reliableinputstream.java

jxta_src_2.41b jxta 2.41b 最新版源码 from www.jxta.org

            }
            ByteArrayInputStream bais =
                new ByteArrayInputStream(elt.getBytes(false));
            msg = WireFormatMessageFactory.fromWire(bais,
                                                    Defs.MIME_TYPE_MSG,
                                                    null);
        } catch (IOException ex) {
            if (LOG.isEnabledFor(Level.WARN)) {
                LOG.warn("Could not deserialize message " +
                         elt.getElementName() + ": " + ex.getMessage());
            }
            return null;
        }
        return msg;
    }

    /**
     *  queue messages by sequence number.
     */
    private void queueIncomingMessage(Message msg) {

        if (LOG.isEnabledFor(Level.DEBUG)) {
            LOG.debug( "Queue Incoming Message begins for " +  msg );
        }

        long startEnqueue = TimeUtils.timeNow();

        Message.ElementIterator e =
            msg.getMessageElements(Defs.NAMESPACE, Defs.MIME_TYPE_BLOCK);

        // OK look for jxta message
        while (!closed && !closing && e.hasNext()) {
            MessageElement elt = (MessageElement) e.next();
            e.remove();

            int msgSeqn = 0;
            try {
                msgSeqn = Integer.parseInt(elt.getElementName());
            } catch (NumberFormatException n) {
                if (LOG.isEnabledFor(Level.WARN)) {
                    LOG.warn( "Discarding element (" + elt.getElementName() +
                              ") Not one of ours." );
                }
                continue;
            }

            IQElt newElt = new IQElt();
            newElt.seqnum = msgSeqn;
            newElt.elt = elt;
            newElt.ackd = false;

            // OK we must inqueue:
            // Wait until someone dequeues if we are at the size limit

            // XXX AA 4/15/2003: where is the check for
            // size limit and the code to wait?

            // XXX JCH better not to wait anyway. Rely on the sender to not
            // do that too badly, and drop the message if it does, or just take it
            // (as we do right now).

            // see if this is a duplicate
            if (newElt.seqnum <= sequenceNumber) {
                if (LOG.isEnabledFor(Level.DEBUG)) {
                    LOG.debug("RCVD OLD MESSAGE : Discard seqn#" +
                              newElt.seqnum + " now at seqn#" +
                              sequenceNumber);
                }
                break;
            }

            synchronized (inputQueue) {

                // dbl check with the lock held.
                if (closing || closed) {
                    return;
                }

                // Insert this message into the input queue.
                //   1. Do not add duplicate messages
                //   2. Store in increasing sequence nos.
                int insertIndex = inputQueue.size();
                boolean duplicate = false;

                for (int j = 0; j < inputQueue.size(); j++) {
                    IQElt iq = (IQElt) inputQueue.get(j);
                    if (newElt.seqnum < iq.seqnum) {
                        insertIndex = j;
                        break;
                    } else if (newElt.seqnum == iq.seqnum) {
                        duplicate = true;
                        break;
                    }
                }

                if (duplicate) {
                    if (LOG.isEnabledFor(Level.DEBUG)) {
                        LOG.debug("RCVD OLD MESSAGE : " +
                                  " Discard duplicate msg, seqn#" +
                                  newElt.seqnum);
                    }
                    break;
                }

                inputQueue.add(insertIndex, newElt);

                if (LOG.isEnabledFor(Level.DEBUG)) {
                    LOG.debug("Enqueued msg with seqn#" + newElt.seqnum +
                              " at index " + insertIndex );
                }

