keepalivefilter.java

mina是以Java实现的一个开源的网络程序框架

    /**
     * Creates a new instance.
     */
    public KeepAliveFilter(
            KeepAliveMessageFactory messageFactory,
            IdleStatus interestedIdleStatus, KeepAliveRequestTimeoutHandler policy,
            int keepAliveRequestInterval, int keepAliveRequestTimeout) {
        if (messageFactory == null) {
            throw new NullPointerException("messageFactory");
        }
        if (interestedIdleStatus == null) {
            throw new NullPointerException("interestedIdleStatus");
        }
        if (policy == null) {
            throw new NullPointerException("policy");
        }

        this.messageFactory = messageFactory;
        this.interestedIdleStatus = interestedIdleStatus;
        requestTimeoutHandler = policy;

        setRequestInterval(keepAliveRequestInterval);
        setRequestTimeout(keepAliveRequestTimeout);
    }

    public IdleStatus getInterestedIdleStatus() {
        return interestedIdleStatus;
    }

    public KeepAliveRequestTimeoutHandler getRequestTimeoutHandler() {
        return requestTimeoutHandler;
    }

    public void setRequestTimeoutHandler(KeepAliveRequestTimeoutHandler timeoutHandler) {
        if (timeoutHandler == null) {
            throw new NullPointerException("timeoutHandler");
        }
        requestTimeoutHandler = timeoutHandler;
    }

    public int getRequestInterval() {
        return requestInterval;
    }

    public void setRequestInterval(int keepAliveRequestInterval) {
        if (keepAliveRequestInterval <= 0) {
            throw new IllegalArgumentException(
                    "keepAliveRequestInterval must be a positive integer: " +
                    keepAliveRequestInterval);
        }
        requestInterval = keepAliveRequestInterval;
    }

    public int getRequestTimeout() {
        return requestTimeout;
    }

    public void setRequestTimeout(int keepAliveRequestTimeout) {
        if (keepAliveRequestTimeout <= 0) {
            throw new IllegalArgumentException(
                    "keepAliveRequestTimeout must be a positive integer: " +
                    keepAliveRequestTimeout);
        }
        requestTimeout = keepAliveRequestTimeout;
    }

    public KeepAliveMessageFactory getMessageFactory() {
        return messageFactory;
    }

    /**
     * Returns <tt>true</tt> if and only if this filter forwards
     * a {@link IoEventType#SESSION_IDLE} event to the next filter.
     * By default, the value of this property is <tt>false</tt>.
     */
    public boolean isForwardEvent() {
        return forwardEvent;
    }

    /**
     * Sets if this filter needs to forward a
     * {@link IoEventType#SESSION_IDLE} event to the next filter.
     * By default, the value of this property is <tt>false</tt>.
     */
    public void setForwardEvent(boolean forwardEvent) {
        this.forwardEvent = forwardEvent;
    }

    @Override
    public void onPreAdd(IoFilterChain parent, String name,
            NextFilter nextFilter) throws Exception {
        if (parent.contains(this)) {
            throw new IllegalArgumentException(
                    "You can't add the same filter instance more than once. " +
            "Create another instance and add it.");
        }
    }

    @Override
    public void onPostAdd(
            IoFilterChain parent, String name, NextFilter nextFilter) throws Exception {
        resetStatus(parent.getSession());
    }

    @Override
    public void onPostRemove(
            IoFilterChain parent, String name, NextFilter nextFilter) throws Exception {
        resetStatus(parent.getSession());
    }

    @Override
    public void messageReceived(
            NextFilter nextFilter, IoSession session, Object message) throws Exception {
        try {
            if (messageFactory.isRequest(session, message)) {
                Object pongMessage =
                    messageFactory.getResponse(session, message);

                if (pongMessage != null) {
                    nextFilter.filterWrite(
                            session, new DefaultWriteRequest(pongMessage));
                }
            }

            if (messageFactory.isResponse(session, message)) {
                resetStatus(session);
            }
        } finally {
            if (!isKeepAliveMessage(session, message)) {
                nextFilter.messageReceived(session, message);
            }
        }
    }

    @Override
    public void messageSent(
            NextFilter nextFilter, IoSession session, WriteRequest writeRequest) throws Exception {
        Object message = writeRequest.getMessage();
        if (!isKeepAliveMessage(session, message)) {
            nextFilter.messageSent(session, writeRequest);
        }
    }

    @Override
    public void sessionIdle(
            NextFilter nextFilter, IoSession session, IdleStatus status) throws Exception {
        if (status == interestedIdleStatus) {
            if (!session.containsAttribute(WAITING_FOR_RESPONSE)) {
                Object pingMessage = messageFactory.getRequest(session);
                if (pingMessage != null) {
                    nextFilter.filterWrite(
                            session,
                            new DefaultWriteRequest(pingMessage));

                    // If policy is OFF, there's no need to wait for
                    // the response.
                    if (getRequestTimeoutHandler() != KeepAliveRequestTimeoutHandler.DEAF_SPEAKER) {
                        markStatus(session);
                        if (interestedIdleStatus == IdleStatus.BOTH_IDLE) {
                            session.setAttribute(IGNORE_READER_IDLE_ONCE);
                        }
                    } else {
                        resetStatus(session);
                    }
                }
            } else {
                handlePingTimeout(session);
            }
        } else if (status == IdleStatus.READER_IDLE) {
            if (session.removeAttribute(IGNORE_READER_IDLE_ONCE) == null) {
                if (session.containsAttribute(WAITING_FOR_RESPONSE)) {
                    handlePingTimeout(session);
                }
            }
        }

        if (forwardEvent) {
            nextFilter.sessionIdle(session, status);
        }
    }

    private void handlePingTimeout(IoSession session) throws Exception {
        resetStatus(session);
        KeepAliveRequestTimeoutHandler handler = getRequestTimeoutHandler();
        if (handler == KeepAliveRequestTimeoutHandler.DEAF_SPEAKER) {
            return;
        }

        handler.keepAliveRequestTimedOut(this, session);
    }

    private void markStatus(IoSession session) {
        session.getConfig().setIdleTime(interestedIdleStatus, 0);
        session.getConfig().setReaderIdleTime(getRequestTimeout());
        session.setAttribute(WAITING_FOR_RESPONSE);
    }

    private void resetStatus(IoSession session) {
        session.getConfig().setReaderIdleTime(0);
        session.getConfig().setWriterIdleTime(0);
        session.getConfig().setIdleTime(
                interestedIdleStatus, getRequestInterval());
        session.removeAttribute(WAITING_FOR_RESPONSE);
    }

    private boolean isKeepAliveMessage(IoSession session, Object message) {
        return messageFactory.isRequest(session, message) ||
        messageFactory.isResponse(session, message);
    }
}