abstractpollingconnectionlessioacceptor.java

mina是以Java实现的一个开源的网络程序框架

        public void updateTrafficControl(T session) {
            throw new UnsupportedOperationException();
        }

        public void dispose() {
        }

        public boolean isDisposed() {
            return false;
        }

        public boolean isDisposing() {
            return false;
        }
    }

    /**
     * Starts the inner Acceptor thread.
     */
    private void startupAcceptor() {
        if (!selectable) {
            registerQueue.clear();
            cancelQueue.clear();
            flushingSessions.clear();
        }

        synchronized (lock) {
            if (acceptor == null) {
                acceptor = new Acceptor();
                executeWorker(acceptor);
            }
        }
    }

    private boolean scheduleFlush(T session) {
        if (session.setScheduledForFlush(true)) {
            flushingSessions.add(session);
            return true;
        } else {
            return false;
        }
    }

    /**
     * This private class is used to accept incoming connection from 
     * clients. It's an infinite loop, which can be stopped when all
     * the registered handles have been removed (unbound). 
     */
    private class Acceptor implements Runnable {
        public void run() {
            int nHandles = 0;
            lastIdleCheckTime = System.currentTimeMillis();

            while (selectable) {
                try {
                    int selected = select();

                    nHandles += registerHandles();

                    if (selected > 0) {
                        processReadySessions(selectedHandles());
                    }

                    long currentTime = System.currentTimeMillis();
                    flushSessions(currentTime);
                    nHandles -= unregisterHandles();

                    notifyIdleSessions(currentTime);

                    if (nHandles == 0) {
                        synchronized (lock) {
                            if (registerQueue.isEmpty() && cancelQueue.isEmpty()) {
                                acceptor = null;
                                break;
                            }
                        }
                    }
                } catch (Exception e) {
                    ExceptionMonitor.getInstance().exceptionCaught(e);

                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e1) {
                    }
                }
            }

            if (selectable && isDisposing()) {
                selectable = false;
                try {
                    destroy();
                } catch (Exception e) {
                    ExceptionMonitor.getInstance().exceptionCaught(e);
                } finally {
                    disposalFuture.setValue(true);
                }
            }
        }
    }

    @SuppressWarnings("unchecked")
    private void processReadySessions(Iterator<H> handles) {
        while (handles.hasNext()) {
            H h = handles.next();
            handles.remove();
            try {
                if (isReadable(h)) {
                    readHandle(h);
                }

                if (isWritable(h)) {
                    for (IoSession session : getManagedSessions().values()) {
                        scheduleFlush((T) session);
                    }
                }
            } catch (Throwable t) {
                ExceptionMonitor.getInstance().exceptionCaught(t);
            }
        }
    }

    private void readHandle(H handle) throws Exception {
        IoBuffer readBuf = IoBuffer.allocate(
                getSessionConfig().getReadBufferSize());

        SocketAddress remoteAddress = receive(handle, readBuf);
        if (remoteAddress != null) {
            IoSession session = newSessionWithoutLock(
                    remoteAddress, localAddress(handle));

            readBuf.flip();

            IoBuffer newBuf = IoBuffer.allocate(readBuf.limit());
            newBuf.put(readBuf);
            newBuf.flip();

            session.getFilterChain().fireMessageReceived(newBuf);
        }
    }

    private void flushSessions(long currentTime) {
        for (; ;) {
            T session = flushingSessions.poll();
            if (session == null) {
                break;
            }

            session.setScheduledForFlush(false);

            try {
                boolean flushedAll = flush(session, currentTime);
                if (flushedAll && !session.getWriteRequestQueue().isEmpty(session) &&
                    !session.isScheduledForFlush()) {
                    scheduleFlush(session);
                }
            } catch (Exception e) {
                session.getFilterChain().fireExceptionCaught(e);
            }
        }
    }

    private boolean flush(T session, long currentTime) throws Exception {
        // Clear OP_WRITE
        setInterestedInWrite(session, false);

        final WriteRequestQueue writeRequestQueue = session.getWriteRequestQueue();
        final int maxWrittenBytes =
            session.getConfig().getMaxReadBufferSize() +
            (session.getConfig().getMaxReadBufferSize() >>> 1);

        int writtenBytes = 0;
        try {
            for (; ;) {
                WriteRequest req = session.getCurrentWriteRequest();
                if (req == null) {
                    req = writeRequestQueue.poll(session);
                    if (req == null) {
                        break;
                    }
                    session.setCurrentWriteRequest(req);
                }

                IoBuffer buf = (IoBuffer) req.getMessage();
                if (buf.remaining() == 0) {
                    // Clear and fire event
                    session.setCurrentWriteRequest(null);
                    buf.reset();
                    session.getFilterChain().fireMessageSent(req);
                    continue;
                }

                SocketAddress destination = req.getDestination();
                if (destination == null) {
                    destination = session.getRemoteAddress();
                }

                int localWrittenBytes = send(session, buf, destination);
                if (localWrittenBytes == 0 || writtenBytes >= maxWrittenBytes) {
                    // Kernel buffer is full or wrote too much
                    setInterestedInWrite(session, true);
                    return false;
                } else {
                    setInterestedInWrite(session, false);

                    // Clear and fire event
                    session.setCurrentWriteRequest(null);
                    writtenBytes += localWrittenBytes;
                    buf.reset();
                    session.getFilterChain().fireMessageSent(req);
                }
            }
        } finally {
            session.increaseWrittenBytes(writtenBytes, currentTime);
        }

        return true;
    }

    private int registerHandles() {
        for (;;) {
            AcceptorOperationFuture req = registerQueue.poll();
            if (req == null) {
                break;
            }

            Map<SocketAddress, H> newHandles = new HashMap<SocketAddress, H>();
            List<SocketAddress> localAddresses = req.getLocalAddresses();
            try {
                for (SocketAddress a: localAddresses) {
                    H handle = open(a);
                    newHandles.put(localAddress(handle), handle);
                }
                boundHandles.putAll(newHandles);

                getListeners().fireServiceActivated();
                req.setDone();
                return newHandles.size();
            } catch (Exception e) {
                req.setException(e);
            } finally {
                // Roll back if failed to bind all addresses.
                if (req.getException() != null) {
                    for (H handle: newHandles.values()) {
                        try {
                            close(handle);
                        } catch (Exception e) {
                            ExceptionMonitor.getInstance().exceptionCaught(e);
                        }
                    }
                    wakeup();
                }
            }
        }

        return 0;
    }

    private int unregisterHandles() {
        int nHandles = 0;
        for (;;) {
            AcceptorOperationFuture request = cancelQueue.poll();
            if (request == null) {
                break;
            }

            // close the channels
            for (SocketAddress a: request.getLocalAddresses()) {
                H handle = boundHandles.remove(a);
                if (handle == null) {
                    continue;
                }

                try {
                    close(handle);
                    wakeup(); // wake up again to trigger thread death
                } catch (Throwable e) {
                    ExceptionMonitor.getInstance().exceptionCaught(e);
                } finally {
                    nHandles ++;
                }
            }

            request.setDone();
        }

        return nHandles;
    }

    private void notifyIdleSessions(long currentTime) {
        // process idle sessions
        if (currentTime - lastIdleCheckTime >= 1000) {
            lastIdleCheckTime = currentTime;
            AbstractIoSession.notifyIdleness(
                    getListeners().getManagedSessions().values().iterator(),
                    currentTime);
        }
    }
}