Class AckMcastSenderWindow

java.lang.Object
org.jgroups.stack.AckMcastSenderWindow

public class AckMcastSenderWindow extends Object
Keeps track of ACKs from receivers for each message. When a new message is sent, it is tagged with a sequence number and the receiver set (set of members to which the message is sent) and added to a hashtable (key = sequence number, val = message + receiver set). Each incoming ACK is noted and when all ACKs for a specific sequence number haven been received, the corresponding entry is removed from the hashtable. A retransmission thread periodically re-sends the message point-to-point to all receivers from which no ACKs have been received yet. A view change or suspect message causes the corresponding non-existing receivers to be removed from the hashtable.

This class may need flow control in order to avoid needless retransmissions because of timeouts.

Version:
$Id: AckMcastSenderWindow.java,v 1.14.2.1 2008/01/22 10:01:01 belaban Exp $
Author:
Bela Ban June 9 1999, 2007, John Georgiadis May 8 2001
  • Field Details

    • log

      protected static final org.apache.commons.logging.Log log
      Default retransmit thread suspend timeout (ms)
  • Constructor Details

  • Method Details

    • add

      public void add(long seqno, Message msg, Vector receivers)
      Adds a new message to the hash table.
      Parameters:
      seqno - The sequence number associated with the message
      msg - The message (should be a copy!)
      receivers - The set of addresses to which the message was sent and from which consequently an ACK is expected
    • ack

      public void ack(long seqno, Address sender)
      An ACK has been received from sender. Tag the sender in the hash table as 'received'. If all ACKs have been received, remove the entry all together.
      Parameters:
      seqno - The sequence number of the message for which an ACK has been received.
      sender - The sender which sent the ACK
    • remove

      public void remove(Address obj)
      Remove obj from all receiver sets and wake up retransmission thread.
      Parameters:
      obj - the sender to remove
    • suspect

      public void suspect(Address suspected)
      Process with address suspected is suspected: remove it from all receiver sets. This means that no ACKs are expected from this process anymore.
      Parameters:
      suspected - The suspected process
    • getStableMessages

      public List getStableMessages()
      Returns:
      a copy of stable messages, or null (if non available). Removes all stable messages afterwards
    • clearStableMessages

      public void clearStableMessages()
    • size

      public long size()
      Returns:
      the number of currently pending msgs
    • getNumberOfResponsesExpected

      public long getNumberOfResponsesExpected(long seqno)
      Returns the number of members for a given entry for which acks have to be received
    • getNumberOfResponsesReceived

      public long getNumberOfResponsesReceived(long seqno)
      Returns the number of members for a given entry for which acks have been received
    • printDetails

      public String printDetails(long seqno)
      Prints all members plus whether an ack has been received from those members for a given seqno
    • waitUntilAllAcksReceived

      public void waitUntilAllAcksReceived(long timeout)
      Waits until all outstanding messages have been ACKed by all receivers. Takes into account suspicions and view changes. Returns when there are no entries left in the hashtable. While waiting, no entries can be added to the hashtable (they will be discarded).
      Parameters:
      timeout - Miliseconds to wait. 0 means wait indefinitely.
    • stop

      public void stop()
      Stop the rentransmition and clear all pending msgs.

      If this retransmitter has been provided an externally managed scheduler, then just clear all msgs and the associated tasks, else stop the scheduler. In this case the method blocks until the scheduler's thread is dead. Only the owner of the scheduler should stop it.

    • reset

      public void reset()
      Remove all pending msgs from the hashtable. Cancel all associated tasks in the retransmission scheduler
    • toString

      public String toString()
      Overrides:
      toString in class Object