kangkaisen commented on a change in pull request #1818: Add frame_of_reference page URL: https://github.com/apache/incubator-doris/pull/1818#discussion_r328904145
########## File path: be/src/util/frame_of_reference_coding.cpp ########## @@ -0,0 +1,364 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +#include "util/frame_of_reference_coding.h" + +#include <algorithm> +#include <cstring> + +#include "util/bit_util.h" +#include "util/coding.h" + +namespace doris { + +static inline uint8_t bits(const uint64_t v) { + return v == 0 ? 0 : 64 - __builtin_clzll(v); +} + +template<typename T> +const T* ForEncoder<T>::copy_value(const T *p_data, size_t count) { + memcpy(&_buffered_values[_buffered_values_num], p_data, count * sizeof(T)); + _buffered_values_num += count; + p_data += count; + return p_data; +} + +template<typename T> +void ForEncoder<T>::put_batch(const T* in_data, size_t count) { + if (_buffered_values_num + count < ForCoding::FRAME_VALUE_NUM) { + copy_value(in_data, count); + _values_num += count; + return; + } + + // 1. padding one frame + size_t padding_num = ForCoding::FRAME_VALUE_NUM - _buffered_values_num; + in_data = copy_value(in_data, padding_num); + bit_packing_one_frame_value(_buffered_values); + + // 2. process frame by frame + size_t frame_size = (count - padding_num) / ForCoding::FRAME_VALUE_NUM; + for (size_t i = 0; i < frame_size; i++) { + // directly encode value to the bit_writer, don't buffer the value + _buffered_values_num = ForCoding::FRAME_VALUE_NUM; + bit_packing_one_frame_value(in_data); + in_data += ForCoding::FRAME_VALUE_NUM; + } + + // 3. process remaining value + size_t remaining_num = (count - padding_num) % ForCoding::FRAME_VALUE_NUM; + if (remaining_num > 0) { + copy_value(in_data, remaining_num); + } + + _values_num += count; +} + +// todo(kks): improve this method by SIMD instructions + +// Use as few bit as possible to store a piece of integer data. +// param[in] input: the integer list need to pack +// param[in] in_num: the number integer need to pack +// param[in] bit_width: how many bit we use to store each integer data +// param[out] out: the packed result + +// For example: +// The input is int32 list: 1, 2, 4, 8 and bit_width is 4 +// The output will be: 0001 0010 0100 1000 +template<typename T> +void ForEncoder<T>::bit_pack(T *input, uint8_t in_num, int bit_width, uint8_t *output) { + if (in_num == 0 || bit_width == 0) { + return; + } + + T in_mask = 0; + int bit_index = 0; + *output = 0; + for (int i = 0; i < in_num; i++) { + in_mask = 1 << (bit_width - 1); + for (int k = 0; k < bit_width; k++) { + if (bit_index > 7) { + bit_index = 0; + output++; + *output = 0; + } + *output |= (((input[i] & in_mask) >> (bit_width - k - 1)) << (7 - bit_index)); + in_mask >>= 1; + bit_index++; + } + } +} + +template<typename T> +void ForEncoder<T>::bit_packing_one_frame_value(const T* input) { + T min = input[0]; + T max = input[0]; + bool is_ascending = true; + uint8_t bit_width = 0; + + for (uint8_t i = 1; i < _buffered_values_num; ++i) { + if (is_ascending) { + if (input[i] < input[i - 1]) { + is_ascending = false; + } else { + bit_width = std::max(bit_width, bits(input[i]- input[i - 1])) ; + } + } + + if (input[i] < min) { + min = input[i]; + continue; + } + + if (input[i] > max) { + max = input[i]; + } + } + + if (sizeof(T) == 8) { + put_fixed64_le(_buffer, min); + } else { + put_fixed32_le(_buffer, min); + } + + // improve for ascending order input, we could use fewer bit + T delta_values[ForCoding::FRAME_VALUE_NUM]; + u_int8_t order_flag = 0; + if (is_ascending) { + delta_values[0] = 0; + for (uint8_t i = 1; i < _buffered_values_num; ++i) { + delta_values[i] = input[i] - input[i - 1]; + } + order_flag = 1; + } else { + bit_width = bits(static_cast<T>(max - min)); + for (uint8_t i = 0; i < _buffered_values_num; ++i) { + delta_values[i] = input[i] - min; + } + } + // 2 bit order_flag + 6 bit bit_width + uint8_t order_flag_and_bit_width = order_flag << 6 | bit_width; + _order_flag_and_bit_widths.push_back(order_flag_and_bit_width); + + uint32_t packing_len = BitUtil::Ceil(_buffered_values_num * bit_width, 8); + + _buffer->reserve(_buffer->size() + packing_len); Review comment: OK ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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