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

Nested Classes
Modifier and Type Class and Description

protected class MERGE3.InfoSender

static class MERGE3.MergeHeader

protected class MERGE3.ViewConsistencyChecker

Nested Classes
Modifier and Type	Class and Description
`protected class`	`MERGE3.InfoSender`
`static class`	`MERGE3.MergeHeader`
`protected class`	`MERGE3.ViewConsistencyChecker`

Field Summary

Fields
Modifier and Type	Field and Description
`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 boolean`	`only_coords_run_consistency_checker`
`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.Map<Address,ViewId>`	`views`

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

Constructor Summary

Constructors
Constructor and Description

MERGE3()

Constructors
Constructor and Description
`MERGE3()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`protected void`	`addInfo(Address sender, ViewId view_id, java.lang.String logical_name, PhysicalAddress physical_addr)` Adds received INFO to views hashmap
`void`	`checkInconsistencies()`
`void`	`clearViews()`
`protected long`	`computeCheckInterval()`
`protected java.util.Map<ViewId,java.util.Set<Address>>`	`convertViews()`
`protected MERGE3.MergeHeader`	`createInfo()`
`static java.util.List<View>`	`detectDifferentViews(java.util.Map<Address,View> map)`
`protected boolean`	`differentViewIds()`
`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()`
`static Buffer`	`marshal(View view)`
`protected View`	`readView(byte[] buffer, int offset, int length)`
`void`	`sendInfo()`
`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
accept, afterCreationHook, destroy, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getLog, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, isErgonomics, level, parse, printStats, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, resetStatistics, resetStats, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, start, statsEnabled, up

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
```
  - only_coords_run_consistency_checker
```
protected boolean only_coords_run_consistency_checker
```
  - check_interval
```
protected long check_interval
```
  - local_addr
```
protected Address local_addr
```
  - view
```
protected volatile 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.Map<Address,ViewId> 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()
```
  - sendInfo
```
public void sendInfo()
```
  - checkInconsistencies
```
public void checkInconsistencies()
```
  - 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)
```
  - marshal
```
public static Buffer marshal(View view)
```
  - readView
```
protected View readView(byte[] buffer,
                        int offset,
                        int length)
```
  - createInfo
```
protected MERGE3.MergeHeader createInfo()
```
  - addInfo
```
protected void addInfo(Address sender,
                       ViewId view_id,
                       java.lang.String logical_name,
                       PhysicalAddress physical_addr)
```
    Adds received INFO to views hashmap
  - convertViews
```
protected java.util.Map<ViewId,java.util.Set<Address>> convertViews()
```
  - differentViewIds
```
protected boolean differentViewIds()
```

Class MERGE3

Nested Class Summary

Field Summary

Fields inherited from class org.jgroups.stack.Protocol

Constructor Summary

Method Summary

Methods inherited from class org.jgroups.stack.Protocol

Methods inherited from class java.lang.Object

Field Detail

min_interval

max_interval

max_participants_in_merge

only_coords_run_consistency_checker

check_interval

local_addr

view

timer

info_sender

view_consistency_checker

views

view_rsps

transport_supports_multicasting

cluster_name

is_coord

num_merge_events

Constructor Detail

MERGE3

Method Detail

getViews

isViewConsistencyCheckerRunning

isMergeTaskRunning

isInfoSenderRunning

dumpViews

clearViews

sendInfo

checkInconsistencies

init

stop

getMinInterval

setMinInterval

getMaxInterval

setMaxInterval

computeCheckInterval

isMergeRunning

startInfoSender

stopInfoSender

startViewConsistencyChecker

stopViewConsistencyChecker

down

up

detectDifferentViews

marshal

readView

createInfo

addInfo

convertViews

differentViewIds