GMS (JBoss Application Server: Build 7.1.2.Final API)

java.lang.Object
- org.jgroups.stack.Protocol
- - org.jgroups.protocols.pbcast.GMS

All Implemented Interfaces:

DiagnosticsHandler.ProbeHandler
```
public class GMS
extends Protocol
implements DiagnosticsHandler.ProbeHandler
```
Group membership protocol. Handles joins/leaves/crashes (suspicions) and emits new views accordingly. Use VIEW_ENFORCER on top of this layer to make sure new members don't receive any messages until they are members

Author:

Bela Ban

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class GMS.GmsHeader

Nested Classes
Modifier and Type	Class and Description
`static class`	`GMS.GmsHeader`

Field Summary

Fields
Modifier and Type	Field and Description
`protected AckCollector`	`ack_collector` To collect VIEW_ACKs from all members
`protected Class<Callable<Boolean>>`	`flushInvokerClass`
`protected Address`	`local_addr`
`protected long`	`ltime`
`protected Membership`	`members`
`protected AckCollector`	`merge_ack_collector`
`protected int`	`num_prev_mbrs`
`protected TimeScheduler`	`timer`
`protected View`	`view`

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

Constructor Summary

Constructors
Constructor and Description

GMS()

Constructors
Constructor and Description
`GMS()`

Method Summary

Methods
Modifier and Type	Method and Description
`MergeId`	`_getMergeId()`
`protected boolean`	`_startFlush(View new_view, int maxAttempts, long randomFloor, long randomCeiling)`
`void`	`becomeClient()`
`void`	`becomeCoordinator()`
`void`	`becomeParticipant()`
`void`	`cancelMerge()`
`void`	`castViewChangeWithDest(View new_view, Digest digest, JoinRsp jr, Collection<Address> newMembers)` Broadcasts the new view and digest, and waits for acks from all members in the list given as argument.
`protected Address`	`determineCoordinator()`
`Object`	`down(Event evt)` An event is to be sent down the stack.
`String`	`dumpViewHandlerHistory()`
`String`	`dumpViewHandlerQueue()`
`void`	`fixDigests()`
`Digest`	`getDigest()` Sends down a GET_DIGEST event and waits for the GET_DIGEST_OK response, or timeout, whichever occurs first
`GmsImpl`	`getImpl()`
`long`	`getJoinTimeout()`
`String`	`getLocalAddress()`
`boolean`	`getLogCollectMessages()`
`long`	`getMaxBundlingTime()`
`String`	`getMembers()`
`String`	`getMergeId()`
`Merger`	`getMerger()` Only used for internal testing, don't use this method !
`long`	`getMergeTimeout()`
`View`	`getNextView(Collection<Address> new_mbrs, Collection<Address> old_mbrs, Collection<Address> suspected_mbrs)` Computes the next view.
`int`	`getNumberOfViews()`
`int`	`getNumMembers()`
`String`	`getView()`
`long`	`getViewAckCollectionTimeout()`
`Tuple<View,Digest>`	`getViewAndDigest()` Returns the current view and digest
`int`	`getViewHandlerSize()`
`ViewId`	`getViewId()`
`Map<String,String>`	`handleProbe(String... keys)` Handles a probe.
`void`	`init()` Called after instance has been created (null constructor) and before protocol is started.
`void`	`installView(View new_view)`
`void`	`installView(View new_view, Digest digest)` Sets the new view and sends a VIEW_CHANGE event up and down the stack.
`boolean`	`isCoordinator()`
`boolean`	`isMergeInProgress()`
`boolean`	`isMergeKillerRunning()`
`boolean`	`isMergeTaskRunning()`
`boolean`	`isViewBundling()`
`boolean`	`isViewHandlerSuspended()`
`void`	`mergeDigest(Digest d)` Send down a MERGE_DIGEST event
`String`	`printMergeIdHistory()`
`String`	`printPreviousMembers()`
`String`	`printPreviousViews()`
`List<Integer>`	`providedDownServices()` List of events that are provided to layers below (they will be handled when sent down from below).
`List<Integer>`	`requiredDownServices()` List of events that are required to be answered by some layer below.
`void`	`resetStats()`
`void`	`resumeViewHandler()`
`void`	`sendJoinResponse(JoinRsp rsp, Address dest)`
`void`	`setDigest(Digest d)` Send down a SET_DIGEST event
`void`	`setImpl(GmsImpl new_impl)`
`void`	`setJoinTimeout(long t)`
`void`	`setLogCollectMessages(boolean flag)`
`void`	`setMaxBundlingTime(long max_bundling_time)`
`void`	`setMergeTimeout(long timeout)`
`void`	`setPrintLocalAddr(boolean flag)`
`void`	`setPrintLocalAddress(boolean flag)`
`void`	`setViewAckCollectionTimeout(long view_ack_collection_timeout)`
`void`	`setViewBundling(boolean view_bundling)`
`void`	`start()` This method is called on a `Channel.connect(String)`.
`void`	`stop()` This method is called on a `Channel.disconnect()`.
`String[]`	`supportedKeys()` Returns a list of supported keys
`void`	`suspect(String suspected_member)`
`void`	`suspendViewHandler()`
`Object`	`up(Event evt)` An event was received from the layer below.
`protected boolean`	`wouldBeNewCoordinator(Address potential_new_coord)` Checks whether the potential_new_coord would be the new coordinator (2nd in line)

