Package org.jgroups.protocols

Class RED

java.lang.Object

org.jgroups.stack.Protocol

org.jgroups.protocols.RED

All Implemented Interfaces:

Lifecycle

public class RED
extends Protocol

Implementation of Random Early Drop: messages are discarded when the bundler's queue in the transport nears exhaustion. See Floyd and Van Jacobsen's paper for details.

Since:

5.0.0, 4.2.2

Author:

Bela Ban

Field Summary

Fields

Modifier and Type	Field	Description
protected double	avg_queue_size
protected Bundler	bundler
protected java.util.concurrent.atomic.LongAdder	dropped_msgs
protected boolean	enabled
protected java.util.concurrent.locks.Lock	lock
protected long	max
protected double	max_threshold
protected long	min
protected double	min_threshold
protected int	queue_capacity
protected long	span
protected java.util.concurrent.atomic.LongAdder	total_msgs
protected double	weight
protected double	weight_factor

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
RED()

Method Summary

Modifier and Type	Method	Description
protected static double	checkRange(double val, double min, double max, java.lang.String name)
protected double	computeAverage(double old_avg, int new_queue_size)
protected double	computeDropProbability(double avg)	Computes a probability P with which the message should get dropped.
java.lang.Object	down(Message msg)	A message is sent down the stack.
protected boolean	drop(double avg)
long	getDroppedMessages()
double	getDropRate()
double	getMinThreshold()
long	getTotalMessages()
boolean	isEnabled()
void	resetStats()
RED	setEnabled(boolean e)
void	start()	This method is called on a JChannel.connect(String); starts work.
java.lang.String	toString()
void	up(MessageBatch batch)	Sends up a multiple messages in a MessageBatch.

Methods inherited from class org.jgroups.stack.Protocol

accept, addPolicy, addr, addr, afterCreationHook, destroy, down, down, enableStats, getAddress, getComponents, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getLog, getName, getPolicies, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, init, isErgonomics, level, parse, policies, providedDownServices, providedUpServices, removePolicy, requiredDownServices, requiredUpServices, resetStatistics, setAddress, setDownProtocol, setErgonomics, setId, setLevel, setPolicies, setProtocolStack, setSocketFactory, setUpProtocol, setValue, statsEnabled, stop, up, up

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

enabled

protected boolean enabled

queue_capacity

protected int queue_capacity

min_threshold

protected double min_threshold

min

protected long min

max_threshold

protected double max_threshold

max

protected long max

avg_queue_size

protected double avg_queue_size

weight_factor

protected double weight_factor

dropped_msgs

protected final java.util.concurrent.atomic.LongAdder dropped_msgs

total_msgs

protected final java.util.concurrent.atomic.LongAdder total_msgs

bundler

protected Bundler bundler

lock

protected final java.util.concurrent.locks.Lock lock

span

protected long span

weight

protected double weight

Constructor Detail

RED

public RED()

Method Detail

isEnabled

public boolean isEnabled()

setEnabled

public RED setEnabled(boolean e)

getMinThreshold

public double getMinThreshold()

getDroppedMessages

public long getDroppedMessages()

getTotalMessages

public long getTotalMessages()

getDropRate

public double getDropRate()

start

public void start()
           throws java.lang.Exception

Description copied from class: Protocol

This method is called on a JChannel.connect(String); starts work. Protocols are connected ready to receive events. Will be called from bottom to top.

Specified by:

start in interface Lifecycle

Overrides:

start in class Protocol

Throws:

java.lang.Exception - Thrown if protocol cannot be started successfully. This will cause the ProtocolStack to fail, so JChannel.connect(String) will throw an exception

resetStats

public void resetStats()

Overrides:

resetStats in class Protocol

down

public java.lang.Object down(Message msg)

Description copied from class: Protocol

A message is sent down the stack. Protocols may examine the message and do something (e.g. add a header) with it, before passing it down.

Overrides:

down in class Protocol

up

public void up(MessageBatch batch)

Description copied from class: Protocol

Sends up a multiple messages in a MessageBatch. The sender of the batch is always the same, and so is the destination (null == multicast messages). Messages in a batch can be OOB messages, regular messages, or mixed messages, although the transport itself will create initial MessageBatches that contain only either OOB or regular messages.

The default processing below sends messages up the stack individually, based on a matching criteria (calling Protocol.accept(Message)), and - if true - calls Protocol.up(org.jgroups.Event) for that message and removes the message. If the batch is not empty, it is passed up, or else it is dropped.

Subclasses should check if there are any messages destined for them (e.g. using MessageBatch.iterator(Predicate)), then possibly remove and process them and finally pass the batch up to the next protocol. Protocols can also modify messages in place, e.g. ENCRYPT could decrypt all encrypted messages in the batch, not remove them, and pass the batch up when done.

Overrides:

up in class Protocol

Parameters:

batch - The message batch

toString

public java.lang.String toString()

Overrides:

toString in class Protocol

computeAverage

protected double computeAverage(double old_avg,
                                int new_queue_size)

computeDropProbability

protected double computeDropProbability(double avg)

Computes a probability P with which the message should get dropped. min_threshold < avg < max_threshold. Probability increases linearly with min moving toward max

drop

protected boolean drop(double avg)

checkRange

protected static double checkRange(double val,
                                   double min,
                                   double max,
                                   java.lang.String name)