multiplexedmanagedconnection.java

OpenJMS是一个开源的Java Message Service API 1.0.2 规范的实现,它包含有以下特性： *. 它既支持点到点（point-to-point）（PTP）模型和发布/订

                // multiplexer handles endpoint closure
                multiplexer.close();
                if (thread != Thread.currentThread()) {
                    try {
                        // wait for the multiplexer thread to terminate
                        thread.join();
                    } catch (InterruptedException exception) {
                        _log.debug(exception);
                    }
                }
            } else {
                if (endpoint != null) {
                    try {
                        endpoint.close();
                    } catch (IOException exception) {
                        throw new ResourceException("Failed to close endpoint",
                                                    exception);
                    }
                }
            }
        } finally {
            synchronized (this) {
                _multiplexer = null;
                _multiplexThread = null;
                _endpoint = null;
            }
        }
    }

    /**
     * Returns the principal associated with this connection.
     *
     * @return the principal associated with this connection,
     *         or <code>null<code> if none is set
     */
    public Principal getPrincipal() {
        return _principal;
    }

    /**
     * Determines if the security principal that owns this connection is the
     * same as that supplied.
     * <p/>
     * NOTE: If this is a server-side instance, the principal is only available
     * once the connection has been established, by {@link
     * #setInvocationHandler}
     *
     * @param principal the principal to compare. May be <code>null</code>.
     * @return <code>true</code> if the principal that owns this connection is
     *         the same as <code>principal</code>
     */
    public boolean hasPrincipal(Principal principal) {
        boolean result = false;
        if ((_principal != null && _principal.equals(principal))
                || (_principal == null && principal == null)) {
            result = true;
        }
        return result;
    }

    /**
     * Invoked for an invocation request.
     *
     * @param channel the channel the invocation is on
     */
    public void request(Channel channel) {
        _invoker.invoke(new ChannelInvocation(channel, getCaller()));
    }

    /**
     * Invoked when the connection is closed by the peer.
     */
    public void closed() {
        notifyClosed();
    }

    /**
     * Invoked when an error occurs on the multiplexer.
     *
     * @param error the error
     */
    public void error(Throwable error) {
        notifyError(error);
    }

    /**
     * Notifies of a successful ping.
     *
     * @param token the token sent in the ping
     */
    public void pinged(int token) {
        ManagedConnectionListener listener = getConnectionEventListener();
        if (listener != null) {
            listener.pinged(this);
        }
    }

    /**
     * Invoke a method on a remote object.
     *
     * @param connection the connection invoking the request
     * @param request    the request
     * @return the response
     */
    protected Response invoke(Connection connection, Request request) {
        Response response;
        Multiplexer multiplexer;
        synchronized (this) {
            multiplexer = _multiplexer;
        }
        if (multiplexer != null) {
            Channel channel = null;
            try {
                channel = multiplexer.getChannel();
                response = channel.invoke(request);
                channel.release();
            } catch (Exception exception) {
                _log.debug(exception, exception);
                response = new Response(exception);
                if (channel != null) {
                    channel.destroy();
                }
            }
        } else {
            response = new Response(new ResourceException("Connection lost"));
        }

        return response;
    }

    /**
     * Creates the endpoint to multiplex data over.
     *
     * @return the endpoint to multiplex data over
     * @throws IOException for any I/O error
     */
    protected abstract Endpoint createEndpoint() throws IOException;

    /**
     * Create a new client-side multiplexer.
     *
     * @param endpoint  the endpoint to multiplex messages over
     * @param principal the security principal
     * @return a new client-side multiplexer
     * @throws IOException       if an I/O error occurs
     * @throws SecurityException if connection is refused by the server
     */
    protected Multiplexer createMultiplexer(Endpoint endpoint,
                                            Principal principal)
            throws IOException, SecurityException {
        return new Multiplexer(this, endpoint, principal);
    }

    /**
     * Create a new server-side multiplexer.
     *
     * @param endpoint      the endpoint to multiplex messages over
     * @param authenticator the connection authetnicator
     * @return a new server-side multiplexer
     * @throws IOException       if an I/O error occurs
     * @throws ResourceException if the authenticator cannot authenticate
     */
    protected Multiplexer createMultiplexer(Endpoint endpoint,
                                            Authenticator authenticator)
            throws IOException, ResourceException {
        return new Multiplexer(this, endpoint, authenticator);
    }

    /**
     * Helper to determine if this is a client-side or server side instance.
     *
     * @return <code>true</code> if this is a client-side instance, otherwise
     *         <code>false</code>
     */
    protected boolean isClient() {
        return (_authenticator == null);
    }

    /**
     * Helper to return an {@link Caller} instance, denoting the client
     * performing a method invocation. Only applicable for server-side, and only
     * after the multiplexer has been created.
     *
     * @return the caller instance, or <code>null</code> if it hasn't been
     *         initialised
     */
    protected Caller getCaller() {
        return _caller;
    }

    /**
     * Returns the thread group to associate with allocated threads.
     *
     * @return the thread group to associate with allocated threads, or
     *         <code>null</code> to use the default thread group.
     */
    protected synchronized ThreadGroup getThreadGroup() {
        if (_group == null) {
            _group = new ThreadGroup(getDisplayName());
        }
        return _group;
    }

    /**
     * Helper to generate a descriptive name, for display purposes.
     * <p/>
     * This implementation returns the remote URI, concatenated with "[client]"
     * if this is a client connection, or "[server]" if it is a server
     * connection.
     *
     * @return the display name
     */
    protected String getDisplayName() {
        StringBuffer name = new StringBuffer();
        URI uri = null;
        try {
            uri = getRemoteURI();
        } catch (ResourceException ignore) {
            if (_log.isDebugEnabled()) {
                _log.debug("Failed to determine remote URI", ignore);
            }
        }
        if (uri != null) {
            name.append(uri.toString());
        } else {
            name.append("<unknown>");
        }
        if (isClient()) {
            name.append("[client]");
        } else {
            name.append("[server]");
        }
        return name.toString();
    }

}