Methods inherited from class org.jgroups.stack.Protocol
destroy, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getId, getLevel, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getValue, isErgonomics, printStats, providedUpServices, requiredUpServices, resetStatistics, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, statsEnabled

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

- Field Detail
  - num_prev_mbrs
```
protected int num_prev_mbrs
```
  - flushInvokerClass
```
protected Class<Callable<Boolean>> flushInvokerClass
```
  - local_addr
```
protected Address local_addr
```
  - members
```
protected final Membership members
```
  - view
```
protected View view
```
  - ltime
```
protected long ltime
```
  - timer
```
protected TimeScheduler timer
```
  - ack_collector
```
protected final AckCollector ack_collector
```
    To collect VIEW_ACKs from all members
  - merge_ack_collector
```
protected final AckCollector merge_ack_collector
```
- Constructor Detail
  - GMS
```
public GMS()
```
- Method Detail
  - getViewId
```
public ViewId getViewId()
```
  - getViewAndDigest
```
public Tuple<View,Digest> getViewAndDigest()
```
    Returns the current view and digest
  - getView
```
public String getView()
```
  - getNumberOfViews
```
public int getNumberOfViews()
```
  - getLocalAddress
```
public String getLocalAddress()
```
  - getMembers
```
public String getMembers()
```
  - getNumMembers
```
public int getNumMembers()
```
  - getJoinTimeout
```
public long getJoinTimeout()
```
  - setJoinTimeout
```
public void setJoinTimeout(long t)
```
  - getMergeTimeout
```
public long getMergeTimeout()
```
  - setMergeTimeout
```
public void setMergeTimeout(long timeout)
```
  - getMergeId
```
public String getMergeId()
```
  - isMergeInProgress
```
public boolean isMergeInProgress()
```
  - getMerger
```
public Merger getMerger()
```
    Only used for internal testing, don't use this method !
  - printMergeIdHistory
```
public String printMergeIdHistory()
```
  - printPreviousMembers
```
public String printPreviousMembers()
```
  - setPrintLocalAddress
```
public void setPrintLocalAddress(boolean flag)
```
  - setPrintLocalAddr
```
public void setPrintLocalAddr(boolean flag)
```
  - getViewAckCollectionTimeout
```
public long getViewAckCollectionTimeout()
```
  - setViewAckCollectionTimeout
```
public void setViewAckCollectionTimeout(long view_ack_collection_timeout)
```
  - isViewBundling
```
public boolean isViewBundling()
```
  - setViewBundling
```
public void setViewBundling(boolean view_bundling)
```
  - getMaxBundlingTime
```
public long getMaxBundlingTime()
```
  - setMaxBundlingTime
```
public void setMaxBundlingTime(long max_bundling_time)
```
  - getViewHandlerSize
```
public int getViewHandlerSize()
```
  - isViewHandlerSuspended
```
public boolean isViewHandlerSuspended()
```
  - dumpViewHandlerQueue
```
public String dumpViewHandlerQueue()
```
  - dumpViewHandlerHistory
```
public String dumpViewHandlerHistory()
```
  - suspendViewHandler
```
public void suspendViewHandler()
```
  - resumeViewHandler
```
public void resumeViewHandler()
```
  - printPreviousViews
```
public String printPreviousViews()
```
  - suspect
```
public void suspect(String suspected_member)
```
  - isCoordinator
```
public boolean isCoordinator()
```
  - _getMergeId
```
public MergeId _getMergeId()
```
  - setLogCollectMessages
```
public void setLogCollectMessages(boolean flag)
```
  - getLogCollectMessages
```
public boolean getLogCollectMessages()
```
  - resetStats
```
public void resetStats()
```
    Overrides:
    
    resetStats in class Protocol
  - requiredDownServices
```
public List<Integer> requiredDownServices()
```
    Description copied from class: Protocol
    
    List of events that are required to be answered by some layer below.
    
    Overrides:
    
    requiredDownServices in class Protocol
    
    Returns:
    Vector (of Integers)
  - providedDownServices
```
public List<Integer> providedDownServices()
```
    Description copied from class: Protocol
    
    List of events that are provided to layers below (they will be handled when sent down from below).
    
