ClickHouse/dbms/include/DB/IO/ZlibDeflatingWriteBuffer.h

#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;
};

}