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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

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package org.jgroups.protocols;

import org.jgroups.Address;
import org.jgroups.Message;
import org.jgroups.annotations.MBean;
import org.jgroups.annotations.ManagedAttribute;
import org.jgroups.annotations.Property;
import org.jgroups.conf.AttributeType;
import org.jgroups.util.CreditMap;
import org.jgroups.util.NonBlockingCreditMap;
import org.jgroups.util.Tuple;

import java.util.List;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.Consumer;


/**
 * Non-blocking alternative to {@link MFC}.

 * JIRA: JIRA: https://issues.redhat.com/browse/JGRP-2172
 * @author Bela Ban
 * @since 4.0.4
 */
@MBean(description="Simple non-blocking flow control protocol based on a credit system")
public class MFC_NB extends MFC {
    @Property(description="Max number of bytes of all queued messages for a given destination. If a given destination " +
      "has no credits left and the message cannot be added to the queue because it is full, then the sender thread " +
      "will be blocked until there is again space available in the queue, or the protocol is stopped.",type=AttributeType.BYTES)
    protected int                     max_queue_size=10_000_000;
    protected final Consumer send_function=msg -> down_prot.down(msg);
    protected Future               credit_send_task;


    public int      getMaxQueueSize()      {return max_queue_size;}
    public MFC_NB   setMaxQueueSize(int s) {this.max_queue_size=s; return this;}

    @ManagedAttribute(description="Whether or not messages are currently being queued due to insufficient credits")
    public boolean isQueuing() {
        return ((NonBlockingCreditMap)credits).isQueuing();
    }

    @ManagedAttribute(description="The number of messages currently queued due to insufficient credit"
      ,type=AttributeType.SCALAR)
    public int getNumberOfQueuedMessages() {
        return ((NonBlockingCreditMap)credits).getQueuedMessages();
    }

    @ManagedAttribute(description="The total size of all currently queued messages",type=AttributeType.BYTES)
    public int getQueuedSize() {
        return ((NonBlockingCreditMap)credits).getQueuedMessageSize();
    }

    @ManagedAttribute(description="The number of times messages have been queued due to insufficient credits"
      ,type=AttributeType.SCALAR)
    public int getNumberOfQueuings() {
        return ((NonBlockingCreditMap)credits).getEnqueuedMessages();
    }



    protected CreditMap createCreditMap(long max_creds) {
        return new NonBlockingCreditMap(max_creds, max_queue_size, new ReentrantLock(true), send_function);
    }

    public void start() throws Exception {
        super.start();
        if(max_block_time > 0) {
            credit_send_task=getTransport().getTimer()
              .scheduleWithFixedDelay(this::sendCreditRequestsIfNeeded, max_block_time, max_block_time, TimeUnit.MILLISECONDS);
        }
    }

    public void stop() {
        super.stop();
        if(credit_send_task != null)
            credit_send_task.cancel(true);
    }

    @Override
    protected Object handleDownMessage(final Message msg, int length) {
        Address dest=msg.getDest();
        if(dest != null) // 2nd line of defense, not really needed
            return down_prot.down(msg);

        if(running) {
            if(credits.decrement(msg, length, 0)) // timeout is ignored
                return down_prot.down(msg);

            // message was queued
            if(needToSendCreditRequest()) {
                List> targets=credits.getMembersWithCreditsLessThan(min_credits);
                for(Tuple tuple: targets)
                    sendCreditRequest(tuple.getVal1(), Math.min(max_credits, max_credits - tuple.getVal2()));
            }
            return null;
        }
        return down_prot.down(msg);
    }

    /**
     * Checks the sent table: if some credits are in queueing mode and credits left are less than min_credits:
     * send a credit request
     */
    protected void sendCreditRequestsIfNeeded() {
        if(credits.getMinCredits() < min_credits && needToSendCreditRequest()) {
            List> targets=credits.getMembersWithCreditsLessThan(min_credits);
            for(Tuple tuple: targets)
                sendCreditRequest(tuple.getVal1(), Math.min(max_credits, max_credits - tuple.getVal2()));
        }
    }


}