    Overrides:
    
    providedDownServices in class Protocol
    
    Returns:
    Vector
  - setImpl
```
public void setImpl(GmsImpl new_impl)
```
  - getImpl
```
public GmsImpl getImpl()
```
  - init
```
public void init()
          throws 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:
    
    Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor will throw an exception
  - start
```
public void start()
           throws Exception
```
    Description copied from class: Protocol
    
    This method is called on a Channel.connect(String). Starts work. Protocols are connected and queues are ready to receive events. Will be called from bottom to top. This call will replace the START and START_OK events.
    
    Overrides:
    
    start in class Protocol
    
    Throws:
    
    Exception - Thrown if protocol cannot be started successfully. This will cause the ProtocolStack to fail, so Channel.connect(String) 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
  - becomeCoordinator
```
public void becomeCoordinator()
```
  - becomeParticipant
```
public void becomeParticipant()
```
  - becomeClient
```
public void becomeClient()
```
  - fixDigests
```
public void fixDigests()
```
  - cancelMerge
```
public void cancelMerge()
```
  - isMergeTaskRunning
```
public boolean isMergeTaskRunning()
```
  - isMergeKillerRunning
```
public boolean isMergeKillerRunning()
```
  - getNextView
```
public View getNextView(Collection<Address> new_mbrs,
               Collection<Address> old_mbrs,
               Collection<Address> suspected_mbrs)
```
    Computes the next view. Returns a copy that has old_mbrs and suspected_mbrs removed and new_mbrs added.
  - castViewChangeWithDest
```
public void castViewChangeWithDest(View new_view,
                          Digest digest,
                          JoinRsp jr,
                          Collection<Address> newMembers)
```
    Broadcasts the new view and digest, and waits for acks from all members in the list given as argument. If the list is null, we take the members who are part of new_view
    
    Parameters:
    new_view -
    digest -
    newMembers -
  - sendJoinResponse
```
public void sendJoinResponse(JoinRsp rsp,
                    Address dest)
```
  - installView
```
public void installView(View new_view)
```
  - installView
```
public void installView(View new_view,
               Digest digest)
```
    Sets the new view and sends a VIEW_CHANGE event up and down the stack. If the view is a MergeView (subclass of View), then digest will be non-null and has to be set before installing the view.
  - determineCoordinator
```
protected Address determineCoordinator()
```
  - wouldBeNewCoordinator
```
protected boolean wouldBeNewCoordinator(Address potential_new_coord)
```
    Checks whether the potential_new_coord would be the new coordinator (2nd in line)
  - setDigest
```
public void setDigest(Digest d)
```
    Send down a SET_DIGEST event
  - mergeDigest
```
public void mergeDigest(Digest d)
```
    Send down a MERGE_DIGEST event
  - getDigest
```
public Digest getDigest()
```
    Sends down a GET_DIGEST event and waits for the GET_DIGEST_OK response, or timeout, whichever occurs first
  - _startFlush
```
protected boolean _startFlush(View new_view,
                  int maxAttempts,
                  long randomFloor,
                  long randomCeiling)
```
  - up
```
public 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
  - down
```
public 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
  - handleProbe
```
public Map<String,String> handleProbe(String... keys)
```
    Description copied from interface: DiagnosticsHandler.ProbeHandler
    
    Handles a probe. For each key that is handled, the key and its result should be in the returned map.
    
    Specified by:
    
    handleProbe in interface DiagnosticsHandler.ProbeHandler
    
    Returns:
    Map. A map of keys and values. A null return value is permissible.
  - supportedKeys
```
public String[] supportedKeys()
```
    Description copied from interface: DiagnosticsHandler.ProbeHandler
    
    Returns a list of supported keys
    
    Specified by:
    
    supportedKeys in interface DiagnosticsHandler.ProbeHandler

Class GMS

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

num_prev_mbrs

flushInvokerClass

local_addr

members

view

ltime

timer

ack_collector

merge_ack_collector

Constructor Detail

GMS

Method Detail

getViewId

getViewAndDigest

getView

getNumberOfViews

getLocalAddress

getMembers

getNumMembers

getJoinTimeout

setJoinTimeout

getMergeTimeout

setMergeTimeout

getMergeId

isMergeInProgress

getMerger

printMergeIdHistory

printPreviousMembers

setPrintLocalAddress

setPrintLocalAddr

getViewAckCollectionTimeout

setViewAckCollectionTimeout

isViewBundling

setViewBundling

getMaxBundlingTime

setMaxBundlingTime

getViewHandlerSize

isViewHandlerSuspended

dumpViewHandlerQueue

dumpViewHandlerHistory

suspendViewHandler

resumeViewHandler

printPreviousViews

suspect

isCoordinator

_getMergeId

setLogCollectMessages

getLogCollectMessages

resetStats

requiredDownServices

providedDownServices

setImpl

getImpl

init

start

stop

becomeCoordinator

becomeParticipant

becomeClient

fixDigests

cancelMerge

isMergeTaskRunning

isMergeKillerRunning

getNextView

castViewChangeWithDest

sendJoinResponse

installView

installView

determineCoordinator

wouldBeNewCoordinator

setDigest