ClickHouse/src/IO/ReadBufferFromEmptyFile.h

25 lines
648 B
C++

#pragma once
#include <IO/ReadBuffer.h>
#include <IO/ReadBufferFromFileBase.h>
namespace DB
{
/// In case of empty file it does not make any sense to read it.
///
/// Plus regular readers from file has an assert that buffer is not empty, that will fail:
/// - ReadBufferFromFileDescriptor
/// - SynchronousReader
/// - ThreadPoolReader
class ReadBufferFromEmptyFile : public ReadBufferFromFileBase
{
private:
bool nextImpl() override { return false; }
std::string getFileName() const override { return "<empty>"; }
off_t seek(off_t /*off*/, int /*whence*/) override { return 0; }
off_t getPosition() override { return 0; }
};
}