                inputQueue.notifyAll();
            }
        }
        if (listener != null) {
            Message newmsg = null;
            while (true) {
                try {
                    newmsg = nextMessage(false);
                } catch (IOException io) {
                    //do nothing as this exception will never occur
                }
                if (newmsg == null) {
                    break;
                }
                try {
                    if (LOG.isEnabledFor(Level.DEBUG)) {
                        LOG.debug("In listener mode, calling back listener");
                    }
                    listener.processIncomingMessage(newmsg);
                } catch (Throwable t) {
                    if (LOG.isEnabledFor(Level.WARN)) {
                        LOG.warn("Failed to notify message listener", t);
                    }
                }
            }
        }
        if (LOG.isEnabledFor(Level.DEBUG)) {
            long waited = TimeUtils.toRelativeTimeMillis(TimeUtils.timeNow(),
                          startEnqueue);
            LOG.debug("Queue Incoming Message for " + msg +
                     " completed in " + waited + " msec.");
        }
    }

    long nextRetransRequest =
        TimeUtils.toAbsoluteTimeMillis(TimeUtils.ASECOND);

    /**
     *  Dequeue the message with the desired sequence number waiting as needed
     *  until the message is available.
     *
     *  @param desiredSeqn the sequence number to be dequeued.
     *  @return the Message Element with the desired sequence number or null if
     *  the queue has been closed.
     */
    private MessageElement dequeueMessage(int desiredSeqn, boolean blocking) throws IOException {
        IQElt iQ = null;

        // Wait for incoming message here
        long startDequeue = TimeUtils.timeNow();
        long whenToTimeout = startDequeue + timeout;
        int wct = 0;

        synchronized (inputQueue) {
            while(!closed) {
                if(inputQueue.size() == 0) {
                    if(!blocking) {
                        return null;
                    }
                    if (closing) {
                        return null;
                    }
                    try {
                        wct++;
                        inputQueue.wait(TimeUtils.ASECOND);
                        if (whenToTimeout < TimeUtils.timeNow()) {
                            throw new SocketTimeoutException("Read timeout reached");
                        }
                    } catch (InterruptedException e) {
                        Thread.interrupted(); // just continue
                    }
                    // reset retrans request timer since we don't want to immediately
                    // request retry after a long wait for out of order messages.

                    nextRetransRequest =
                        TimeUtils.toAbsoluteTimeMillis(TimeUtils.ASECOND);
                    continue;
                }

                iQ = (IQElt) inputQueue.get(0); // FIFO

                if (iQ.seqnum < desiredSeqn) {
                    // Ooops a DUPE slipped in the head of the queue undetected
                    // (seqnum consistency issue).
                    // Just drop it.
                    inputQueue.remove(0);
                    // if such is the case then notify the other end so that
                    // the message does not remain in the retry queue eventually
                    // triggering a broken pipe exception
                    sendACK(iQ.seqnum);
                    continue;
                } else if (iQ.seqnum != desiredSeqn) {
                    if (TimeUtils.toRelativeTimeMillis(nextRetransRequest) < 0) {
                        if (LOG.isEnabledFor(Level.DEBUG)) {
                            LOG.debug("Trigger retransmission. Wanted seqn#" +
                                      desiredSeqn + " found seqn#" +
                                      iQ.seqnum);
                        }
                        sendACK(desiredSeqn - 1);
                        nextRetransRequest =
                             TimeUtils.toAbsoluteTimeMillis(TimeUtils.ASECOND);
                    }
                    if(!blocking) {
                        if (LOG.isEnabledFor(Level.DEBUG)) {
                            LOG.debug("Message out of sequece in Non-Blocking mode. returning");
                        }
                        //not the element of interest return nothing
                        return null;
                    }
                    try {
                        wct++;
                        inputQueue.wait(TimeUtils.ASECOND);
                        if (whenToTimeout < TimeUtils.timeNow()) {
                            throw new SocketTimeoutException("Read timeout reached");
                        }
                    } catch (InterruptedException e) {
                        throw new InterruptedIOException("IO interrupted ");
                    }
                    continue;
                }
                inputQueue.remove(0);
                break;
            }
        }
        nextRetransRequest = 0;
        // if we are closed then we return null
        if (null == iQ) {
            return null;
        }

