org.jgroups.protocols

Class FD_SIMPLE

java.lang.Object

org.jgroups.stack.Protocol

org.jgroups.protocols.FD_SIMPLE

public class FD_SIMPLE
extends Protocol

Simple failure detection protocol. Periodically sends a are-you-alive message to a randomly chosen member (excluding itself) and waits for a response. If a response has not been received within timeout msecs, a counter associated with that member will be incremented. If the counter exceeds max_missed_hbs, that member will be suspected. When a message or a heartbeat are received, the counter is reset to 0.

Version:

$Revision: 1.31 $

Author:

Bela Ban Aug 2002

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FD_SIMPLE.FdHeader

Field Summary

Fields inherited from class org.jgroups.stack.Protocol

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

Constructor Summary

Constructors

Constructor and Description
FD_SIMPLE()

Method Summary

Methods

Modifier and Type	Method and Description
Object	down(Event evt) An event is to be sent down the stack.
void	init() Called after instance has been created (null constructor) and before protocol is started.
void	stop() This method is called on a Channel.disconnect().
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, getId, getLevel, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, 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

Constructor Detail

FD_SIMPLE

public FD_SIMPLE()

Method Detail

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

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

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