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dbms: removed useless copy [#CONV-2546].

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This commit is contained in:
Alexey Milovidov 2011-06-17 21:31:41 +00:00
parent e60253110a
commit f488fbbff5
1 changed files with 8 additions and 28 deletions
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36
dbms/include/DB/IO/CompressedReadBuffer.h
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@ -21,54 +21,34 @@ private:
ReadBuffer & in;
std::vector<char> compressed_buffer;
std::vector<char> decompressed_buffer;
char scratch[QLZ_SCRATCH_DECOMPRESS];
size_t pos_in_buffer;
public:
CompressedReadBuffer(ReadBuffer & in_)
: in(in_),
compressed_buffer(QUICKLZ_HEADER_SIZE),
pos_in_buffer(0)
compressed_buffer(QUICKLZ_HEADER_SIZE)
{
}
/** Читает и разжимает следующий кусок сжатых данных. */
void readCompressedChunk()
bool next()
{
if (in.eof())
return false;
in.readStrict(&compressed_buffer[0], QUICKLZ_HEADER_SIZE);
size_t size_compressed = qlz_size_compressed(&compressed_buffer[0]);
size_t size_decompressed = qlz_size_decompressed(&compressed_buffer[0]);
compressed_buffer.resize(size_compressed);
decompressed_buffer.resize(size_decompressed);
internal_buffer.resize(size_decompressed);
in.readStrict(&compressed_buffer[QUICKLZ_HEADER_SIZE], size_compressed - QUICKLZ_HEADER_SIZE);
qlz_decompress(&compressed_buffer[0], &decompressed_buffer[0], scratch);
qlz_decompress(&compressed_buffer[0], &internal_buffer[0], scratch);
pos_in_buffer = 0;
}
bool next()
{
if (pos_in_buffer == decompressed_buffer.size())
{
if (in.eof())
return false;
readCompressedChunk();
}
size_t bytes_to_copy = std::min(decompressed_buffer.size() - pos_in_buffer,
static_cast<size_t>(DEFAULT_READ_BUFFER_SIZE));
std::memcpy(working_buffer.begin(), &decompressed_buffer[pos_in_buffer], bytes_to_copy);
pos_in_buffer += bytes_to_copy;
pos = working_buffer.begin();
working_buffer = Buffer(working_buffer.begin(), working_buffer.begin() + bytes_to_copy);
working_buffer = Buffer(working_buffer.begin(), working_buffer.begin() + size_decompressed);
return true;
}