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55 lines
1.5 KiB
C++
55 lines
1.5 KiB
C++
#include <IO/HashingWriteBuffer.h>
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#include <iomanip>
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namespace DB
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{
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/// computation of the hash depends on the partitioning of blocks
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/// so you need to compute a hash of n complete pieces and one incomplete
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template <typename Buffer>
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void IHashingBuffer<Buffer>::calculateHash(DB::BufferBase::Position data, size_t len)
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{
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if (len)
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{
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/// if the data is less than `block_size`, then put them into buffer and calculate hash later
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if (block_pos + len < block_size)
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{
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memcpy(&BufferWithOwnMemory<Buffer>::memory[block_pos], data, len);
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block_pos += len;
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}
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else
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{
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/// if something is already written to the buffer, then we'll add it
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if (block_pos)
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{
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size_t n = block_size - block_pos;
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memcpy(&BufferWithOwnMemory<Buffer>::memory[block_pos], data, n);
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append(&BufferWithOwnMemory<Buffer>::memory[0]);
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len -= n;
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data += n;
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block_pos = 0;
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}
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while (len >= block_size)
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{
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append(data);
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len -= block_size;
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data += block_size;
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}
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/// write the remainder to its buffer
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if (len)
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{
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memcpy(&BufferWithOwnMemory<Buffer>::memory[0], data, len);
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block_pos = len;
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}
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}
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}
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}
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template class IHashingBuffer<DB::ReadBuffer>;
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template class IHashingBuffer<DB::WriteBuffer>;
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}
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