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#include <Disks/IO/WriteBufferFromTemporaryFile.h>
#include <IO/ReadBufferFromFile.h>
#include <Disks/TemporaryFileOnDisk.h>
#include <fcntl.h>
namespace DB
{
namespace ErrorCodes
{
extern const int CANNOT_SEEK_THROUGH_FILE;
}
WriteBufferFromTemporaryFile::WriteBufferFromTemporaryFile(TemporaryFileOnDiskHolder && tmp_file_)
: WriteBufferFromFile(tmp_file_->getAbsolutePath(), DBMS_DEFAULT_BUFFER_SIZE, O_RDWR | O_TRUNC | O_CREAT, /* throttler= */ {}, 0600)
, tmp_file(std::move(tmp_file_))
{
}
class ReadBufferFromTemporaryWriteBuffer : public ReadBufferFromFile
{
public:
static ReadBufferPtr createFrom(WriteBufferFromTemporaryFile * origin)
{
int fd = origin->getFD();
std::string file_name = origin->getFileName();
off_t res = lseek(fd, 0, SEEK_SET);
if (-1 == res)
throwFromErrnoWithPath("Cannot reread temporary file " + file_name, file_name,
ErrorCodes::CANNOT_SEEK_THROUGH_FILE);
return std::make_shared<ReadBufferFromTemporaryWriteBuffer>(fd, file_name, std::move(origin->tmp_file));
}
ReadBufferFromTemporaryWriteBuffer(int fd_, const std::string & file_name_, TemporaryFileOnDiskHolder && tmp_file_)
: ReadBufferFromFile(fd_, file_name_), tmp_file(std::move(tmp_file_))
{}
TemporaryFileOnDiskHolder tmp_file;
};
ReadBufferPtr WriteBufferFromTemporaryFile::getReadBufferImpl()
{
/// ignore buffer, write all data to file and reread it
finalize();
auto res = ReadBufferFromTemporaryWriteBuffer::createFrom(this);
/// invalidate FD to avoid close() in destructor
setFD(-1);
file_name = {};
return res;
}
WriteBufferFromTemporaryFile::~WriteBufferFromTemporaryFile() = default;
}
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