nioreceiver.java

业界著名的tomcat服务器的最新6.0的源代码。

//                    }
//                }
//                else
                if ( key.interestOps() == 0 ) {
                    //check for keys that didn't make it in.
                    ObjectReader ka = (ObjectReader) key.attachment();
                    if ( ka != null ) {
                        long delta = now - ka.getLastAccess();
                        if (delta > (long) getTimeout() && (!ka.isAccessed())) {
                            log.warn("Channel key is registered, but has had no interest ops for the last "+getTimeout()+" ms. (cancelled:"+ka.isCancelled()+"):"+key+" last access:"+new java.sql.Timestamp(ka.getLastAccess()));
//                            System.out.println("Interest:"+key.interestOps());
//                            System.out.println("Ready Ops:"+key.readyOps());
//                            System.out.println("Valid:"+key.isValid());
                            ka.setLastAccess(now);
                            //key.interestOps(SelectionKey.OP_READ);
                        }//end if
                    } else {
                        cancelledKey(key);
                    }//end if
                }//end if
            }catch ( CancelledKeyException ckx ) {
                cancelledKey(key);
            }
        }
    }


    /**
     * get data from channel and store in byte array
     * send it to cluster
     * @throws IOException
     * @throws java.nio.channels.ClosedChannelException
     */
    protected void listen() throws Exception {
        if (doListen()) {
            log.warn("ServerSocketChannel already started");
            return;
        }
        
        setListen(true);

        while (doListen() && selector != null) {
            // this may block for a long time, upon return the
            // selected set contains keys of the ready channels
            try {
                events();
                socketTimeouts();
                int n = selector.select(getTcpSelectorTimeout());
                if (n == 0) {
                    //there is a good chance that we got here
                    //because the TcpReplicationThread called
                    //selector wakeup().
                    //if that happens, we must ensure that that
                    //thread has enough time to call interestOps
//                    synchronized (interestOpsMutex) {
                        //if we got the lock, means there are no
                        //keys trying to register for the
                        //interestOps method
//                    }
                    continue; // nothing to do
                }
                // get an iterator over the set of selected keys
                Iterator it = selector.selectedKeys().iterator();
                // look at each key in the selected set
                while (it.hasNext()) {
                    SelectionKey key = (SelectionKey) it.next();
                    // Is a new connection coming in?
                    if (key.isAcceptable()) {
                        ServerSocketChannel server = (ServerSocketChannel) key.channel();
                        SocketChannel channel = server.accept();
                        channel.socket().setReceiveBufferSize(getRxBufSize());
                        channel.socket().setSendBufferSize(getTxBufSize());
                        channel.socket().setTcpNoDelay(getTcpNoDelay());
                        channel.socket().setKeepAlive(getSoKeepAlive());
                        channel.socket().setOOBInline(getOoBInline());
                        channel.socket().setReuseAddress(getSoReuseAddress());
                        channel.socket().setSoLinger(getSoLingerOn(),getSoLingerTime());
                        channel.socket().setTrafficClass(getSoTrafficClass());
                        channel.socket().setSoTimeout(getTimeout());
                        Object attach = new ObjectReader(channel);
                        registerChannel(selector,
                                        channel,
                                        SelectionKey.OP_READ,
                                        attach);
                    }
                    // is there data to read on this channel?
                    if (key.isReadable()) {
                        readDataFromSocket(key);
                    } else {
                        key.interestOps(key.interestOps() & (~SelectionKey.OP_WRITE));
                    }

                    // remove key from selected set, it's been handled
                    it.remove();
                }
            } catch (java.nio.channels.ClosedSelectorException cse) {
                // ignore is normal at shutdown or stop listen socket
            } catch (java.nio.channels.CancelledKeyException nx) {
                log.warn("Replication client disconnected, error when polling key. Ignoring client.");
            } catch (Throwable x) {
                try {
                    log.error("Unable to process request in NioReceiver", x);
                }catch ( Throwable tx ) {
                    //in case an out of memory error, will affect the logging framework as well
                    tx.printStackTrace();
                }
            }

        }
        serverChannel.close();
        if (selector != null)
            selector.close();
    }

    

    /**
     * Close Selector.
     *
     * @see org.apache.catalina.tribes.transport.ClusterReceiverBase#stopListening()
     */
    protected void stopListening() {
        setListen(false);
        if (selector != null) {
            try {
                selector.wakeup();
                selector.close();
            } catch (Exception x) {
                log.error("Unable to close cluster receiver selector.", x);
            } finally {
                selector = null;
            }
        }
    }

    // ----------------------------------------------------------

    /**
     * Register the given channel with the given selector for
     * the given operations of interest
     */
    protected void registerChannel(Selector selector,
                                   SelectableChannel channel,
                                   int ops,
                                   Object attach) throws Exception {
        if (channel == null)return; // could happen
        // set the new channel non-blocking
        channel.configureBlocking(false);
        // register it with the selector
        channel.register(selector, ops, attach);
    }

    /**
     * Start thread and listen
     */
    public void run() {
        try {
            listen();
        } catch (Exception x) {
            log.error("Unable to run replication listener.", x);
        }
    }

    // ----------------------------------------------------------

    /**
     * Sample data handler method for a channel with data ready to read.
     * @param key A SelectionKey object associated with a channel
     *  determined by the selector to be ready for reading.  If the
     *  channel returns an EOF condition, it is closed here, which
     *  automatically invalidates the associated key.  The selector
     *  will then de-register the channel on the next select call.
     */
    protected void readDataFromSocket(SelectionKey key) throws Exception {
        NioReplicationTask task = (NioReplicationTask) getTaskPool().getRxTask();
        if (task == null) {
            // No threads/tasks available, do nothing, the selection
            // loop will keep calling this method until a
            // thread becomes available, the thread pool itself has a waiting mechanism
            // so we will not wait here.
            if (log.isDebugEnabled()) log.debug("No TcpReplicationThread available");
        } else {
            // invoking this wakes up the worker thread then returns
            //add task to thread pool
            task.serviceChannel(key);
            getExecutor().execute(task);
        }
    }


}