java.lang.Object
- org.jgroups.stack.Protocol
- - org.jgroups.protocols.ReliableMulticast
  - - org.jgroups.protocols.NAKACK4

All Implemented Interfaces:

Lifecycle, DiagnosticsHandler.ProbeHandler
```
public class NAKACK4
extends ReliableMulticast
```
New multicast protocol based on fixed-size xmit windows and message ACKs
Details: https://issues.redhat.com/browse/JGRP-2780

Since:

5.4

Author:

Bela Ban

Nested Class Summary
- Nested classes/interfaces inherited from class org.jgroups.protocols.ReliableMulticast
  ReliableMulticast.Entry, ReliableMulticast.LastSeqnoResender, ReliableMulticast.RetransmitTask

Field Summary

Fields
Modifier and Type	Field	Description
`protected AckTable`	`ack_table`
`protected int`	`ack_threshold`
`protected java.util.concurrent.atomic.LongAdder`	`acks_received`
`protected java.util.function.IntBinaryOperator`	`add_acks`
`protected int`	`capacity`

Fields inherited from class org.jgroups.protocols.ReliableMulticast
avg_batch_size, BATCH_ACCUMULATOR, become_server_queue, become_server_queue_size, cached_batches, digest_history, discard_delivered_msgs, DUMMY_OOB_MSG, HAS_HEADER, is_server, is_trace, last_seqno_resender, leaving, local_send_entry, local_xmit_table, log_discard_msgs, log_not_found_msgs, max_batch_size, max_xmit_req_size, members, no_dummy_and_no_oob_delivered_msgs_and_no_dont_loopback_msgs, num_messages_received, num_messages_sent, remove_filter, reuse_message_batches, running, send_atomically, sends_can_block, seqno, SEQNO_GETTER, stability_msgs, stable_xmit_map, suppress_log_non_member, suppress_time_non_member_warnings, timer, use_mcast_xmit, use_mcast_xmit_req, view, xmit_from_random_member, xmit_interval, xmit_reqs_received, xmit_reqs_sent, xmit_rsps_received, xmit_rsps_sent, xmit_table, xmit_task, xmit_task_map

Fields inherited from class org.jgroups.stack.Protocol
after_creation_hook, down_prot, ergonomics, id, local_addr, log, policies, stack, stats, up_prot

Constructor Summary

Constructors
Constructor Description

NAKACK4()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`int`	`ackThreshold()`
`NAKACK4`	`ackThreshold(int t)`
`protected boolean`	`addToSendBuffer(Buffer<Message> win, long seq, Message msg, java.util.function.Predicate<Message> filter)`	Adds the message to the send buffer.
`protected void`	`adjustReceivers(java.util.List<Address> members)`	Removes old members from xmit-table and adds new members to xmit-table (at seqnos hd=0, hr=0).
`int`	`capacity()`
`NAKACK4`	`capacity(int c)`
`void`	`changeCapacity(int new_capacity)`	Changes the capacity of the buffer, basically by creating a new buffer and copying the messages from the old one.
`protected Buffer<Message>`	`createXmitWindow(long initial_seqno)`
`void`	`destroy()`	This method is called on a `JChannel.close()`.
`AverageMinMax`	`getAvgTimeBlocked()`
`long`	`getNumBlockings()`
`long`	`getNumDroppedMessages()`
`long`	`getNumUnackedMessages()`
`long`	`getNumUnackedMessages(Address dest)`
`protected void`	`handleAck(Address sender, long ack)`
`void`	`init()`	Called after a protocol has been created and before the protocol is started.
`protected boolean`	`needToSendAck(ReliableMulticast.Entry e)`
`protected boolean`	`needToSendAck(ReliableMulticast.Entry e, int num_acks)`
`java.lang.String`	`printAckTable()`
`protected void`	`reset()`
`void`	`resetStats()`
`protected void`	`sendAck(Address to, Buffer<Message> win)`
`void`	`sendAcks()`
`protected void`	`sendAcks(boolean always_send)`
`boolean`	`sendBufferCanBlock()`	Whether addition of a message to the send buffer can block
`void`	`sendPendingAcks()`
`protected void`	`stable(Digest digest)`	Garbage collect messages that have been seen by all members.

