ClickHouse/dbms/include/DB/IO/ZlibDeflatingWriteBuffer.h
Alexey Zatelepin 600bb5f29a [#METR-23582]
* introduce ZlibDeflatingWriteBuffer and ZlibInflatingReadBuffer
* use them instead of Poco streams
* seamlessly uncompress multiple concatenated gzip streams
2017-01-07 20:22:58 +03:00

46 lines
1021 B
C++

#pragma once
#include <DB/IO/WriteBuffer.h>
#include <DB/IO/BufferWithOwnMemory.h>
#include <DB/IO/ZlibCompressionMethod.h>
#include <zlib.h>
namespace DB
{
namespace ErrorCodes
{
extern const int ZLIB_DEFLATE_FAILED;
}
/// Performs compression using zlib library and writes compressed data to out_ WriteBuffer.
class ZlibDeflatingWriteBuffer : public BufferWithOwnMemory<WriteBuffer>
{
public:
ZlibDeflatingWriteBuffer(
WriteBuffer & out_,
ZlibCompressionMethod compression_method,
int compression_level,
size_t buf_size = DBMS_DEFAULT_BUFFER_SIZE,
char * existing_memory = nullptr,
size_t alignment = 0);
/// Flush all pending data and write zlib footer to the underlying buffer.
/// After the first call to this function, subsequent calls will have no effect and
/// an attempt to write to this buffer will result in exception.
void finish();
~ZlibDeflatingWriteBuffer() override;
private:
void nextImpl() override;
WriteBuffer & out;
z_stream zstr;
bool finished = false;
};
}