abstracttopicconsumerendpoint.java

来自「OpenJMS是一个开源的Java Message Service API 1.」· Java 代码 · 共 472 行 · 第 1/2 页

     * @return <code>true</code> if the listener accepted the message;
     * @throws JMSException         if the listener fails to handle the message
     * @throws PersistenceException if there is a persistence related problem
     */
    public boolean persistentMessageAdded(MessageHandle handle,
                                          MessageImpl message)
            throws JMSException, PersistenceException {
        boolean accepted = true;

        // if the 'noLocal' indicator is set, and the message arrived on
        // the same connection, ignore the message
        if (getNoLocal() && message.getConnectionId() == getConnectionId()) {
            accepted = false;
        } else {
            // create a message handle for this consumer
            handle = new TopicConsumerMessageHandle(handle, this);
            if (isPersistent()) {
                // and make it persistent if this is a durable consumer
                handle.add();
            }

            if (!_handles.contains(handle)) {
                // if the message is not already in the cache then add it
                addMessage(handle);
            } else {
                accepted = false;
                _log.warn("Endpoint=" + this + " already has message cached: " +
                          handle);
            }
        }
        return accepted;
    }

    /**
     * This event is called when a message is removed from the
     * <code>DestinationCache</code>.
     *
     * @param messageId the identifier of the removed message
     * @throws JMSException         if the listener fails to handle the message
     * @throws PersistenceException if there is a persistence related problem
     */
    public void persistentMessageRemoved(String messageId)
            throws JMSException, PersistenceException {
        MessageHandle handle = _handles.remove(messageId);
        if (handle != null) {
            handle.destroy();
        }
    }


    /**
     * Invoked when a destination is created.
     *
     * @param destination the destination that was added
     */
    public void destinationAdded(JmsDestination destination) {
        // no-op
    }

    /**
     * Invoked when a destination is removed.
     *
     * @param destination the destination that was removed
     */
    public void destinationRemoved(JmsDestination destination) {
        // no-op
    }

    /**
     * Invoked when a message cache is created.
     *
     * @param destination the destination that messages are being cached for
     * @param cache       the corresponding cache
     */
    public void cacheAdded(JmsDestination destination,
                           DestinationCache cache) {
        if (destination instanceof JmsTopic) {
            JmsTopic myTopic = (JmsTopic) getDestination();
            JmsTopic topic = (JmsTopic) destination;
            if (myTopic.match(topic) && !_caches.containsKey(topic)) {
                _caches.put(topic, cache);
                cache.addConsumer(this);
            }
        }
    }

    /**
     * Invoked when a message cache is removed.
     *
     * @param destination the destination that messages are no longer being
     *                    cached for
     * @param cache       the corresponding cache
     */
    public void cacheRemoved(JmsDestination destination,
                             DestinationCache cache) {
        if (destination instanceof JmsTopic) {
            _caches.remove(destination);
        }
    }

    /**
     * Registers this with the associated {@link DestinationCache}s. The
     * consumer may receive messages immediately.
     *
     * @throws JMSException for any JMS error
     */
    protected void init() throws JMSException {
        JmsTopic topic = (JmsTopic) getDestination();

        // register the endpoint with the destination
        if (topic.isWildCard()) {
            // if the topic is a wild card then we need to retrieve a
            // set of matching destination caches.
            _caches = _destinations.getTopicDestinationCaches(topic);
            // for each cache register this endpoint as a consumer of
            // it's messages. Before doing so register as a destination
            // event listener with the DestinationManager
            _destinations.addDestinationEventListener(this);
            DestinationCache[] caches = getDestinationCaches();
            for (int i = 0; i < caches.length; ++i) {
                caches[i].addConsumer(this);
            }
        } else {
            // if the topic is not a wildcard then we need to get the
            // destination cache. If one does not exist then we need to
            // create it.
            DestinationCache cache = _destinations.getDestinationCache(topic);
            _caches.put(topic, cache);
            cache.addConsumer(this);
        }
    }

    /**
     * Set the connection identifier.
     *
     * @param connectionId the identity of the connection that owns this
     *                     consumer
     * @see #getConnectionId
     */
    protected void setConnectionId(long connectionId) {
        _connectionId = connectionId;
    }

    /**
     * Add the handle to the cache.
     *
     * @param handle the message handle to add
     */
    protected void addMessage(MessageHandle handle) {
        _handles.add(handle);
        notifyMessageAvailable();
    }

    /**
     * Return the next available message to the client.
     *
     * @return the next message, or <code>null</code> if none is available
     * @throws JMSException for any error
     * @param cancel
     */
    protected MessageHandle doReceive(Condition cancel) throws JMSException {
        MessageHandle result = null;
        MessageHandle handle;
        while (!cancel.get() && (handle = _handles.removeFirst()) != null) {
            if (_log.isDebugEnabled()) {
                _log.debug("doReceive() - next available=" + handle.getMessageId());
            }
            // ensure that the message still exists
            MessageImpl message = handle.getMessage();
            if (message != null) {
                if (selects(message)) {
                    // got a message which is applicable for the endpoint
                    result = handle;
                    break;
                } else {
                    // message has been filtered out so destroy the handle.
                    handle.destroy();
                }
            }
        }
        if (_log.isDebugEnabled()) {
            _log.debug("doReceive() - result=" + (result != null ? result.getMessageId() : null));
        }
        return result;
    }

    /**
     * Closes this endpoint.
     */
    protected void doClose() {
        // unregister as a destination event listener
        _destinations.removeDestinationEventListener(this);

        // unregister from the destination before continuing
        DestinationCache[] caches = getDestinationCaches();
        for (int i = 0; i < caches.length; ++i) {
            caches[i].removeConsumer(this);
        }
        _caches.clear();

        if (!isPersistent()) {
            // for non-persistent consumers, destroy all outstanding message
            // handles
            MessageHandle[] handles = _handles.toArray();
            for (int i = 0; i < handles.length; ++i) {
                MessageHandle handle = handles[i];
                try {
                    handle.destroy();
                } catch (JMSException exception) {
                    _log.error(exception, exception);
                }
            }
        }
    }

    /**
     * Returns the destination manager.
     *
     * @return the destination manager
     */
    protected DestinationManager getDestinationManager() {
        return _destinations;
    }

    /**
     * Returns the destination caches.
     *
     * @return the destination caches
     */
    protected DestinationCache[] getDestinationCaches() {
        return (DestinationCache[]) _caches.values().toArray(
                new DestinationCache[0]);
    }

}