Methods inherited from class org.jgroups.protocols.ReliableMulticast
becomeServerQueue, clearCachedBatches, clearNonMemberCache, deliver, deliverBatch, discardDeliveredMsgs, discardDeliveredMsgs, down, down, flushBecomeServerQueue, getBecomeServerQueueSize, getBecomeServerQueueSizeActual, getBuf, getCurrentSeqno, getDigest, getDigest, getEntry, getMaxXmitReqSize, getNonMemberMessages, getNumMessagesReceived, getNumMessagesSent, getSizeOfAllMessages, getSizeOfAllMessagesInclHeaders, getSuppressTimeNonMemberWarnings, getXmitInterval, getXmitRequestsReceived, getXmitRequestsSent, getXmitResponsesReceived, getXmitResponsesSent, getXmitTableCapacity, getXmitTableMissingMessages, getXmitTableUndeliveredMsgs, handleHighestSeqno, handleMessage, handleMessageBatch, handleProbe, handleXmitReq, handleXmitRsp, isTrace, isTrace, isXmitTaskRunning, logDiscardMessages, logDiscardMessages, logNotFoundMessages, logNotFoundMessages, mergeDigest, msgFromXmitRsp, overwriteDigest, printBatches, printCachedBatches, printDigestHistory, printMessages, printStabilityMessages, providedUpServices, queueMessage, removeAndDeliver, resend, retransmit, retransmit, reuseMessageBatches, reuseMessageBatches, send, sendAtomically, sendAtomically, sendBuf, sendEntry, sendsCanBlock, sendsCanBlock, sendXmitRsp, setBecomeServerQueueSize, setDigest, setDigest, setDiscardDeliveredMsgs, setLevel, setMaxXmitReqSize, setSuppressTimeNonMemberWarnings, setTimer, setXmitFromRandomMember, setXmitInterval, sizeOfAllMessages, start, startRetransmitTask, stop, stopRetransmitTask, supportedKeys, triggerXmit, unknownMember, up, up, up, useMcastXmit, useMcastXmit, useMcastXmitReq, useMcastXmitReq, xmitFromRandomMember, xmitFromRandomMember

Methods inherited from class org.jgroups.stack.Protocol
accept, addPolicy, addr, addr, afterCreationHook, down, enableStats, getAddress, getComponents, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getLog, getName, getPolicies, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, isErgonomics, level, parse, policies, providedDownServices, removePolicy, requiredDownServices, requiredUpServices, resetStatistics, setAddress, setDownProtocol, setErgonomics, setId, setPolicies, setProtocolStack, setSocketFactory, setUpProtocol, setValue, statsEnabled, toString

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - ack_table
```
protected final AckTable ack_table
```
  - capacity
```
protected int capacity
```
  - ack_threshold
```
protected int ack_threshold
```
  - acks_received
```
protected final java.util.concurrent.atomic.LongAdder acks_received
```
  - add_acks
```
protected final java.util.function.IntBinaryOperator add_acks
```
- Constructor Detail
  - NAKACK4
```
public NAKACK4()
```
- Method Detail
  - capacity
```
public int capacity()
```
  - capacity
```
public NAKACK4 capacity(int c)
```
  - ackThreshold
```
public int ackThreshold()
```
  - ackThreshold
```
public NAKACK4 ackThreshold(int t)
```
  - getNumUnackedMessages
```
public long getNumUnackedMessages()
```
  - getNumUnackedMessages
```
public long getNumUnackedMessages(Address dest)
```
  - getNumBlockings
```
public long getNumBlockings()
```
  - getNumDroppedMessages
```
public long getNumDroppedMessages()
```
  - getAvgTimeBlocked
```
public AverageMinMax getAvgTimeBlocked()
```
  - createXmitWindow
```
protected Buffer<Message> createXmitWindow(long initial_seqno)
```
    Specified by:
    
    createXmitWindow in class ReliableMulticast
  - sendBufferCanBlock
```
public boolean sendBufferCanBlock()
```
    Description copied from class: ReliableMulticast
    
    Whether addition of a message to the send buffer can block
    
    Overrides:
    
    sendBufferCanBlock in class ReliableMulticast
  - resetStats
```
public void resetStats()
```
    Overrides:
    
    resetStats in class ReliableMulticast
  - init
```
public void init()
          throws java.lang.Exception
```
    Description copied from class: Protocol
    
    Called after a protocol has been created and before the protocol is started. Attributes are already set. Other protocols are not yet connected and events cannot yet be sent.
    
