ClickHouse/dbms/src/IO/ZlibDeflatingWriteBuffer.cpp

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#include <IO/ZlibDeflatingWriteBuffer.h>
namespace DB
{
ZlibDeflatingWriteBuffer::ZlibDeflatingWriteBuffer(
WriteBuffer & out_,
ZlibCompressionMethod compression_method,
int compression_level,
size_t buf_size,
char * existing_memory,
size_t alignment)
: BufferWithOwnMemory<WriteBuffer>(buf_size, existing_memory, alignment)
, out(out_)
{
zstr.zalloc = Z_NULL;
zstr.zfree = Z_NULL;
zstr.opaque = Z_NULL;
zstr.next_in = 0;
zstr.avail_in = 0;
zstr.next_out = 0;
zstr.avail_out = 0;
int window_bits = 15;
if (compression_method == ZlibCompressionMethod::Gzip)
{
window_bits += 16;
}
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wold-style-cast"
int rc = deflateInit2(&zstr, compression_level, Z_DEFLATED, window_bits, 8, Z_DEFAULT_STRATEGY);
#pragma GCC diagnostic pop
if (rc != Z_OK)
throw Exception(std::string("deflateInit2 failed: ") + zError(rc), ErrorCodes::ZLIB_DEFLATE_FAILED);
}
ZlibDeflatingWriteBuffer::~ZlibDeflatingWriteBuffer()
{
try
{
finish();
int rc = deflateEnd(&zstr);
if (rc != Z_OK)
throw Exception(std::string("deflateEnd failed: ") + zError(rc), ErrorCodes::ZLIB_DEFLATE_FAILED);
}
catch (...)
{
tryLogCurrentException(__PRETTY_FUNCTION__);
}
}
void ZlibDeflatingWriteBuffer::nextImpl()
{
if (!offset())
return;
zstr.next_in = reinterpret_cast<unsigned char *>(working_buffer.begin());
zstr.avail_in = offset();
do
{
out.nextIfAtEnd();
zstr.next_out = reinterpret_cast<unsigned char *>(out.position());
zstr.avail_out = out.buffer().end() - out.position();
int rc = deflate(&zstr, Z_NO_FLUSH);
out.position() = out.buffer().end() - zstr.avail_out;
if (rc != Z_OK)
throw Exception(std::string("deflate failed: ") + zError(rc), ErrorCodes::ZLIB_DEFLATE_FAILED);
}
while (zstr.avail_in > 0 || zstr.avail_out == 0);
}
void ZlibDeflatingWriteBuffer::finish()
{
if (finished)
return;
next();
while (true)
{
out.nextIfAtEnd();
zstr.next_out = reinterpret_cast<unsigned char *>(out.position());
zstr.avail_out = out.buffer().end() - out.position();
int rc = deflate(&zstr, Z_FINISH);
out.position() = out.buffer().end() - zstr.avail_out;
if (rc == Z_STREAM_END)
return;
if (rc != Z_OK)
throw Exception(std::string("deflate finish failed: ") + zError(rc), ErrorCodes::ZLIB_DEFLATE_FAILED);
}
finished = true;
}
}