Package org.jgroups.protocols

Class DAISYCHAIN

java.lang.Object
org.jgroups.stack.Protocol
org.jgroups.protocols.DAISYCHAIN
public class DAISYCHAIN extends Protocol
Implementation of daisy chaining. Multicast messages are sent to our neighbor, which sends them to its neighbor etc. A TTL restricts the number of times a message is forwarded. The advantage of daisy chaining is that - for point-to-point transports such as TCP - we can avoid the N-1 issue: when A sends a multicast message to 10 members, it needs to send it 9 times. With daisy chaining, it sends it 1 time, and in the next round, can already send another message. This leads to much better throughput, see the ref in the JIRA.

Should be inserted just above MERGE2, in TCP based configurations. JIRA: https://jira.jboss.org/browse/JGRP-1021

Since:
2.11
Author:
Bela Ban

  • Field Details

    • local_addr

      protected Address local_addr

    • next

      protected Address next

    • view_size

      protected int view_size

    • default_pool

      protected Executor default_pool

    • oob_pool

      protected Executor oob_pool

    • send_queue

      protected BlockingQueue<Message> send_queue

    • forward_queue

      protected BlockingQueue<Message> forward_queue

    • forward

      protected volatile boolean forward

    • running

      protected volatile boolean running

    • msgs_forwarded

      public int msgs_forwarded

    • msgs_sent

      public int msgs_sent

  • Constructor Details

    • DAISYCHAIN

      public DAISYCHAIN()

  • Method Details

    • getElementsInForwardQueue

      public int getElementsInForwardQueue()

    • getElementsInSendQueue

      public int getElementsInSendQueue()

    • init

      public void init() throws Exception
      Description copied from class: Protocol
      Called after instance has been created (null constructor) and before protocol is started. Properties are already set. Other protocols are not yet connected and events cannot yet be sent.
      Overrides:
      init in class Protocol
      Throws:
      Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor will throw an exception

    • start

      public void start() throws Exception
      Description copied from class: Protocol
      This method is called on a Channel.connect(String). Starts work. Protocols are connected and queues are ready to receive events. Will be called from bottom to top. This call will replace the START and START_OK events.
      Overrides:
      start in class Protocol
      Throws:
      Exception - Thrown if protocol cannot be started successfully. This will cause the ProtocolStack to fail, so Channel.connect(String) will throw an exception

    • stop

      public void stop()
      Description copied from class: Protocol
      This method is called on a Channel.disconnect(). Stops work (e.g. by closing multicast socket). Will be called from top to bottom. This means that at the time of the method invocation the neighbor protocol below is still working. This method will replace the STOP, STOP_OK, CLEANUP and CLEANUP_OK events. The ProtocolStack guarantees that when this method is called all messages in the down queue will have been flushed
      Overrides:
      stop in class Protocol

    • down

      public Object down(Event evt)
      Description copied from class: Protocol
      An event is to be sent down the stack. The layer may want to examine its type and perform some action on it, depending on the event's type. If the event is a message MSG, then the layer may need to add a header to it (or do nothing at all) before sending it down the stack using down_prot.down(). In case of a GET_ADDRESS event (which tries to retrieve the stack's address from one of the bottom layers), the layer may need to send a new response event back up the stack using up_prot.up().
      Overrides:
      down in class Protocol

    • up

      public Object up(Event evt)
      Description copied from class: Protocol
      An event was received from the layer below. Usually the current layer will want to examine the event type and - depending on its type - perform some computation (e.g. removing headers from a MSG event type, or updating the internal membership list when receiving a VIEW_CHANGE event). Finally the event is either a) discarded, or b) an event is sent down the stack using down_prot.down() or c) the event (or another event) is sent up the stack using up_prot.up().
      Overrides:
      up in class Protocol

    • processQueues

      protected Object processQueues()

    • handleView

      protected void handleView(View view)