroll(23);
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unroll(24); unroll(25); unroll(26);
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for (i = 27; i <= capa && i <= 62; i++) {
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c = LL27_38[i-27];
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if (c <= h) {
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h -= c;
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}
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else {
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h += c * (i - n - 1);
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n = i;
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if (L27_38[i-27] - h < part) return n-1;
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}
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}
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for(i = 63; i <= capa; i++) {
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c = L / (i * (i - 1));
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if (c <= h) {
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h -= c;
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}
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else {
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h += c * (i - n - 1);
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n = i;
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if (L / i - h < part) return n - 1;
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}
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}
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} while(0);
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return n - 1;
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}
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