        sendACK(desiredSeqn);

        if (LOG.isEnabledFor(Level.DEBUG)) {
            long waited =
                TimeUtils.toRelativeTimeMillis(TimeUtils.timeNow(),
                                               startDequeue);
            LOG.debug("DEQUEUED seqn#" + iQ.seqnum + " in " + waited +
                     " msec on input queue" );
            if (wct > 0) {
                LOG.debug("DEQUEUE waited " + wct + " times on input queue");
            }
        }
        if (LOG.isEnabledFor(Level.DEBUG)) {
           LOG.debug("DEQUEUE waited " + wct + " times on input queue");
        }
        return iQ.elt;
    }


    /**
     * {@inheritDoc}
     */
    public int available() throws IOException {
        if(listener != null) {
            throw new IOException("available() not supported in async mode");
        }
        if (closed) {
            throw new IOException("Stream closed");
        }
        synchronized (record) {
            if (record.inputStream != null) {
                if ((record.size == 0) || (record.nextByte == record.size)) {
                    if (inputQueue.size() == 0) {
                        return 0;
                    }
                    // reset the record
                    record.resetRecord();      // GC as necessary(inputStream byte[])
                    if (LOG.isEnabledFor(Level.DEBUG)) {
                        LOG.debug("local_read: getting next data block at seqn#" +
                                  (sequenceNumber + 1));
                    }
                    MessageElement elt = dequeueMessage(sequenceNumber + 1, false);
                    if (null == elt) {
                        return 0;
                    }
                    sequenceNumber += 1;       // next msg sequence number
                    // Get the length of the Record
                    record.size = elt.getByteLength();
                    record.inputStream = elt.getStream();
                }
                return record.inputStream.available();
            }
        }
        return 0;
    }
    /**
     *
     */
    private int local_read(byte[] buf, int offset, int length) throws IOException {

        if(listener != null) {
            throw new IOException("read() not supported in async mode");
        }
        synchronized (record) {
            if ((record.size == 0) || (record.nextByte == record.size)) {

                // reset the record
                record.resetRecord(); // GC as necessary(inputStream byte[])

                if (LOG.isEnabledFor(Level.DEBUG)) {
                    LOG.debug("local_read: getting next data block at seqn#" +
                              (sequenceNumber + 1));
                }

                MessageElement elt = dequeueMessage(sequenceNumber + 1, true);

                if (null == elt) {
                    return -1;
                }

                sequenceNumber += 1; // next msg sequence number

                // Get the length of the Record
                record.size = elt.getByteLength();
                record.inputStream = elt.getStream();

                if (LOG.isEnabledFor(Level.DEBUG)) {
                    LOG.debug("local_read: new seqn#" + sequenceNumber +
                              ", bytes = " + record.size );
                }
            }

            // return the requested Record data
            // These calls should NEVER ask for more data than is in the
            // received Record.

            long left = record.size - record.nextByte;
            int copyLen = (int) Math.min(length, left);
            int copied = 0;

            do {
                int res = record.inputStream.read(buf, offset + copied,
                                                  copyLen - copied);

                if (res < 0) {
                    break;
                }
                copied += res;
            } while (copied < copyLen);

            record.nextByte += copied;
            if (DEBUGIO) {
                if (LOG.isEnabledFor(Level.DEBUG)) {
                    LOG.debug("local_read: Requested " + length +
                              ", Read " + copied + " bytes");
                }
            }

            return copied;
        }
    }

    /**
     * Returns the message listener for this pipe
     * @return MsgListener
     *
     */
    public MsgListener getListener() {
        return listener;
    }

    /**
     *  The listener interface for receiving {@link net.jxta.endpoint.Message} 
     * 
     */
    public interface MsgListener {

        /**
         * Called for each message received.
         *
         * @param message The message to be received.
         */
        void processIncomingMessage(Message message);

    }
}