org.jgroups.protocols
Class MERGE3

java.lang.Object
  org.jgroups.stack.Protocol
      org.jgroups.protocols.MERGE3

public class MERGE3
extends Protocol

Protocol to discover subgroups; e.g., existing due to a network partition (that healed). Example: group {p,q,r,s,t,u,v,w} is split into 3 subgroups {p,q}, {r,s,t,u} and {v,w}. This protocol will eventually send a MERGE event with the views of each subgroup up the stack: {p,r,v}.

Works as follows (https://issues.jboss.org/browse/JGRP-1387): every member periodically broadcasts its address (UUID), logical name, physical address and ViewID information. Other members collect this information and see if the ViewIds are different (indication of different subpartitions). If they are, the member with the lowest address (first in the sorted list of collected addresses) sends a MERGE event up the stack, which will be handled by GMS. The others do nothing.

The advantage compared to MERGE2 is that there are no merge collisions caused by multiple merges going on. Also, the INFO traffic is spread out over max_interval, and every member sends its physical address with INFO, so we don't need to fetch the physical address first.

Since:

3.1

Author:

Bela Ban, Nov 2011

Nested Class Summary

protected class	MERGE3.InfoSender
static class	MERGE3.MergeHeader
protected class	MERGE3.ViewConsistencyChecker

Field Summary

protected long	check_interval
protected java.lang.String	cluster_name
protected java.util.concurrent.Future<?>	info_sender
protected boolean	is_coord
protected Address	local_addr
protected long	max_interval
protected int	max_participants_in_merge
protected long	min_interval
protected int	num_merge_events
protected TimeScheduler	timer
protected boolean	transport_supports_multicasting
protected View	view
protected java.util.concurrent.Future<?>	view_consistency_checker
protected ResponseCollector<View>	view_rsps
protected java.util.concurrent.ConcurrentMap<ViewId,java.util.SortedSet<Address>>	views

Fields inherited from class org.jgroups.stack.Protocol

down_prot, ergonomics, id, log, name, stack, stats, up_prot

Constructor Summary

MERGE3()

Method Summary

void	clearViews()
protected long	computeCheckInterval()
static java.util.List<View>	detectDifferentViews(java.util.Map<Address,View> map)
java.lang.Object	down(Event evt) An event is to be sent down the stack.
java.lang.String	dumpViews()
long	getMaxInterval()
long	getMinInterval()
int	getViews()
void	init() Called after instance has been created (null constructor) and before protocol is started.
boolean	isInfoSenderRunning()
protected boolean	isMergeRunning()
boolean	isMergeTaskRunning()
boolean	isViewConsistencyCheckerRunning()
void	setMaxInterval(long val)
void	setMinInterval(long i)
protected void	startInfoSender()
protected void	startViewConsistencyChecker()
void	stop() This method is called on a Channel.disconnect().
protected void	stopInfoSender()
protected void	stopViewConsistencyChecker()
java.lang.Object	up(Event evt) An event was received from the layer below.

Methods inherited from class org.jgroups.stack.Protocol

destroy, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, isErgonomics, printStats, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, resetStatistics, resetStats, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, start, statsEnabled

Methods inherited from class java.lang.Object

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

Field Detail

min_interval

protected long min_interval

max_interval

protected long max_interval

max_participants_in_merge

protected int max_participants_in_merge

check_interval

protected long check_interval

local_addr

protected Address local_addr

view

protected View view

timer

protected TimeScheduler timer

info_sender

protected java.util.concurrent.Future<?> info_sender

view_consistency_checker

protected java.util.concurrent.Future<?> view_consistency_checker

views

protected final java.util.concurrent.ConcurrentMap<ViewId,java.util.SortedSet<Address>> views

view_rsps

protected final ResponseCollector<View> view_rsps

transport_supports_multicasting

protected boolean transport_supports_multicasting

cluster_name

protected java.lang.String cluster_name

is_coord

protected volatile boolean is_coord

num_merge_events

protected int num_merge_events

Constructor Detail

MERGE3

public MERGE3()

Method Detail

getViews

public int getViews()

isViewConsistencyCheckerRunning

public boolean isViewConsistencyCheckerRunning()

isMergeTaskRunning

public boolean isMergeTaskRunning()

isInfoSenderRunning

public boolean isInfoSenderRunning()

dumpViews

public java.lang.String dumpViews()

clearViews

public void clearViews()

init

public void init()
          throws java.lang.Exception

Description copied from class: Protocol

Called after instance has been created (null constructor) and before protocol is started. Properties are already set. Other protocols are not yet connected and events cannot yet be sent.

Overrides:

init in class Protocol

Throws:

java.lang.Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor will throw an exception

stop

public void stop()

Description copied from class: Protocol

This method is called on a Channel.disconnect(). Stops work (e.g. by closing multicast socket). Will be called from top to bottom. This means that at the time of the method invocation the neighbor protocol below is still working. This method will replace the STOP, STOP_OK, CLEANUP and CLEANUP_OK events. The ProtocolStack guarantees that when this method is called all messages in the down queue will have been flushed

Overrides:

stop in class Protocol

getMinInterval

public long getMinInterval()

setMinInterval

public void setMinInterval(long i)

getMaxInterval

public long getMaxInterval()

setMaxInterval

public void setMaxInterval(long val)

computeCheckInterval

protected long computeCheckInterval()

isMergeRunning

protected boolean isMergeRunning()

startInfoSender

protected void startInfoSender()

stopInfoSender

protected void stopInfoSender()

startViewConsistencyChecker

protected void startViewConsistencyChecker()

stopViewConsistencyChecker

protected void stopViewConsistencyChecker()

down

public java.lang.Object down(Event evt)

Description copied from class: Protocol

An event is to be sent down the stack. The layer may want to examine its type and perform some action on it, depending on the event's type. If the event is a message MSG, then the layer may need to add a header to it (or do nothing at all) before sending it down the stack using down_prot.down(). In case of a GET_ADDRESS event (which tries to retrieve the stack's address from one of the bottom layers), the layer may need to send a new response event back up the stack using up_prot.up().

Overrides:

down in class Protocol

up

public java.lang.Object up(Event evt)

Description copied from class: Protocol

An event was received from the layer below. Usually the current layer will want to examine the event type and - depending on its type - perform some computation (e.g. removing headers from a MSG event type, or updating the internal membership list when receiving a VIEW_CHANGE event). Finally the event is either a) discarded, or b) an event is sent down the stack using down_prot.down() or c) the event (or another event) is sent up the stack using up_prot.up().

Overrides:

up in class Protocol

detectDifferentViews

public static java.util.List<View> detectDifferentViews(java.util.Map<Address,View> map)