IoUringFileRegion Class — netty Architecture

Source Code

transport-classes-io_uring/src/main/java/io/netty/channel/uring/IoUringFileRegion.java lines 27–190

final class IoUringFileRegion implements FileRegion {
    private static final InternalLogger logger = InternalLoggerFactory.getInstance(IoUringFileRegion.class);

    private static final short SPLICE_TO_PIPE = 1;
    private static final short SPLICE_TO_SOCKET = 2;

    final DefaultFileRegion fileRegion;
    private FileDescriptor[] pipe;
    private int transferred;
    private int pipeLen = -1;

    IoUringFileRegion(DefaultFileRegion fileRegion) {
        this.fileRegion = fileRegion;
    }

    void open() throws IOException {
        fileRegion.open();
        if (pipe == null) {
            pipe = FileDescriptor.pipe();
        }
    }

    IoUringIoOps splice(int fd) {
        if (pipeLen == -1) {
            return spliceToPipe();
        }
        return spliceToSocket(fd, pipeLen);
    }

    IoUringIoOps spliceToPipe() {
        int fileRegionFd = Native.getFd(fileRegion);
        int len = (int) (count() - transferred());
        int offset =  (int) (position() + transferred());
        return IoUringIoOps.newSplice(
                fileRegionFd, offset,
                pipe[1].intValue(), -1L,
                len, Native.SPLICE_F_MOVE, SPLICE_TO_PIPE);
    }

    private IoUringIoOps spliceToSocket(int socket, int len) {
        return IoUringIoOps.newSplice(
                pipe[0].intValue(), -1L,
                socket, -1L,
                len, Native.SPLICE_F_MOVE, SPLICE_TO_SOCKET);
    }

    /**
     * Handle splice result
     *
     * @param result    the result
     * @param data      the data that was submitted as part of the SPLICE.
     * @return          the number of bytes that should be considered to be transferred.
     */
    int handleResult(int result, short data) {
        assert result >= 0;
        if (data == SPLICE_TO_PIPE) {
            // This is the result for spliceToPipe
            transferred += result;
            pipeLen = result;
            return 0;
        }
        if (data == SPLICE_TO_SOCKET) {
            // This is the result for spliceToSocket
            pipeLen -= result;
            assert pipeLen >= 0;
            if (pipeLen == 0) {
                if (transferred() >= count()) {
                    // We transferred the whole file
                    return -1;
                }
                pipeLen = -1;
            }
            return result;
        }
        throw new IllegalArgumentException("Unknown data: " + data);
    }

    @Override
    public long position() {
        return fileRegion.position();
    }