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68 lines
2.6 KiB
C++
68 lines
2.6 KiB
C++
#include <Columns/ColumnConst.h>
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#include <Columns/ColumnVector.h>
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#include <Common/typeid_cast.h>
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#include <Common/assert_cast.h>
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#include <type_traits>
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#ifdef __SSE2__
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#define LIBDIVIDE_USE_SSE2 1
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#endif
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#include <libdivide.h>
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namespace DB
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{
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template <typename T>
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IColumn::Selector createBlockSelector(
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const IColumn & column,
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const std::vector<UInt64> & slots)
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{
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const auto total_weight = slots.size();
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size_t num_rows = column.size();
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IColumn::Selector selector(num_rows);
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/** Modulo of division of negative numbers to positive number in C++11 is negative (so called truncated division).
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* This is not suitable for our task. So we will process signed numbers as unsigned.
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* It is not near like remainder of division, but is suitable for our task.
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*/
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using UnsignedT = std::make_unsigned_t<T>;
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/// const columns contain only one value, therefore we do not need to read it at every iteration
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if (isColumnConst(column))
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{
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const auto data = assert_cast<const ColumnConst &>(column).getValue<T>();
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const auto shard_num = slots[static_cast<UnsignedT>(data) % total_weight];
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selector.assign(num_rows, shard_num);
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}
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else
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{
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/// libdivide support only UInt32 and UInt64.
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using TUInt32Or64 = std::conditional_t<sizeof(UnsignedT) <= 4, UInt32, UInt64>;
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libdivide::divider<TUInt32Or64> divider(total_weight);
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const auto & data = typeid_cast<const ColumnVector<T> &>(column).getData();
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for (size_t i = 0; i < num_rows; ++i)
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selector[i] = slots[static_cast<TUInt32Or64>(data[i]) - (static_cast<TUInt32Or64>(data[i]) / divider) * total_weight];
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}
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return selector;
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}
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/// Explicit instantiations to avoid code bloat in headers.
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template IColumn::Selector createBlockSelector<UInt8>(const IColumn & column, const std::vector<UInt64> & slots);
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template IColumn::Selector createBlockSelector<UInt16>(const IColumn & column, const std::vector<UInt64> & slots);
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template IColumn::Selector createBlockSelector<UInt32>(const IColumn & column, const std::vector<UInt64> & slots);
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template IColumn::Selector createBlockSelector<UInt64>(const IColumn & column, const std::vector<UInt64> & slots);
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template IColumn::Selector createBlockSelector<Int8>(const IColumn & column, const std::vector<UInt64> & slots);
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template IColumn::Selector createBlockSelector<Int16>(const IColumn & column, const std::vector<UInt64> & slots);
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template IColumn::Selector createBlockSelector<Int32>(const IColumn & column, const std::vector<UInt64> & slots);
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template IColumn::Selector createBlockSelector<Int64>(const IColumn & column, const std::vector<UInt64> & slots);
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}
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