FileDescriptor Class — netty Architecture

Source Code

transport-native-unix-common/src/main/java/io/netty/channel/unix/FileDescriptor.java lines 35–240

public class FileDescriptor {

    private static final AtomicIntegerFieldUpdater<FileDescriptor> stateUpdater =
            AtomicIntegerFieldUpdater.newUpdater(FileDescriptor.class, "state");

    private static final int STATE_CLOSED_MASK = 1;
    private static final int STATE_INPUT_SHUTDOWN_MASK = 1 << 1;
    private static final int STATE_OUTPUT_SHUTDOWN_MASK = 1 << 2;
    private static final int STATE_ALL_MASK = STATE_CLOSED_MASK |
                                              STATE_INPUT_SHUTDOWN_MASK |
                                              STATE_OUTPUT_SHUTDOWN_MASK;

    /**
     * Bit map = [Output Shutdown | Input Shutdown | Closed]
     */
    volatile int state;
    final int fd;

    public FileDescriptor(int fd) {
        checkPositiveOrZero(fd, "fd");
        this.fd = fd;
    }

    /**
     * Return the int value of the filedescriptor.
     */
    public final int intValue() {
        return fd;
    }

    protected boolean markClosed() {
        for (;;) {
            int state = this.state;
            if (isClosed(state)) {
                return false;
            }
            // Once a close operation happens, the channel is considered shutdown.
            if (casState(state, state | STATE_ALL_MASK)) {
                return true;
            }
        }
    }

    /**
     * Close the file descriptor.
     */
    public void close() throws IOException {
        if (markClosed()) {
            int res = close(fd);
            if (res < 0) {
                throw newIOException("close", res);
            }
        }
    }

    /**
     * Returns {@code true} if the file descriptor is open.
     */
    public boolean isOpen() {
        return !isClosed(state);
    }

    public final int write(ByteBuffer buf, int pos, int limit) throws IOException {
        int res = write(fd, buf, pos, limit);
        if (res >= 0) {
            return res;
        }
        return ioResult("write", res);
    }

    public final int writeAddress(long address, int pos, int limit) throws IOException {
        int res = writeAddress(fd, address, pos, limit);
        if (res >= 0) {
            return res;
        }
        return ioResult("writeAddress", res);
    }

    public final long writev(ByteBuffer[] buffers, int offset, int length, long maxBytesToWrite) throws IOException {
        long res = writev(fd, buffers, offset, min(IOV_MAX, length), maxBytesToWrite);
        if (res >= 0) {