org.jgroups.protocols

Class VERIFY_SUSPECT

java.lang.Object

org.jgroups.stack.Protocol

org.jgroups.protocols.VERIFY_SUSPECT

All Implemented Interfaces:

java.lang.Runnable

public class VERIFY_SUSPECT
extends Protocol
implements java.lang.Runnable

Catches SUSPECT events traveling up the stack. Verifies that the suspected member is really dead. If yes, passes SUSPECT event up the stack, otherwise discards it. Has to be placed somewhere above the FD layer and below the GMS layer (receiver of the SUSPECT event). Note that SUSPECT events may be reordered by this protocol.

Version:

$Id: VERIFY_SUSPECT.java,v 1.32.2.2 2008/09/03 15:13:37 vlada Exp $

Author:

Bela Ban

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	VERIFY_SUSPECT.VerifyHeader

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	shutting_down

Fields inherited from class org.jgroups.stack.Protocol

down_prot, log, props, stack, stats, up_prot

Constructor Summary

Constructors

Constructor and Description
VERIFY_SUSPECT()

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.Object	down(Event evt) An event is to be sent down the stack.
java.lang.String	getName()
void	init() Called after instance has been created (null constructor) and before protocol is started.
void	run() Will be started when a suspect is added to the suspects hashtable.
boolean	setProperties(java.util.Properties props) Configures the protocol initially.
void	start() This method is called on a Channel.connect(String).
void	stop() This method is called on a Channel.disconnect().
java.lang.Object	up(Event evt) An event was received from the layer below.

Methods inherited from class org.jgroups.stack.Protocol

destroy, downThreadEnabled, dumpStats, enableStats, getDownProtocol, getProperties, getProtocolStack, getThreadFactory, getTransport, getUpProtocol, printStats, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, resetStats, setDownProtocol, setPropertiesInternal, setProtocolStack, setUpProtocol, statsEnabled, upThreadEnabled

Methods inherited from class java.lang.Object

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

Field Detail

shutting_down

protected boolean shutting_down

Constructor Detail

VERIFY_SUSPECT

public VERIFY_SUSPECT()

Method Detail

getName

public java.lang.String getName()

Specified by:

getName in class Protocol

setProperties

public boolean setProperties(java.util.Properties props)

Description copied from class: Protocol

Configures the protocol initially. A configuration string consists of name=value items, separated by a ';' (semicolon), e.g.:

 "loopback=false;unicast_inport=4444"
 

Overrides:

setProperties in class Protocol

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

run

public void run()

Will be started when a suspect is added to the suspects hashtable. Continually iterates over the entries and removes entries whose time have elapsed. For each removed entry, a SUSPECT event is passed up the stack (because elapsed time means verification of member's liveness failed). Computes the shortest time to wait (min of all timeouts) and waits(time) msecs. Will be woken up when entry is removed (in case of successful verification of that member's liveness). Terminates when no entry remains in the hashtable.

Specified by:

run in interface java.lang.Runnable

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

start

public void start()
           throws java.lang.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:

java.lang.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