    Specified by:
    
    init in interface Lifecycle
    
    Overrides:
    
    init in class ReliableMulticast
    
    Throws:
    
    java.lang.Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the the channel constructor will throw an exception
  - destroy
```
public void destroy()
```
    Description copied from class: Protocol
    
    This method is called on a JChannel.close(). Does some cleanup; after the call, the VM will terminate
    
    Specified by:
    
    destroy in interface Lifecycle
    
    Overrides:
    
    destroy in class Protocol
  - printAckTable
```
public java.lang.String printAckTable()
```
  - sendAcks
```
public void sendAcks()
```
  - sendPendingAcks
```
public void sendPendingAcks()
```
  - sendAcks
```
protected void sendAcks(boolean always_send)
```
  - changeCapacity
```
public void changeCapacity(int new_capacity)
```
    Changes the capacity of the buffer, basically by creating a new buffer and copying the messages from the old one. This method is only supposed to be used by perf testing, so DON'T USE!
  - adjustReceivers
```
protected void adjustReceivers(java.util.List<Address> members)
```
    Description copied from class: ReliableMulticast
    
    Removes old members from xmit-table and adds new members to xmit-table (at seqnos hd=0, hr=0). This method is not called concurrently
    
    Overrides:
    
    adjustReceivers in class ReliableMulticast
  - reset
```
protected void reset()
```
    Overrides:
    
    reset in class ReliableMulticast
  - stable
```
protected void stable(Digest digest)
```
    Description copied from class: ReliableMulticast
    
    Garbage collect messages that have been seen by all members. Update sent_msgs: for the sender P in the digest which is equal to the local address, garbage collect all messages <= seqno at digest[P]. Update xmit_table: for each sender P in the digest and its highest seqno seen SEQ, garbage collect all delivered_msgs in the retransmit buffer corresponding to P which are <= seqno at digest[P].
    
    Overrides:
    
    stable in class ReliableMulticast
  - handleAck
```
protected void handleAck(Address sender,
                         long ack)
```
    Overrides:
    
    handleAck in class ReliableMulticast
  - needToSendAck
```
protected boolean needToSendAck(ReliableMulticast.Entry e)
```
    Overrides:
    
    needToSendAck in class ReliableMulticast
  - needToSendAck
```
protected boolean needToSendAck(ReliableMulticast.Entry e,
                                int num_acks)
```
    Overrides:
    
    needToSendAck in class ReliableMulticast
  - sendAck
```
protected void sendAck(Address to,
                       Buffer<Message> win)
```
    Overrides:
    
    sendAck in class ReliableMulticast
  - addToSendBuffer
```
protected boolean addToSendBuffer(Buffer<Message> win,
                                  long seq,
                                  Message msg,
                                  java.util.function.Predicate<Message> filter)
```
    Description copied from class: ReliableMulticast
    
    Adds the message to the send buffer. The loop tries to handle temporary OOMEs by retrying if add() failed
    
    Overrides:
    
    addToSendBuffer in class ReliableMulticast

Class NAKACK4

Nested Class Summary

Nested classes/interfaces inherited from class org.jgroups.protocols.ReliableMulticast

Field Summary

Fields inherited from class org.jgroups.protocols.ReliableMulticast

Fields inherited from class org.jgroups.stack.Protocol

Constructor Summary

Method Summary

Methods inherited from class org.jgroups.protocols.ReliableMulticast

Methods inherited from class org.jgroups.stack.Protocol

Methods inherited from class java.lang.Object

Field Detail

ack_table

capacity

ack_threshold

acks_received

add_acks

Constructor Detail

NAKACK4

Method Detail

capacity

capacity

ackThreshold

ackThreshold

getNumUnackedMessages

getNumUnackedMessages

getNumBlockings

getNumDroppedMessages

getAvgTimeBlocked

createXmitWindow

sendBufferCanBlock

resetStats

init

destroy

printAckTable

sendAcks

sendPendingAcks

sendAcks

changeCapacity

adjustReceivers

reset

stable

handleAck

needToSendAck

needToSendAck

sendAck

addToSendBuffer