Package org.jgroups.stack

Class AckMcastSenderWindow

  • public class AckMcastSenderWindow
extends java.lang.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 Detail

      • log

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

    • Constructor Detail

      • AckMcastSenderWindow

        public AckMcastSenderWindow​(AckMcastSenderWindow.RetransmitCommand cmd,
                            Interval retransmit_intervals,
                            TimeScheduler sched)
        Create and start the retransmitter
        Parameters:
        cmd - the callback object for retranmissions
        retransmit_intervals - the interval between two consecutive retransmission attempts
        sched - the external scheduler to use to schedule retransmissions
        Throws:
        java.lang.IllegalArgumentException - if cmd is null

      • AckMcastSenderWindow

        public AckMcastSenderWindow​(AckMcastSenderWindow.RetransmitCommand cmd,
                            TimeScheduler sched)
        Create and start the retransmitter
        Parameters:
        cmd - the callback object for retranmissions
        sched - the external scheduler to use to schedule retransmissions
        Throws:
        java.lang.IllegalArgumentException - if cmd is null

      • AckMcastSenderWindow

        public AckMcastSenderWindow​(AckMcastSenderWindow.RetransmitCommand cmd,
                            Interval retransmit_intervals)
        Create and start the retransmitter
        Parameters:
        cmd - the callback object for retranmissions
        retransmit_intervals - the interval between two consecutive retransmission attempts
        Throws:
        java.lang.IllegalArgumentException - if cmd is null

      • AckMcastSenderWindow

        public AckMcastSenderWindow​(AckMcastSenderWindow.RetransmitCommand cmd)
        Create and start the retransmitter
        Parameters:
        cmd - the callback object for retranmissions
        Throws:
        java.lang.IllegalArgumentException - if cmd is null

    • Method Detail

      • add

        public void add​(long seqno,
                Message msg,
                java.util.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 java.util.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 java.lang.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 java.lang.String toString()
        Overrides:
        toString in class java.lang.Object