Method PreadSafe

util/system/direct_io.cpp:149–169

}

size_t TDirectIOBufferedFile::PreadSafe(void* buffer, size_t byteCount, ui64 offset) {
    if (FlushedToDisk < offset + byteCount) {
        File.FlushData();
        FlushedToDisk = FlushedBytes;
    }

#ifdef _linux_
    ssize_t bytesRead = 0;
    do {
        bytesRead = pread(File.GetHandle(), buffer, byteCount, offset);
    } while (bytesRead == -1 && errno == EINTR);

    if (bytesRead < 0) {
        ythrow yexception() << "error while pread file: " << LastSystemError() << "(" << LastSystemErrorText() << ")";
    }

    return bytesRead;
#else
    return File.Pread(buffer, byteCount, offset);
#endif
}

size_t TDirectIOBufferedFile::ReadFromFile(void* buffer, size_t byteCount, ui64 offset) {
    SetDirectIO(true);